Document:

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[NOTE:  the Warrant issued to Safeguard Delaware, Inc. omits Sections 18(a)
        and (b)]

THESE SECURITIES HAVE NOT BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE
COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN
EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
"SECURITIES ACT"), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT
TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO
AN AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE
REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH
APPLICABLE STATE SECURITIES LAWS.

THIS WARRANT DOES NOT REQUIRE PHYSICAL SURRENDER OF THE WARRANT UPON ANY PARTIAL
EXERCISE HEREOF. AS A RESULT FOLLOWING ANY EXERCISE OF ANY PORTION OF THIS
WARRANT, THE OUTSTANDING NUMBER OF SHARES ISSUABLE UPON EXERCISE OF THIS WARRANT
MAY BE LESS THAN THE AMOUNT OF SHARES SET FORTH BELOW.

                          COMMON STOCK PURCHASE WARRANT

                           TO PURCHASE [_____________]
                            SHARES OF COMMON STOCK OF

                       CHROMAVISION MEDICAL SYSTEMS, INC.

        THIS CERTIFIES that, for value received, ______________ and its
        successors and assigns (the "HOLDER") is entitled, upon the terms and
        subject to the conditions hereinafter set forth, at any time and from
        time to time on and after the date hereof ("COMMENCEMENT DATE"), and on
        and prior to 8:00 p.m. Eastern Time on the fifth (5th) anniversary of
        the Commencement Date (the "EXPIRATION DATE"), but not thereafter, to
        subscribe for and purchase from CHROMAVISION MEDICAL SYSTEMS, INC., a
        Delaware corporation (the "COMPANY"), ______________ shares (the
        "WARRANT SHARES") of common stock, $0.01 par value per share ("COMMON
        STOCK"), of the Company. The purchase price of one share of Common Stock
        under this Warrant shall be the Exercise Price, as defined below and as
        may be adjusted from time to time pursuant to the terms hereof. The
        Exercise Price and the number of shares for which this Warrant is
        exercisable shall be subject to adjustment as provided herein. This
        Warrant is being issued in connection with the Securities Purchase
        Agreement dated on or about the date hereof (the "PURCHASE AGREEMENT")
        entered into between the Company, the Holder and the other Purchasers
        named therein (if any).

1.      DEFINITIONS. Capitalized terms used herein and not otherwise defined
        shall have the meaning ascribed thereto in the Purchase Agreement. As
        used in this Warrant, the following terms shall have the following
        respective meanings:

        "CHANGE IN CONTROL TRANSACTION" will be deemed to exist if (i) there
        occurs any consolidation, merger or other business combination of the
        Company with or into any other corporation or other entity or person
        (whether or not the Company is the surviving

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        corporation), or any other corporate reorganization or transaction or
        series of related transactions in which in any of such events the voting
        stockholders of the Company prior to such event cease to own 50% or more
        of the voting stock, or corresponding voting equity interests, of the
        surviving corporation after such event (including without limitation any
        "going private" transaction under Rule 13e-3 promulgated pursuant to the
        Exchange Act or tender offer by the Company under Rule 13e-4 promulgated
        pursuant to the Exchange Act for 20% or more of the Company's Common
        Stock), (ii) any person (as defined in Section 13(d) of the Exchange
        Act), together with its affiliates and associates (as such terms are
        defined in Rule 405 under the Act), beneficially owns or is deemed to
        beneficially own (as described in Rule 13d-3 under the Exchange Act
        without regard to the 60-day exercise period) in excess of 50% of the
        Company's voting power, (iii) there is a replacement of more than
        one-half of the members of the Company's Board of Directors which is not
        approved by those individuals who are members of the Company's Board of
        Directors immediately prior to such replacement, (iv) in one or a series
        of related transactions, there is a sale or transfer of all or
        substantially all of the assets of the Company, determined on a
        consolidated basis, or (v) the Company enters into an agreement
        providing for an event set forth in (i), (ii), (iii) or (iv) above,
        pursuant to which the Common Stock is converted or reclassified into
        other securities, cash or property.

        "CONVERTIBLE SECURITIES" means any convertible securities, warrants,
        options or other rights to subscribe for or to purchase or exchange for,
        shares of Common Stock.

        "EXCHANGE ACT" shall mean the Securities Exchange Act of 1934, as
        amended.

        "EXERCISE PRICE" means $6.8604 ("INITIAL EXERCISE PRICE"), provided,
        however, that on and after the one-year anniversary of the Commencement
        Date, the Exercise Price hereunder shall be automatically adjusted to
        (and shall thereafter equal, until further adjusted) an exercise price
        (the "ADJUSTED PRICE") equal to the lesser of (A) the Initial Exercise
        Price and (B) the average of the closing bid prices for the Common Stock
        on the Principal Market during the Pricing Period (as defined below),
        provided that the Exercise Price shall not be adjusted to a figure that
        is less than the Floor Price, except pursuant to an adjustment required
        under Section 13 below; in each case such Exercise Price shall be
        subject to adjustment (or further adjustment, as the case may be) as
        provided herein.

        "FLOOR PRICE" shall mean $4.0019, as such figure may be adjusted
        pursuant hereto.

        "PRICING PERIOD" shall mean the period of twenty (20) consecutive
        Trading Days immediately preceding the one-year anniversary of the
        Commencement Date.

        "PRINCIPAL MARKET" shall mean the Approved Market or such other market
        or exchange on which the Common Stock is then principally traded.

        "SECURITIES ACT" shall mean the Securities Act of 1933, as amended.

        "TRADING DAY" shall mean a day on which there is trading on the
        Principal Market.

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2.      TITLE OF WARRANT. The Company shall register this Warrant, upon records
        to be maintained by the Company for that purpose, in the name of the
        record holder hereof from time to time. The Company may deem and treat
        the registered holder of this Warrant as the absolute owner hereof for
        the purpose of any exercise hereof or any distribution to the holder,
        and for all other purposes, and the Company shall not be affected by
        notice to the contrary except as provided herein.

                      With the written consent of the Company, such written
        consent not to be unreasonably withheld, prior to the expiration hereof
        and subject to compliance with applicable laws, this Warrant and all
        rights hereunder are transferable, in whole or in part, at the office or
        agency of the Company by the holder hereof in person or by duly
        authorized attorney, upon surrender of this Warrant together with (a)
        the Assignment Form annexed hereto properly endorsed, and (b) any other
        documentation reasonably necessary to satisfy the Company that such
        transfer is in compliance with all applicable securities laws; provided
        that no such transfer may be made to a person that is not an "accredited
        investor" as defined in Rule 501 of Regulation D of the Securities Act;
        and provided further that no consent of the Company is required for any
        transfer or assignment in whole or in part from time to time to an
        affiliate of the Purchaser or the then holder of this Warrant that is an
        "accredited investor." The term "HOLDER" as used herein shall refer to
        the Holder or any subsequent permitted transferee of this Warrant. If
        this Warrant is duly assigned in accordance with the terms hereof, then
        the Company agrees, upon the request of the assignee, to amend or
        supplement promptly any effective registration statement covering the
        Warrant Shares so that such assignee is entitled to be a selling
        stockholder thereunder.

3.      AUTHORIZATION OF SHARES. The Company covenants that all shares of Common
        Stock which may be issued upon the exercise of rights represented by
        this Warrant will, upon exercise of the rights represented by this
        Warrant and payment of the Exercise Price as set forth herein, be duly
        authorized, validly issued, fully paid and nonassessable and free from
        all taxes, liens, encumbrances and charges in respect of the issue
        thereof (other than taxes in respect of any transfer occurring
        contemporaneously with such issue or otherwise specified herein).

4.      EXERCISE OF WARRANT.

(a)     Exercise Procedure. Exercise of the purchase rights represented by this
        Warrant may be made at any time and from time to time, in whole or in
        part, on or after the Commencement Date but before 8:00 p.m. Eastern
        Time on the Expiration Date, by delivering the Notice of Exercise
        annexed hereto duly completed and executed (which delivery may be by
        facsimile) to the Company at the principal office of the Company (or
        such other office or agency of the Company as it may designate by notice
        in writing to the registered holder hereof at the address of such holder
        appearing on the books of the Company), and upon payment of the full
        Exercise Price of the shares thereby purchased (subject to subsection
        (b) below), the holder of this Warrant shall be entitled to receive a
        certificate for the number of shares of Common Stock so purchased.
        Subject to subsection (b) below, payment of the Exercise Price of the
        shares shall be by certified check or cashier's check or by wire
        transfer to an account designated by the Company in

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        an aggregate amount equal to the Exercise Price multiplied by the number
        of shares being purchased.

