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                                                                Exhibit 10.16(a)



                           SHARE REPURCHASE AGREEMENT

         This SHARE REPURCHASE AGREEMENT (this "AGREEMENT") is made as of
October 10, 2001 between JOHN A. FRIEDE, in his individual capacity
("STOCKHOLDER"), and NOMOS CORPORATION (the "COMPANY").

                                   BACKGROUND

         A. Stockholder is the holder of an option (the "OPTION") to purchase
917,500 shares (the "SHARES") of the Company's common stock, par value $.0001
per share (the "COMMON STOCK"), at a purchase price of $.50 per share, which
Option is currently one-third vested.

         B. Stockholder desires to exercise the Option in full, and the Company,
pursuant to resolutions of the Board of Directors (the "BOARD") dated of even
date herewith, has authorized such exercise; provided that, Stockholder enter
into this Agreement for the purpose of (a) subjecting the unvested Shares to
repurchase by the Company, and (b) limiting the transferability of such Shares,
in each case for a period corresponding to the vesting schedule under the
Option.

                                    AGREEMENT

         The parties hereto, intending to be legally bound, agree as follows:

         1. UNVESTED SHARES. As used in this Agreement, the term "UNVESTED
SHARES" shall mean, initially, all of the Shares; PROVIDED, that so long as no
Repurchase Event (as defined in Section 3 below) has occurred, then:

            (a) on December 15, 2001, one-third of the Shares shall
automatically vest and shall no longer be deemed to be "Unvested Shares"
hereunder;

            (b) on December 15, 2002, the remaining one-third of the Shares
shall automatically vest and shall no longer be deemed to be "Unvested Shares"
hereunder.

In addition, in the event that a Repurchase Event occurs, any Unvested Shares
that are not purchased by the Company in accordance with Section 3 of this
Agreement shall automatically vest and shall no longer be deemed "Unvested
Shares."

         2. RESTRICTIONS. Stockholder shall have all rights and privileges of a
stockholder of the Company as to the Unvested Shares, except that the following
restrictions shall apply:

            (a) No Unvested Shares may be sold, transferred, assigned, pledged
or otherwise encumbered or disposed of, any transfer made or purportedly made in
violation of this restriction shall be null and void, and the Company shall not
register or record such attempted transfer in its books and records;

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            (b) Each Unvested Share shall be subject to repurchase by the
Company in accordance with Section 3 of this Agreement;

            (c) As security for the faithful performance of this Agreement,
Stockholder, immediately upon receipt of any certificate representing Unvested
Shares, shall deliver such certificate, together with one or more stock powers
endorsed in blank by Stockholder to the Secretary of the Company to be held in
custody by the Secretary; and

            (d) Each certificate representing Unvested Shares shall bear
substantially the following legend, which shall be in addition to any other
legends required by law or contract:

            THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO
            REPURCHASE BY NOMOS CORPORATION AND ARE SUBJECT TO TRANSFER
            RESTRICTIONS, AS PROVIDED IN A SHARE REPURCHASE AGREEMENT AMONG
            NOMOS AND THE HOLDER HEREOF, A COPY OF WHICH IS ON FILE WITH THE
            SECRETARY OF NOMOS.

         Upon the vesting of any Shares previously constituting Unvested Shares,
the Secretary shall, at Stockholder's request, deliver to Stockholder a
certificate or certificates representing such vested Shares, which shall be free
of the legend described in Section 2(d) of this Agreement.

         3. UNVESTED SHARE PURCHASE RIGHTS. In the event of the voluntary or
involuntary departure, resignation, or termination of Stockholder from his
position as a member of the Board, for whatever reason except death (any such
event, a "REPURCHASE EVENT"), all Unvested Shares held by Stockholder shall be
subject to purchase by the Company pursuant to the following terms and
conditions of this Section 3.

            (a) The Company may, but shall not be obligated to, purchase some or
all of such Unvested Shares by giving written notice thereof to Stockholder
within thirty (30) days after the Repurchase Event, specifying (i) the number of
Unvested Shares the Company wishes to purchase, and (ii) the date on which the
Company desires to purchase such Unvested Shares, which date shall not be later
than (90) days following the date on which such notice is given.

