THE
        SECURITIES EVIDENCED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
        ACT OF
        1933, AS AMENDED (THE "ACT"),
        AND MAY NOT BE SOLD, TRANSFERRED, ASSIGNED OR HYPOTHECATED UNLESS (A) THERE
        IS AN EFFECTIVE REGISTRATION STATEMENT UNDER THE ACT, AND APPLICABLE STATE
        SECURITIES LAWS, COVERING ANY SUCH TRANSACTION INVOLVING SAID SECURITIES,
        (B) THE COMPANY RECEIVES AN OPINION OF LEGAL COUNSEL FOR THE HOLDER
        OF
        THESE SECURITIES SATISFACTORY TO THE COMPANY STATING THAT SUCH TRANSACTION
        IS
        EXEMPT FROM REGISTRATION, OR (C) THE COMPANY OTHERWISE SATISFIES ITSELF
        THAT SUCH TRANSACTION IS EXEMPT FROM REGISTRATION.

      


      POSITRON
        CORPORATION

      


      CONVERTIBLE
        PROMISSORY NOTE

      


      
        	$_____________	
                Houston,
                  Texas

              


      

      October
        31, 2005

      


      POSITRON
        CORPORATION, a Texas corporation (the "Company"),
        the
        principal office of which is located at 1304 Langham Creek Drive, #300, Houston,
        Texas 77084, for value received hereby promises to pay to Imagin Diagnostic
        Centres, Inc., 1835 Yonge St., Suite 500, Toronto,
        Ontario, Canada M4S, or its registered assigns (the "Holder"),
        the
        sum of _________________________ Dollars ($__________), or such lesser amount
        as
        shall then equal the outstanding principal amount hereof on the terms and
        conditions set forth hereinafter. The principal hereof and any unpaid accrued
        interest hereon, as set forth below, shall be due and payable on the earlier
        to
        occur of (i) October 31, 2008 (the "Maturity
        Date")
        or
        (ii) when declared due and payable by the Holder upon the occurrence
        of an
        Event of Default (as defined below). Commencing on the Maturity Date, all
        principal and accrued interest hereunder shall be payable upon demand. Payment
        for all amounts due hereunder shall be made by mail to the registered address
        of
        the Holder. All numbers expressed herein as "$" or "dollars" are in United
        States dollars.

      


      The
        following is a statement of the rights of the Holder of this Note and the
        conditions to which this Note is subject, and to which the Holder hereof,
        by the
        acceptance of this Note, agrees:

      


      1. Definitions.
        Except
        as otherwise defined herein, each capitalized term used herein shall have
        the
        meaning assigned to it in the Note Purchase Agreement dated as of October
        31,
        2005 (the "Purchase
        Agreement").
        As
        used in this Note, the following terms, unless the context otherwise requires,
        have the following meanings:

      


      
        
           

        

        
           

          
            

          

        

        
           

        

      

      (a) "Business
        Day"
        shall
        mean a day other than Saturday, Sunday or a public holiday under the laws
        of the
        State of Texas.

      


      (b) "Company"
        includes any corporation that shall succeed to or assume the obligations
        of the
        Company under this Note.

      


      (c) "Holder,"
        when
        the context refers to a holder of this Note, shall mean any person who shall
        at
        the time be the registered holder of this Note.

      


      (d) "Operating
        Cash Flow"
        shall
        mean the sum of net income, depreciation, change in accruals and change in
        accounts payable, minus change in accounts receivable, minus change in
        inventories.

      


      2. Interest.
        Simple
        interest shall accrue at the rate of ten percent (10%) per annum on
        the
        principal of this Note outstanding during the period beginning the date of
        funding of this Note and ending on the date that the principal amount of
        this
        Note is repaid. Interest shall be calculated on the basis of a 365-day year
        for
        the actual number of days elapsed. Accrued interest shall be payable in cash
        annually on the anniversary date of this note; provided however, that at
        the
        Company's option, the accrued interest shall be payable by issuance to Holder
        of
        a new note identical in form to this Note and in an amount equal to the accrued
        interest not otherwise paid in cash. In the event that a payment date falls
        on a
        non-Business Day, payment shall be made on the next Business Day, while taking
        into account such extra days in calculating the accrued interest. In the
        event
        of an earlier conversion, acceleration or payment of the Note, interest shall
        be
        payable in cash on such date.