(b)     Cashless Exercise. Alternatively, and only in the event the Warrant
        Shares are not subject to Effective Registration, the Holder may
        exercise this Warrant, in whole or in part in a "cashless" or
        "net-issue" exercise by delivering to the offices of the Company or any
        transfer agent for the Common Stock a Notice of Exercise specifying the
        number of Warrant Shares to be delivered to such Warrant holder
        ("DELIVERABLE SHARES") and the number of Warrant Shares with respect to
        which this Warrant is being exercised ("EXERCISED SHARES"). The number
        of Deliverable Shares shall be calculated as follows:

<TABLE>
<S>                                                       <C>
        # of Deliverable Shares = # of Exercised Shares x Fair Market Value of Common Stock less Exercise Price
                                                          -----------------------------------------------------
                                                                    Fair Market Value of Common Stock
</TABLE>

        "FAIR MARKET VALUE" shall be deemed to be the last reported sale price
        of Common Stock on the Trading Day immediately prior to the date of
        exercise, or, if not reported, the fair market value of such Common
        Stock as reasonably determined by the Company and such Holder.

(c)     Issuance of Warrant Shares and Unexercised Warrants. Subject to
        subsection (d) below, in the event that this Warrant is not exercised in
        full, the number of Warrant Shares for which this Warrant may be
        exercised shall be reduced by the number of such Warrant Shares for
        which this Warrant is exercised and/or surrendered pursuant to this
        Section 4, and the Company, at its expense, shall within five (5)
        Trading Days, issue and deliver to or upon the order of the Holder a new
        Warrant of like tenor in the name of the Holder or as the Holder (upon
        payment by the Holder of any applicable transfer taxes) may request,
        reflecting such remaining number of Warrant Shares.

        All exercises of this Warrant will be deemed to occur as of the date of
        receipt by the Company of a validly executed Notice of Exercise (or such
        later date as may be indicated on such Notice of Exercise) (such date
        being referred to herein as the "EXERCISE DATE"), and certificates for
        shares of Common Stock purchased hereunder shall be delivered to the
        Holder hereof within three (3) Trading Days after the Exercise Date. The
        Holder may withdraw its Notice of Exercise under Section 3(a) or 3(b)
        upon written notice to the Company at any time thereafter, in whole or
        in part, if the Company fails to timely deliver the applicable
        certificates to the Holder as provided in this Warrant.

        In lieu of delivering physical certificates representing the Warrant
        Shares issuable upon conversion of this Warrant, provided the Company's
        transfer agent is a participant in the Depository Trust Company ("DTC")
        Fast Automated Securities Transfer ("FAST") program, upon request of the
        holder, the Company shall use its best efforts to cause its transfer
        agent to electronically transmit the Warrant Shares issuable upon
        exercise to the holder, by crediting the account of the holder's prime
        broker with DTC through its Deposit Withdrawal Agent Commission ("DWAC")
        system. The time periods for delivery described above shall apply to the
        electronic transmittals through the DWAC system. The Company agrees to
        use its best commercially reasonable efforts to coordinate with DTC to
        accomplish this objective.

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(d)     Book-Entry. Notwithstanding anything to the contrary set forth herein,
        upon partial exercise of this Warrant in accordance with the terms
        hereof, the Holder shall not be required to physically surrender this
        Warrant to the Company unless such Holder is purchasing the full amount
        of Warrant Shares then represented by this Warrant. The Holder and the
        Company shall maintain records showing the number of Warrant Shares so
        purchased hereunder and the dates of such purchases or shall use such
        other method, reasonably satisfactory to the Holder and the Company, so
        as not to require physical surrender of this Warrant upon each such
        exercise.

5.      NO FRACTIONAL SHARES OR SCRIP. No fractional Warrant Shares or scrip
        representing fractional Warrant Shares shall be issued upon the exercise
        of this Warrant. Any fractional share or scrip shall be rounded up to
        the nearest whole number.

6.      CHARGES, TAXES AND EXPENSES. Issuance of certificates for shares of
        Common Stock upon the exercise of this Warrant shall be made without
        charge to the holder hereof for any issue or transfer tax or other
        incidental expense in respect of the issuance of such certificate, all
        of which taxes and expenses shall be paid by the Company, and such
        certificates shall be issued in the name of the holder of this Warrant
        or in such name or names as may be directed by the holder of this
        Warrant; provided, however, that in the event certificates for shares of
        Common Stock are to be issued in a name other than the name of the
        holder of this Warrant, this Warrant when surrendered for exercise shall
        be accompanied by the Assignment Form attached hereto duly executed by
        the holder hereof; and provided further, that the Company shall not be
        required to pay any tax or taxes or any other fees or expenses
        applicable to the holder or its transferee which may be payable in
        respect of any transfer involved in the issuance of any Warrant
        certificates or any certificates for the Warrant Shares in a name other
        than the name of the holder.

7.      CLOSING OF BOOKS. The Company will at no time close its shareholder
        books or records in any manner which interferes with the timely exercise
        of this Warrant.

8.      NO RIGHTS AS SHAREHOLDER UNTIL EXERCISE. Subject to Sections 12 and 13
        of this Warrant and the provisions of any other written agreement
        between the Company and the Holder, prior to the exercise of this
        Warrant as provided herein, the Holder shall not be entitled to vote or
        receive dividends or be deemed the holder of Warrant Shares or any other
        securities of the Company that may at any time be issuable on the
        exercise hereof for any purpose, nor shall anything contained herein be
        construed to confer upon the Holder, as such, any of the rights of a
        stockholder of the Company or any right to vote for the election of
        directors or upon any matter submitted to stockholders at any meeting
        thereof, or to give or withhold consent to any corporate action (whether
        upon any recapitalization, issuance of stock, reclassification of stock,
        change of par value, or change of stock to no par value, consolidation,
        merger, conveyance or otherwise) or to receive notice of meetings, or to
        receive dividends or subscription rights. However, at the time of the
        exercise of this Warrant pursuant to Section 4 hereof, the Warrant
        Shares so purchased hereunder shall be deemed to be issued to such
        Holder as the record owner of such shares as of the close of business on
        the date on which this Warrant shall have been exercised.

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9.      REMEDIES. If the Company shall fail to deliver to the Holder the Warrant
        Shares to be issued to the Holder hereunder in accordance with the terms
        of the Purchase Agreement by the third Trading Day following the
        Exercise Date, whether by physical delivery of certificates or by
        book-entry transfer through DTC for such Warrant Shares, the Company
        shall, in addition to any other remedies under this Warrant or the
        Transaction Documents or at law or in equity, pay as additional damages
        in cash to the Holder, by the seventh (7th) Trading Day following the
        Exercise Date, an amount equal to one percent (1%), and on each
        succeeding fifth (5th) Trading Day thereafter until such Warrant Shares
        are delivered, an amount equal to two percent (2%), of the value of the
        Warrant Shares not delivered to the Holder by such third (3rd) Trading
        Day following the Exercise Date, based on the Fair Market Value as of
        the Exercise Date. The Company acknowledges that this remedy is partial
        and non-exclusive.

10.     LOSS, THEFT, DESTRUCTION OR MUTILATION OF WARRANT; DENOMINATION. In the
        event that any holder notifies the Company that its Warrant(s) have been
        lost, stolen or destroyed, then replacement Warrant(s) identical in all
        respects to the original Warrant(s) (except for any registration number
        and any adjustments to the Exercise Price or the number of Warrant
        Shares issuable hereunder pursuant hereto, if different than that shown
        on the original Warrant(s)) shall be delivered to the holder by the
        Company within three (3) Trading Days, provided that such holder
        executes and delivers to the Company an agreement reasonably
        satisfactory to the Company to indemnify the Company from any loss
        incurred by it in connection with such Warrants. This Warrant is
        exchangeable for an equal aggregate number of Warrants of different
        denominations, as requested by the holder surrendering the same. No
        service charge will be made for such registration, replacement, transfer
        or exchange.

11.     SATURDAYS, SUNDAYS, HOLIDAYS, ETC. If the last or appointed day for the
        taking of any action or the expiration of any right required or granted
        herein shall be a Saturday, Sunday or a legal holiday, then such action
        may be taken or such right may be exercised on the next succeeding day
        not a legal holiday.

12.     EFFECT OF CERTAIN EVENTS. If at any time while this Warrant or any
        portion hereof is outstanding and unexpired there shall be a Change in
        Control Transaction, then the Holder shall have the right thereafter to
        purchase, by exercise of this Warrant and payment of the aggregate
        Exercise Price in effect immediately prior to such Change in Control
        Transaction, the kind and amount of consideration including cash, stock,
        other securities, assets or any other property, which it would have
        owned or have been entitled to receive upon or after the happening of
        such transaction had this Warrant been exercised immediately prior
        thereto, subject to further adjustment as provided in Section 13. The
        Company shall not consummate a Change in Control Transaction unless the
        entity resulting from such transaction (if not the Company), or such
        transferee entity, as the case may be, shall expressly assume, by
        supplemental agreement reasonably satisfactory in form and substance to
        the Holder, the due and punctual performance and observance of each and
        every covenant and condition of this Warrant to be performed and
        observed by the Company.

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13.     ADJUSTMENTS OF EXERCISE PRICE AND NUMBER OF WARRANT SHARES. For purposes
        of any adjustment of the Exercise Price pursuant to this Section 13, the
        "Exercise Price" shall be deemed to be the Initial Exercise Price, the
        Adjusted Price, the Floor Price and each closing bid price during the
        Pricing Period which occurs prior to the applicable event set forth
        below (in each case as such Initial Exercise Price, Floor Price and/or
        closing bid price may have been previously adjusted hereunder).