            (b) The closing of the purchase of any Unvested Shares pursuant to
this Section 3 shall be held at the principle executive offices of the Company
on the date specified in the notice given pursuant to Section 3(a) of this
Agreement or on such other date as may be agreed to in writing by the parties.
At any such closing, (i) the Company shall deliver to Stockholder the Repurchase
Price (as defined in Section 3(c) of this Agreement) for such Unvested Shares
and (ii) the Secretary of the Company shall surrender for cancellation, pursuant
to the aforementioned stock power(s), the certificate(s) representing such
Unvested Shares.

            (c) The purchase price (the "REPURCHASE PRICE") to be paid by the
Company to Stockholder for the purchase of any Unvested Shares shall be $0.50
per share.


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            4. TERMINATION. This Agreement shall automatically terminate upon
the earlier of (i) the date on which there are no longer any Unvested Shares,
(ii) the date on which all of the Unvested Shares are repurchased by the Company
in accordance with Section 3 hereof, or (iii) the death of Stockholder. Upon
termination of this Agreement, the terms and conditions contained herein shall
terminate and no longer be of any force or effect, except for any rights arising
from the prior breach of this Agreement to the extent such rights have not been
expressly waived by the non-breaching party.

            5. NOTICES. All notices, consents, requests, demands and other
communications required or permitted hereunder:

                  (i) shall be in writing;

                  (ii) shall be sent by messenger, certified or registered
United States mail, a reliable express delivery service or telecopier (with a
copy sent by one of the foregoing means), charges prepaid as applicable, to the
appropriate address(es) or number(s) set forth below; and

                  (iii) shall be deemed to have been given on the date of
receipt by the addressee (or, if the date of receipt is not a business day, on
the first business day after the date of receipt), as evidenced by (A) a receipt
executed by the addressee (or a responsible person in his or her office) or a
notice to the effect that such addressee refused to accept such communication,
if sent by messenger, United States mail or express delivery service, or (B) a
receipt generated by the sender's telecopier showing that such communication was
sent to the appropriate number on a specified date, if sent by telecopier.

         If to the Company, all such communications shall be sent to the
following address (or such other address as may be provided by the Company to
Stockholder):

                  NOMOS Corporation
                  2591 Wexford Bayne Road
                  Sewickley, PA 15143
                  Attn: Secretary

         If to Stockholder, to the address or number set forth in the records of
the Company for the purpose of giving notice to Stockholder.

         6. NO RIGHT TO BOARD MEMBERSHIP. STOCKHOLDER ACKNOWLEDGES AND AGREES
THAT THIS AGREEMENT DOES NOT AFFORD STOCKHOLDER ANY RIGHT TO CONTINUED
MEMBERSHIP ON THE BOARD.

         7. MISCELLANEOUS. This Agreement: (a) may be amended only by a writing
signed by each of the parties; (b) may not be assigned, pledged or otherwise
transferred, whether by operation of law or otherwise, without the prior consent
of the other party; (c) may be executed in several counterparts, each of which
is deemed an original but all of which constitute one and the same instrument;
(d) contains the entire agreement of the parties with respect to the


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transactions contemplated hereby and supersedes all prior written and oral
agreements, and all contemporaneous oral agreements, relating to such
transactions; (e) is governed by, and will be construed and enforced in
accordance with, the laws of the State of Delaware without giving effect to any
conflict of laws rules; and (f) is binding upon, and will inure to the benefit
of, the parties and their respective heirs, successors and permitted assigns.
The waiver by a party of any breach or violation of any provision of this
Agreement will not operate as, or be construed to be, a waiver of any subsequent
breach or violation hereof.



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         IN WITNESS WHEREOF, the parties hereto have executed this Share
Repurchase Agreement as of the date first written above.


                                        /s/ John A. Friede
                                        ----------------------------------------
                                        John A. Friede
                                        in his individual capacity



                                        NOMOS CORPORATION


                                        By: /s/ John W. Manzetti
                                           -------------------------------------

                                        Name: John W. Manzetti
                                             -----------------------------------

                                        Title: President and Chief
                                               Executive Officer
                                              ----------------------------------


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