SCHEDULE 14AUNITED STATES

(Rule 14a-101)SECURITIES AND EXCHANGE COMMISSION

INFORMATION REQUIRED IN PROXY STATEMENTWASHINGTON, D.C. 20549

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrantx

Filed by a Party other than the Registrant¨

Check the appropriate box:

IMPAC MEDICAL SYSTEMS, INC.Medical Systems, Inc.

(Name of Registrant as Specified in Its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

Payment of Filing Fee (Check the appropriate box):

common stock, par value $0.001 per share, of IMPAC

10,795,876 shares of common stock, including (i) 9,949,964 shares of common stock issued and outstanding as of January 31, 2005, (ii) the anticipated issuance of approximately 39,138 shares of common stock in April 2005 pursuant to the 2002 Employee Stock Purchase Plan and (iii) 806,774 shares of common stock subject to in-the-money options outstanding as of January 31, 2005

$24.00 per share, which represents the price to be paid in cash per share of IMPAC common stock pursuant to the Agreement and Plan of Merger, dated as of January 17, 2005, by and among IMPAC, Elekta AB (publ) and Erbium Acquisition Corporation

$250,658,214.77 (which is equal to the sum of (A) 9,989,102 shares of common stock multiplied by $24.00 per share and (B) in-the-money options to purchase 806,774 shares of common stock multiplied by $13.5351 per share (which is the difference between $24.00 and $10.4649, the weighted average exercise price per share of the in-the-money options))

$29,502.47 (calculated pursuant to Section 14(g) of the Exchange Act by multiplying the proposed maximum aggregate value of the transaction by 0.00011770)

100 West Evelyn Avenue

Mountain View, California 94041

January 12, 2004[                    ] [    ], 2005

Dear Stockholder:To Our Stockholders:

You are cordially invited to attend the 2004 Annual Meeting2005 annual meeting of Stockholdersstockholders of IMPAC Medical Systems, Inc. to be held on Tuesday, February 17, 2004[                    ], 2005 at 9:8:00 AMa.m. Pacific Time at the Stanford Park Hotel, 100 El Camino Real, Menlo Park,offices of Orrick, Herrington & Sutcliffe LLP, The Orrick Building, 405 Howard Street, San Francisco, California 94025.94105.

Our Secretary’s formal noticeAt the annual meeting, we will ask you to consider and vote upon the proposed acquisition of IMPAC by Elekta AB (publ), to be effected by means of a merger of IMPAC with Erbium Acquisition Corporation, an indirect wholly owned subsidiary of Elekta. If the merger is completed, you will be entitled to receive $24.00 in cash for each share of IMPAC common stock that you own (without interest and less applicable withholding taxes).

At the annual meeting, we will also ask you to consider and vote upon a proposal to elect two directors to serve on our board of directors. If the merger proposal is approved and the merger is consummated, our board of directors will be replaced by the board of directors of Erbium at the effective time of the merger.

After careful consideration, our board of directors has determined that the terms and conditions of the merger and the related merger agreement are advisable, fair to, and in the best interests of, IMPAC and its stockholders, and unanimously recommends that you vote “FOR” the merger proposal. Among the factors that our board of directors considered was the fairness opinion delivered orally to our board of directors on January 16, 2005 by our financial advisor, William Blair & Company, L.L.C., and subsequently confirmed in writing, to the effect that, as of such date and based upon and subject to qualifications and limitations stated in the written opinion, the merger price of $24.00 per share is fair from a financial point of view to our stockholders. The full text of the fairness opinion is attached as Annex C to the proxy statement, and we urge you to read it carefully.

Your vote is very important. We cannot complete the merger unless the merger agreement is approved and adopted by holders of a majority of our outstanding shares of common stock. Whether or not you plan to attend the meeting, please complete, date, sign and promptly return the enclosed proxy in the enclosed postage prepaid envelope prior to the meeting so that your shares will be represented at the meeting. Returning the proxy does not deprive you of your right to attend the meeting and to vote your shares in person.

The enclosed proxy statement provides you with detailed information about the Proxy Statement appear on the following pages and describe the mattersproposals to be acted upon at the Annual Meeting. You also will haveannual meeting. We urge you to read the opportunity to hear what has happened in our business in the past year and to ask questions.entire proxy statement carefully.

We hope thatto see you can join us. However, whether or not you plan to attend, please sign and return your proxy inat the enclosed envelope as soon as possible so that your vote will be counted.meeting.

Sincerely,

Joseph K. Jachinowski

President and Chief Executive Officer

IMPAC Medical Systems, Inc.

100 West Evelyn Avenue

Mountain View, California 94041

January 12, 2004This proxy statement is first being mailed to IMPAC stockholders on or about [                    ] [    ], 2005.

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

100 West Evelyn Avenue

Mountain View, California 94041

To Our Stockholders:

Notice is hereby given that we will hold the 2005 annual meeting of stockholders of IMPAC Medical Systems, Inc. will hold its Annual Meeting of Stockholderson [                    ], 2005 at 9:8:00 AM on Tuesday, February 17, 2004a.m. Pacific Time at the Stanford Park Hotel, 100 El Camino Real, Menlo Park,offices of Orrick, Herrington & Sutcliffe LLP, The Orrick Building, 405 Howard Street, San Francisco, California 94025.94105.

At thisthe meeting, weyou will ask you:be asked to consider and vote upon the following matters:

meeting.

Your BoardThese items of Directorsbusiness are more fully described in the proxy statement accompanying this notice.

The board of directors has selected December 31, 2003chosen [                    ], 2005 as the record date for determiningused to determine the stockholders entitledthat will be eligible to vote at the meeting. A listannual meeting and at any adjournment thereof. If you owned stock of stockholdersIMPAC as of the record date, you are invited to attend the annual meeting and to vote on thatthe merger. At the close of business on the record date, will be available for inspection at 100 West Evelyn Avenue, Mountain View, California 94041, for ten days before the meeting.

This Proxy Statement, a proxy cardthere were [                    ] shares of IMPAC common stock outstanding and the 2003 Annual Report to Stockholders are being distributed on or about January 12, 2004, to those entitled to vote.

Your vote is very important. We cannot complete the merger unless the merger agreement is approved and adopted by holders of a majority of the outstanding shares of our common stock. Whether or not you plan to attend the meeting, please complete, date, sign and promptly return the enclosed proxy in the enclosed postage prepaid envelope prior to the meeting so that your shares will be represented at the meeting. Returning the proxy does not deprive you of your right to attend the meeting and to vote your shares in person.

By Order of the Board of Directors

David A. Auerbach

Secretary

Mountain View, California

[                    ] [    ], 2005

TABLE OF CONTENTS

i

ii

GENERAL INFORMATIONFORWARD-LOOKING STATEMENTS

This proxy statement contains certain forward-looking statements and information relating to IMPAC that are subject to safe harbors created under the U.S. federal securities laws. These forward-looking statements include, among other things, statements concerning whether and when the proposed transaction with Elekta will close, whether conditions to the proposed merger will be satisfied, the effect of the proposed merger on our business and operating results, and other statements qualified by words such as “anticipate,” “believe,” “intend,” “may,” and other words of similar import. These statements are based on our current expectations and beliefs and are subject to numerous risks and uncertainties that could cause actual results to differ materially from those set forth in the forward-looking statements, including, among others:

Should one or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those described herein.

The statements made in this proxy statement represent our views as of the date of this proxy statement, and it should not be assumed that the statements made herein remain accurate as of any future date. We undertake no duty to any person to update the statements in this proxy statement under any circumstances, except as otherwise required by law.

QUESTIONS AND ANSWERS ABOUT THE ANNUAL MEETING AND THE PROPOSED MERGER

The following questions and answers are provided for your convenience, and briefly address some commonly asked questions regarding the proposed merger and the IMPAC annual meeting of stockholders. The questions and answers may not address all questions that may be important to you as an IMPAC stockholder. You should carefully read this entire proxy statement, including each of the annexes, for a more complete description of the matters to be acted upon at the annual meeting.

Proposal 2—Proposal 2 asks you to grant IMPAC management discretionary authority to adjourn the annual meeting. If this proposal is passed, we may adjourn the annual meeting one or more times (but not to a date later than May 31, 2005). If, for example, we do not receive proxies from stockholders holding a sufficient number of shares to approve the proposed transaction described in Proposal 1, we could use the additional time to solicit additional proxies in favor of the merger.

Proposal 3—Proposal 3 asks you to vote in favor of the election of Joseph K. Jachinowski and Gregory M. Avis to our board of directors. If the merger proposal is approved and the merger is consummated, our board of directors will be replaced by the board of directors of Erbium Acquisition Corporation.

Q:	Does the board of directors of IMPAC recommend voting in favor of the merger proposal?

On the record date, IMPAC had 9,832,045 shares election of common stock, $0.001 par value, outstanding. Voting can take placedirectors. If you do not submit a proxy card or vote in person at the Annual Meeting only if stockholders owning a majority of the issued and outstanding stock entitled to vote at theannual meeting, are present in person or represented by proxy. We include the shares of persons who abstain in determining those present and entitled to vote, but exclude shares held by brokers in “street” or “nominee” name when the broker indicates that you have not voted and the broker lacks discretionary authority to vote your shares (i.e., “broker non-votes”).will not be counted for or against the adjournment proposal, but if you mark “ABSTAIN” with respect to the adjournment proposal, this will have the effect of a vote against the proposal.

1

SUMMARY

This summary highlights important information discussed in greater detail elsewhere in this proxy statement. This summary may not contain all of the information that is important to you. You should read this entire document carefully, including all of the documents attached as annexes, for a more complete understanding of the transaction. In particular, we encourage you to review the merger agreement attached as Annex A, as this is the primary legal document that governs the proposed transaction.

The proposalparties (see page 13)

IMPAC Medical Systems, Inc.

IMPAC Medical Systems, Inc., a Delaware corporation, is a leading provider of oncology IT solutions that streamline both clinical and business operations to amendhelp improve the process of delivering quality patient care. With systems designed for anatomic pathology, medical oncology, radiation oncology, imaging, clinical laboratory, and restatecancer registry, IMPAC supports the 2002 Stock Plan requiresentire team of healthcare professionals who contribute to the affirmative votecare of a majority of votes cast affirmatively or negatively. Accordingly, abstentionsthe cancer patient. Supporting more than 2,500 installations worldwide, IMPAC provides practical solutions that deliver better overall communication, process efficiency and quality patient care.

Our common stock is traded on the proposalNasdaq National Market under the symbol “IMPC.”

Elekta AB (publ)

Elekta AB (publ) is an international medical technology company, providing highly advanced clinical solutions for high precision radiation treatment of cancer and for non- or minimally invasive treatment of brain disorders. Elekta’s systems and solutions are used at over 2,000 hospitals around the world to amendtreat cancer and to diagnose and treat brain disorders, including tumors, vascular malformations and functional disorders.

Elekta was founded in 1972 and is headquartered in Stockholm, Sweden. The company is listed on Stockholmsbörsen (Stockholm Stock Exchange) under the 2002 Stock Planticker EKTAb.

Erbium Acquisition Corporation

Erbium Acquisition Corporation, which is referred to in this proxy statement as “Merger Sub,” is a Delaware corporation and an indirect wholly owned subsidiary of Elekta. Merger Sub was formed in January 2005 solely for the purpose of effecting the proposed transaction. If the transaction is consummated, Merger Sub will cease to exist after it merges with IMPAC.

Summary of the transaction

The merger (see page 14) and the merger agreement (see page 33)

Elekta, Merger Sub and IMPAC have no effectentered into a merger agreement that provides for the acquisition of IMPAC by Elekta, to be effected by the merger of IMPAC with Merger Sub. As a result of the merger, IMPAC will cease to be an independent, publicly traded company, and will become an indirect wholly owned subsidiary of Elekta. The merger will be completed when all of the conditions to completion of the merger are satisfied or waived, including approval and adoption of the merger agreement and approval of the merger by IMPAC’s stockholders. However, the merger agreement may be terminated, and the merger not completed, under certain circumstances that are described in this proxy statement and in the merger agreement.

Upon completion of the merger, each outstanding share of IMPAC common stock, other than shares held by stockholders exercising appraisal rights, will be converted into the right to receive $24.00 in cash (without interest and less applicable withholding taxes).

Upon completion of the merger, each outstanding option to purchase IMPAC common stock, including unvested options, with an exercise price less than $24.00 will be cancelled and the holder of such option will be entitled to receive a one-time cash payment (net of any statutory tax withholdings) equal to the number of shares of IMPAC stock subject to the option, multiplied by the difference between $24.00 and the per share exercise price of the option. Each outstanding option to purchase IMPAC common stock with an exercise price equal to or greater than $24.00 will be cancelled without payment.

The merger agreement is attached to this proxy statement as Annex A. We urge you to read it carefully.

IMPAC market price information (see page 60)

IMPAC’s common stock is quoted on The Nasdaq National Market under the symbol “IMPC.” On January 14, 2005, the last full trading day before the public announcement of the proposed merger, the closing price of our common stock was $19.75. On [                    ], 2005, the most recent practicable date prior to the mailing of this item. If a broker indicatesproxy statement, the closing price of our common stock was $[            ].

Annual meeting of IMPAC stockholders (see page 10)

IMPAC will hold the 2005 annual meeting of its stockholders on [                    ], 2005 at 8:00 a.m. Pacific Time at the proxy that it does not have discretionary authority as to certain shares tooffices of Orrick, Herrington & Sutcliffe LLP, The Orrick Building, 405 Howard Street, San Francisco, California 94105. At the meeting, IMPAC stockholders will consider and vote on a particular matter, those sharesproposal to approve the merger and approve and adopt the merger agreement. In addition, IMPAC stockholders will consider and vote on a proposal to grant IMPAC management the discretionary authority to adjourn the annual meeting one or more times, but not be considered as present andto a date later than May 31, 2005.

Only holders of record of IMPAC common stock on [                    ], 2005, the record date for the annual meeting, are entitled to notice of and to vote with respect to that matter. Therefore, a broker “non-vote” will have no effect onat the proposal to amendannual meeting.

The approval and restateadoption of the 2002 Stock Plan, whichmerger agreement requires the affirmative vote of a majority of the shares representedof IMPAC common stock outstanding at the Annual Meetingclose of business on the record date. The proposal to grant IMPAC management discretionary authority to adjourn the annual meeting requires the approval of the holders of at least a majority of the shares held by those present or represented by proxy at the annual meeting and eligible to vote on the proposal that are voted “for,” “against” or “abstain” with respect to the proposal.

