REGISTRATION RIGHTS AGREEMENT

This Registration Rights Agreement (this " Agreement ") is made and entered into as of October 31, 2005 by and between Imagin Diagnostic Centres, Inc., 1835 Yonge St., Suite 500, Toronto, Ontario, Canada M4S, (" Purchaser "), and Positron Corporation, a Texas corporation (the " Company ").

WHEREAS, concurrent with the execution of this Agreement the Company and Purchaser are entering into a Note Purchase Agreement (as defined below) pursuant to which Purchaser will purchase from the Company Convertible Promissory Notes in the aggregate principal amount of $400,000 (the " Notes "); and

WHEREAS, the Notes are convertible at the option of the holders into shares of the Company's Common Stock (the "Common Stock ").

NOW, THEREFORE, in consideration of the mutual promises, representations, warranties and conditions set forth in this Agreement, the parties hereto, intending to be legally bound, hereby agree as follows:

1.   Definitions . For purposes of this Agreement, in addition to the definitions set forth above and elsewhere herein, the following terms shall have the following respective meanings:

" Acquisition Shares " shall mean the shares of Common Stock which the Purchaser will have a right to acquire upon the conversion of the Notes.

" Commission " shall mean the United States Securities and Exchange Commission and any successor agency.

" Demand Date " shall mean the date the Company receives the written request for registration of Registrable Stock from Purchaser pursuant to Section 3 hereof.

" Exchange Act " shall mean the Securities Exchange Act of 1934, as amended, or any similar federal statute, and the rules and regulations of the Commission thereunder, all as the same shall be in effect at the time.

" Holder " shall mean the Purchaser and all transferees or assignees thereof to whom the rights under this Agreement are assigned in accordance with the provisions of Section 8 hereof.

" Note Purchase Agreement " shall mean the Note Purchase Agreement between the Company and the Purchaser, dated as of October 31, 2005.

" Person " shall mean an individual, corporation, partnership, limited partnership, syndicate, person (including, without limitation, a "person" as defined in Section 13(d)(3) of the Exchange Act), trust, association or entity or government, political subdivision, agency or instrumentality of a government.

" Register, " " registered " and " registration " shall refer to a registration effected by preparing and filing a registration statement or similar document in compliance with the Securities Act and the declaration or ordering of effectiveness of such registration statement or document.

" Registrable Stock " shall mean (a) the Acquisition Shares, (b) any shares of Common Stock or other capital stock issued as a dividend, or other distribution with respect to, or in exchange for, or in replacement of, any of the Acquisition Shares and (c) any shares of capital stock issued by way of a stock split of the Acquisition Shares referred to in clause (a) above. For purposes of this Agreement, any Registrable Stock shall cease to be Registrable Stock when (i) a registration statement covering such Registrable Stock has been declared effective and such Registrable Stock has been disposed of pursuant to such effective registration statement, (ii) such Registrable Stock is sold by a person in a transaction in which the rights under the provisions of this Agreement are not assigned, or (iii) all such Registrable Stock may be sold by any and all Holders pursuant to Rule 144(k) (or any similar provision then in force, but not Rule 144A) under the Securities Act without registration under the Securities Act.

" Securities Act " shall mean the Securities Act of 1933, as amended, or any similar federal statute, and the rules and regulations of the Commission thereunder, all as the same shall be in effect at the time.

2.   Restrictive Legend . Each certificate representing Acquisition Shares shall, except as otherwise provided in this Section 2, be stamped or otherwise imprinted with a legend substantially in the form set forth in the Note Purchase Agreement. A certificate shall not bear such legend if in the opinion of counsel satisfactory to the Company or the Company shall determine that the securities being sold thereby may be publicly sold without registration under the Securities Act or the transfer of such securities is permitted under the provisions of Regulation D, Rule 144(k) or Rule 144A (or any rule permitting public sale without registration under the Securities Act).