(a)     Stock Dividends, Splits, Combinations and Reclassifications. If, to the
        extent not covered by Section 12 above, the Company or any Subsidiary,
        at any time while this Warrant or any portion thereof is issued,
        outstanding and unexpired: (A) shall declare or pay a stock dividend or
        otherwise make a distribution or distributions on any equity securities
        (including securities convertible into or exchangeable or exercisable
        for such equity securities) in shares of Common Stock; (B) subdivide the
        then outstanding Common Stock into a larger number of shares; (C)
        combine the then outstanding Common Stock into a smaller number of
        shares; or (D) issue any shares of its capital stock in a
        reclassification of the Common Stock (including without limitation in
        connection with any merger or consolidation), then the Exercise Price
        then in effect hereunder shall be adjusted by multiplying the Exercise
        Price by a fraction, the numerator of which shall be the number of
        shares of Common Stock (excluding treasury shares, if any) outstanding
        before such event and the denominator of which shall be the number of
        shares of Common Stock (excluding treasury shares, if any) outstanding
        after such event. Any adjustment made pursuant to this Section 13(a)
        shall become effective immediately after the record date for the
        determination of shareholders entitled to receive such dividend or
        distribution and shall become effective immediately after the effective
        date in the case of a subdivision or combination.

(b)     Distributions. If the Company or any Subsidiary, at any time while this
        Warrant is outstanding, shall distribute to all holders of Common Stock
        evidences of its indebtedness or assets or cash or rights or warrants to
        subscribe for or purchase any security of the Company or any of its
        subsidiaries, then the Exercise Price in effect at the opening of
        business on the day following the date fixed for the determination of
        holders of Common Stock entitled to receive such distribution shall be
        adjusted by multiplying such Exercise Price by a fraction, the numerator
        of which shall be the Fair Market Price (as defined below) per share of
        the Common Stock less the then fair market value as reasonably
        determined by the Board of Directors of the portion of the evidences of
        indebtedness or assets or rights or warrants so distributed (and for
        which an adjustment to the Exercise Price has not previously been made
        pursuant to the terms of this Section 13) applicable to one share of
        Common Stock, and the denominator of which shall be such Fair Market
        Price per share of the Common Stock, such adjustment to become effective
        immediately after the opening of business on the day following the date
        fixed for the determination of holders of Common Stock entitled to
        receive such distribution. "FAIR MARKET PRICE" shall mean the closing
        market price per share of Common Stock on the Principal Market on the
        Trading Day next preceding such fixed determination date or such other
        date on which the Fair Market Price is being determined. The Company
        shall deliver to each holder of Warrants a notice setting forth the
        Exercise Price after such adjustment and setting forth a brief statement
        of the facts requiring such adjustment and the computation thereof. In
        the event that the Exercise Price shall change by more than

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        5%, the holders of Warrants shall have the right to have the fair market
        value determined by an independent nationally reputable investment
        banker mutually selected by the Company and the Holder, at the Company's
        expense.

(c)     Security Issuances/Reductions. In the event that the Company or any of
        its subsidiaries (X) issues or sells any Common Stock or Convertible
        Securities or (Y) directly or indirectly effectively reduces the
        conversion, exercise or exchange price for any Convertible Securities
        which are currently outstanding, in any case under clause (X) or (Y) at
        or to an effective purchase price per share which is less than the
        greater of (1) the average closing sale price per share of Common Stock
        on the Principal Market over the five (5) Trading Days immediately
        preceding such issue, sale or reduction, or, in the case of issuances to
        holders of its Common Stock, the date fixed for the determination of
        stockholders entitled to receive such Common Stock or Convertible
        Securities ("AVERAGE MARKET PRICE"), or (2) the Exercise Price, then in
        each such case, the Exercise Price in effect immediately prior to such
        issue, sale or reduction, or record date, as applicable, shall be
        reduced effective concurrently with such issue, sale or reduction, or
        record date, to an amount determined by multiplying the Exercise Price
        then in effect by a fraction, (x) the numerator of which shall be the
        sum of (1) the number of shares of Common Stock outstanding immediately
        prior to such issue, sale or reduction, or record date, plus (2) the
        number of shares of Common Stock which the aggregate consideration
        received by the Company for such additional shares would purchase at
        such Exercise Price or Average Market Price, as the case may be, and (y)
        the denominator of which shall be the number of shares of Common Stock
        of the Company deemed outstanding immediately after such issue, sale or
        reduction, or record date (with securities to be issued to holders of
        Common Stock deemed to be outstanding as of the record date).

                      The foregoing provisions of this subsection (c) shall not
        apply to sales or issuances of shares of Common Stock or rights to
        purchase or acquire Common Stock from the Company (1) pursuant to the
        Company's employee, officer or director bona fide stock option or stock
        incentive plans and programs duly adopted by the Company's Board of
        Directors, (2) to consultants as reasonable compensation for services
        rendered, (3) up to 657,150 shares of Common Stock at a minimum purchase
        price of $7 per share pursuant to the existing agreement between the
        Company and VennWorks LLC entered into in January 2001 (such 657,150
        shares and $7 figure subject to appropriate and equitable adjustment for
        stock splits, stock dividends and similar standard anti-dilution
        events), (4) upon exercise of warrants to purchase up to 56,070 shares
        of Common Stock issued to a wholly-owned subsidiary of Safeguard
        Scientifics, Inc. and VennWorks LLC in September 2000 at an exercise
        price of $12.48 per share (subject to appropriate and equitable
        adjustment for stock splits, stock dividends and similar standard
        anti-dilution events) or (5) pursuant to an underwritten public offering
        by the Company (excluding "equity line" transactions or issuances under
        a "shelf" registration statement) resulting in net proceeds to the
        Company in excess of $20 million.

                      For purposes of the preceding paragraph, in the event that
        the effective purchase price is less than both the Average Market Price
        and the Exercise Price, then the calculation method which yields the
        greatest downward adjustment in the Exercise Price shall be used.

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                      For the purposes of the foregoing adjustments, in the case
        of the issuance of any Convertible Securities, the maximum number of
        shares of Common Stock issuable upon exercise, exchange or conversion of
        such Convertible Securities shall be deemed to be outstanding, provided
        that no further adjustment shall be made upon the actual issuance of
        Common Stock upon exercise, exchange or conversion of such Convertible
        Securities.

(d)     Inverse Proportional Adjustments to Exercise Price and Warrant Shares.
        In the event of any adjustment in the number of Warrant Shares issuable
        hereunder upon exercise, the Exercise Price shall be inversely
        proportionately increased or decreased, as the case may be, such that
        aggregate purchase price for Warrant Shares upon full exercise of this
        Warrant shall remain the same. Similarly, in the event of any adjustment
        in the Exercise Price hereunder, excluding only the adjustment to the
        Adjusted Price on the one-year anniversary of the Commencement Date, the
        number of Warrant Shares issuable hereunder upon exercise shall be
        inversely proportionately increased or decreased as the case may be,
        such that aggregate purchase price for Warrant Shares upon full exercise
        of this Warrant shall remain the same.

14.     NOTICES.  If:

                      (i)    the Company shall declare a dividend (or any other
                             distribution) on its Common Stock; or

                      (ii)   the Company shall declare a special nonrecurring
                             cash dividend on or a redemption of its Common
                             Stock; or

                      (iii)  the Company shall authorize the granting to all
                             holders of the Common Stock rights or warrants to
                             subscribe for or purchase any shares of capital
                             stock of any class or of any rights; or

                      (iv)   the approval of any stockholders of the Company
                             shall be required in connection with any
                             reclassification of the Common Stock of the
                             Company, any consolidation or merger to which the
                             Company is a party, any sale or transfer of all or
                             substantially all of the assets of the Company, or
                             any compulsory share exchange whereby the Common
                             Stock is converted into other securities, cash or
                             property; or

                      (v)    the Company shall authorize the voluntary
                             dissolution, liquidation or winding up of the
                             affairs of the Company;

        then the Company shall cause to be facsimiled and mailed to each Holder
        at their last addresses as they shall appear upon the Warrant register
        of the Company, at least 20 business days prior to the applicable record
        or effective date hereinafter specified, a notice stating (x) the date
        on which a record is to be taken for the purpose of such dividend,
        distribution, redemption, rights or warrants, or if a record is not to
        be taken, the date fixed to determine which holders of Common Stock of
        record will be entitled to such dividend, distributions, redemption,
        rights or warrants and/or (y) the date on which such

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        reclassification, consolidation, merger, sale, transfer or share
        exchange is expected to become effective or close, and the date as of
        which it is expected that holders of Common Stock of record shall be
        entitled to exchange their shares of Common Stock for securities, cash
        or other property deliverable upon such reclassification, consolidation,
        merger, sale, transfer, share exchange, dissolution, liquidation or
        winding up.