The directors and executive officers of IMPAC and their affiliates own approximately 33.3% of the shares entitled to vote at the annual meeting. The holders of approximately 33.1% of the outstanding shares of IMPAC common stock, including three of our directors and executive officers and their respective affiliates, have entered into stockholder agreements with Elekta and Merger Sub pursuant to which they have agreed to vote all shares of IMPAC stock for which they have voting power in favor of the merger proposal and against any alternative acquisition proposal or any other action or agreement that would interfere with the completion of the merger.

Opinion of IMPAC’s financial advisor (see page 21)

In deciding to approve the merger, our board of directors considered, among other things, an opinion from William Blair & Company, L.L.C. (“William Blair”), our financial advisor, as to the fairness of the $24.00 price per share merger consideration from a financial point of view. The opinion of William Blair is attached as Annex C. We urge you to read it carefully to understand the procedures followed, assumptions made, matters considered and limitations on the review undertaken by William Blair. This opinion is directed to our board of directors and is not a recommendation to any stockholder with respect to any matter relating to the merger.

Conditions to closing the merger (see page 38)

Completion of the merger depends upon the satisfaction or waiver of a number of conditions, including the following:

Termination of the merger agreement (see page 39)

The merger agreement may be terminated at any time prior to the effective time of the merger, notwithstanding adoption of the merger agreement by our stockholders:

Termination fee (see page 40)

We are obligated to pay Elekta a termination fee equal to $10 million in cash if the merger agreement is terminated because our board of directors has withdrawn or modified in a manner adverse to Elekta its approval or recommendation in favor of the merger or approved, endorsed or recommended an alternative acquisition proposal. We are also obligated to pay Elekta the $10 million termination fee if (A) Elekta terminates the merger agreement because (i) there is a material inaccuracy in any of our representations or warranties or a material breach of our covenants and agreements in the merger agreement or (ii) our stockholders fail to adopt the merger agreement by May 31, 2005, and (B) within 12 months following such termination, we consummate a business combination, as defined on page 27.

Restrictions on solicitation (see page 37)

Until the merger is completed or the merger agreement is terminated, we have agreed not to take any of the following actions directly or indirectly:

However, if we receive an unsolicited acquisition proposal and our board of directors determines, after consulting with our advisors, that such proposal is a superior proposal, as defined on page 37, and that failure to act on such proposal would be reasonably likely to be a breach of the board’s fiduciary duties, then, if certain other conditions are satisfied:

If we receive an acquisition proposal, then we must provide notice thereof (including the identity of the person making the proposal and the material terms of the proposal) to Elekta within 24 hours and keep Elekta informed of the status of such proposal. In any event, unless the merger agreement is terminated, we may not enter into a letter of intent, agreement in principle, acquisition agreement or other similar agreement relating to an acquisition proposal.

Interests of executive officers and directors of IMPAC in the merger (see page 27)

When considering the recommendation of our board of directors in favor of the merger, you should be aware that certain of our executive officers and members of our board of directors may have interests in the merger that are different from, or in addition to, the interests of our stockholders generally. Such interests include the following:

Regulatory matters (see page 32)

The merger is subject to U.S. and certain foreign antitrust laws. We have made the required filings with the Department of Justice and the Federal Trade Commission, and are currently awaiting expiration of (and seeking early termination of) the applicable waiting periods. The Department of Justice, the Federal Trade Commission or any foreign agency, as well as a state or private person, could take action under the antitrust laws, including seeking to enjoin the merger.

Appraisal rights of IMPAC stockholders (see page 29 and Annex D)

Stockholders who do not wish to accept the $24.00 per share cash consideration payable in the merger may seek, under Delaware law, judicial appraisal of the fair value of their shares by the Delaware Court of Chancery. This value could be more or less than or the same as the merger consideration of $24.00 in cash per share. This right of appraisal is subject to a number of restrictions and technical requirements. Generally, in order to exercise appraisal rights, among other things: you must not vote in favor of the proposal to approve the merger and approve and adopt the merger agreement; you must make a written demand on us for appraisal in compliance with Delaware law before the annual meeting; and you must hold your shares of record continuously from the time of making a written demand for appraisal until the merger occurs.

Merely voting against the merger agreement will not preserve your right of appraisal under Delaware law. Also, if you submit a proxy that is not marked “AGAINST” or “ABSTAIN,” this proxy will be voted for the merger proposal, and will result in the waiver of your appraisal rights. If you hold shares in the name of a broker or other nominee, you must instruct your nominee to take the steps necessary to enable you to assert appraisal rights. If you or your nominee fails to follow all of the steps required by the statute, you will lose your right of appraisal. Please see the section entitled “Appraisal rights of IMPAC stockholders” and Section 262 of the Delaware General Corporation Law, which sets forth the appraisal rights and is attached as Annex D to this proxy statement, for more information.

INFORMATION CONCERNING THE ANNUAL MEETING AND VOTING OF PROXIES

Date, time and place of annual meeting

Purpose of the annual meeting

At the annual meeting, you will be asked to consider and vote upon the following items:

We do not currently anticipate that any other matters of business will be brought before the meeting.

Record date and outstanding shares

Only stockholders of record as of [                    ], 2005, the record date for the annual meeting, are entitled to notice of and to vote at the meeting. You will be entitled to exercise one vote for each share of IMPAC common stock you owned as of the record date.

As of the record date, there were [            ] shares of IMPAC common stock outstanding and entitled to vote, thereon.held of record by approximately [            ] stockholders. As of the record date, directors, executive officers and other affiliated stockholders of IMPAC as a group beneficially owned [            ] shares of IMPAC common stock. These shares constituted approximately [    ]% of all of the outstanding shares of IMPAC common stock as of the record date.

Quorum requirement

In order to conduct business at the annual meeting, a quorum must be present. The presence, in person or by proxy, of the holders of at least a majority of the issued and outstanding shares of IMPAC common stock that are entitled to vote as of the record date constitutes a quorum. If you submit a properly executed proxy card, even if you abstain from voting, you will be considered part of the quorum. Broker non-votes will also count as present at the annual meeting for establishing a quorum. A broker non-vote occurs with respect to any proposal when a broker is not permitted to vote on that proposal without instruction from the beneficial owner of the shares and no instruction is given. If a quorum is not present at the annual meeting, the annual meeting will be adjourned or postponed to solicit additional proxies.

Votes necessary to approve the proposals

Proposal No. 1—Approval of the Acquisition of IMPAC, Including the Merger, and Approval and Adoption of the Merger Agreement. This proposal must be approved by the holders of at least a majority of the shares of IMPAC common stock outstanding on the record date.

Proposal No. 2—Discretionary Authority to Adjourn the Annual Meeting. This proposal must be approved by the holders of at least a majority of the shares held by those present or represented by proxy at the annual meeting and eligible to vote on this proposal that are voted “FOR”, “AGAINST” or “ABSTAIN” with respect to this proposal.

Proposal No. 3—Election of Joseph K. Jachinowski and Gregory M. Avis to our Board of Directors. With regard to the election of directors, the nominees receiving the most votes are elected as directors.

IMPAC stockholders holding approximately 33.1% of the outstanding shares of IMPAC common stock as of the record date have agreed to vote all of their shares of IMPAC common stock in favor of the merger proposal and the adjournment proposal. See the section entitled “The Merger—Stockholder agreements” on page 26.

Voting in person

If you plan to attend the meeting and wish to vote in person, we will provide you with a ballot at the meeting. We encourage you to vote by proxy even if you plan to attend the meeting. You can always change your vote at the meeting (although note that attendance at the meeting does not, in and of itself, constitute a revocation of your proxy).

Voting of proxies

General. All shares represented by a properly signed and dated proxy will be voted at the annual meeting in accordance with the instructions indicated on the proxy. Proxies that are properly signed and dated but which do not contain voting instructions will be voted “FOR” the merger proposal, “FOR” the adjournment proposal and “FOR” the election of the nominees for director. The proxy holder may vote the proxy in its discretion as to any other matter that is properly brought before the meeting, if any.

Abstentions. You may abstain from voting on any or all proposals. IMPAC will count a properly executed proxy, even if you mark “ABSTAIN” with respect to all proposals, as present for purposes of determining whether a quorum is present. However, the shares represented by that proxy will not be voted at the annual meeting. Because the affirmative vote of at least a majority of the outstanding shares of IMPAC common stock on the record date is required to approve the merger proposal, if you mark your proxy “ABSTAIN” with respect to the merger proposal, it will have the effect of a vote against this proposal. Likewise, because the affirmative vote of at least a majority of the shares represented in person or by proxy at the annual meeting and eligible to vote on the adjournment proposal that are voted “FOR”, “AGAINST” or “ABSTAIN” with respect to this proposal are required to approve the adjournment proposal, if you mark your proxy “ABSTAIN” with respect to the adjournment proposal, it will have the effect of a vote against this proposal. With respect to the election of nominees to our board of directors, if you withhold your authority to vote for any nominee, your vote will not count for or against the nominee.

Broker non-votes. If your broker holds your shares in its name, the broker cannot vote your shares on the merger proposal or the adjournment proposal without your instructions. If you fail to provide these instructions, this results in a “broker non-vote.” You should follow the directions provided by your broker regarding how to instruct your broker to vote your shares. Because the affirmative vote of at least a majority of the outstanding shares of IMPAC common stock is required to approve the merger proposal, if you do not instruct your broker how to vote, it will have the effect of a vote against this proposal. Because only shares actually voted on the

adjournment proposal will determine the outcome of any vote on the adjournment proposal, if you do not instruct your broker how to vote, your proxy will have no effect on the adjournment proposal. With respect to the election of nominees to our board of directors, a broker non-vote will not count for or against the nominee.

Voting shares in person that are held through brokers. If your shares are held by your broker or another nominee and you wish to vote those shares in person at the annual meeting, you must obtain from the nominee holding your IMPAC common stock a properly executed legal proxy identifying you as an IMPAC stockholder, authorizing you to act on behalf of the nominee at the annual meeting and identifying the number of shares with respect to which the authorization is granted.

How to revoke your proxy

You may revoke your proxy at any time before it is exercised at the annual meeting by taking any of the following actions:

If you have instructed a broker to vote your shares, you must follow directions received from your broker to change those instructions.

Proxy solicitation

This proxy solicitation is made by the board of directors of IMPAC, and all proxy solicitation costs will be paid by us. We have engaged [                    ] to assist in the solicitation of proxies and to verify records relating to the solicitation. [                    ] will receive a service fee and the reimbursement of customary out-of-pocket expenses that are not expected to exceed $[            ] in the aggregate. Our directors, officers and employees may also solicit proxies, without additional remuneration, by telephone, facsimile, electronic mail and in person. We also will reimburse brokers and other custodians, nominees and fiduciaries for their expenses in sending these materials to you and obtaining your voting instructions.

You should send in your proxy by mail without delay, but please do not send in any stock certificates with your proxy. After the merger, Elekta will arrange for instructions to be sent to you regarding how to exchange your IMPAC stock certificates for the $24.00 per share cash payment (without interest and less applicable withholding taxes) to be paid in the merger.

PROPOSAL 1—ACQUISITION OF IMPAC BY ELEKTA

THE PARTIES

IMPAC Medical Systems, Inc.

100 West Evelyn Avenue

Mountain View, California 94041

Tel: (650) 623-8800

IMPAC Medical Systems, Inc., a Delaware corporation, is a leading provider of oncology IT solutions that streamline both clinical and business operations to help improve the process of delivering quality patient care. With systems designed for anatomic pathology, medical oncology, radiation oncology, imaging, clinical laboratory, and cancer registry, IMPAC supports the entire team of healthcare professionals who contribute to the care of the cancer patient. Supporting more than 2,500 installations worldwide, IMPAC provides practical solutions that deliver better overall communication, process efficiency and quality patient care.

Our common stock is traded on the Nasdaq National Market under the symbol “IMPC.”

Elekta AB (publ)

Kungstensgatan 18

Box 7593 SE-103 93

Stockholm, Sweden

Tel: 46-8-587-254-00

Elekta is an international medical technology company, providing highly advanced clinical solutions for high precision radiation treatment of cancer and for non- or minimally invasive treatment of brain disorders. Clinical solutions include among others Leksell Gamma Knife^® for non-invasive treatment of brain surgery and Elekta Synergy^® for image guided radiation therapy (IGRT) as well as associated software systems.

Elekta’s systems and solutions are used at over 2,000 hospitals around the world to treat cancer and to diagnose and treat brain disorders, including tumors, vascular malformations and functional disorders.

By developing clinical solutions through close collaborative relationships with clinical partners in research and advanced product development, Elekta is addressing the healthcare system’s need for reduced hospitalization costs and also patients’ wish for less traumatic treatment options. All of Elekta’s solutions employ non-invasive or minimally invasive techniques and are therefore clinically effective, gentle on the patient and cost-effective.

Elekta was founded in 1972 and is headquartered in Stockholm, Sweden. The company is listed on Stockholmsbörsen (Stockholm Stock Exchange) under the ticker EKTAb.

Erbium Acquisition Corporation

4775 Peachtree Industrial Blvd.

Building 300, Suite 300

Norcross, Georgia 30092

Tel: (770) 300-9725

Erbium Acquisition Corporation, which is referred to in this proxy statement as “Merger Sub” is a Delaware corporation and an indirect wholly owned subsidiary of Elekta. Merger Sub was formed in January 2005 solely for the purpose of effecting the proposed transaction. If the transaction is consummated, Merger Sub will cease to exist after it merges with IMPAC.

Significant transactions between IMPAC and Elekta

In March 2003, IMPAC and Elekta began exploring development of an enhanced interface between each company’s products, as well as possible co-marketing efforts in the global market. Throughout late 2003, discussions continued regarding possible joint product offerings, and on December 2, 2003, IMPAC and Elekta jointly announced an agreement to develop a standards-based interface to connect the Elekta product lines of digital linear accelerators with IMPAC’s oncology information management products. Coordinated product development efforts continued through the next year, and in October 2004, IMPAC and Elekta jointly announced that they had entered into a two-year renewable sales consulting agreement under which Elekta was granted non-exclusive rights to offer IMPAC’s oncology information system products and services in select markets throughout the world. In October 2004, IMPAC and Elekta also announced that they had entered into an agreement to collaborate on future development of enhanced interfaces to connect the Elekta product lines with IMPAC’s software.