      


      3. Events
        of Default.
        If any
        of the events specified in this Section 3 shall occur (herein individually
        referred to as an "Event
        of Default"),
        the
        Holder of the Note may, so long as such condition exists, declare the entire
        principal and unpaid accrued interest hereon immediately due and payable,
        by
        notice in writing to the Company:

      


      (a) The
        Company shall default in the payment of any part of the principal or accrued
        and
        unpaid interest on this Note after it shall become due and payable, whether
        at
        maturity or at a date fixed for prepayment or by acceleration or otherwise;
        or

      


      (b) The
        institution by the Company of proceedings to be adjudicated as bankrupt or
        insolvent, or the consent by it to institution of bankruptcy or insolvency
        proceedings against it or the filing by it of a petition or answer or consent
        seeking reorganization or release under the federal Bankruptcy Act, or any
        other
        applicable federal or state law, or the consent by it to the filing of any
        such
        petition or the appointment of a receiver, liquidator, assignee, trustee
        or
        other similar official of the Company, or of any substantial part of its
        property, or the making by it of an assignment for the benefit of creditors,
        or
        the taking of corporate action by the Company in furtherance of any such
        action;
        or

      


      (c) If,
        within sixty (60) days after the commencement of an action against
        the
        Company, without the consent or acquiescence of the Company (and service
        of
        process in connection therewith on the Company) seeking any bankruptcy,
        insolvency, reorganization, liquidation, dissolution or similar relief under
        any
        present or future statute, law or regulation, such action shall not have
        been
        resolved in favor of the Company or all orders or proceedings thereunder
        affecting the operations or the business of the Company stayed, or if the
        stay
        of any such order or proceeding shall thereafter be set aside, or if, within
        sixty (60) days after the appointment without the consent or acquiescence
        of the Company of any trustee, receiver or liquidator of the Company or of
        all
        or any substantial part of the properties of the Company, such appointment
        shall
        not have been vacated; or 

      


      
        
           

        

        
          -2-

          
            

          

        

        
           

        

      

      (d) Any
        material breach by the Company of any representation, warranty or covenant
        contained in the Purchase Agreement or this Note.

      


      (e) As
        of
        January 1, 2006, the Company shall not have obtained stockholder approval
        to
        amend its Articles of Incorporation to increase the number of shares of its
        authorized Common Stock to account for the conversion of this Note.

      


      In
        the
        case of an Event of Default pursuant to (b) or (c) above, all amounts
        shall
        automatically, without notice, become immediately due and payable and
        collectible by Holder pursuant to applicable law. 

       

      4. Conversion.

      


      4.1 Conversion.
        The principal amount of this Note, or any portion thereof may be converted
        by
        the Holder at any time prior to Maturity into the number of fully paid shares
        of
        the Company's Common Stock as is determined by dividing the unpaid principal
        under the Note by the Conversion Price (as hereinafter defined) in effect
        at the
        time of conversion. Accrued but unpaid interest shall be payable in cash
        at the
        time of conversion.

      


      4.2 Conversion
        Price. The Conversion Price (the "Conversion Price") applicable per share
        of
        Common Stock shall initially be equal to $0.02, subject to adjustment from
        time
        to time in accordance with Section 4.3 below. 

      


      4.3 Adjustments
        to the Conversion Price. The Conversion Price shall be subject to adjustment
        from time to time as follows:

      


      4.3.1 Adjustment
        Upon Stock Dividends, Subdivisions or Splits.
        If, at
        any time, the number of shares of Common Stock outstanding is increased by
        a
        stock dividend payable in shares of Common Stock or by a subdivision or split-up
        of shares of Common Stock, then, following the record date for the determination
        of holders of Common Stock entitled to receive such stock dividend, or to
        be
        affected by such subdivision or split-up, the Conversion Price shall be
        appropriately decreased so that the number of shares of Common Stock issuable
        on
        conversion of Note shall be increased in proportion to such increase in
        outstanding shares.