15.     VOLUNTARY ADJUSTMENT BY THE COMPANY. The Company may at its option, at
        any time during the term of this Warrant, reduce but not increase the
        then current Exercise Price to any amount and for any period of time
        deemed appropriate by the Board of Directors of the Company.

16.     NOTICE OF ADJUSTMENT. Whenever the number of Warrant Shares or number or
        kind of securities or other property purchasable upon the exercise of
        this Warrant or the Exercise Price is adjusted (including without
        limitation the adjustment to the Adjusted Price), the Company shall
        promptly facsimile and mail by registered or certified mail, return
        receipt requested, to the registered holder of this Warrant a notice
        setting forth the number of Warrant Shares (and other securities or
        property) purchasable upon the exercise of this Warrant and the Exercise
        Price of such Warrant Shares after giving effect to such adjustment,
        setting forth a brief statement of the facts requiring such adjustment
        and setting forth the computation by which such adjustment was made.

17.     AUTHORIZED SHARES. The Company covenants that during the period this
        Warrant is outstanding and exercisable, it will reserve from its
        authorized and unissued Common Stock a sufficient number of shares to
        provide for the issuance of the Warrant Shares upon the exercise of any
        and all purchase rights under this Warrant (without regard to the
        limitations contained in Section 18 below). The Company further
        covenants that its issuance of this Warrant shall constitute full
        authority to its officers who are charged with the duty of executing
        stock certificates to execute and issue the necessary certificates for
        the Warrant Shares upon the exercise of the purchase rights under this
        Warrant. The Company will take all such reasonable action as is
        necessary and within its control to assure that such Warrant Shares may
        be issued as provided herein without violation of any applicable law or
        regulation, or of any requirements of the Principal Market or any other
        domestic securities exchange or market upon which the Common Stock may
        be listed.

18.     EXERCISE LIMITATION.

(a)     Notwithstanding anything to the contrary contained herein, the number of
        shares of Common Stock that may be acquired by the Holder upon exercise
        pursuant to the terms hereof shall not exceed a number that, when added
        to the total number of shares of Common Stock deemed beneficially owned
        by such Holder (other than by virtue of the ownership of securities or
        rights to acquire securities (including the Warrant Shares) that have
        limitations on the Holder's right to convert, exercise or purchase
        similar to the limitation set forth herein), together with all shares of
        Common Stock deemed beneficially owned (other than by virtue of the
        ownership of securities or rights to acquire securities that have
        limitations on the right to convert, exercise or purchase similar to the
        limitation set forth herein) by the Holder's "affiliates" (as defined in
        Rule 144 of the

                                       10
<PAGE>   11

        Securities Act) ("AGGREGATION PARTIES") that would be aggregated for
        purposes of determining whether a group under Section 13(d) of the
        Exchange Act exists, would exceed 9.9% of the total issued and
        outstanding shares of the Common Stock (the "RESTRICTED OWNERSHIP
        PERCENTAGE"). Each Holder shall have the right (x) at any time and from
        time to time to reduce its Restricted Ownership Percentage immediately
        upon notice to the Company and (y) (subject to waiver) at any time and
        from time to time, to increase its Restricted Ownership Percentage
        immediately in the event of the announcement as pending or planned, of a
        Change in Control Transaction.

(b)     The Holder covenants at all times on each day (each such day being
        referred to as a "COVENANT DAY") as follows: During the balance of such
        Covenant Day and the succeeding sixty-one (61) days (the balance of such
        Covenant Day and the succeeding 61 days being referred to as the
        "COVENANT PERIOD") such Holder will not acquire shares of Common Stock
        pursuant to any right (including, without limitation, exercise of this
        Warrant) existing at the commencement of the Covenant Period to the
        extent the number of shares so acquired by such Holder and its
        Aggregation Parties (ignoring all dispositions) would exceed:

                      (i)    the Restricted Ownership Percentage of the total
                             number of shares of Common Stock outstanding at the
                             commencement of the Covenant Period, minus

                      (ii)   the number of shares of Common Stock actually owned
                             by such Holder and its Aggregation Parties at the
                             commencement of the Covenant Period.

                      A new and independent covenant will be deemed to be given
        by the Holder as of each moment of each Covenant Day. No covenant will
        terminate, diminish or modify any other covenant. The Holder agrees to
        comply with each such covenant. This Section 18 controls in the case of
        any conflict with any other provision of the Purchase Agreement or any
        agreement entered into in connection therewith.

                      The Company's obligation to issue Common Stock which would
        exceed such limits referred to in this Section 18 shall be suspended to
        the extent necessary until such time, if any, as shares of Common Stock
        may be issued in compliance with such restrictions, provided that the
        Expiration Date shall not be extended therefor.

(c)     Notwithstanding anything contained herein, in no event shall the Company
        be obligated to issue shares of Common Stock hereunder to the extent
        that the total number of shares issued or deemed issued to the Holder
        under the Purchase Agreement would exceed 19.9% of the Company's issued
        and outstanding shares of Common Stock on the date of issuance hereof,
        unless otherwise approved in advance by the Company's shareholders.
        Instead, the Company shall redeem this Warrant to the extent necessary
        for such consideration as is required to place the Holder in the same
        economic position they would have been if not for such limitation or as
        otherwise provided under the Purchase Agreement.

                                       11
<PAGE>   12

19.     MISCELLANEOUS.

(a)     Issue Date; Choice of Law; Venue; Jurisdiction; No Jury Trial. THE
        PROVISIONS OF THIS WARRANT SHALL BE CONSTRUED AND SHALL BE GIVEN EFFECT
        IN ALL RESPECTS AS IF IT HAD BEEN ISSUED AND DELIVERED BY THE COMPANY ON
        THE DATE HEREOF. THIS WARRANT SHALL BE BINDING UPON ANY SUCCESSORS OR
        PERMITTED ASSIGNS OF THE COMPANY. THIS WARRANT WILL BE CONSTRUED AND
        ENFORCED IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW
        YORK, EXCEPT FOR MATTERS ARISING UNDER THE SECURITIES ACT, WITHOUT
        REFERENCE TO PRINCIPLES OF CONFLICTS OF LAW. EACH OF THE PARTIES
        CONSENTS TO THE EXCLUSIVE JURISDICTION OF THE STATE AND FEDERAL COURTS
        SITTING IN THE COUNTY OF NEW YORK IN THE STATE OF NEW YORK IN CONNECTION
        WITH ANY DISPUTE ARISING UNDER THIS WARRANT AND HEREBY WAIVES, TO THE
        MAXIMUM EXTENT PERMITTED BY LAW, ANY OBJECTION, INCLUDING ANY OBJECTION
        BASED ON FORUM NON CONVENIENS, TO THE BRINGING OF ANY SUCH PROCEEDING IN
        SUCH JURISDICTION. EACH PARTY HEREBY AGREES THAT IF THE OTHER PARTY TO
        THIS WARRANT OBTAINS A JUDGMENT AGAINST IT IN SUCH A PROCEEDING, THE
        PARTY WHICH OBTAINED SUCH JUDGMENT MAY ENFORCE SAME BY SUMMARY JUDGMENT
        IN THE COURTS OF ANY COUNTRY HAVING JURISDICTION OVER THE PARTY AGAINST
        WHOM SUCH JUDGMENT WAS OBTAINED, AND EACH PARTY HEREBY WAIVES ANY
        DEFENSES AVAILABLE TO IT UNDER LOCAL LAW AND AGREES TO THE ENFORCEMENT
        OF SUCH A JUDGMENT. EACH PARTY TO THIS WARRANT IRREVOCABLY CONSENTS TO
        THE SERVICE OF PROCESS IN ANY SUCH PROCEEDING BY THE MAILING OF COPIES
        THEREOF BY REGISTERED OR CERTIFIED MAIL, POSTAGE PREPAID, TO SUCH PARTY
        AT ITS ADDRESS IN ACCORDANCE WITH SECTION 19(c). NOTHING HEREIN SHALL
        AFFECT THE RIGHT OF ANY PARTY TO SERVE PROCESS IN ANY OTHER MANNER
        PERMITTED BY LAW. EACH PARTY WAIVES ITS RIGHT TO A TRIAL BY JURY.

(b)     Modification and Waiver. This Warrant and any provisions hereof may be
        changed, waived, discharged or terminated only with the written approval
        of the holder hereof. Any amendment effected in accordance with this
        paragraph shall be binding upon the Holder, each future holder of this
        Warrant and the Company. No waivers of, or exceptions to, any term,
        condition or provision of this Warrant, in any one or more instances,
        shall be deemed to be, or construed as, a further or continuing waiver
        of any such term, condition or provision at any other time.

(c)     Notices. Any notice, request or other document required or permitted to
        be given or delivered to the Holder or future holders hereof or the
        Company shall be personally delivered or facsimiled or shall be sent by
        reputable overnight courier or certified or registered mail, postage
        prepaid, to the Holder or each such holder at its address as shown on
        the books of the Company or to the Company at the address set forth in
        the Purchase Agreement. All notices under this Warrant shall be deemed
        to have been given (i) in the

                                       12
<PAGE>   13

        case of personal or facsimile delivery, on the date of such delivery,
        (ii) in the case of mailing, when received and (iii) in the case of
        overnight courier, upon receipt. A party may from time to time change
        the address to which notices to it are to be delivered or mailed
        hereunder by notice delivered in accordance with the provisions of this
        Section 19(c).