THE MERGER

This section of the proxy statement describes certain aspects of the proposed merger. While we believe that the description covers the material terms of the merger and the related transactions, this summary may not contain all of the information that is important to you. You should read this entire document and the other documents we refer to, including the merger agreement attached hereto as Annex A, carefully for a more complete understanding of the merger.

Background of the merger

In October 2003, representatives of IMPAC and Elekta were engaged in discussions about possible opportunities for the companies to collaborate in their respective markets. As a follow up to those discussions, on October 21, 2003, Laurent Leksell, President and Chief Executive Officer of Elekta, arranged to meet with Joseph Jachinowski, President and Chief Executive Officer of IMPAC, in Salt Lake City, Utah to discuss the potential benefits of a possible business combination between IMPAC and Elekta.

On January 25 and 26, 2004, Mr. Jachinowski and Mr. Leksell, along with representatives of Elekta’s financial advisors, met in New York to continue their discussions of the potential benefits of a business combination between IMPAC and Elekta.

On March 5, 2004, IMPAC’s board of directors held a regularly scheduled meeting and discussed various strategic matters, including Mr. Jachinowski’s discussions with Mr. Leksell regarding a possible business combination with Elekta. IMPAC’s board discussed the relative benefits and disadvantages of a potential business combination with Elekta and other potential business combination opportunities.

On March 24, 2004, IMPAC and Elekta entered into a mutual confidentiality agreement relating to their discussions of a potential business combination.

On April 13 and 14, 2004, Mr. Jachinowski, James Hoey, Executive Vice President and Chief Operating Officer of IMPAC, David Auerbach, Executive Vice President of IMPAC, and Kendra Borrego, Chief Financial Officer of IMPAC, met with Mr. Leksell, Tomas Puusepp, Executive Vice President of Sales, Marketing and Service, and Volker Stieber, Executive Vice President of Technology Development and Operations, of Elekta and representatives of Elekta’s financial advisor in New York to discuss further a possible business combination between IMPAC and Elekta and various due diligence matters. During this meeting, representatives of IMPAC and Elekta discussed their companies’ financial information, products, technology, customer base and sales and marketing activities.

Between April 2004 and June 2004, Elekta continued its preliminary due diligence efforts with respect to IMPAC. Elekta requested various financial, legal and operational information from IMPAC, and IMPAC responded to certain of these inquiries.

On April 26, 2004, Elekta formally engaged Banc of America Securities, Ltd. to act as its financial advisor in connection with a potential business combination with IMPAC.

On April 27, 2004, Mr. Jachinowski and Ms. Borrego of IMPAC, representatives of the investment banking firm William Blair, on behalf of IMPAC, and representatives of IMPAC’s independent accounting firm held a call with Håkan Bergström, Chief Financial Officer of Elekta, and representatives of Banc of America Securities to discuss the restated financial statements that IMPAC had recently filed with the SEC.

On May 17, 2004, IMPAC’s board of directors convened a meeting at which Mr. Jachinowski provided an update on recent discussions with Elekta regarding a potential business combination.

On May 25, 2004, IMPAC’s board of directors held a regularly scheduled meeting. Representatives of William Blair reported to the board on various strategic and financial alternatives, including various potential business combinations. IMPAC’s board discussed the relative benefits and disadvantages of pursuing a potential business combination. IMPAC’s board then authorized management to allow further due diligence by Elekta and to pursue further discussions with Elekta.

On June 8, 2004, Mr. Bergström and a representative of Banc of America Securities met with Mr. Jachinowski, Ms. Borrego and representatives of William Blair at IMPAC’s offices in Mountain View, California to discuss financial due diligence.

On June 23, 2004, Mr. Leksell called Mr. Jachinowski and indicated that, based on the information made available to date, Elekta estimated an initial valuation range for IMPAC’s stock of $20 to $22 per share.

On June 30, 2004, representatives of William Blair spoke with representatives of Banc of America Securities about the proposed valuation offered by Elekta and informed Banc of America that IMPAC would only continue discussions if the proposed valuation were at a minimum of $22.00 per share.

On July 2, 2004, IMPAC formally engaged William Blair to act as its financial advisor in connection with a potential business combination.

Between July 2004 and September 2004, Elekta made several preliminary financial and operational due diligence inquiries, and IMPAC responded to each of these inquiries.

On August 31, 2004 and September 1, 2004, a due diligence meeting was held in San Francisco, California to further discuss financial, legal and other due diligence matters. The meeting was attended by Mr. Jachinowski, Ms. Borrego, Mr. Hoey and Mr. Auerbach of IMPAC, several representatives of Elekta, and representatives of both companies’ financial advisors.

On September 2, 2004, IMPAC’s board of directors held a regularly scheduled meeting. Representatives of William Blair reported on recent discussions with Elekta and noted that they expected to receive a specific indication of interest from Elekta within the next few weeks. Mr. Jachinowski then led a discussion regarding a possible transaction with Elekta, potential alternative transactions and other strategic opportunities. IMPAC’s management and members of IMPAC’s board of directors instructed William Blair to contact additional potential acquirers regarding a possible business combination with IMPAC.

On September 7, 2004, William Blair initiated contact with certain additional potential acquirers regarding a possible business combination with IMPAC. Subsequently, certain of these parties executed confidentiality agreements with IMPAC and were provided financial and operational due diligence materials.

On September 9, 2004 and September 10, 2004, representatives of IMPAC and Elekta and their respective financial advisors met in Chicago, Illinois for further discussions regarding due diligence matters, price considerations and the strategic rationale for a business combination between IMPAC and Elekta.

On September 17, 2004, Mr. Jachinowski and Ms. Borrego of IMPAC and a representative of Elekta held a due diligence call during which they discussed the status of IMPAC’s restatement of its financial statements.

On September 23, 2004, Elekta provided IMPAC with an oral non-binding indication of interest in pursuing an acquisition of IMPAC at an estimated per share price of $22, with such price being subject to detailed due diligence and further financial analysis.

On September 26, 2004, IMPAC’s board of directors convened a meeting to discuss the company’s strategic alternatives, including the current status of the company’s discussions with Elekta and the non-binding indication of interest received from Elekta on September 23, 2004, the status of the company’s ongoing consideration of other potential acquirers, and the results of discussions with certain other potential acquirers that William Blair had contacted at the request of IMPAC’s management and members of its board, as well as the merits and risks of remaining as an independent company. William Blair presented to IMPAC’s board its assessment of potential business combinations with Elekta and certain other potential acquirers, and IMPAC’s outside legal counsel advised the board as to its fiduciary duties to IMPAC’s stockholders. The IMPAC board instructed management and William Blair to continue to explore the various strategic alternatives for IMPAC.

During October 2004, representatives of IMPAC and William Blair had various contacts with certain other potential acquirers regarding due diligence matters.

On October 5, 2004, Mr. Jachinowski and Mr. Leksell met at the American Society for Therapeutic Radiation and Oncology conference in Atlanta, Georgia to discuss the broad economic terms of a possible business combination between IMPAC and Elekta.

On October 8, 2004, Mr. Jachinowski and Ms. Borrego of IMPAC, IMPAC’s outside legal counsel, representatives of Elekta and Elekta’s outside legal counsel held a due diligence call during which they discussed the stockholder lawsuits that had been filed against IMPAC following IMPAC’s financial restatement earlier in the year.

From October 14 through October 20, 2004, representatives of IMPAC, representatives of Elekta and representatives of both companies’ financial advisors held extensive due diligence meetings in Palo Alto, California. In addition, IMPAC granted Elekta and its financial, legal and accounting advisors access to certain due diligence materials. Elekta and its advisors continued their due diligence efforts throughout the remainder of October and November 2004.

On October 25, 2004, one of the other potential acquirers (the “Other Potential Acquirer”) submitted a written preliminary non-binding initial indication of interest.

On October 26 and October 27, 2004, Mr. Jachinowski of IMPAC met with Mr. Leksell and Mr. Puusepp and representatives of Elekta’s financial advisors at the European Society for Therapeutic Radiation and Oncology conference in Amsterdam to further discuss the broad economic terms of a potential business combination.

From October 28 through November 10, 2004, Elekta continued its due diligence review of IMPAC at sites in San Jose, California, Mountain View, California, Henderson, Nevada and Boston, Massachusetts. During this period, representatives of Elekta’s accounting and legal advisors reviewed IMPAC’s customer contracts and representatives of Elekta met with representatives of IMPAC to discuss various due diligence issues.

On October 31, 2004, IMPAC’s board of directors convened a meeting to continue to discuss the company’s strategic alternatives, including the current status of the company’s discussions with Elekta, the status of the company’s ongoing consideration of other potential acquirers, and the results of discussions with certain other potential acquirers that William Blair had contacted, as well as the merits and risks of remaining as an independent company. William Blair reported to the board that all of the other potential acquirers other than Elekta and the Other Potential Acquirer had ultimately decided not to pursue a business combination with IMPAC, and IMPAC’s outside legal counsel advised the board as to its fiduciary duties to IMPAC’s stockholders.

During November 2004, the Other Potential Acquirer continued its review of financial, legal and operational due diligence materials and held several due diligence calls with representatives of IMPAC.

On November 23, 2004, Elekta’s outside legal counsel delivered an initial draft of the merger agreement and form of stockholder agreement to IMPAC and IMPAC’s financial and legal advisors. The terms of the proposed merger agreement included a termination fee of $11.0 million, plus Elekta’s expenses up to $2,500,000, payable by IMPAC upon termination of the merger agreement if the agreement was terminated because IMPAC withdrew its approval of the merger or recommended an alternative transaction or breached a representation or warranty or a covenant contained in the merger agreement. The terms of the proposed form of stockholder agreement included an option, to be granted to Elekta by certain significant IMPAC stockholders, that would allow Elekta to purchase the shares of IMPAC common stock beneficially owned by such stockholders at a price equal to the per share price to be offered in the merger. The options would vest upon termination of the merger agreement and expire 18 months from vesting. Further, should IMPAC consummate an alternative business combination during the period in which the options were vested (but before Elekta exercised the options), the stockholders party to such agreement would be required to pay to Elekta any per share amount in excess of the exercise price that they received as consideration in the alternative business combination.

From November 2004 through early December 2004, representatives of Elekta continued to conduct due diligence activities, but in light of IMPAC’s pending financial restatements and fiscal 2004 year-end audit, they were not granted access to IMPAC’s independent auditors.

On November 30, 2004, the Other Potential Acquirer submitted a revised preliminary non-binding initial indication of interest.

On December 1, 2004, IMPAC’s board of directors held a regularly scheduled meeting and discussed the status of negotiations with Elekta and IMPAC’s ongoing market check. Representatives of William Blair updated the board on the status of IMPAC’s ongoing discussions with Elekta and the Other Potential Acquirer and discussed the indication of interest submitted by the Other Potential Acquirer. IMPAC’s board then authorized management to allow continued due diligence by Elekta and the Other Potential Acquirer and to pursue negotiations with both Elekta and the Other Potential Acquirer.

On December 3, 2004, after having been informed by Mr. Jachinowski that representatives of Elekta would not be able to have access to IMPAC’s independent auditors until after IMPAC completed its year-end audit and filed its Form 10-K for the fiscal year ended September 30, 2004, Mr. Leksell and Mr. Bergström sent a letter to Mr. Jachinowski in which they stated that they believed they could not proceed with any further discussions regarding a possible transaction until they were able to conduct accounting-related due diligence with IMPAC’s independent auditors. Further, they stated that Elekta was suspending discussions with IMPAC until such time as further due diligence could take place, and that at that time Elekta would determine whether there were opportunities to proceed with a possible transaction.

On December 5, 2004, IMPAC’s board of directors convened a meeting to discuss the company’s strategic alternatives, including the current status of the company’s discussions with Elekta, the status of the company’s discussions with the Other Potential Acquirer and the merits and risks of remaining as an independent company.

On December 7, 2004 and December 8, 2004, representatives of IMPAC, William Blair and the Other Potential Acquirer met at IMPAC’s offices in Mountain View, California to discuss various financial, legal and operational due diligence matters.

On December 14, 2004, IMPAC filed its Form 10-K for the fiscal year ended September 30, 2004 with the SEC. Shortly thereafter, representatives of IMPAC contacted representatives of Elekta to reaffirm IMPAC’s desire to discuss a possible transaction and to indicate that IMPAC was willing to grant Elekta’s accounting advisors access to IMPAC’s independent auditors in order to conduct further due diligence. In response, Elekta authorized its financial, legal and accounting advisors to resume their due diligence efforts, which activities continued through late December 2004 and early January 2005.

On December 17, 2004, IMPAC’s outside legal counsel distributed to Elekta’s outside legal counsel proposed revisions to the draft merger agreement and form of stockholder agreement.

In late December 2004, the Other Potential Acquirer informed William Blair that they were no longer interested in pursuing a business combination with IMPAC.

On January 5, 2005, IMPAC’s board of directors convened a meeting to discuss the company’s strategic alternatives, including the current status of the company’s discussions with Elekta, the status of the company’s discussions with other potential acquirers following the termination of discussions with the Other Potential Acquirer, and the merits and risks of remaining as an independent company.

On January 7, 2005, Elekta’s outside legal counsel delivered revised drafts of the merger agreement and form of stockholder agreement to IMPAC and its financial and legal advisors.

Between January 7, 2005 and January 16, 2005, the management teams of IMPAC and Elekta and their respective financial advisors and outside legal counsel had a series of negotiations involving a number of significant issues that remained unresolved, including: the amount of the merger consideration; the amount, and conditions triggering payment, of the termination fee to be payable by IMPAC should the merger agreement be terminated; the threshold that would allow IMPAC to enter into negotiations with third parties to discuss an alternative transaction; and the terms of the option to be granted by certain significant IMPAC stockholders; as well as the remaining terms of the merger agreement, the form of stockholder agreement and related transaction documents. During the course of these negotiations, Elekta ultimately agreed to increase its per share offer price for the merger to $24 and to provide for accelerated vesting of all unvested options exercisable for shares of IMPAC’s common stock.

On January 15, 2005, representatives of IMPAC held a final due diligence call with representatives of Elekta.