      


      4.3.2 Adjustment
        Upon Combinations.
        If, at
        any time, the number of shares of Common Stock outstanding is decreased by
        a
        combination of the outstanding shares of Common Stock into a smaller number
        of
        shares of Common Stock, then, following the record date to determine shares
        affected by such combination, the Conversion Price shall be appropriately
        increased so that the number of shares of Common Stock issuable on conversion
        of
        the Note shall be decreased in proportion to such decrease in outstanding
        shares.

      


      
        
           

        

        
          -3-

          
            

          

        

        
           

        

      

      4.3.3 Adjustment
        Upon Reclassifications, Reorganizations, Consolidations or
        Mergers.
        If, at
        any time when the Note is issued and outstanding, there shall be any merger,
        consolidation, share exchange, recapitalization, reorganization, business
        combination, or other similar event, as a result of which shares of Common
        Stock
        shall be changed into the same or a different number of shares of another
        class
        or classes of stock or securities of the Company or another entity, or in
        case
        of any sale or conveyance of all or substantially all of the assets of the
        Company then the Holder shall thereafter have the right to receive upon
        conversion of the Note, upon the basis and upon the terms and conditions
        specified herein and in lieu of the shares of Common Stock immediately
        theretofore issuable upon conversion, such stock, securities, cash or other
        assets which the Holder of would have been entitled to receive in such
        transaction had the Note been converted in full immediately prior to such
        transaction (without regard to any limitations on conversion contained herein),
        and in any such case appropriate provisions shall be made with respect to
        the
        rights and interests of the Holder to the end that the provisions hereof
        (including, without limitation, provisions for adjustment of the applicable
        Conversion Price and of the number of shares of Common Stock issuable upon
        conversion of the Note) shall thereafter be applicable, as nearly as may
        be
        practicable in relation to any securities or assets thereafter deliverable
        upon
        the conversion of the Note. The above provisions shall similarly apply to
        successive mergers, consolidations, share exchanges, recapitalizations,
        reorganizations, business combinations or other similar events or sales of
        assets.

      


      4.3.4 Deferral
        in Certain Circumstances.
        In any
        case in which the provisions of this Section 4.3 shall require that an
        adjustment shall become effective immediately after a record date of an event,
        the Company may defer until the occurrence of such event issuing to the Holder
        of the Note, converted after such record date and before the occurrence of
        such
        event, the shares of capital stock issuable upon such conversion by reason
        of
        the adjustment required by such event and issuing to such Holder only the
        shares
        of capital stock issuable upon such conversion before giving effect to such
        adjustments; provided, however, that the Company shall deliver to such Holder
        an
        appropriate instrument or due bills evidencing such holder's right to receive
        such additional shares.

      


      4.3.5 Notice
        of Adjustment of Conversion Price.
        Whenever the Conversion Price is adjusted as herein provided: (i) the Company
        shall compute the adjusted Conversion Price in accordance with this Section
        4.3
        and shall prepare a certificate signed by the Chief Financial Officer of
        the
        Company setting forth the adjusted Conversion Price and showing in reasonable
        detail the facts upon which such adjustment is based, and such certificate
        shall
        forthwith be filed at each office or agency maintained for such purpose of
        conversion of the Note; and (ii) a notice stating that the Conversion Price
        has
        been adjusted and setting forth the adjusted Conversion Price shall forthwith
        be
        prepared by the Company, and as soon as practicable after it is prepared,
        such
        notice shall be mailed by the Company at its expense to the Holder at the
        Holder's last addresses as it shall appear in the Company's
        records.