3.   Registration Rights . Upon the written request of Purchaser to the Company, the Company shall use its reasonable best efforts to prepare and file with the Commission a registration statement on an applicable form, signed, pursuant to Section 6(a) of the Securities Act, by the officers and directors of the Company, with respect to the Registrable Stock. If the Company shall fail to register the shares of Registrable Stock, the Company shall deliver the unregistered shares of Registrable Stock to the Purchaser and such shares may be sold pursuant to and subject to the requirements of Rule 144 under the Securities Act. The Company's delivery of the unregistered shares shall be the Purchaser's sole remedy for any failure by the Company to register shares pursuant to this Section 3. In connection with this Section 3, the Company shall:

(a)   cause such registration statement to become effective on or before the three-month anniversary of the Demand Date and to remain effective through and including the earlier of (i) the time when all of the Registrable Stock has been sold pursuant to such registration statement or (ii) the time when all of the Holders of the Registrable Stock can sell all of the Registrable Stock pursuant to Rule 144(k) (or any similar provision then in force, but not Rule 144A) under the Securities Act without registration under the Securities Act.

(b)   prepare and file with the Commission such amendments and supplements to such registration statement, signed, pursuant to Section 6(a) of the Securities Act, by the officers and directors of the Company, and the prospectus used in connection therewith as may be necessary to comply with the provisions of the Securities Act with respect to the disposition of all Registrable Stock covered by such registration statement;

(c)   furnish to the Holders such numbers of copies of the registration statement and the prospectus included therein (including each preliminary prospectus and any amendments or supplements thereto) in conformity with the requirements of the Securities Act and such other documents and information as they may reasonably request;

(d)   use its reasonable best efforts to register or qualify the Registrable Stock covered by such registration statement under such other securities or blue sky laws of such jurisdictions within the United States and Puerto Rico as required by law for the distribution of the Registrable Stock covered by the registration statement; provided, however, that the Company shall not be required in connection therewith or as a condition thereto to qualify to do business in or to file a general consent to service of process in any jurisdiction wherein it would not but for the requirements of this paragraph (d) be obligated to do so; and provided, further, that the Company shall not be required to qualify such Registrable Stock in any jurisdiction in which the securities regulatory authority requires that any Holder submit any shares of its Registrable Stock to the terms, provisions and restrictions of any escrow, lockup or similar agreement(s) for consent to sell Registrable Stock in such jurisdiction unless such Holder agrees to do so;

(e)   promptly notify each Holder for whom such Registrable Stock is covered by such registration statement, at any time when a prospectus relating thereto is required to be delivered under the Securities Act, of the happening of any event as a result of which the prospectus included in such registration statement, as then in effect, includes an untrue statement of a material fact or omits to state any material fact required to be stated therein or necessary to make the statements therein not misleading in light of the circumstances under which they were made, and at the request of any such Holder promptly prepare and furnish to such Holder a reasonable number of copies of a supplement to or an amendment of such prospectus as may be necessary so that, as thereafter delivered to Holders of such securities, such prospectus shall not include any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading in light of the circumstances under which they were made;

(f)   enter into customary agreements and take such other actions as are reasonably required in order to expedite or facilitate the disposition of the Registrable Stock to be so included in the registration statement;

(g)   otherwise use its reasonable best efforts to comply with all applicable rules and regulations of the Commission;

(h)   use its reasonable best efforts to list the Registrable Stock covered by such registration statement with any securities exchange on which Common Stock is then listed; and

(i)   after the effectiveness of the registration statement, cooperate with the Holders to facilitate the timely preparation and delivery of certificates representing the Registrable Stock to be sold, which certificates shall not bear any restrictive legends other than restrictive legends still required to be imposed by the Note Purchase Agreement.

4.   Suspension of Trading . Notwithstanding any other provision of this Agreement, the Company shall have the right at any time to require that all Holders suspend further open market offers and sales of Registrable Stock whenever, and for so long as, in the reasonable judgment of the Company in good faith based upon the advice of counsel satisfactory to the Holders of a majority of the Registrable Stock, there is in existence material undisclosed information or events with respect to the Company (the " Suspension Right ") such that the registration statement would contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading in light of the circumstances under which they were made. In the event the Company exercises the Suspension Right, such suspension will continue for such period of time reasonably necessary for disclosure to occur at a time that is not materially detrimental to the Company or until such time as the registration statement does not include any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading in light of the circumstances under which they were made, each as determined in good faith by the Company. The Company will promptly give the Holders notice, in a writing signed by an executive officer of the Company, of any exercise of the Suspension Right. The Company agrees to notify the Holders promptly upon termination of the Suspension Right. Notwithstanding the foregoing, under no circumstances shall Holder be entitled to exercise the Suspension Right for more than sixty calendar days in any twelve-month period.

5.   Furnish Information . It shall be a condition precedent to the obligations of the Company to take any action pursuant to this Agreement that the Holders shall furnish to the Company