On January 16, 2005, IMPAC’s board of directors convened a meeting. IMPAC’s outside legal counsel advised the board as to its fiduciary duties to IMPAC’s stockholders in considering a possible sale of the company. Representatives of William Blair reviewed the terms of the proposed acquisition by Elekta and verbally provided William Blair’s opinion that the $24.00 per share cash merger consideration was fair to IMPAC’s stockholders from a financial point of view, and stated that William Blair would deliver the written fairness opinion prior to execution of a definitive agreement. IMPAC’s board and management discussed the proposed transaction. IMPAC’s outside legal counsel presented a summary of terms of the definitive merger agreement and the form of stockholder agreement, each of which had been previously circulated to the board. Following a thorough discussion, IMPAC’s board of directors unanimously determined that the merger and the merger agreement were advisable, fair to and in the best interests of IMPAC and its stockholders, and unanimously approved the merger, the merger agreement and the stockholder agreements. The board also unanimously recommended that IMPAC’s stockholders approve the merger and the merger agreement.

On January 17, 2005, Elekta’s board of directors held a meeting at which they considered the merger and authorized the execution and delivery of the merger agreement, the stockholder agreements and related documents.

Later that day, following resolution of various remaining terms of the transaction, the parties executed the merger agreement, and the holders of approximately 33.1% of the outstanding shares of IMPAC stock, including three of IMPAC’s directors and executive officers, entered into stockholder agreements with Elekta.

On January 18, 2005, prior to the commencement of daily trading on the Nasdaq National Market, the parties issued a joint press release announcing the transaction.

IMPAC’s reasons for the merger

In the course of reaching its decision to approve the merger, our board of directors consulted with our management, William Blair and our outside legal counsel. The board also sought and received William Blair’s written opinion as to the fairness, as of the date of such opinion, from a financial point of view, to our stockholders of the consideration to be received by our stockholders in the merger. The board also consulted with outside legal counsel regarding the board’s fiduciary duties, legal due diligence matters, and the terms of the merger agreement and related agreements. Based on these consultations and opinions, and the factors discussed below, the board concluded that entering into the merger agreement with Elekta would yield the highest value for our stockholders and is in the best interests of our stockholders.

The decision of our board of directors was based upon a number of potential benefits of the transaction, including the following:

Our board of directors also considered several additional factors, including the following:

Finally, our board of directors also identified and considered a number of countervailing factors in its deliberations concerning the proposed transaction, including the following:

The preceding discussion is not meant to be an exhaustive description of the information and factors considered by our board of directors, but is believed to address the material information and factors considered. In view of the wide variety of factors considered in connection with its evaluation of the merger and the complexity of these matters, our board of directors did not find it practicable to, and did not, quantify or otherwise attempt to assign relative weights to the various factors considered in reaching its determination. In considering the factors described above, individual members of the board may have given different weight to different factors.

Recommendation of IMPAC’s board of directors

After careful consideration, our board of directors has determined that the terms of the merger are advisable, fair to, and in the best interests of, IMPAC and its stockholders, has approved and adopted the merger agreement and the merger, and recommends to our stockholders that they vote “FOR” the proposal to approve the merger and to approve and adopt the merger agreement.

In considering the recommendation of our board of directors with respect to the merger, you should be aware that certain directors and executive officers of IMPAC have interests in the merger that are different from,

or are in addition to, the interests of IMPAC stockholders generally. Please see the section entitled “The Merger—Interests of executive officers and directors of IMPAC in the merger” on page 27.

Opinion of William Blair & Company, L.L.C.

William Blair was retained to act as a financial advisor to IMPAC in connection with the proposed merger involving IMPAC. As part of its engagement, IMPAC requested William Blair to render an opinion as to whether the consideration to be received by the holders of the common stock of IMPAC was fair to such holders from a financial point of view. On January 16, 2005, William Blair delivered its oral opinion, subsequently confirmed in writing, to the effect that, as of that date and based upon and subject to the assumptions and qualifications stated in its opinion, the consideration of $24.00 in cash per share of common stock of IMPAC was fair, from a financial point of view, to the holders of the outstanding shares of common stock of IMPAC.

William Blair provided the opinion described above for the information and assistance of the IMPAC board of directors in connection with its consideration of the merger. William Blair’s opinion to the IMPAC board of directors was one of many factors taken into consideration by the IMPAC board of directors in making its determination to approve the merger agreement. The terms of the merger agreement, however, were determined through negotiations between IMPAC and Elekta and were approved by the IMPAC board of directors.

The full text of William Blair’s written opinion, dated January 17, 2005, is attached as Annex C to this proxy statement and incorporated into this proxy statement by reference. You are urged to read the entire opinion carefully to learn about the assumptions made, procedures followed, matters considered and qualifications and limitations on the scope of the review undertaken by William Blair in rendering its opinion. William Blair’s opinion relates only to the fairness, from a financial point of view, to IMPAC’s stockholders of the consideration to be received in the proposed merger, does not address any other aspect of the proposed merger or any related transaction, and does not constitute a recommendation to any stockholder as to how that stockholder should vote with respect to the approval of the merger agreement or the merger. William Blair did not address the merits of the underlying decision by IMPAC to engage in the merger. The following summary of William Blair’s opinion does not purport to be a complete description of the analysis performed by William Blair in connection with such opinion and is qualified in its entirety by reference to the full text of the written opinion of William Blair attached to this proxy statement as Annex C. William Blair’s opinion was directed to the IMPAC board of directors for its benefit and use in evaluating the fairness of the common stock merger consideration. We urge you to read the opinion carefully and in its entirety.

In connection with rendering its opinion and performing its related financial analyses, William Blair examined or discussed:

William Blair also held discussions with members of the senior management of IMPAC to discuss the foregoing, considered other matters which it deemed relevant to its inquiry, and took into account such accepted financial and investment banking procedures and considerations as it deemed relevant. In connection with its engagement, William Blair was requested to approach, and held discussions with, certain third parties to solicit indications of interest in a possible acquisition of IMPAC.

In rendering its opinion, William Blair assumed and relied upon, without independent verification, the accuracy and completeness of all the information examined by or otherwise reviewed or discussed with William Blair for purposes of its opinion, including, without limitation, the Forecasts provided by senior management. William Blair did not make or obtain an independent valuation or appraisal of the assets, liabilities or solvency of IMPAC. William Blair was advised by senior management of IMPAC that the Forecasts were reasonably prepared on bases reflecting the best currently available estimates and judgments of the senior management of IMPAC. In that regard, William Blair assumed, with the consent of the IMPAC board of directors, that (i) the Forecasts would be achieved and (ii) all material assets and liabilities (contingent or otherwise) of IMPAC were as disclosed in IMPAC’s financial statements or other information made available to William Blair. William Blair expressed no opinion with respect to the Forecasts or the estimates and judgments on which they were based. William Blair further expressed no opinion with respect to the terms of the stockholder agreements dated January 17, 2005 between Elekta, Merger Sub and certain stockholders of IMPAC.

William Blair’s opinion did not address the merits of the underlying decision by IMPAC to engage in the merger, and the opinion does not constitute a recommendation to any stockholder as to how such stockholder should vote with respect to the proposed merger. William Blair’s opinion was based upon economic, market, financial and other conditions existing on, and other information disclosed to William Blair as of, the date of such opinion. Although subsequent developments may affect its opinion, William Blair does not have any obligation to update, revise or reaffirm its opinion. William Blair relied as to all legal matters on advice of counsel to IMPAC, and assumed that the merger would be consummated on the terms described in the merger agreement, without any waiver of any material terms or conditions by IMPAC.

The following is a summary of the material financial analyses performed and material factors considered by William Blair to arrive at its opinion. William Blair performed certain procedures, including each of the financial analyses described below, and reviewed with the IMPAC board of directors the assumptions upon which such analyses were based, as well as other factors. Although the summary does not purport to describe all of the analyses performed or factors considered by William Blair in this regard, it does discuss those considered by William Blair to be material in arriving at its opinion.

Summary table. The following table summarizes the implied per share equity value for IMPAC derived from the analyses indicated, as described in each respective section. The following table does not include the premiums paid analysis, which is not conducive to determining an implied value per share of the merger consideration. In applying the various valuation methodologies to IMPAC’s business and operations and the circumstances of the proposed merger, William Blair made qualitative judgments as to the significance and relevance of each analysis. The methodologies and imputed value ranges derived from these analyses should be considered as a whole and in the context of their narrative description, including the methodologies and assumptions underlying these analyses. Considering the imputed value ranges without considering the full narrative description of the financial analyses, including underlying methodologies and assumptions, could create a misleading or incomplete view of the financial analyses performed by William Blair.

Comparable public company analysis. William Blair reviewed and compared certain financial information relating to IMPAC to corresponding financial information, ratios and public market multiples for certain publicly traded companies with operations in the healthcare information technology market and market capitalizations in excess of $40 million that William Blair deemed relevant. The comparable companies selected by William Blair were AllScripts Healthcare Solutions, Inc., Cedara Software Corp., Mediware Information Systems, Inc., Merge Technologies Incorporated, NetSmart Technologies, Inc., Quality Systems, Inc., Cerner Corporation, Computer Programs and Systems, Inc., Eclipsys Corporation, IDX Systems Corporation, Quadramed Corporation, Varian Medical Systems, Inc. and Elekta. William Blair selected these companies because they are the publicly traded companies that engage in businesses reasonably comparable to IMPAC’s business.

Among the information William Blair considered were revenue, EBITDA and net income. The operating results and the corresponding derived multiples for IMPAC and the comparable companies were based on each company’s most recent available publicly disclosed financial information, closing share prices as of January 13, 2005 and consensus Wall Street analysts’ earnings per share estimates for calendar year 2005.

William Blair then derived a range of implied per share equity values for IMPAC by applying the multiples from the selected comparable companies to the corresponding data for IMPAC. Information regarding the multiples from William Blair’s analysis of selected comparable publicly traded companies, including the range of implied per share equity values for IMPAC derived from these multiples, is provided in the following table.

The mean of the low and high implied transaction per share equity values for IMPAC implied by the comparable public company analysis is approximately $13.16 per share and $37.96 per share, respectively, as compared to the purchase price for IMPAC of $24.00 per share.

None of the selected companies is identical to IMPAC. Accordingly, any analysis of the selected comparable publicly traded companies necessarily involved complex considerations and judgments concerning the differences in financial and operating characteristics and other factors that would necessarily affect the analysis of trading multiples of the selected comparable publicly traded companies.

Comparable transactions analysis. William Blair performed an analysis of selected recent business combinations consisting of transactions in excess of $50 million in value, announced subsequent to January 1, 2000 and involving domestic healthcare information technology companies based on publicly available information. In total, William Blair examined seven transactions that were chosen based on William Blair’s judgment that they were generally similar, in whole or in part, to the proposed merger. The selected transactions were not intended to be representative of the entire range of possible transactions in the healthcare information technology industry. The seven transactions examined were (target/acquirer):

•

Shared Medical Systems Corporation/Siemens Medical Engineering Group

William Blair reviewed the consideration paid in the selected comparable transactions in terms of the total value of such transactions as a multiple of revenue and EBITDA for the latest twelve months (“LTM”) prior to the announcement of such transactions. William Blair then derived a range of implied per share equity values for IMPAC by applying the multiples from the selected comparable transactions to the corresponding data for IMPAC. Information regarding the multiples from William Blair’s analysis of selected comparable transactions, including the range of implied per share equity values for IMPAC derived from these multiples, is provided in the following table:

The mean of the low and high implied transaction per share equity values for IMPAC implied by the comparable transactions analysis is approximately $15.06 per share and $63.43 per share, respectively, as compared to the purchase price for IMPAC of $24.00 per share.

None of these transactions or associated companies is identical to the merger or IMPAC. Accordingly, any analysis of the selected comparable transactions necessarily involved complex considerations and judgments concerning the differences in financial and operating characteristics, parties involved and terms of their transactions and other factors that would necessarily affect the implied value of IMPAC versus the values of the companies in the selected comparable transactions.

Discounted cash flow analysis. The discounted cash flow methodology is most appropriate for companies that exhibit relatively steady or somewhat predictable streams of future cash flow. For a company with limited intermediate and long-term cash flow visibility the preponderance of the value can be in the terminal value, which is extremely sensitive to assumptions about the sustainable long-term growth of the company. William Blair took the foregoing limitation into account in using this discounted cash flow methodology in the context of its overall analysis of the transaction.

William Blair utilized the Forecasts to perform a discounted cash flow analysis of IMPAC’s projected future cash flows for the period commencing January 1, 2005 and ending September 30, 2008. Using discounted cash flow methodology, William Blair calculated the present values of the projected free cash flows for IMPAC. In this analysis, William Blair calculated terminal values assuming exit multiples ranging from 7.0x to 9.0x the projected 2008 EBITDA and growth rates in perpetuity of free cash flow beyond 2008 of 1.0% to 4.0%. William Blair used discount rates ranging from 15.0% to 19.0%. William Blair selected the terminal value inputs range based on William Blair’s review of factors projected to be relevant at the time of the exit, including, among other matters, the trading multiples of certain comparable companies, the transaction multiples of certain comparable transactions and certain industry growth rates. William Blair determined the appropriate discount rate range based upon an analysis of the weighted average cost of capital of IMPAC and other comparable companies that William Blair deemed relevant in its expertise and judgment. William Blair aggregated (1) the present value of the free cash flows over the applicable forecast period with (2) the present value of the range of terminal values. The aggregate present value of these items represented the enterprise value range. An equity value was determined by adding back the current amount of net cash. William Blair calculated the implied per share equity value range by dividing the resulting equity values by the fully diluted share count of 10.4 million. The implied transaction per share equity values for IMPAC implied by the discounted cash flow analysis using EBITDA exit

multiples ranged from $28.51 per share to $36.31 per share. The implied transaction per share equity values for IMPAC implied by the discounted cash flow analysis using perpetuity growth rates ranged from $25.08 per share to $36.78 per share. The mean of the low and high implied transaction per share equity values for IMPAC implied by the discounted cash flow analysis is approximately $26.80 per share and $36.55 per share, respectively, as compared to the purchase price for IMPAC of $24.00 per share.