(d)     Severability. Whenever possible, each provision of this Warrant shall be
        interpreted in such manner as to be effective and valid under applicable
        law, but if any provision of this Warrant is held to be invalid, illegal
        or unenforceable in any respect under any applicable law or rule in any
        jurisdiction, such invalidity, illegality or unenforceability shall not
        affect the validity, legality or enforceability of any other provision
        of this Warrant in such jurisdiction or affect the validity, legality or
        enforceability of any provision in any other jurisdiction, but this
        Warrant shall be reformed, construed and enforced in such jurisdiction
        as if such invalid, illegal or unenforceable provision had never been
        contained herein.

(e)     No Impairment. The Company shall not, by amendment of its Certificate of
        Incorporation or through any reorganization, transfer of assets,
        consolidation, merger, dissolution, issuance or sale of securities or
        any other voluntary action, avoid or seek to avoid the observance or
        performance of any of the terms of this Warrant, but shall at all times
        in good faith assist in the carrying out of all such terms and in the
        taking of all such action as may be necessary or appropriate in order to
        protect the rights of the Warrant holder granted hereunder against
        impairment. Without limiting the generality of the foregoing, the
        Company (a) shall not increase the par value of any Warrant Shares above
        the amount payable therefor on such exercise, and (b) shall take all
        such action as may be reasonably necessary or appropriate in order that
        the Company may validly and legally issue fully paid and nonassessable
        Warrant Shares on the exercise of this Warrant.

(f)     Specific Performance. The Company acknowledges and agrees that
        irreparable damage would occur in the event that the Company fails to
        perform any of the provisions of this Warrant in accordance with its
        specific terms. It is accordingly agreed that the Holder shall be
        entitled to seek an injunction or injunctions to prevent or cure
        breaches of the provisions of this Warrant and to enforce specifically
        the terms and provisions hereof, this being in addition to any other
        remedy to which the Holder may be entitled at law or in equity.

                            [Signature Page Follows]

                                       13
<PAGE>   14

                      IN WITNESS WHEREOF, the Company has caused this Warrant to
        be duly executed by its officers thereunto duly authorized.

        Dated: July 10, 2001

                                     CHROMAVISION MEDICAL SYSTEMS, INC.

                                     By: ______________________________
                                     Name: Kevin C. O'Boyle
                                     Title: Executive Vice President, Operations
                                            and Chief Financial Officer

        ATTEST:

        Sign:  ______________________________
        Print Name:

                                       14
<PAGE>   15

                               NOTICE OF EXERCISE

             (To be executed by the Holder to exercise the right to
          purchase shares of Common Stock under the foregoing Warrant)

To:  CHROMAVISION MEDICAL SYSTEMS, INC.
Re:  COMMON  STOCK  PURCHASE  WARRANT  issued to _________________ on July ___,
     2001 to purchase shares of Common Stock (the "Warrant")

(1)  CHECK ONE:

_______ (a) The undersigned hereby elects to purchase ________ shares of Common
        Stock of CHROMAVISION MEDICAL SYSTEMS, INC. pursuant to Section 4(a) of
        the Warrant, and will tender payment of the purchase price in full,
        together with all applicable transfer taxes payable pursuant to the
        Warrant, if any.

                                       OR

_______ (b) The undersigned hereby exercises the Warrant with respect ________
        shares of Common Stock of CHROMAVISION MEDICAL SYSTEMS, INC. on a
        cashless, "net basis" pursuant to Section 4(b) of the Warrant, and
        hereby instructs the Company to deliver _______ shares of Common Stock
        to the holder of the Warrant based on a Fair Market Value of $____.

(2)  Please issue a certificate or certificates representing said shares of
     Common Stock in the name of the undersigned or in such other name as is
     specified below:

                      ________________________________
                      Name
                      ________________________________
                      Address
                      ________________________________

(3)  Please issue a new Warrant for the unexercised portion of the attached
     Warrant in the name of the undersigned or in such other name as is
     specified below:

                      ________________________________
                      Name
                      ________________________________
                      Address
                      ________________________________

(4)  The undersigned represents as of the date hereof that, after giving effect
     to the exercise of this Warrant pursuant to this Notice of Exercise, the
     undersigned will remain in compliance with Section 18(b) of the Warrant and
     not exceed the "Restricted Ownership Percentage" contained in Section 18(a)
     of the Warrant.

Dated: _______________                  Print Name of Holder:
                                        ________________________________________
                                        (Sign) By:______________________________
                                        Print Name:
                                        Print Title:

<PAGE>   16

                                 ASSIGNMENT FORM

                    (To assign the foregoing Warrant, execute
                 this form and supply the required information.
                 Do not use this form to exercise the Warrant.)

FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers unto
________________________________ the right represented by the within Warrant to
purchase ____________ shares of Common Stock of CHROMAVISION MEDICAL SYSTEMS,
INC. to which the within Warrant relates and appoints ________________ attorney
to transfer said right on the books of CHROMAVISION MEDICAL SYSTEMS, INC. with
full power of substitution in the premises.

Dated:

___________________

                              __________________________________________________
                              (Signature must conform in all respects to name
                              of holder as specified on the face of the Warrant)

                              __________________________________________________
                              Address of Transferee

                              __________________________________________________

                              __________________________________________________

In the presence of:

__________________________LOAN AGREEMENT
                                 --------------

     THIS  AGREEMENT  is made as of the 29th day of  June,  2001 by and  between
POSITRON CORPORATION ("Borrower"),  a Texas corporation with its principal place
of business at 1304 Langham Creek Drive,  Houston,  Texas 77084 and IMATRON INC.
("Lender"), a New Jersey corporation with its principal place of business at 389
Oyster Point Blvd., So. San Francisco, CA 94080.

                                R E C I T A L S:
                                ----------------

     WHEREAS, Borrower previously has borrowed certain funds from Lender and has
repaid such funds pursuant to the terms of the applicable loan agreement; and

     WHEREAS,  Borrower has  requested  Lender to make certain  further loans to
Borrower  for working  capital and  certain  other needs as provided  herein and
Lender is agreeable to make such loans upon the terms and conditions hereof;

     NOW THEREFORE,  in consideration of these premises and the mutual covenants
and agreements  herein contained and other valuable  consideration,  the receipt
and adequacy of which the parties hereto acknowledge, the parties have agreed as
follows:

     1. Definitions.
        ------------

     As used in  this  Loan  Agreement,  the  following  terms  shall  have  the
following meanings unless the context requires otherwise:

     Borrower's Obligations means all present and future obligations of Borrower
to  Lender  hereunder,  under  the  Note,  or any  other  document  executed  in
connection herewith.

     Default means any event set forth in Section 6.1 hereof.

     Lender's  Obligations means all present and future obligations of Lender to
Borrower hereunder, or any other document executed in connection herewith.

     Loan  Agreement  means this Loan Agreement and all  attachments,  exhibits,
schedules hereto, all as may be amended from time to time.

     Loan Rate means 10% or, if lower than 10%, the highest rate  permissible by
law.

     Payment Dates means the first day of each calendar month.

     2. LOANS.
        -----

     2.1 Lender agrees, on terms and conditions of this Loan Agreement,  to make
loans (hereinafter called individually a "Loan" and,  collectively "The Loans"),
to Borrower in an aggregate  principal  amount at any one time outstanding up to
but not  exceeding  Two Million  Dollars  ($2,000,000).  Within such limit,  and
subject to the various conditions set forth herein,  Borrower may borrow, repay,
re-borrow  at any  time or from  time to time  from the  date  hereof  up to and
including the earlier of June 30, 2002 and the  termination of the commitment of
Lender, as provided at Section 6.2 below. The obligation of Lender to make Loans
up to but not exceeding such aggregate amount at any one time outstanding herein
is hereinafter called its "Commitment."

     2.2 The  foregoing  notwithstanding,  the  following  shall  be  conditions
precedent each time Borrower  seeks to draw down any portion of the  Commitment:
(a) Within five (5) business days of the effective date of this Loan  Agreement,
Borrower  shall  provide to lender a budget and  estimated  schedule of expenses
("Budget")  reflecting  projected expenses and projected revenue (including Loan
proceeds); (b) Lender shall review the Budget and either approve or revise it in
its sole  judgment;  (c)  Borrower  shall  provide  to Lender at least  three(3)
calendar days' written notice (effective upon receipt) specifying the amount and
date and anticipated use of each requested  borrowing under Section 2.1; and (d)
each requested borrowing must be consistent with the Budget and further shall be
specifically approved by Lender.