      


      4.4 Conversion
        Procedure.

      


      4.4.1 Notice
        of Conversion.
        In
        order to convert this Note (in whole or in part) into full shares of Common
        Stock, the Holder shall surrender the Note, duly endorsed, by either overnight
        courier or by hand, to the principal office of the Company, and shall give
        written notice (the "Conversion
        Notice")
        by
        facsimile (with the original of such notice forwarded with the foregoing
        courier) to the Company at such office that the Company elects to convert
        the
        amount specified therein, which such notice and election shall be irrevocable
        by
        the Holder; provided however, that the Company shall not be obligated to
        issue
        certificates evidencing the shares of the Common Stock issuable upon such
        conversion unless either the Note evidencing the principal amount is delivered
        to the Company as provided above, or the Holder notifies the Company that
        such
        Note(s) have been lost, stolen or destroyed and promptly executes an agreement
        reasonably satisfactory to the Company to indemnify the Company from any
        loss
        incurred by its connection with such Note(s).

      


      
        
           

        

        
          -4-

          
            

          

        

        
           

        

      

      4.4.2 Delivery
        of Stock Certificates.
        Upon
        receipt of such Conversion Notice, the Company shall immediately verify the
        Holder's calculation of the conversion rate and shall use its best efforts
        to
        cause its transfer agent to issue and deliver as promptly as practical to
        the
        Company of such Note(s), or after receipt of such agreement and indemnification,
        to such Holder of Note(s) at the address of the Holder, or to its designee,
        a
        certificate or certificates for the number of shares of Common Stock to which
        the Holder shall be entitled, together with a Note or Notes for the principal
        amount of Notes not submitted for conversion. The issuance of such certificates
        upon conversion of this Note shall be made without charge to the Holder of
        this
        Note for any issuance tax in respect thereof or other cost incurred by the
        Company in connection with such conversion and the related issuance of the
        Common Stock. Upon the conversion of this Note, the Company shall take all
        such
        actions as are necessary in order to insure that the Common Stock issuable
        with
        respect to such conversion shall be validly issued and fully paid.

      


      4.4.3 Effect
        of Conversion.
        The
        date on which the Conversion Notice is given shall be deemed to be the date
        the
        Company received by facsimile the Conversion Notice, and the person or persons
        entitled to receive the shares of Common Stock issuable upon such conversion
        shall be treated for all purposes as the record holder or holders of such
        shares
        of Common Stock on such date. No fractional shares of Common Stock shall
        be
        issued upon conversion of this Note. In lieu of the Company issuing any
        fractional shares to the Holder upon the conversion of this Note, the Company
        shall pay to the Holder the amount of outstanding principal that is not
        converted because its conversion would require fractional shares, such payment
        to be in the form as provided below. Upon conversion of this Note, the Company
        shall be forever released from all of its obligations and liabilities under
        this
        Note,
        except
        that the Company shall be obligated to pay the Holder, within ten (10)
        days
        after the date of such conversion, any interest accrued and unpaid or
        unconverted to and including the date of such conversion, and no
        more.

      


      4.5 Notices
        of Record Date, etc. In the event of:

      


      4.5.1 Any
        taking by the Company of a record of the holders of any class of securities
        of
        the Company for the purpose of determining the holders thereof who are entitled
        to receive any dividend (other than a cash dividend payable out of earned
        surplus at the same rate as that of the last such cash dividend theretofore
        paid) or other distribution, or any right to subscribe for, purchase or
        otherwise acquire any shares of stock of any class or any other securities
        or
        property, or to receive any other right; or

      


      4.5.2 Any
        capital reorganization of the Company, any reclassification or recapitalization
        of the capital stock of the Company or any transfer of all or substantially
        all
        of the assets of the Company to any other person or any consolidation or
        merger
        involving the Company; or

      


      
        
           

        

        
          -5-

          
            

          

        

        
           

        

      

      4.5.3 Any
        voluntary or involuntary dissolution, liquidation or winding-up of the Company,
        

      


      the
        Company will mail to the holder of this Note at least five (5) days
        prior
        to the earliest date specified therein, a notice specifying:

      4.5.3.1
        The
        date
        on which any such record is to be taken for the purpose of such dividend,
        distribution or right, and the amount and character of such dividend,
        distribution or right; and

      


      4.5.3.2
        The
        date
        on which any such reorganization, reclassification, transfer, consolidation,
        merger, dissolution, liquidation or winding-up is expected to become effective
        and the record date for determining shareholders entitled to vote
        thereon.