Premiums paid analysis. William Blair reviewed data from 265 publicly available transactions occurring since January 1, 2001 and with transaction values between $100 million and $500 million in which 100% of the target was acquired. Specifically, William Blair analyzed the acquisition price as a premium to the closing share price one day, one week and four weeks prior to the announcement of the transaction, for all 265 transactions and for a subgroup of those transactions that were cash transactions. William Blair compared the resulting stock price premiums for the reviewed transactions to the premiums implied by the merger based on IMPAC’s stock prices one day, one week and four weeks prior to an assumed announcement on January 14, 2005. Information regarding the premiums from William Blair’s analysis of selected transactions is provided in the following table:

General.The preparation of an opinion regarding fairness is a complex analytic process involving various determinations as to the most appropriate and relevant methods of financial analysis and the application of those methods to the particular circumstances, and, therefore, such an opinion is not readily susceptible to partial analysis or summary description. The preparation of a fairness opinion does not involve a mathematical evaluation or weighing of the results of the individual analyses performed, but requires William Blair to exercise its professional judgment, based on its experience and expertise, in considering a wide variety of analyses taken as a whole. Each of the analyses conducted by William Blair was carried out in order to provide a different perspective on the financial terms of the proposed merger and add to the total mix of information available. William Blair did not form a conclusion as to whether any individual analysis, considered in isolation, supported or failed to support an opinion about the fairness of the consideration to be received by the holders of the common stock of IMPAC. Rather, in reaching its conclusion, William Blair considered the results of the analyses in light of each other and ultimately reached its opinion based on the results of all analyses taken as a whole. William Blair did not place particular reliance or weight on any particular analysis, but instead concluded its

analyses, taken as a whole, supported its determination. Accordingly, notwithstanding the separate factors summarized above, William Blair believes that its analyses must be considered as a whole and that selecting portions of its analyses and the factors considered by it, without considering all analyses and factors, may create an incomplete view of the evaluation process underlying its opinion. No company or transaction used in the above analyses as a comparison is directly comparable to IMPAC or the merger. In performing its analyses, William Blair made numerous assumptions with respect to industry performance, business and economic conditions and other matters. The analyses performed by William Blair are not necessarily indicative of future actual values and future results, which may be significantly more or less favorable than suggested by such analyses.

William Blair has been engaged in the investment banking business since 1935, and regularly undertakes the valuation of investment securities in connection with public offerings, private placements, business combinations, estate and gift tax valuations and similar transactions. William Blair is familiar with IMPAC, having provided certain investment banking services to IMPAC from time to time, including having served as a co-managing underwriter for IMPAC’s follow-on offering of 2,734,956 shares of IMPAC common stock in May 2003 and as a financial advisor to IMPAC in connection with, and having participated in certain of the negotiations leading to, the merger agreement. Furthermore, in the ordinary course of its business, William Blair may from time to time trade the securities of IMPAC for its own account and for the accounts of its customers, and accordingly may at any time hold a long or short position in such securities.

IMPAC hired William Blair based on its qualifications and expertise in providing financial advice to companies and its reputation as a nationally recognized investment banking firm. Pursuant to a letter agreement dated July 2, 2004, IMPAC agreed to pay William Blair upon consummation of the merger, a fee equal to a percentage of the total consideration received by the Company and its stockholders as a result of the merger, which is an amount approximately equal to $2.4 million, less the amount of $500,000 which was payable to William Blair upon the delivery of its opinion as to the fairness, from a financial point of view, of the consideration to be received by IMPAC’s common stockholders and less the amount of $100,000 which was payable to William Blair upon the signing of the engagement letter. In addition, IMPAC has agreed to reimburse William Blair for all of its out-of-pocket expenses (including fees and expenses of its counsel) reasonably incurred by it in connection with its services and will indemnify William Blair against potential liabilities arising out of its engagement.

Stockholder agreements

Elekta and Merger Sub have entered into stockholder agreements with several significant IMPAC stockholders, including Joseph Jachinowski, James Hoey and David Auerbach, each of whom is a director and executive officer of IMPAC, and their respective affiliates. The stockholder agreements require these IMPAC stockholders to vote all shares of IMPAC stock for which they have voting power in favor of the adoption of the merger agreement and approval of the merger, against any acquisition proposal or any action or agreement that would interfere with the completion of the merger and, unless Merger Sub instructs otherwise, against certain other corporate actions, including any change in our board of directors or amendment of our certificate of incorporation. In order to secure these obligations, these stockholders also granted Merger Sub a proxy and power of attorney with respect to these matters. The stockholder agreements apply only to the exercise of voting rights attaching to IMPAC shares and do not limit the discretion of any stockholder who is a director of IMPAC with respect to his duties as a director.

The stockholder agreements also provide Merger Sub an option to purchase all or any portion of the IMPAC common stock owned by these stockholders at a price of $24.00 per share at any time within 12 months following the termination of the merger agreement, but only if the merger agreement is terminated because our board of directors has withdrawn or modified in a manner adverse to Elekta its approval or recommendation in favor of the merger proposal or approved, endorsed or recommended an alternative acquisition proposal. In addition, these stockholders agreed not to transfer any IMPAC stock except in connection with the merger or to Merger Sub as provided under the stockholder agreements.

The stockholder agreements also provide that if we consummate a business combination, as defined below, within 12 months following the termination of the merger agreement and any or all of the shares of our common stock that are subject to a stockholder agreement are sold to any person other than Elekta at a price in excess of $24.00 per share, then the amount by which the per share price exceeds $24.00 will be shared equally between Elekta and the stockholder who is a party to the stockholder agreement.

For purposes of the stockholder agreements and the merger agreement, a “business combination” means (A) a merger, consolidation, business combination, recapitalization, liquidation, dissolution or similar transaction pursuant to which our stockholders immediately preceding such transaction hold less then 50% of the aggregate equity interests of the surviving or resulting entity of such transaction or any direct or indirect parent thereto; (B) a sale or other disposition by us or our subsidiaries of assets (in a transaction or series of transactions) representing in excess of 50% of the aggregate fair market value of our business immediately prior to such sale; or (C) the acquisition by any person or group (including by way of a tender offer or an exchange offer or issuance by us), directly or indirectly, of beneficial ownership or a right to acquire beneficial ownership of shares representing in excess of 50% of the voting power of the then outstanding shares of our common stock.

The voting requirements and the transfer restrictions provided in the stockholder agreements will terminate upon the earliest to occur of the termination of the merger agreement or the completion of the merger, except that if the merger agreement is terminated, the transfer restrictions will survive for 12 months following termination of the merger agreement.

As of the record date, the IMPAC stockholders who entered into a stockholder agreement collectively held 3,291,765 shares of outstanding IMPAC common stock, representing approximately 33.1% of the outstanding shares of IMPAC common stock. None of the IMPAC stockholders who are parties to a stockholder agreement were paid additional consideration in connection with entering into the stockholder agreement.

The form of stockholder agreement is attached as Annex B, and we urge you to read it carefully.

Interests of executive officers and directors of IMPAC in the merger

When considering the recommendation of our board of directors in favor of the merger, you should be aware that certain of our executive officers and members of our board of directors may have interests in the merger that are different from, or in addition to, the interests of our stockholders generally. Such interests include the following:

These interests are described below in greater detail. Our board of directors was aware of, and considered the interests of, our directors and executive officers in approving the merger agreement and the merger.

Stock options. Certain of our executive officers and directors hold unvested options to purchase shares of IMPAC common stock and will be entitled to full acceleration of vesting of their unvested stock options as of the effective time of the merger. Upon completion of the merger, each outstanding option to purchase IMPAC common stock with an exercise price less than $24.00 will be cancelled and the holder of such option will be entitled to receive a one-time cash payment (net of any statutory tax withholdings) equal to the number of shares

of IMPAC stock subject to the option, multiplied by the difference between $24.00 and the per share exercise price of the option. Each outstanding option to purchase IMPAC common stock with an exercise price equal to or greater than $24.00 will be cancelled without payment.

The following table sets forth for each of our directors and executive officers the total number of unvested option shares that will accelerate upon closing and the net value thereof, assuming a closing date of April 30, 2005 for hypothetical purposes, as well as the total number of vested options held by the director or executive officer at the closing and the net value thereof:

Indemnification of directors and executive officers and insurance. The merger agreement provides that Elekta will cause the surviving corporation to continue to provide all rights of indemnification for acts or omissions occurring at or prior to the effective time of the merger that exist in favor of our directors or executive officers as provided in our certificate of incorporation or bylaws for a period of six years after the merger. Elekta has also agreed to cause the surviving corporation in the merger to fulfill and honor in all respects all of our obligations pursuant to any indemnification agreements between us and our directors and officers in effect as of the date of the merger agreement.

Prior to the effective time of the merger, we will purchase a “run-on” directors’ and officers’ liability insurance policy that will cover those persons who are covered by our directors’ and officers’ liability insurance policies as of the effective time of the merger for a period of six years after the effective time and provide coverage with respect to matters occurring prior to the effective time that is at least equal to the coverage provided under our current directors’ and officers’ liability insurance policies. If such run-on policy is not available, the surviving corporation will maintain in effect directors’ and officers’ liability insurance policies for six years after the effective time that will provide coverage that is at least equal to the coverage provided under our current directors’ and officers’ liability insurance policies to those persons who are covered by our directors’ and officers’ liability insurance policies as of the effective time at an annual cost not greater than 150 percent of the premium for our current directors’ and officers’ liability insurance policies. However, if such insurance cannot be maintained at such cost, the surviving corporation will maintain as much of such insurance as can be maintained at a cost equal to 150 percent of our current annual premiums for such insurance.

Severance and other benefits upon termination.We entered into a change of control severance agreement with Kendra Borrego, our Chief Financial Officer, in January 2005. The agreement provides that if Ms. Borrego’s employment is terminated as a result of involuntary termination (as defined in the agreement) within twelve months after a change of control of IMPAC, including the proposed merger, she will receive a severance payment equal to 100% of her base salary (as in effect immediately prior to the change of control) for six months and continued coverage in health insurance, life insurance and other similar benefits in effect on the date of termination for a period of six months.

No employment agreements. Although it is not a condition to closing the merger, our current executive officers are expected to continue employment with Elekta following the merger on terms and at compensation levels generally commensurate to what they currently receive at IMPAC. As of the date of this proxy statement, however, none of our executive officers has entered into an employment agreement with Elekta.

Appraisal rights of IMPAC stockholders

Under Section 262 of the Delaware General Corporation Law, IMPAC stockholders have the right to object to the merger and demand in writing that IMPAC pay the fair value of their shares. Determination of fair value is based on all relevant factors, but excludes any appreciation or depreciation in anticipation of the applicable merger. Stockholders who elect to exercise appraisal rights must comply with all of the procedures set forth in Section 262 to preserve those rights. These procedures are complicated and must be followed completely. Failure to comply with Section 262 may cause a termination of your appraisal rights. The following information is only a summary of the required procedures and is qualified in its entirety by reference to the provisions of Section 262. Please review Section 262, a copy of which is attached to this proxy statement as Annex D, for the complete procedures. Neither Elekta nor IMPAC will give you any notice other than as described in this document and as required by the Delaware General Corporation Law.

General requirements. Section 262 generally requires the following:

Requirements for written demand for appraisal.A written demand for appraisal of IMPAC stock must be signed by, or in the name of, the stockholder of record who owns the shares at the time the demand is made and should be signed as the stockholder’s name appears on the stock certificates. If you are the beneficial owner of IMPAC stock but not the stockholder of record, you must have the stockholder of record submit the demand for appraisal.

If you hold IMPAC stock in a fiduciary capacity, including as a trustee, guardian or custodian, you must disclose the fact that you are signing the demand for appraisal in that capacity.

If you own IMPAC stock with more than one person, such as in a joint tenancy or tenancy in common, all of the owners must sign, or have signed for them, the demand for appraisal. An authorized agent, which could include one or more of the joint owners, may sign the demand for appraisal for a stockholder of record; however, the agent must expressly disclose who the stockholder of record is and that he is signing the demand as that stockholder’s agent.

If you are a record owner, such as a broker, who holds IMPAC stock as a nominee for others, you may exercise appraisal rights with respect to shares held for one or more beneficial owners, while not exercising appraisal rights for other beneficial owners. In this case, you should specify in the written demand for appraisal the number of shares as to which you wish to demand appraisal. If the demand does not expressly specify the number of shares as to which appraisal is sought, we will assume that it covers all the shares of IMPAC stock that are in your name.

If you elect to exercise your appraisal rights, you should address the written demand to IMPAC Medical Systems, Inc., 100 West Evelyn Avenue, Mountain View, California 94041, Attention: Corporate Secretary. As required by Section 262, we must receive all written demands for appraisal before the vote concerning the merger is taken. As explained above, this written demand should be signed by, or on behalf of, the stockholder of record. The written demand for appraisal should specify the stockholder’s name and mailing address, the number of shares of stock owned, and that the stockholder is demanding appraisal of such stockholder’s shares. If you hold your shares of IMPAC common stock in a brokerage account or in other nominee form and you wish to exercise appraisal rights, you should consult with your broker or other nominee to determine the appropriate procedures for the making of a demand for appraisal by the nominee.

Written notice. Within ten days after the closing of the merger, we must give written notice that the merger has become effective to each stockholder who has made proper demand for appraisal and who has not voted for or consented to the merger.

Petition with the chancery court. Within 120 days after the closing of the merger, either IMPAC or any stockholder who has complied with the conditions of Section 262, may file a petition in the Delaware Court of Chancery requesting that the court determine the value of the shares of IMPAC stock held by all of the stockholders who are entitled to appraisal rights. If you intend to exercise your rights of appraisal, you should file such a petition with the court. We have no intention at this time to file such a petition. Because we have no obligation to file such a petition, if you do not expect any mattersfile such a petition within 120 days after the closing, you will lose your rights of appraisal.

Withdrawal of demand. If you demand appraisal rights, upon the closing of the merger you will not listedbe entitled to receive payment of the consideration provided for in the Proxy Statementmerger agreement. If you change your mind and decide you no longer want to come beforepursue your appraisal rights, you may withdraw your demand for appraisal rights at any time within 60 days after the meeting.closing of the merger. After the 60th day after the closing of the merger, you may withdraw your demand for appraisal rights only with the written consent of IMPAC. If you withdraw your demand for appraisal rights, you will receive the merger consideration provided in the merger agreement.

Request for appraisal rights statement. If you have complied with the conditions of Section 262, you are entitled to receive a statement from us setting forth the number of shares that have demanded appraisal rights and the number of stockholders who own those shares. In order to receive this statement, you must send a written request to us within 120 days after the closing of the merger. We have ten days after receiving such a request to mail the statement to the stockholder.