     2.3 Repayments. The foregoing further notwithstanding, Borrower shall repay
interest  on a  monthly  basis by the 15th of the month  following  the month in
which it accrues, and shall further repay such portions of the principal amounts
outstanding  as of the  following  dates:  fifty  percent (50%) of all principal
amounts  outstanding  as of December  31,  2001 shall be repaid  within five (5)
business days of December 31, 2001;  seventy-five (75%) of all principal amounts
outstanding  as of March 31, 2002 shall be repaid  within five (5) business days
of  March  31,  2002;  and  100% of all  principal  amounts  plus  all  interest
outstanding as of June 30, 2002 shall be repaid no later than June 30, 2002.

     2.4  Borrower's  obligations  to pay the  principal  of and interest on the
Loans shall be  evidenced by its grid  promissory  note in the form of Exhibit A
hereto (the "Note")  payable to the order of Lender.  The Note shall reflect the
amount of the  Commitment,  with actual Loans,  repayments and balances noted by
Lender on the grid attached to the Note and made a part thereof.  The Note shall
bear interest on the unpaid principal amount thereof until such principal amount
shall be paid in full at a per annum  rate  equal to the Loan  Rate  (based on a
year of 365 or actual number of days elapsed).  The Loan Rate shall apply to the
average  outstanding  principal balance on the Note during any month which shall
be the summation of the daily  balances  during such month divided by the number
of days in the  particular  month.  Unless  accelerated  in accordance  with the
provisions  of this Loan  Agreement,  the  interest on the Note for any calendar
month shall be paid within  fifteen (15) days of each  consecutive  Payment Date
immediately  following  such calendar  month until full payment of the Loan (and
related interest),  with the first Payment Date being the first day of the month
immediately following execution of this Agreement. All principal and interest on
the Note shall be due and payable in full on June 30, 2002.  If any Payment Date
(or other  date for  payment  hereunder)  falls on a day which is not a business
day, such Payment Date (or other date of payment)  shall be the next  succeeding
business day.

     2.5 Mandatory Repayment.  The foregoing  notwithstanding,  beginning on and
after  any date,  from the date of this Loan  Agreement  to the  termination  of
Lender's  Commitment,  that Borrower  receives  third party  financing,  whether
equity or debt  ("Financing"),  in an amount  in  excess  of Five  Million  U.S.
Dollars ($5,000,000) in the aggregate  ("Financing  Threshold"),  Borrower shall
repay,  twenty-five  percent (25%) of each dollar  received  above the Financing
Threshold  from such  Financing,  toward any and all  amounts of  principal  and
interest  outstanding  under this Loan  Agreement  until such  amounts have been
fully  repaid  and  further,  Lender's  Commitment  shall  terminate  and not be
renewed. Solely by way of example, in the event Borrower shall receive Financing
in an  aggregate  amount of  $4,000,000  at any time  during  the first nine (9)
months  of this  Agreement,  and six (6)  months  thereafter  Borrower  receives
additional  Financing in an amount  $1,500,000,  Borrower shall repay to Lender,
promptly following receipt of the $1,500,000,  the sum of $125,000  representing
twenty-five  percent  (25%)  of  all  Financing  received  above  the  Financing
Threshold,  which amount  shall be applied to all interest  accrued on the Loans
and  unpaid to that date  plus,  to the  extent  that  accrued  unpaid  interest
constitutes   less  than   $125,000,   that  amount  of  principal   outstanding
representing  the difference  between the amount of accrued unpaid  interest and
$125,000.  Thereafter,  twenty-five  percent (25%) of every dollar of additional
Financing  provided to Borrower shall be paid over to Lender,  and no more Loans
shall be authorized,  until the full amount of any and all unpaid  principal and
interest on the Loans shall have been paid.

     2.6 All  payments to Lender shall be paid by Borrower to Lender at Lender's
address as follows:  Imatron Inc., 389 Oyster Point Blvd., So. San Francisco, CA
94080, Attn. President.  All amounts paid shall be applied first, to the payment
of all interest accrued and payable with respect to the Note; and second, to the
payment of outstanding  principal of the Loan; and third,  following Default, to
the payment of all expenses and charges,  including reasonable  attorneys' fees,
included  by Lender for the  protection  of its rights or the  pursuance  of its
remedies.

     2.7 The  Loans or any  part  thereof  may be  prepaid  at any time  without
penalty.

     2.8 The interest and other charges  charged with respect to the Loans shall
not exceed the highest rate permissible under any law which a court of competent
jurisdiction  or an  arbitrator  or  panel  of  arbitrators  shall,  in a  final
determination, deem applicable to the Loans. As of the date of execution of this
Loan Agreement, the parties hereto, in good faith, agree that the total interest
and other  charges  payable by Borrower  to Lender  under the terms of this Loan
Agreement do not exceed the maximum legal interest rate applicable to the Loans.
If it is determined  that Lender has received  interest and other  consideration
with respect to the Loans in excess of the highest rate applicable to the Loans,
Lender shall  promptly  refund not more than such excess  amount to Borrower and
the provisions  hereof shall be deemed  amended to provide for such  permissible
rate.

     3. CONDITIONS OF LENDING.
        ---------------------

     The  obligations of Lender to make a Loan is subject to the  fulfillment of
the following conditions:

     3.1 The following  documents shall have been duly authorized,  executed and
delivered  by the  Borrower  to the Lender,  and shall be in form and  substance
satisfactory to the Lender and its counsel and shall be in full force and effect
on the date of the Loan.

         Prior to the first Loan:

     (a)  an executed Loan Agreement,  and all executed documents,  certificates
          and instruments contemplated by this Loan Agreement, including but not
          limited  to  the  Security  Agreement;

     b)   a  certified  copy of the  resolution  of the  Board of  Directors  of
          Borrower, certified by the Secretary or a responsible officer thereof,
          duly  authorizing  execution,  delivery and  performance  of this Loan
          Agreement and the Note contemplated hereby;

     (c)  a certificate  of recent date from the Secretary of State of the state
          of incorporation of Borrower as to its good standing;

     (d)  an incumbency certificate of Borrower dated as of the date of funding,
          as to (i) the person or persons authorized to execute and deliver this
          Loan  Agreement,  the  Note,  the  Security  Agreement,  and any other
          documents  to be  executed  on behalf of them in  connection  with the
          transactions contemplated hereby and (ii) the signature of each person
          or persons;

     (e)  the executed Note;

     (f)  documentary evidence  satisfactory to Lender that any and all liens or
          other security  interests on any of Borrower's  tangible or intangible
          property, including but not limited to accounts, computer hardware and
          software, copyrights,  equipment,  inventory, licenses, patents, trade
          secrets,  trademarks,  general  intangibles,  chattel  paper  or other
          property,  and all  proceeds  thereof,  shall  have been  released  or
          otherwise  subordinated to Lender's  security  interests  contemplated
          herein; and

     (g)  an expense  plan and budget,  including  an  acceptable  cash  control
          system for managing expenditures within the plan and budget, ("Expense
          Plan"), attached hereto as Schedule 3.1(g).

     For  each Loan (including the first):

     (h)  an officer's  certificate in the form of Exhibit B which shall include
          the written request from Borrower  setting forth the requested  amount
          of the Loan and the  proposed  date of  borrowing;

     (i)  for each Loan after the first Loan,  documentary evidence satisfactory
          to Lender,  including  but not limited to Exhibit B, that  Borrower is
          adhering strictly to the Expense Plan; and

     (j)  such other  documents  and evidence with respect to Borrower as Lender
          may reasonably request.

     3.2 On the date of each  borrowing  pursuant to Section  2.1 above,  (i) no
Default  or event  that with the giving of notice or lapse of time or both would
constitute a Default  hereunder  has occurred and is  continuing or would result
from the  performance of this Loan  Agreement,  (ii) no material  adverse change
shall  have  occurred  since the date of this Loan  Agreement  in the  financial
condition or operations  of the Borrower,  and (iii) there shall be no juridical
proceeding or regulatory  action  instituted by or against the Borrower,  or, to
the best of Borrower's knowledge,  any threatened proceeding or action which may
materially  adversely  affect the business,  property,  operation,  or financial
condition of the Borrower.  By acceptance of a Loan,  Borrower  represents as of
such Loan date,  that each of the foregoing  items is true.

     3.3  Borrower  shall have  entered  issued to Imatron a Warrant to Purchase
Common  Stock,  materially in the form of Exhibit D, covering the purchase of up
to six million  (6,000,000)  shares of  Borrower's  common  stock at an exercise
price of $ 0.30 for the period  beginning on the date of issuance of the Warrant
and ending June 30, 2006.

     3.4 Borrower and Imatron  shall have  entered  into a  Registration  Rights
Agreement materially in the form of Exhibit E, pursuant to which Borrower agrees
to register the common shares  underlying the Warrant  pursuant to certain terms
and conditions.

     4. REPRESENTATIONS AND WARRANTIES.
        ------------------------------

     4.1 Borrower is a corporation  duly organized and validly  existing in good
standing under the laws of the state of Texas.

     4.2 Borrower has full corporate  power to own its  properties,  to carry on
its business as now being  conducted  and has full  corporate  power to execute,
deliver and perform all of its  obligations  under this Loan  Agreement  and the
Note.