      


      4.6 Notice
        of
        Prepayment. The Company shall mail to the holder of this Note at least sixty
        (60) days prior to repayment of any principal due hereunder.

      


      4.7 Reservation
        of Stock Issuable Upon Conversion. The Company shall, prior to conversion
        of
        this Note into Common Stock, reserve and keep available out of its authorized
        but unissued shares of Common Stock solely for the purpose of effecting the
        conversion of the Note such number of its shares of Common Stock as shall
        from
        time to time be sufficient to effect the conversion of the Note. The Company
        shall at all times reserve and keep available out of its authorized but unissued
        Common Stock, such number of its duly authorized Common Stock as shall be
        sufficient to effect the conversion of the Common Stock into Common Stock
        in
        accordance with its Articles. If at any relevant time the number of authorized
        but unissued shares of Common Stock shall not be sufficient to effect the
        conversion of the entire outstanding principal amount of this Note, in addition
        to such other remedies as shall be available to the holder of this Note,
        the
        Company will use its reasonable efforts to forthwith take such corporate
        action
        as may be necessary to increase its authorized but unissued shares of Common
        Stock to such number of shares as shall be sufficient for such
        purposes.

      


      5. Assignment.
        Subject
        to the restrictions on transfer described in Section 8 below, the
        rights
        and obligations of the Company and the Holder of this Note shall be binding
        upon
        and benefit the successors, assigns, heirs, administrators and transferees
        of
        the parties.

      


      6. Waiver
        and Amendment.
        Any
        provision of this Note may be amended, waived or modified (either generally
        or
        in a particular instance, either retroactively or prospectively, and either
        for
        a specified period of time or indefinitely), upon the written consent of
        the
        Company and of the Holder.

      


      7. Waiver
        of Notice.
        The
        Company hereby waives notice, presentment, demand, protest and notice of
        dishonor.

      


      
        
           

        

        
          -6-

          
            

          

        

        
           

        

      

      8. Transfer
        of this Note or Securities Issuable on Conversion Hereof.
        Transfer of this Note or the Common Stock and Common Stock issuable upon
        conversion thereof shall only be made in accordance with Section 4.7 and
        4.8 of
        the Purchase Agreement. All transferees of this Note agree to be bound by
        the
        obligations set forth under Sections 1.6, 1.7 and Section 4 (and related
        definitions) of the Purchase Agreement, which Sections are incorporate herein
        by
        reference. In connection with any such transfer, such transferee shall sign
        an
        acknowledgment stating that it will become bound by the terms of such sections
        Purchase Agreement. Holder understands and agrees that each certificate held
        by
        Holder representing Common Stock and Common Stock issuable upon conversion
        of
        this Note, or any other securities issued in respect of this Note issuable
        upon
        conversion thereof upon any stock split, stock dividend, recapitalization,
        merger, consolidation or similar event, shall bear the following legend (in
        addition to any legend required under applicable federal or state securities
        laws): 

      


      "THE
        SHARES REPRESENTED BY THIS CERTIFICATE ARE RESTRICTED BY THE TERMS OF, AND
        ARE
        SUBJECT TO RESTRICTIONS ON TRANSFER AND RIGHTS OF SALE AS PROVIDED IN A NOTE
        PURCHASE AGREEMENT BETWEEN THE COMPANY AND THE HOLDER HEREOF, OR ITS SUCCESSOR,
        A COPY OF WHICH IS AVAILABLE FROM THE COMPANY."