Chancery court procedures. If you properly file a petition for appraisal in the Court of Chancery and deliver a copy to us, we will then have 20 days to file in the office of the Register in Chancery a list of the names and addresses of all stockholders who have demanded appraisal rights and have not reached an agreement with us as to the value of their shares. If the court decides it is appropriate, it has the power to conduct a hearing to determine whether the stockholders have fully complied with Section 262 of the Delaware General Corporation Law and whether they are entitled to appraisal rights. If ordered by the court, the Register in Chancery will then send notice of the time and place fixed for the hearing to all of the stockholders on the list provided by us. The court may also require you to submit your stock certificates to the Register in Chancery so that it can note on the certificates that an appraisal proceeding is pending. If you do not follow the court’s directions, you may be dismissed from the proceeding.

Appraisal of chancery shares. After the Court of Chancery determines which stockholders are entitled to appraisal rights, the court will appraise their shares of IMPAC stock. To determine the fair value of the shares, the court will consider all relevant factors except for any appreciation or depreciation due to the anticipation or accomplishment of the merger. After the Court of Chancery determines the fair value of the shares, it will direct us to pay that value to the stockholders who are entitled to appraisal rights. The court can also direct us to pay interest, simple or compound, on that value if the court determines that interest is appropriate. In order to receive the fair value for your shares, you must surrender your stock certificates to us.

The Court of Chancery could determine that the fair value of shares of IMPAC stock is more than, the same as, or less than the merger consideration. In other matter is presented, your signed proxy card giveswords, if you demand appraisal rights, you could receive less consideration than you would under the individuals namedmerger agreement.

Costs and expenses of appraisal proceeding. The costs of the appraisal proceeding may be assessed against IMPAC and the stockholders participating in the appraisal proceeding, as proxyholders the authorityCourt of Chancery deems equitable under the circumstances. You may also request that the court allocate the expense of the appraisal action incurred by any stockholder pro rata against the value of all of the shares entitled to appraisal.

Loss of stockholder’s rights. If you demand appraisal rights, after the closing of the merger you will not be entitled to:

If no petition for appraisal is filed within 120 days of the closing of the merger, or if you deliver a written withdrawal of your demand for appraisal, either within 60 days after the closing of the merger or with our written consent, then your rights to appraisal will cease and you will be entitled to receive the cash payment for your shares provided by Rule 14a-4(c)the terms of the merger agreement. However, an appraisal proceeding in the Court of Chancery cannot be dismissed without the court’s approval. The court may condition its approval upon any terms that it deems just.

If you fail to comply strictly with these procedures you will lose your appraisal rights. Consequently, if you wish to exercise your appraisal rights, we strongly urge you to consult a legal advisor before attempting to exercise your appraisal rights.

Material U.S. federal income tax consequences of the merger

The following is a summary of United States federal income tax consequences of the merger to our stockholders. The discussion is for general information only and does not purport to consider all aspects of United States federal income taxation that might be relevant to our stockholders. The discussion is based on the Internal Revenue Code of 1986, as amended, Treasury regulations, administrative rulings and court decisions in effect as of the date of this proxy statement, all of which are subject to change at any time, possibly with retroactive effect. The discussion applies only to stockholders who hold shares of our common stock as capital assets, and may not apply to shares of our common stock received in connection with the exercise of employee stock options or otherwise as compensation, or to certain types of stockholders (including insurance companies, mutual funds, tax-exempt organizations, financial institutions, broker-dealers, and persons who hold their shares as part of a hedge, straddle or conversion transaction) who may be subject to special rules. This discussion does not discuss the tax consequences to any stockholder who, for United States federal income tax purposes, is a non-resident alien individual, foreign corporation, foreign partnership or foreign estate or trust, and does not address any aspect of state, local or foreign tax laws.

The receipt of cash for shares of IMPAC common stock in the merger will be a taxable transaction for United States federal income tax purposes. In general, a stockholder who surrenders shares of our common stock for cash in the merger will recognize capital gain or loss for United States federal income tax purposes equal to the difference, if any, between the amount of cash received and the stockholder’s adjusted tax basis in the shares of our common stock surrendered. Gain or loss will be determined separately for each block of shares (i.e., shares acquired at the same cost in a single transaction) surrendered for cash in the merger. This gain or loss will be long-term capital gain or loss provided that a stockholder’s holding period for the shares is more than one year at the time of the consummation of the merger. Capital gains of individuals derived in respect of capital assets held for more than one year are eligible for reduced rates of taxation. There are limitations on the deductibility of capital losses.

Backup withholding may apply to the payments to which a holder of shares or other payee is entitled under the merger agreement, unless the stockholder or other payee provides a taxpayer identification number (social security number, in the case of individuals, or employer identification number, in the case of other stockholders), certifies that the number is correct, and otherwise complies with the backup withholding tax rules. Each of our stockholders and, if applicable, each other payee, should complete and sign the Substitute Form W-9 included as part of the letter of transmittal to be mailed to you shortly after completion of the merger in order to provide the information and certification necessary to avoid backup withholding tax, unless an exemption applies and is established in a manner satisfactory to the paying agent. Any amounts withheld under the backup withholding rules will be allowed as a refund or a credit against the holder’s United States federal income tax liability provided the required information is furnished to the Internal Revenue Service.

The United States federal income tax consequences set forth above are for general information purposes only and are not intended to constitute a complete description of all tax consequences relating to the merger. Because individual circumstances may differ, each stockholder is urged to consult the stockholder’s tax advisor regarding the applicability of the rules discussed above to the stockholder and the particular tax effects to the stockholder of the merger, including the application of state, local and foreign tax laws.

Litigation related to the merger

On January 21, 2005, an alleged holder of IMPAC common stock filed a purported class action lawsuit, “Stakely v. IMPAC Medical Systems, Inc., et al.” in California Superior Court for the County of Santa Clara. The complaint names as defendants IMPAC and each member of our board of directors. The complaint alleges that, in pursuing the merger with Elekta and approving the merger agreement, the directors violated their fiduciary duties to the holders of IMPAC common stock by, among other things, failing to implement a process designed to maximize stockholder value, engaging in self-dealing and securing benefits for certain officers and directors of IMPAC at the expense of the plaintiffs and other stockholders. The prayer for relief seeks a preliminary and permanent injunction to enjoin the company from consummating the merger, as well as attorneys’ fees and other remedies.

Regulatory matters

The proposed transaction is subject to the requirements of the Hart-Scott-Rodino Antitrust Improvements Act of 1976. The Hart-Scott-Rodino Act prevents certain transactions from being completed until required information and materials are furnished to the Antitrust Division of the Department of Justice and the Federal Trade Commission and the appropriate waiting periods expire or are terminated. On January 26, 2005, IMPAC and Elekta filed pre-merger notifications with the Department of Justice and the Federal Trade Commission. The waiting period will expire on February 27, 2005, unless earlier terminated, or extended by a request for additional information and materials by the Antitrust Division or the Federal Trade Commission.

The Antitrust Division of the Department of Justice or the Federal Trade Commission may challenge the merger on antitrust grounds either before or after expiration of the waiting period. Accordingly, at any time

before or after the completion of the merger, either the Antitrust Division of the Department of Justice or the Federal Trade Commission could take action under the antitrust laws. Other persons could take action under the antitrust laws, including seeking to enjoin the merger. Additionally, at any time before or after the completion of the merger, notwithstanding that the applicable waiting period expired or ended, any state could take action under the antitrust laws. A challenge to the merger could be made and if a challenge is made there is no assurance that we would prevail.

We are not aware of any other material governmental or regulatory approval required for completion of the merger, other than compliance with the applicable corporate law of Delaware.

If the merger is completed, IMPAC common stock will be delisted from the Nasdaq National Market and will be deregistered under the Securities Exchange Act of 1934 (the “Exchange Act”).1934.

THE MERGER AGREEMENT

This section of the document describes selected portions of the merger agreement. While we believe that the description covers the material terms of the merger agreement, this summary may not contain all of the information that is important to you. The merger agreement is attached to this document as Annex A and we urge you to carefully read this document in its entirety.

The merger and merger consideration

The merger agreement provides for the acquisition of IMPAC by Elekta to be effected through a merger of Merger Sub, a newly formed and indirect wholly owned subsidiary of Elekta, with and into IMPAC. As a result of the merger, Merger Sub will cease to exist, and IMPAC will survive the merger and will become an indirect wholly owned subsidiary of Elekta. The merger will be completed when all of the conditions to completion of the merger are satisfied or waived, and will become effective upon the filing of a certificate of merger with the Secretary of State of the State of Delaware.

At the effective time of the merger, each outstanding share of IMPAC common stock, other than shares held by stockholders who properly exercise and perfect their appraisal rights, will be converted into the right to receive $24.00 in cash, without interest and less applicable withholding taxes. At the effective time of the merger, all outstanding shares of IMPAC common stock will automatically be cancelled and no shares will remain outstanding.

Conversion of shares and procedures for exchange of stock certificates for cash

The conversion of your shares of IMPAC stock into the right to receive $24.00 per share in cash will occur automatically at the effective time of the merger. As soon as reasonably practicable after the effective time of the merger, [                    ], the paying agent, will send to each IMPAC stockholder as of the effective time a letter of transmittal and instructions for surrendering stock certificates in exchange for the merger consideration. Please do not surrender any of your IMPAC stock certificates until you receive the letter of transmittal and other materials for such surrender from the paying agent. After you deliver your IMPAC stock certificates to the paying agent along with an executed letter of transmittal and any other required documents, your IMPAC stock certificates will be canceled and you will be entitled to receive the cash payment of $24.00 per share, without interest and less applicable withholding taxes.

In the event of a transfer of ownership of shares of common stock which is not registered in our transfer records, payment of the merger consideration for the transferred shares may be made to the transferee if the stock certificate representing such shares is presented to the paying agent, accompanied by all documents reasonably required by the paying agent to evidence the transfer and evidence that any applicable stock transfer taxes relating to the transfer have been paid.

If your stock certificate has been lost, stolen or destroyed, the paying agent will deliver to you the applicable merger consideration for the shares represented by that certificate if:

Please do not send in your stock certificates now. You should deliver your stock certificates only pursuant to instructions set forth in the letter of transmittal that will be mailed to you after the effective time. In all cases, the merger consideration will be provided only in accordance with the procedures set forth in the letter of transmittal.

The paying agent will deliver to Elekta any funds made available to the paying agent which have not been disbursed to holders of IMPAC stock certificates 180 days after the effective time of the merger. Anyone still holding IMPAC stock certificates after that time may only seek payment of the merger consideration directly from Elekta.

The cash paid to you upon conversion of your shares of IMPAC common stock will be issued in full satisfaction of all rights relating to your shares of IMPAC common stock.

Treatment of IMPAC stock options

At the effective time of the merger, each outstanding option to purchase IMPAC common stock, including unvested options, with an exercise price less than $24.00 per share will be cancelled and the holder of such option will be entitled to receive a one-time cash payment (net of any statutory tax withholdings) equal to the number of shares of IMPAC stock subject to the option multiplied by the difference between $24.00 and the per share exercise price of the option. Each outstanding option to purchase IMPAC common stock with an exercise price equal to or greater than $24.00 per share will be cancelled without payment.

Treatment of IMPAC’s employee stock purchase plan

Our employee stock purchase plan will be terminated immediately prior to the effective time of the merger. Any purchase rights outstanding at the time of termination of the purchase plan will be exercised, and each share of IMPAC common stock acquired upon exercise of such purchase right will be converted in the merger into the right to receive $24.00 in cash, without interest and less applicable withholding taxes.

Representations and warranties

The merger agreement contains various customary representations and warranties that we made to Elekta and Merger Sub, including, among others, representations and warranties relating to:

The merger agreement also contains various customary representations and warranties that Elekta and Merger Sub made to us, including, among others, representations and warranties relating to:

The representations and warranties in the merger agreement are complicated and are not easily summarized. We urge you to read the sections of the merger agreement entitled “Representations and Warranties of the Company,” and “Representations and Warranties of Parent and Merger Sub” carefully.

Covenants regarding the conduct of IMPAC’s business

We have agreed that from the date of the merger agreement until the earlier of the termination of the merger agreement and the effective time of the merger, we will conduct our business only in the ordinary course consistent with past practice, and will use all reasonable efforts to preserve our current business organization, retain the services of our current key officers and employees and preserve the goodwill of those engaged in material business relationships with us. To that end, except as otherwise provided for in the merger agreement, we will not, without the prior consent of Elekta:

or authorize the issuance of any other securities in respect of, in lieu of or in substitution for shares of our capital stock, purchase, redeem or otherwise acquire any shares of our capital stock or any rights, warrants or options to acquire any such shares, except from holders of options to acquire our stock in full or partial payment of the exercise price payable by the holder upon exercise of the options;

These covenants are complicated and not easily summarized. We urge you to read the section of the merger agreement entitled “Conduct of Business of Company” carefully.

Restrictions on solicitation

Until the merger is completed or the merger agreement is terminated, we have agreed not to take any of the following actions directly or indirectly:

However, if we receive an unsolicited, written, bona fide acquisition proposal prior to consummation of the proposed merger with Elekta and if the conditions specified below are met, we may furnish the same information as was previously furnished to Elekta to, and enter into, maintain or continue discussions or negotiations with, any person that makes an acquisition proposal (provided that the person enters into a confidentiality agreement on terms at least as favorable to us as Elekta’s confidentiality agreement with us), but only after we have provided 24 hours advance notice to Elekta of our intention to do so. Before we may take any of the above actions, our board of directors must have reasonably determined in good faith, after consultation with and based upon the advice of our financial advisor and independent legal counsel, that the failure to take such actions would be reasonably likely to constitute a breach of its fiduciary duties to our stockholders, and that the acquisition proposal is a superior proposal, as defined below.

In addition, if our board of directors makes the determinations set forth in the preceding sentence, the board may (i) withdraw or modify its approval of the merger agreement and its recommendation in favor of the merger or (ii) approve or recommend the alternative acquisition proposal, provided that (a) at least three business days have elapsed following delivery to Elekta of written notice that our board has made the required determinations and (b) the board continues to reasonably believe at the end of such three business day period that the acquisition proposal constitutes a superior proposal. If we receive an acquisition proposal, then we must provide notice thereof (including the identity of the person making the proposal and the material terms of the proposal) to Elekta within 24 hours and keep Elekta informed of the status of such proposal. In any event, unless the merger agreement is terminated, we may not enter into a letter of intent, agreement in principle, acquisition agreement or other similar agreement relating to an acquisition proposal.

