POSITRON CORPORATION NOTE PURCHASE AGREEMENT

THIS NOTE PURCHASE AGREEMENT (the " Agreement ") is made as of October 31, 2005 by and between Positron Corporation, a Texas corporation (the " Company "), and Imagin Diagnostic Centers, Inc. (" Investor "). All numbers expressed herein as "$" or "dollars" are in United States dollars.

WHEREAS, the Company desires to issue Convertible Promissory Notes in the aggregate principal amount of $400,000, subject to the terms and conditions set forth in this Agreement.

WHEREAS, the Investor desires to purchase the Convertible Promissory Notes, subject to the terms and conditions set forth in this Agreement.

NOW, THEREFORE, in consideration of the respective undertakings, covenants and agreements of the parties set forth herein, the parties hereby agree as follows:

1.1   Issuance of the Notes . The Company has authorized the issuance and sale to the Investor of, and, subject to and in reliance upon the representations, warranties, terms and conditions of this Agreement, the Investor the have agreed to purchase, the Company's Convertible Promissory Notes (individually, a " Note ," and collectively, the " Notes "), in the aggregate principal amount of $400,000. Each Note shall be substantially in the form set forth in Exhibit A hereto.

1.2   Closing . The Company agrees to issue and sell to the Investor, and, subject to and in reliance upon the representations, warranties, terms and conditions of this Agreement, the Investor agrees to purchase, the Notes for the aggregate purchase price of $400,000 (the "Aggregate Purchase Price"). Such purchase and sale shall take place (a) at the initial closing (the "Closing") to be held at the offices of the Company on October 31, 2005, at 10:00 A.M., or such other date as the parties shall agree (the " First Closing Date "), and at subsequent closings (" Subsequent Closings ") which shall occur upon 30 days written notice to Investor by the Company. At each Subsequent Closing Investor shall purchase a Note in a principal amount determined by the Company of not more than $200,000. Subsequent Closings shall be held not more frequently than every 30 days. At the Closings, the Company will issue a Note, dated the such date, payable to the order of Investor, in the principal amount of $200,000 in the case of the First Closing and in an amount specified in the Company's notice in the case of the Subsequent Closings in exchange for cash. In the event the Company shall not have sold and issued to Investor pursuant to the notices provided for herein the full amount of the Aggregate Purchase Price on or before December 31, 2005, the right of the Company to sell any additional Notes and the obligation of the Investor to purchase any additional Notes shall terminate.

1.3   Payments and Endorsements . Payments of principal, interest and premium, if any, on the Notes, shall be made directly by wire transfer or by checks duly mailed or delivered to the Investor at address specified in the Notes without any presentment or notation of payment, except that prior to any transfer of any Note, the holder of record shall endorse on such Note a record of the date to which interest has been paid and all payments made on account of principal of such Note.

1.4   Payment on Non-Business Days . Whenever any payment to be made shall be due on a day which is not a Business Day, such payment may be made on the next succeeding Business Day, and such extension of time shall in such case be included in the computation of payment of interest due.

1.5   Registration, etc . The Company shall maintain at its principal office a register of the Notes and shall record therein the name and address of the registered holder of the Notes, the address to which notices are to be sent and the address to which payments are to be made as designated by the registered holder if other than the address of the holder, and the particulars of all transfers, exchanges and replacements of the Notes. No transfer of a Note shall be valid unless made on such register for the registered holder or his executors or administrators or his or their duly appointed attorney, upon surrender therefor for exchange as hereinafter provided, accompanied by an instrument in writing, in form and execution reasonably satisfactory to the Company. Each Note issued hereunder, whether originally or upon transfer, exchange or replacement of a Note or Notes, shall be registered on the date of execution thereof by the Company and shall be dated the date to which interest has been paid on such Note or Notes. The registered holder of the Note shall be that Person in whose name the Note has been so registered by the Company. A registered holder shall be deemed the owner of a Note for all purposes of this Agreement and, subject to the provisions hereof, shall be entitled to the principal, premium, if any, and interest evidenced by such Note free from all equities or rights of set-off or counterclaim among the Company and the transferor of such registered holder or any previous registered holder of such Note.