      


      9. Notices.
        Any
        notice, request or other communication required or permitted hereunder shall
        be
        in writing and shall be deemed to have been duly given if personally delivered
        or if sent by nationally recognized courier service or mailed by registered
        or
        certified mail, postage prepaid, to the respective addresses of the parties
        as
        set forth herein or if sent by facsimile to the respective facsimile numbers
        of
        the parties set forth herein. Any party hereto may by notice so given change
        its
        address for future notice hereunder. Notice shall conclusively be deemed
        to have
        been given and received when personally delivered or three (3) Business
        Days after deposited in the mail or one Business Day after sent by courier
        or
        upon confirmation of facsimile delivery in the manner set forth
        above.

      


      10. Loss,
        Theft or Destruction of Note.
        Upon
        receipt by the Company of evidence reasonably satisfactory to it of the loss,
        theft or destruction of this Note and of indemnity or security reasonably
        satisfactory to it, the Company will make and deliver a new Note which shall
        carry the same rights to interest (unpaid and to accrue) carried by this
        Note,
        stating that such Note is issued in replacement of this Note, making reference
        to the original date of issuance of this Note, (and any successors hereto)
        and
        dated as of such cancellation, in lieu of this Note.

      


      11. Usury
        Disclosure.
        Regardless of any provision contained in this Note, it is expressly stipulated
        and agreed that the intent of the Holder and the Company is to comply at
        all
        times with all usury and other laws relating to this Note. If the laws of
        the
        State of Texas would now or hereafter render usurious, or are revised, repealed
        or judicially interpreted as to render usurious, the indebtedness evidenced
        by
        this Note, or if any prepayment by the Company results in the Company's having
        paid any interest in excess of that permitted by law, then it is the Holder's
        and the Company's express intent that all excess amounts theretofore collected
        by the Holder be credited to the principal balance of this Note (or, if this
        Note has been paid in full, refunded to the Company), and the provisions
        of this
        Note immediately be deemed reformed the amounts therefor collectible hereunder
        reduced, without the necessity of execution of any new document, so as to
        comply
        with the then applicable law, but so as to permit the recovery of the fullest
        amount otherwise called for hereunder.

      


      
        
           

        

        
          -7-

          
            

          

        

        
           

        

      

      12. No
        Shareholder Rights.
        Nothing
        contained in this Note shall be construed as conferring upon the Holder or
        any
        other person the right to vote or to consent or to receive notice as a
        shareholder in respect of meetings of shareholders for the election of directors
        of the Company or any other matters or any rights whatsoever as a shareholder
        of
        the Company.

      


      13. Governing
        Law.
        This
        Agreement shall be governed by and construed in accordance with the laws
        of the
        State of Texas, excluding that body of law relating to conflict of
        laws.

      


      14. Heading;
        References.
        All
        headings used herein are used for convenience only and shall not be used
        to
        construe or interpret this Note. Except as otherwise indicated, all references
        herein to Sections refer to Sections hereof.

      


      [Remainder
        of page intentionally left blank]


      
        
           

        

        
          -8-

          
            

          

        

        
           

        

      


      IN
        WITNESS WHEREOF, the Company has caused this Note to be issued as of the
        date
        first set forth above.

      


      
        	COMPANY:	
                POSITRON CORPORATION,
                  a
                  Texas corporation

                 

                 

                
                  By:                                                                               
                    

                  Patrick
                    G. Rooney, Chairman of the Board

                  


                         
                    Address:     1304
                    Langham Creek Drive, #300

                                               
                    Houston, Texas 77084

                                               
                    Facsimile:
                    281-492-2961

                

              


      

      



      
        
           

        

        
          -9-

          
            

          

        

        
           

          
          

        

      


      


      NOTICE
        OF CONVERSION

      (To
        Be
        Signed Only Upon Conversion of Note)

      


      TO
        POSITRON CORPORATION

      


      The
        undersigned, the holder of the foregoing Note, hereby surrenders such Note
        for
        conversion into ___ shares of Common Stock of POSITRON CORPORATION, to the
        extent of ________________________ dollars ($____________) unpaid principal
        amount of such Note, and requests that the certificates for such shares be
        issued in the name of, and delivered to,
        _________________________________________, whose address is
        __________________________________________________.

      


      Dated:
        ________________________.

      


      


      
        	 	
                                                                                                         

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

                


                Address