An “acquisition proposal” means any contract, proposal or other indication of interest from a third party regarding:

A “superior proposal” means an acquisition proposal involving at least two-thirds of the shares of our capital stock or all or substantially all of our assets that our board of directors determines, after consulting with our financial advisors and independent legal counsel, to be more favorable to our stockholders than the merger (after considering any adjustment to the terms and conditions of the merger in response to an acquisition proposal) and is reasonably likely of being completed.

Other agreements

Access to information. We have agreed to provide Elekta with reasonable access to our books and records, subject to confidentiality obligations and other restrictions.

Public announcements. We and Elekta have agreed to consult with each other before issuing, and provide the other party the opportunity to review and comment upon, any press release, SEC filing or other public statement regarding the proposed merger, and neither we nor Elekta shall issue any such press release or make any such public statement prior to such consultation, except as may be required by law or the rules of any national securities exchange or the Nasdaq National Market.

Consents, approvals and filings. We and Elekta have agreed to promptly make all required regulatory filings and to use commercially reasonable efforts to take all appropriate action necessary to consummate the merger, including obtaining all required consents and approvals.

Employee benefit matters. Elekta has agreed to honor all accrued obligations and benefits under our employee benefit plans and any employment or severance agreements between us and any of our current or former employees. Elekta has also agreed to offer our employees who continue to be employed by the surviving corporation employee benefits commensurate in all material respects with the benefits provided to Elekta’s U.S. employees. In addition, Elekta has agreed to pay retention bonuses to certain IMPAC managers and sales representatives in July 2006, or, in some cases, at Elekta’s option, in October 2005, and to provide additional incentives to IMPAC sales personnel for sales to certain customers.

Indemnification of officers and directors. See “The Merger—Interests of executive officers and directors of IMPAC in the merger” on page 27 for a summary of this provision.

Section 16 matters. We have agreed to take all such steps as may be required (to the extent permitted under applicable law) to cause any dispositions of our common stock (including derivative securities with respect thereto) in connection with the merger by each individual who is subject to the reporting requirements of Section 16(a) of the Securities Exchange Act of 1934 with respect to our common stock to be exempt under Rule 16b-3 promulgated under the Exchange Act.

Conditions to closing the merger

The parties’ respective obligations to complete the merger are subject to the satisfaction or waiver of each of the following conditions:

Elekta’s obligations to complete the merger are subject to the satisfaction or waiver of each of the following additional conditions:

A:

To be considered for presentation correct which, individually or in the proxy statement for IMPAC’s 2005 Annual Meetingaggregate, could not reasonably be expected to have a material adverse effect on us (provided that this exception does not apply to representations and warranties relating to our capital structure) or prevent or materially delay the closing of Stockholders, a stockholder proposal must be received at IMPAC’s offices no sooner than October 20, 2004 nor any later than November 19, 2004.the merger;

2Our obligations to complete the merger are subject to the satisfaction or waiver of each of the following additional conditions:

For purposes of the merger agreement, a “material adverse effect” with respect to us means a material adverse effect (i) on our ability to perform our obligations under the merger agreement or to consummate the transactions contemplated thereby, or (ii) on us resulting from a change, development or event involving our business, financial condition or results of operation, provided that any decrease in the market price or trading volume of our common stock, in and of themselves, will not be deemed to be a material adverse effect. In addition, a material adverse effect does not include such an effect resulting from:

Termination of the merger agreement

The merger agreement may be terminated at any time prior to the effective time of the merger, notwithstanding adoption of the merger agreement by our stockholders:

Termination fee

We are obligated to pay Elekta a termination fee equal to $10 million in cash if the merger agreement is terminated because our board of directors has withdrawn or modified in a manner adverse to Elekta its approval or recommendation in favor of the merger or approved, endorsed or recommended an alternative acquisition proposal. We are also obligated to pay Elekta the $10 million termination fee if (A) Elekta terminates the merger agreement because there is (i) a material inaccuracy in any of our representations or warranties or a material breach of our covenants and agreements in the merger agreement or (ii) our stockholders fail to adopt the merger agreement by May 31, 2005 and (B) within 12 months following such termination, we consummate a business combination.

Our board of directors recommends that you vote “FOR” the proposal to approve the acquisition of IMPAC, including the merger, and to approve and adopt the merger agreement.

PROPOSAL ONE2—ADJOURNMENT OF THE IMPAC ANNUAL MEETING

If at the IMPAC annual meeting on [                    ], 2005, the number of shares of IMPAC common stock present or represented and voting in favor of approval of the merger and adoption of the merger agreement is insufficient to approve the merger under Delaware law and under our certificate of incorporation, our management may move to adjourn the annual meeting in order to enable our board of directors to continue to solicit additional proxies in favor of the merger and adoption of the merger agreement. In that event, we will ask you to vote only upon the adjournment proposal, and not the merger proposal.

In this proposal, we are asking you to authorize the holder of any proxy solicited by our board of directors to vote in favor of adjourning the annual meeting, and any later adjournments, to a date or dates not later than May 31, 2005. If the stockholders approve the adjournment proposal, we may adjourn the annual meeting, and any adjourned session of the annual meeting, to a date not later than May 31, 2005 and use the additional time to solicit additional proxies in favor of the merger proposal, including the solicitation of proxies from stockholders that have previously voted against the merger proposal. Among other things, approval of the adjournment proposal could mean that, even if we had received proxies representing a sufficient number of votes to defeat the merger proposal, we may adjourn the annual meeting without a vote on the merger proposal and seek to convince the holders of those shares to change their votes to votes in favor of the merger proposal.

The adjournment proposal requires the approval of a majority of the votes represented in person or by proxy at the annual meeting and eligible to vote on the proposal. Accordingly, broker non-votes will have no effect on the outcome of this proposal, but abstentions will have the effect of a vote against this proposal. No proxy that is specifically marked “AGAINST” approval of the merger proposal will be voted in favor of the adjournment proposal, unless it is specifically marked “FOR” the discretionary authority to adjourn the annual meeting to a later date.

Our board of directors believes that if the number of shares of IMPAC common stock present or represented at the annual meeting and voting in favor of the merger is insufficient to approve the merger proposal, it is in the best interests of our stockholders to enable the board, for a limited period of time, to continue to seek to obtain a sufficient number of additional votes in favor of the merger to bring about its approval.

Our board of directors recommends that you vote “FOR” the proposal to authorize the adjournment of the annual meeting to a date or dates not later than May 31, 2005.

PROPOSAL 3—ELECTION OF DIRECTORS

IMPAC’s Boardboard of Directorsdirectors is divided into three classes serving staggered three-year terms. At the Annual Meeting,annual meeting, you and the other stockholders will elect two individuals to serve as directors until the 2007 Annual Meeting.2008 annual meeting. If the merger is completed, the nominees for director elected by our stockholders at the annual meeting will serve as directors only until the effective time of the merger. Each of the nominees is now a member of our Boardboard of Directors.directors.

The individuals named as proxyholders will vote your proxy for the election of the two nominees unless you direct them to withhold your votes. If any nominee becomes unable to serve as a director before the meeting (or decides not to serve), the individuals named as proxyholders may vote for a substitute. We recommend a

Our board of directors recommends that you voteFOR “For” each of the nominees.

Below are the names and ages of the nominees and directors, the years they became directors, their principal occupations or employment for at least the past five years and certain of their other directorships.

Nominees for Electionelection for a Three-Year Term Endingthree-year term ending with the 2007 Annual Meeting2008 annual meeting

Directors continuing in office until the 2006 annual meeting

•      Robert J. Becker, M.D.		Age 82. Dr. Becker has been a director of IMPAC since June 1996. Dr. Becker has served as the President of Becker Consulting Corporation, a healthcare consulting firm, since 1990. Prior to founding Becker Consulting, Dr. Becker founded HealthCare Compare Corporation, a company specializing in healthcare utilization review (now First Health Group Corporation, a health benefits company) and served as Chairman from 1982 to 1990. Dr. Becker holds an M.D. degree from the Medical College of Wisconsin.
•      Gregory T. Schiffman		Age 47. Mr. Schiffman has been a director of IMPAC since February 2003. Mr. Schiffman has served as Senior Vice President and Chief Financial Officer of Affymetrix, Inc., a biotechnology company, since October 2002, and served as Vice President and Chief Financial Officer of Affymetrix from August 2001 through October 2002. From March 2001 through August 2001, he served as Vice President, Finance of Affymetrix. Prior to joining Affymetrix, Mr. Schiffman was Vice President, Controller of Applied Biosystems from October 1998. From 1987 through 1998, Mr. Schiffman held various managerial and financial positions at Hewlett Packard Company. Mr. Schiffman holds an M.B.A. degree from J.L. Kellogg Graduate School of Management at Northwestern University and a B.S. degree in accounting from DePaul University.

Directors continuing in office until the 2007 annual meeting

Directors Continuing in Office Until the 2005 Annual Meeting

3Except for Joseph K. Jachinowski and James P. Hoey, who are brothers-in-law, there are no family relationships among any of our directors or executive officers.

Directors Continuing in Office Until the 2006 Annual Meeting

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Board Independenceindependence

Upon consideration of the criteria and requirements regarding director independence set forth in NASD Rules 4200 and 4350, the Boardboard of Directorsdirectors has determined that each of Dr. Rose, Mr. Avis, Dr. Becker and Mr. Schiffman has met the standards of independence established by the NASD.

Committees of the Boardboard of Directors; Meetingsdirectors; meetings

During the fiscal year ended September 30, 2003,2004, the Boardboard of directors held four8 meetings. EachExcept for Robert J. Becker, each of the directors attended at least 75% of the aggregate number of meetings of the Boardboard and the committees of the Boardboard on which he or she served. The Boardboard has an Audit Committee and a Compensation Committee. The Boardboard has adopted a written Audit Committee Charter, a copy of which is attached as Appendix A.Charter. The Boardboard does not have a nominating committee or a committee performing the functions of a nominating committee.

Audit Committee

The responsibilities of the Audit Committee include:

For a complete listing of the Audit Committee’s responsibilities, see the Audit Committee Charter, attachedwhich was filed with the Securities and Exchange Commission as Appendix Aan attachment to thisIMPAC’s proxy statement.statement for the 2004 annual meeting of stockholders and is available at www.sec.gov.

The current members of the Audit Committee are Gregory M. Avis, Christopher M. Rose and Gregory T. Schiffman (Chairman), three independent directors. The Audit Committee met four26 times during fiscal year 2003.2004. Upon consideration of the attributes of an audit committee financial expert as set forth in Item 401(h) of Regulation S-K promulgated by the Securities and Exchange Commission, the Boardboard of Directorsdirectors determined that Mr. Schiffman possessed these attributes through his experience as Senior Vice President and Chief Financial Officer of Affymetrix, Inc., and he was designated as the Audit Committee financial expert. Mr. Schiffman is independent as such term is defined in Item 7(d)(3)(iv)(A) of Schedule 14A under the Securities Exchange Act of 1934, as amended.Act.

Compensation Committee

The responsibilities of the Compensation Committee include:

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The current members of the Compensation Committee are Gregory M. Avis (Chairman), Robert J. Becker and Christopher M. Rose, three independent directors. The Compensation Committee met one time4 times during fiscal year 2003.2004.

Director Nominationsnominations

Due to the limited size of, and lack of turnover in, our Board,board, the Boardboard has determined that it is not appropriate at this time to establish a separate Nominating Committee.nominating committee. Potential candidates are discussed by the entire Board, and directorboard. A majority of the members of our board have been determined by the board to be independent under the standards established by the NASD. Director nominees are then selected by a majority of the independent directors meeting in executive session. Both of the nominees included on this year’s proxy card are executive officers and/or directors standing for re-election.

The Boardboard believes that it is necessary that thea majority of the Board mustmembers of the board be composed of independent directors as set forth in NASD Rules 4200 and 4350 and desirable to have at least one financial expert on the Boardboard as set forth in Section 401(h) of Regulation S-K promulgated by the SEC.Securities and Exchange Commission. When considering potential director candidates, the Boardboard also considers the candidate’s character, judgment, diversity, age, skills, including financial literacy, and experience in the context of the needs of the Board. To date, the company has not paid any fees to any third party to identify or evaluate or assist in identifying or evaluating potential nominees.board.

Our bylaws include a procedure whereby our stockholders can nominate persons for election to the Board.board. A stockholder may recommend nominees for director by notifying our Corporate Secretary in writing (at our Mountain View headquarters) not less than 90 nor more than 120 days before the anniversary of the prior year’s annual meeting. The Boardnotice must include the full name, age, business and residence addresses, principal occupation or employment of the nominee, the number of shares of IMPAC common stock the nominee beneficially owns, any other information about the nominee that must be disclosed in proxy solicitations under Regulation 14A of the Exchange Act, and the nominee’s written consent to the nomination and to serving as a director, if elected. The board will consider director candidates recommended by our stockholders in a similar manner as those recommended by members of management or other directors. The notice procedures are described above under the heading “General Information.” To date, we have not received any recommended nominees from any non-management stockholder or group of stockholders that beneficially owns five percent of our voting stock.

Shareholder CommunicationsStockholder communications with Directorsdirectors

Our Boardboard of Directorsdirectors welcomes communications from our stockholders. Stockholders may send communications to the Boardboard of Directors,directors, or to any Directordirector in particular, c/o IMPAC Medical Systems, Inc., 100 West Evelyn Avenue, Mountain View, CA 94041. Any correspondence addressed to the Boardboard of Directorsdirectors or to any one of our Directorsdirectors care of our offices is forwarded by us to the addressee without review by management.

We encourage, but do not require, the members of our Boardboard of Directorsdirectors to attend our annual meetings. TheThree members of our board of directors attended the 2004 Annual Meeting will be IMPAC’s first annual meeting since our initial public offering in November 2002.

6of stockholders.