     4.3 The  execution,  delivery  and  performance  by  Borrower  of this Loan
Agreement,   the  Note,  the  Security   Agreement  and  all  related  documents
contemplated  by this  transaction  have been duly  authorized  by all necessary
corporate  action of Borrower and do not violate any provision of law,  statute,
rule or regulation,  applicable to Borrower, or any judgment, franchise, permit,
order,  decree,  ruling, writ or injunction of any court or administrative body,
applicable to Borrower, or of Borrower's  certificate of incorporation,  by-laws
or the terms of any of its  securities or result in the breach of, or constitute
a Default under, or require any consent under, any indenture,  bank loan, credit
agreement or other  agreement or instrument  to which  Borrower is a party or by
which Borrower or any of its property may be bound or affected.

     4.4 No filings, recordations, notifications,  registrations, notarizations,
authentications  or other  formalities  or property,  stamp or similar  taxes or
duties  and  no  approvals,  licenses,  orders,   authorizations,   consents  or
undertakings of any governmental bodies or regulatory,  supervisory  authorities
are necessary in connection  with the  execution,  delivery and  performance  by
Borrower of this Loan Agreement or the Note, or for the payment to Lender of all
sums hereunder or under the Note or for the legality,  validity,  binding effect
or enforceability hereof or thereof.

     4.5 Except as disclosed and described in Schedule 4.5 hereto,  Borrower has
good and  marketable  title to, or a valid  leasehold  interest in, the tangible
personal  property or other  properties  and assets  used by it,  located on its
premises, or shown on the most recent balance sheet, free and clear of all liens
or other security interests.

     4.6 This Loan Agreement and the Note, have been duly executed and delivered
by  Borrower  and  are  legal,  valid  and  binding   obligations  of  Borrower,
enforceable in accordance with their respective terms, subject to (i) the effect
of any applicable bankruptcy,  insolvency,  reorganization,  moratorium or other
similar laws affecting the enforcement of creditors' rights generally,  (ii) the
availability  of the remedies of specific  performance  or injunctive  relief as
subject  to the  discretion  of the court  before  which a  proceeding  for such
remedies  may be brought,  and (iii) the  exercise by any court before which any
proceeding may be brought of equitable judicial discretion.

     4.7 Borrower has  delivered to Lender its  unaudited  balance  sheet of the
Borrower and the related  statements of income,  retained earnings and cash flow
of Borrower  (collectively  "Financial  Statements")  for the three month period
ending March 31, 2001, and further has updated the Financial  Statements through
May 31, 2001 so that the financial  status of Borrower as of that date is fairly
represented.  Such balance  sheet and  statement  fairly  present the  financial
condition of the  Borrower as of such date(s) and the results of the  operations
of the  Borrower  for the  period  ended on such  date(s),  and such  statements
through March 31, 2001 have been prepared in accordance with generally  accepted
accounting  principles  consistently  applied,  and contain any disclosure  that
would normally be required by financial  statements  prepared in accordance with
generally accepted accounting principles.  Since the end of the period reflected
in such financial  statements  there has been no material adverse change in such
condition or operations.

     4.8 Except as disclosed and  described on Schedule 4.8,  Borrower has filed
all  applicable  tax  returns  required  to be filed by it, and has paid or made
provisions  for the payment of all taxes which have become due  pursuant to said
returns or pursuant to any assessment received by Borrower except such taxes, if
any, as are being contested in good faith and as to which adequate reserves have
been provided in accordance with generally accepted accounting  principles,  and
warrants that such returns properly  reflect the United States,  state and local
income and tax liability of the Borrower for the period covered thereby.

     4.9 Except as disclosed and fully  described on Schedule  4.9,  there is no
action,  suit  or  proceeding  pending  or,  to the  knowledge  of the  Borrower
threatened,  against  the  Borrower  or any of its  property  before  any court,
governmental department, administrative agency or instrumentality which, if such
action,  suit or proceeding were adversely  determined,  would materially affect
the  financial  condition  or the results of  operations  of the Borrower or its
business or the ability of the  Borrower to perform its  obligations  hereunder.
4.10 Except as disclosed and described on Schedule

     4.10  hereto,  Borrower  is not in default on or has  otherwise  delayed or
postponed  payment of any  accounts  payable or other  liabilities  in excess of
$25,000 outside the ordinary course of business.

     4.11 Each Loan shall be fully  applied by  Borrower  solely for its working
capital  needs or for the  purchase  of  equipment  or  leasehold  improvements,
consistent with Schedule  3.1(g) and the cash control  system,  and for no other
purpose.

     4.12 No broker or finder  acting on behalf of  Borrower  brought  about the
obtaining,  making  or  closing  of this  Loan  Agreement  and  Borrower  has no
obligation  to pay any  finder's  or  brokerage  fees  in  connection  with  the
transactions contemplated herein.

     4.13 As of the date of  execution  of this Loan  Agreement,  the  aggregate
interest and other charges payable by Borrower to Lender under the terms of this
Loan Agreement do not exceed the maximum legal  interest rate  applicable to the
Loans.

     5. COVENANTS.
        ---------

     Borrower  hereby  covenants and agrees that until  satisfaction  of all its
obligations, it shall:

     5.1 Preserve and maintain its  corporate  existence  and all of its rights,
privileges and franchises,  and continue the conduct of its present  business in
an orderly,  efficient and regular manner;  comply in all material respects with
all  applicable  laws,  rules,   regulations  and  orders  of  any  governmental
authority,  non-compliance  with which  would  materially  affect the ability of
Borrower to perform its obligations.

     5.2 Make payments or  commitments  for payments  only in strict  compliance
with the Budget,  the Expense Plan and the cash control system,  or otherwise as
authorized by Lender.

     5.3 Furnish Lender  promptly with any financial  information or statements,
and other current information  regarding or relating to Borrower,  as reasonably
requested by Lender, other than information  relating to Borrower's  proprietary
know-how and technology information.

     5.4 Timely file any and all tax returns and tax filings  required under any
governmental  statute or regulation and timely pay and discharge,  when due, all
tax  obligations,  and  material  obligations  to third  parties,  except  those
obligations  being  contested in good faith,  and for which  Borrower shall have
maintained,   in  accordance  with  generally  accepted  accounting  principles,
adequate reserves for the payment of the same.

     5.5  Notify  Lender  immediately  upon  receipt  of  notice  of  any  lien,
attachment,  administrative or judicial proceeding, pending or threatened claim,
dispute,  litigation  or  governmental  proceedings,  material to the  financial
condition or operations of Borrower,  which for this purpose shall be any amount
in excess of $ 10,000; provide immediate written notice to Lender of any Default
or event  which  with the  lapse  of time or  giving  of  notice  or both  would
constitute a Default.

     5.6 Promptly and duly execute and deliver to Lender such further documents,
instruments  and assurances and take such further action as Lender may from time
to time reasonably  request in order to carry out the intent and purpose of this
Loan  Agreement and to establish and protect the rights and remedies  created or
intended to be created in favor of Lender hereunder.

     5.7  Reimburse  Borrower  for its  costs  and  reasonable  attorneys'  fees
incurred in enforcing its rights pursuant to the provisions of this Agreement.

     6. DEFAULTS AND REMEDIES.
        ---------------------

     6.1 Any of the following shall  constitute a default by Borrower  hereunder
("Default"):  (a) failure by Borrower to pay any amounts  hereunder or under any
Note when due and such remains unremedied for a period of fifteen (15) days from
the due date;  or (b)  failure of  Borrower  to comply  with any  provisions  or
perform any of its  obligations  arising under this Loan  Agreement  (other than
those  referred  to in clause (a) above),  or if, but only if,  such  failure to
comply is remediable, it remains unremedied by Borrower for a period of ten (10)
days from notice to Borrower;  or (c) any  representations or warranties made or
given  by  Borrower  in  connection  with  this  Loan  Agreement  were  false or
misleading  when made,  in any  material  way; or (d)  subjection  of any of the
assets in an amount in excess of  $10,000.00  of Borrower to  attachment,  levy,
execution,  forfeiture  or  cancellation  or other  administrative  or  judicial
process which is not or cannot be removed with reasonable diligence within sixty
(60) days from the subjection  thereof,  or (e)  commencement of any insolvency,
bankruptcy  or  similar  proceedings,  by or  against  Borrower,  including  any
assignment  by  Borrower  for the benefit of  creditors,  and in the case of any
involuntary  proceedings,  such is not  dismissed  within  ninety  (90)  days of
institution;  or the  inability of Borrower to pay its debts as they become due;
or (f) the  liquidation or dissolution  of Borrower or the  commencement  of any
acts relative thereto,  or without the prior written consent of Lender, any sale
or other disposition of all or substantially  all of the assets of Borrower,  or
any merger or  consolidation  of  Borrower,  or the  cessation  of  business  by
Borrower; or (g) a default by Borrower under any agreement for borrowed money or
under any lease,  except with  regard to the lease of premises  located at 16350
Park Ten Place,  Houston,  Texas 77084, whereby the holder of the obligation has
accelerated it prior to its stated maturity and such accelerated  amount exceeds
$100,000.00,  except as otherwise disclosed on Schedule 4.10; or (h) there shall
be a money judgment,  in excess of $25,000.00  entered against Borrower which is
not fully  covered by  insurance  or remains  unvacated,  unbonded,  unstayed or
undischarged for more than sixty (60) days.

     6.2 Upon any default, Lender, upon written notice to Borrower, may exercise
any one or more of the following remedies (which remedies shall be cumulative to
the extent  permitted by law):  (a) terminate  any further  obligation of Lender
hereunder  (including  any  obligation to make further  loans);  (b) declare the
remaining  unpaid  principal  balances of the Note,  plus all accrued but unpaid
interest  thereon,   plus  all  other  amounts  due  from  Borrower   hereunder,
immediately  due and payable in full without  notice or demand,  whereupon  such
shall  become due and  payable;  or (c) exercise any other right or remedy which
may be  available  to it under  applicable  law.  Upon a  default  any  proceeds
received from  Borrower  shall be applied by Lender to the  obligations,  in the
order of application as Lender shall elect.

     7. NOTICES; CHANGES.
        ----------------

         Notices, requests or other communications required hereunder to be sent
to either party shall be in writing and shall be by: (a) United States first
class mail, postage prepaid, and addressed to the other party at the address set
forth above (or to such other address as such party shall have designated by
proper notice), effective five days after deposit; (b) by personal or overnight
delivery, effective upon receipt.

     8. GOVERNING LAW.
        -------------

     This Loan Agreement  shall be governed and construed in accordance with the
laws of the State of  California  without  giving  effect to the  principles  of
conflict of laws thereof.

     9. DISPUTE  RESOLUTION.
        -------------------

     9.1 Any controversy or claim between or among the parties arising out of or
relating  to this  Loan  Agreement  or any  related  agreements  or  instruments
("Subject  Documents"),  including any claim based on or arising from an alleged
tort,  shall be  submitted  to and  determined  by  arbitration  before  one (1)
arbitrator  who shall be an attorney  admitted  to practice  law in the state of
California,  in  accordance  with  Title 9 of the U.S.  Code and the  Commercial
Arbitration  Rules  of the  American  Arbitration  Association  ("AAA")  then in
effect,  and shall be held in the county of San  Francisco,  CA. All statutes of
limitations  which would otherwise be applicable  shall apply to any arbitration
proceeding under this  subparagraph 9.1. Judgment upon the award rendered may be
entered in any court having jurisdiction. This subparagraph 9.1 shall apply only
if, at the time of the proposed  submission to AAA, none of the  obligations  to
Lender  described in or covered by any of the Subject  Documents  are secured by
real  property  collateral  or,  if so  secured,  all  parties  consent  to such
submission.

     9.2 If the controversy or claim is not submitted to arbitration as provided
and limited in Section  9.1, but becomes the subject of a judicial  action,  any
party may elect to have all decisions of fact and law determined by a referee in
accordance with  applicable  state law. If such an election is made, the parties
shall  designate to the court a referee or referees  selected under the auspices
of the AAA in the same  manner as  arbitrators  are  selected  in  AAA-sponsored
proceedings.  The referee, or presiding referee of the panel, shall be an active
attorney or retired judge.  Judgment upon the award rendered shall be entered in
the court in which such proceeding was commenced.

     9.3 Except as provided  herein,  no  provision  of, or the  exercise of any
rights under,  Section 9.1,  shall limit the right of any party to exercise self
help remedies such as setoff,  or to obtain  provisional  or ancillary  remedies
such as injunctive  relief or the  appointment of a receiver from a court having
jurisdiction  before,  during  or after the  pendency  of any  arbitration.  The
institution  and  maintenance  of an action  for  judicial  relief or pursuit of
provisional  or ancillary  remedies or exercise of self help remedies  shall not
constitute  a waiver of the right of any  party,  including  the  plaintiff,  to
submit the controversy or claim to arbitrators.

     9.4 The  parties  understand  and  agree  the  arbitration  will  be  their
exclusive form of resolving  disputes  between them regarding the issues covered
by this Agreement.  BOTH PARTIES EXPRESSLY WAIVE THEIR  ENTITLEMENT,  IF ANY, TO
HAVE CONTROVERSIES BETWEEN THEM DECIDED BY A JURY OR COURT OF LAW.

     10. MISCELLANEOUS.
         -------------

     This Loan  Agreement  or any part  hereof,  may not be assigned by Borrower
without the written consent of Lender and shall be binding upon and inure to the
benefit of the parties hereto, their legal representatives, permitted successors
and  assigns.  This Loan  Agreement  and/or the note or any part  thereof may be
assigned by Lender without the consent of Borrower. No amendment hereunder shall
be  effective  unless in  writing  signed by the  parties  hereto  and no waiver
hereunder  shall be  effective  unless  in  writing,  signed  by the party to be
charged.  No  failure  to  exercise,  no delay in  exercising,  and no single or
partial exercise on the part of Lender of any right, remedy, or power hereunder,
shall operate as a waiver thereof or preclude  Lender from  exercising any other
right,  remedy or power  hereunder.  Any provision of this Loan Agreement or the
Note which is unenforceable in any jurisdiction  shall, as to such jurisdiction,
be ineffective to the extent of such  prohibition or  unenforceability,  without
invalidating   the   remaining   provisions   hereof   or  of  the   note.   The
representations,  warranties,  obligations  and  indemnities of Borrower  herein
shall survive the  termination of this Loan Agreement to the extent required for
their full observance and  performance.  The obligation of each comaker (if any)
of this Loan Agreement or the Note shall be primary,  joint and several and each
such comaker  hereby  irrevocably  consents to any extension of time of payments
and/or the execution of any refinancing or restructuring  agreements relative to
this  Loan  Agreement  or the  Note.  In the  event  Borrower  fails to meet any
obligation of it hereunder, Lender may at its option satisfy such obligation and
Borrower shall reimburse  Lender on demand  therefor.  The captions in this Loan
Agreement  are for  convenience  only and shall  not  define or limit any of the
terms hereof.  This Loan Agreement may be executed in counterparts  and all said
counterparts  taken  together  shall be  deemed to  constitute  one and the same
instrument.

     THIS LOAN IS SECURED BY THE TERMS OF THAT  CERTAIN  SECURITY  AGREEMENT  OF
EVEN DATE BY AND  BETWEEN  BORROWER  AND LENDER  HEREUNDER,  ATTACHED  HERETO AS
EXHIBIT C.

<PAGE>

     IN  WITNESS  WHEREOF,  the  parties  hereto  have duly  executed  this Loan
Agreement as of the date first above written.  Borrower  acknowledges  that this
Loan  Agreement  shall not be effective  until accepted by Lender at its address
above.

LENDER:                                    BORROWER:

IMATRON INC.                               POSITRON CORPORATION

By: _____________________________          By: _____________________________

Its: _____________________________         Its: ______________________________

Attest:                                    Attest:

By: ______________________________         By: ______________________________

Its: _____________________________         Its: ______________________________

<PAGE>

                                 Schedule 3.1(g)

                                  Expense Plan

                      (Attach ProForma's for 2001 and 2002)

<PAGE>

                                  Schedule 4.5

                       Exceptions to Good Title to Assets

None

<PAGE>

                                  Schedule 4.5

                       Current Outstanding Loan agreements

None

<PAGE>

                                  Schedule 4.8

                  Overdue tax returns and provisions for taxes

None

<PAGE>

                                  Schedule 4.9

                          Pending or threatened actions

Currently Pending
-----------------

ProFutures Bridge Capital Fund, L.P. v. Positron Corporation, Case No. 00CV7146,
District Court, City and County of Denver,  Colorado.  Complaint for Declaratory
and Other Relief

<PAGE>

                                  Schedule 4.10

        Defaults or delays in payments in excess of $25,000 (a/o 6/29/01)

Payable to                                             Amount Due
-----------                                            ----------

Allen Matkins Leck Gable & Mallory LLP               $  34,267.92

Future Electronics                                   $ 127,778.00

GE Access                                            $ 123,104.59

LFJ Associates                                       $  29,018.11

Photonis                                             $ 126,700.00

Polymer Corporation                                  $ 182,217.26

Primary Sourcing                                     $  45,511.74

Saint-Gobain                                         $ 327,085.44

Sigma Electronics                                    $  34,048.46

Special Products (Invoice 00032969)                  $  29,186.96

Tristar                                              $  95,574.00

TOTAL AP OUTSTANDING (including above)   $1,554,890.46

<PAGE>

                                    EXHIBIT A

                                 PROMISSORY NOTE

<PAGE>

                                    EXHIBIT B

                              OFFICER'S CERTIFICATE

<PAGE>

                                    EXHIBIT C

                               SECURITY AGREEMENT

<PAGE>

                                    EXHIBIT D

                             STOCK PURCHASE WARRANT

<PAGE>

                                    EXHIBIT E

                          REGISTRATION RIGHTS AGREEMENT

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