STOCK OWNERSHIP

Beneficial Ownershipownership of Certain Stockholders, Directorscertain stockholders, directors and Executive Officersexecutive officers

The following table sets forth information regarding the beneficial ownership of our common stock as of December 15, 2003January 31, 2005 by:

Except as otherwise noted, the address of each person listed in the table is c/o IMPAC Medical Systems, Inc., 100 West Evelyn Avenue, Mountain View, California 94041. The table includes all shares of common stock issuable within 60 days of December 15, 2003January 31, 2005 upon the exercise of options beneficially owned by the indicated stockholders on that date. Beneficial ownership is determined in accordance with the rules of the Securities and Exchange Commission and includes voting and investment power over such shares. To our knowledge, except under applicable community property laws or as otherwise indicated, the persons named in the table have sole voting and sole investment control regarding all shares beneficially owned. The applicable percentage of ownership for each stockholder is based on 9,791,4609,949,964 shares of common stock outstanding as of December 15, 2003,January 31, 2005, together with applicable options for that stockholder. Shares of common stock issuable upon exercise of options beneficially owned were deemed outstanding for the purpose of computing the percentage ownership of the person holding these options and other rights, but are not deemed outstanding for computing the percentage ownership of any other person.

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		Number of Shares Beneficially Owned		Number of Shares Beneficially Owned by Filing Person with
				Sole Voting Power		Shared Voting Power		Sole Dispositive Power		Shared Dispositive Power
Maurice J. Duca		239,360		74,897		164,463		74,897		164,463
Steven L. Karan		15,749		15,749		—		15,749		—
Timothy K. Bliss		15,000		15,000		—		15,000		—
William R. Rauth III		64,099		64,099		—		64,099		—
William Rauth IV		1,000		1,000		—		1,000		—
Carol A. Streed		250		250		—		250		—
Luise M. Phelps		1,055,008		1,055,008		—		1,055,008		—
IGSB, LLC		1,051,008		1,051,008		—		1,051,008		—
IGSB IEP I, L.P		1,051,008		1,051,008		—		1,051,008		—
Kelly Fox Flint		100		100		—		100		—

7003,400 shares of common stock of IMPAC reported by Alfred K. Herbert and Linda J. Herbert are held by The Herbert Family Trust and reported by Alfred Herbert and Linda Herbert in their capacities as co-trustees. Alfred Herbert and Linda Herbert share voting and disposition powers with respect to such shares.

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66,463154,463 shares of common stock of IMPAC reported by Suzanne S. Duca and Maurice J. Duca are held by the Duca Partnership and reported by Suzanne Duca and Maurice Duca in their capacities as trustees of The Maurice J. Duca Family Trust and The Suzanne S. Duca Separate Property Trust, respectively, the general partners of the Duca Partnership. Suzanne Duca and Maurice Duca share voting and disposition powers with respect to such securities.

2,095 shares of common stock of IMPAC reported by Maurice Duca are held by the Marie Duca Educational Trust and reported by Maurice Duca in his capacity as trustee.

12,20117,701 shares of common stock of IMPAC reported by Lindsey Duca are held by The Lindsey Duca Trust and reported by Lindsey Duca in her capacity as trustee.

72,802 shares of common stock of IMPAC reported by Maurice J. Duca are held by the Investment Group of Santa Barbara Money Purchase Pension Plan FBO Maurice J. Duca and reported by Maurice J. Duca in his capacity as trustee.

64,099 shares of IMPAC common stock reported by William R. Rauth III are held as follows: 20,699 3,500shares by The Lindsey Duca Trust #2, 9,000 shares by The Michael Duca Trust #1 and 29,400 shares by The Michael Duca Trust #2. All of such shares are reported by William R. Rauth III in his capacity as trustee.

5,000 shares of common stock of IMPAC reported by William R. Rauth III are held by The Lindsey Duca Trust #2, The Michael Duca Trust #1 and The Michael Duca Trust #2, respectively, and reported byCity National Bank as Trustee for the Stradling Yocca Carlson & Rauth Profit Sharing Plan FBO William R. Rauth III. William R. Rauth III in his capacity ashas sole investment control over such shares without consultation with the trustee.

1,350 shares of common stock of IMPAC reported by Luise M. Phelps806,563 and IGSB, LLC are held by IGSB/Cimarron Bonus Fund, LLC and reported by IGSB, LLC, in its capacity as Manager of IGSB/Cimarron Bonus Fund, LLC and by Luise Phelps in her capacity as President of IGSB, LLC.

236,180 and 65,000244,445 shares of common stock of IMPAC are held by IGSB-Karan I, LLC and IGSB-Keenan I, LLC, respectively, and are reported by IGSB IEP I, L.P. in its capacity as a controlling member of IGSB-Karan I, LLC and IGSB-Keenan I, LLC. Such 301,1801,051,008 shares of common stock of IMPAC are also reported by IGSB, LLC, in its capacity as the General Partner of IGSB IEP I, L.P. and by Luise Phelps in her capacity as President of IGSB, LLC.

5,00010,000 shares of common stock of IMPAC reported by ThomasSuzanne S. Duca and Maurice J. RauthDuca are held by The Rauth, Trabert, Holcomb & Seto Retirement Trustthe LaCentra-Sumerlin Charitable Remainder Unitrust and reported by Thomas RauthSuzanne S. Duca and Maurice J. Duca in his capacitytheir capacities as trustee.co-trustees. Suzanne S. Duca and Maurice J. Duca share voting and disposition powers with respect to such securities.

The address of Cimarron Management Company, Inc., and of each of the filing persons above is Cimarron Management Company, Inc., 1485 East Valley Road, Suite H, Santa Barbara, California 93108.

Change in control and voting arrangements. Please see the sections titled “The Merger” on page 14, “The Merger Agreement” on page 33, “The Merger—Interests of executive officers and directors of IMPAC in the merger” on page 27 and “The Merger—Stockholder agreements” on page 26.

Section 16(a) Beneficial Ownership Reporting Compliancebeneficial ownership reporting compliance

Under U.S. securities laws, directors, certain executive officers and persons holding more than 10% of IMPAC’s common stock must report their initial ownership of the common stock and any changes in that ownership to the Securities and Exchange Commission. The Securities and Exchange Commission has designated specific due dates for these reports and IMPAC must identify in this Proxy Statement those persons who did not file these reports when due. Based solely on its review of copies of the reports filed with the Securities and Exchange Commission and written representations of its directors and executive officers, IMPAC believes all persons subject to reporting filed the required reports on time in fiscal year 2003,2004, except for Joseph K. Jachinowski, whoselate filings made by Christopher M. Rose, Gregory M. Avis, Robert J. Becker and Gregory T. Schiffman, each of whom filed a late Form 4 statementin May 2004 reporting stock option grants received in connection with the 2004 annual meeting of changes in beneficial ownership reflecting the exercise by his wife of 15,000 options deemed to be indirectly beneficially owned by him was duestockholders on February 16, 2003, but was filed in March 2003.

917, 2004.

COMPENSATION OF DIRECTORS AND THE NAMED EXECUTIVE OFFICERS

Compensation of Directorsdirectors

Cash Compensation. Except for reimbursement for reasonable travel expenses relating to attendance at board meetings, employee directors are not compensated for their services as directors. Directors who are non-employees receive $500 per board meeting attended. Mr. Avis has not received any director fees.The chair of the Audit Committee also receives an annual retainer of $10,000.

Stock Options. Under our 2002 Stock Plan, each of our non-employee directors receives an option grant to purchase 25,000 shares of our common stock at fair market value on the grant date on the date they join the board. Non-employee directors also receive a stock option grant on the date of each annual meeting under our 2002 Stock Plan to purchase 5,000 shares of our common stock at fair market value on the grant date, provided he or she continues to serve on the Boardboard after such annual meeting. EachAssuming the re-election of ourall non-employee directors, each will receive such a grant on the date of this year’s Annual Meeting, except for Mr. Avis, who has elected not to receive any options in connection with his service as a director.annual meeting. Non-employee director options have a term of ten years and expire within 90 days of the director’s termination of service or one year if such termination is due to death or disability. The initial option grant vests as to 25% of the shares on the first anniversary of the date of grant and thereafter in 36 equal monthly installments, provided the optionee is serving as a director of IMPAC. All subsequent stock option grants to non-employee directors are fully vested upon grant. Employee directors are eligible to participate in our 2002 Stock Plan and, subject to stock ownership limits imposed by the Internal Revenue Service, our 2002 Employee Stock Purchase Plan.

Mr. Schiffman received an additional grant of options to purchase 10,000 shares of IMPAC’s common stock on September 2, 2004 at the fair market value on that date.

Compensation of the Named Executive Officersnamed executive officers

SUMMARY COMPENSATION TABLE

The following table provides summary information concerning the compensation paid during the fiscal yearyears ended September 30, 2003 and September 30, 2004 to the Chief Executive Officer and each of our other three executive officers. We refer to these individuals as the “named executive officers” elsewhere in this Proxy Statement.proxy statement.

(2)	Includes payments for certain automobile expenses and $23,717 paid to executive as reimbursement for taxes incurred upon the receipt of company-provided benefits.

(3)	Includes $7,500 of company contributions to our 401(k) plan and a bonus payment of $35,447payments totaling $22,398 to cover term life, variable universal life and disability insurance premiums.

(3)(4)

Includes payments made for certain automobile expenses and $25,636 paid to executive as reimbursement for taxes incurred upon the receipt of company-provided benefits.

(5)	Includes $10,250 of company contributions to our 401(k) plan and payments totaling $22,398 to cover term life, variable universal life and disability insurance premiums.

(6)	Includes payments for certain automobile expenses and $22,653 paid to executive as reimbursement for taxes incurred upon the receipt of company-provided benefits.

(7)	Includes $7,500 of company contributions to our 401(k) plan and payments totaling $21,265 to cover term life, variable universal life and disability insurance premiums.

(8)	Includes payments made for certain automobile expenses and $24,376 paid to executive as reimbursement for taxes incurred upon the receipt of company-provided benefits.

(9)	Includes $10,250 of company contributions to our 401(k) plan and payments totaling $21,265 to cover term life, variable universal life and disability insurance premiums.

(10)	Includes payments for certain automobile expenses and $22,666 paid to executive as reimbursement for taxes incurred upon the receipt of company-provided benefits.

(11)	Includes $7,500 of company contributions to our 401(k) plan and payments totaling $21,139 to cover term life, variable universal life and disability insurance premiums.

(12)	Includes payments for certain automobile expenses and $24,380 paid to executive as reimbursement for taxes incurred upon the receipt of company-provided benefits.

(13)	Includes $10,250 of company contributions to our 401(k) plan and payments totaling $21,139 to cover term life, variable universal life and disability insurance premiums.

(14)	Represents $7,500 of company contributions to our 401(k) plan.

(15)	Includes $10,497 of company contributions to our 401(k) plan.

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OPTION/SAR GRANTS IN LAST FISCAL YEAR

The following table sets forth certain information regarding the stock options granted to each named executive officer during the fiscal year ended September 30, 2003.2004. None of such persons received awards of stock appreciation rights during fiscal 2003.2004.

to forecast possible future appreciation, if any, of our stock price. Actual gains, if any, on stock option exercises are dependent on the future performance of our common stock as well as the option holder’s continued employment through the vesting period. The potential realizable value calculation assumes that the optionholder waits until the end of the option term to exercise the option.

AGGREGATED OPTION/SAR EXERCISES IN LAST FISCAL YEAR AND FISCAL YEAR-END

OPTIONS/SAR VALUES

The following table provides summary information regarding options to purchase IMPAC common stock that were exercised by the named executive officers during the fiscal year ended September 30, 20032004 and the number and value of unexercised in the money IMPAC options held by the named executive officers at September 30, 2003.2004. The closing price per share of our common stock on September 30, 20032004 was $17.89.$13.37.

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CERTAIN TRANSACTIONS

Compensation Committee Interlockscommittee interlocks and Insider Participationinsider participation

The members of the Compensation Committee of our board of directors are Gregory M. Avis, Robert J. Becker and Christopher M. Rose. None of these individuals has at any time been an officer or employee of ours or any of our subsidiaries.

Management Indebtedness, Certain Relationshipsindebtedness, certain relationships and Related Transactionsrelated transactions

During fiscal 2003,2004, we did not engage in any transaction or series of similar transactions in which the amount involved exceeded or exceeds $60,000 and in which any of our directors or executive officers, any holder of more than 5% of any class of our voting securities or any member of the immediate family of any of the foregoing persons had or will have a direct or indirect material interest, nor was any director or executive officer or any of their family members indebted to us or any of our subsidiaries in any amount in excess of $60,000 at any time, other than the transactionstransaction described below.

On February 14, 2003,April 12, 2004, Suzanne Hoey Jachinowski, our Vice PresidentDirector of Product Marketing, the wife of Joseph K. Jachinowski, our President and Chief Executive Officer, and the sister of James P. Hoey, our Executive Vice President and Chief Operations Officer, exercised options to purchase 5,000 shares of our common stock at an exercise price of $1.34 per share and options to purchase 10,000 shares of our common stock at an exercise price of $3.23$0.32 per share.

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PROPOSAL TWO

AMENDMENT OF THE 2002 STOCK PLANCOMPENSATION COMMITTEE REPORT

General

This is the first time that our public stockholders will be asked to approve the IMPAC Medical Systems, Inc. 2002 Stock Plan. Our Board adopted the IMPAC Medical Systems, Inc. 2002 Stock Plan on May 31, 2002Overview, philosophy and amended and restated the plan on November 15, 2002 (the “Existing Plan”). The Existing Plan was approved by our stockholders on November 15, 2002. Subject to the approval of our stockholders, our Board amended and restated the Existing Plan on November 18, 2003. The amendment and restatement of the Existing Plan requires stockholder approval. At the Annual Meeting of Stockholders, stockholders will be asked to approve the amendment and restatement of the Existing Plan (the “Plan”). The Existing Plan was amended and restated primarily to add stock units and stock appreciation rights to the types of awards that may be granted under the plan. The Existing Plan only provides for the grant of stock options and stock purchase rights. Stock purchase rights are rights to acquire restricted stock. No other material changes were made to the Existing Plan. The term of the Plan remains the same and currently provides that the Plan will terminate on May 31, 2012 unless sooner terminated by our Board.

The Plan’s effectiveness is dependent on the approval of our stockholders at the Annual Meeting of Stockholders.

The following is a summary of the principal features of the Plan. The Plan is attached to this proxy statement as Appendix B. As of December 15, 2003, the fair market value of a share of our common stock (“Share”) was $26.27.