1.6   Limitations on Transferability . The Investor covenants that in no event will it dispose of any Note or any shares of capital stock into which such Note is convertible unless and until Investor shall have complied with Sections 4.7 and 4.8 hereof and (a) the Investor shall have notified the Company of the proposed disposition and shall have furnished the Company with a statement of the circumstances surrounding the proposed disposition, and (b) if requested by the Company, the Investor shall have furnished the Company with an opinion of counsel satisfactory in form and substance to the Company and the Company's counsel to the effect that (x) such disposition will not require registration under the Securities Act and (y) appropriate action necessary for compliance with the Securities Act and any applicable state, local, or foreign law has been taken.

1.7   Replacement of Notes . Upon receipt of evidence satisfactory to the Company of the loss, theft, destruction or mutilation of any Note and, if requested in the case of any such loss, theft or destruction, upon delivery of an indemnity bond or other agreement or security reasonably satisfactory to the Company, or, in the case of any such mutilation, upon surrender and cancellation of such Note, the Company will issue a new Note, of like tenor and amount and dated the date to which interest has been paid, in lieu of such lost, stolen, destroyed or mutilated Note; provided , however , if any Note of which an Investor, its nominee, or any of its partners or affiliates is the registered holder is lost, stolen or destroyed, the affidavit of the registered holder setting forth the circumstances with respect to such loss, theft or destruction shall be accepted as satisfactory evidence thereof, and no indemnification bond or other security shall be required as a condition to the execution and delivery by the Company of a new Note in replacement of such lost, stolen or destroyed Note other than the registered holder's written agreement to indemnify the Company.

1.8   Conversion of Note . All or any portion of the principal amounts of the Notes, may be converted at the option of the Investor, into shares of Common Stock (as defined herein) at a conversion price and on such terms as are provided in the Notes.

For purposes of this Agreement the following terms shall have the following meanings:

2.1   " Articles " shall mean the Company's Articles of Incorporation, as amended, as of the First Closing, and including the Series A Statement, Series C Statement, Series D Statement, Series E Statement and Series F Statement thereto.

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

2.3   " Commission " shall mean the Securities and Exchange Commission.

2.4   " Common Stock " shall mean the Common Stock of the Company, par value $0.01 per share.

2.5   " GAAP " shall mean United States generally accepted accounting principles.

2.6   " Intellectual Property " shall mean patents, patent applications, trademarks, service marks, mask works, trade names, copyrights, trade secrets, information, proprietary rights and processes.

2.7   " Material Adverse Event " shall mean any change, event or effect that is materially adverse to the general affairs, business, operations, assets, condition (financial or otherwise) or results of operations of the Company and its subsidiaries taken as a whole; provided, however, that the following shall not be taken into account in determining a " Material Adverse Event ": (a) any adverse change, event or effect that is directly attributable to conditions affecting the United States economy generally unless such conditions adversely affect the Company in a materially disproportionate manner, and (b) any adverse change, event or effect that is directly attributable to conditions affecting the Company's industry generally, unless such conditions adversely affect the Company in a materially disproportionate manner.

2.8   " Person " shall mean an individual, corporation, partnership, joint venture, limited liability company, trust, or unincorporated organization, or a government or any agency or political subdivision thereof, or any other entity or business form.

2.9   " Preferred Stock " shall mean the Company's Series A Preferred Stock, Series C Preferred Stock, Series D Preferred Stock, Series E Preferred Stock and Series F Preferred Stock.

2.10   " Registration Rights Agreement " shall mean the Registration Rights Agreement dated as of the First Closing by and between the Company and the Investor in the form attached hereto as Exhibit B .

2.11   " Securities Act " shall mean the Securities Act of 1933, as amended and the rules and regulations of the Commission promulgated thereunder.

2.12   " Series A Preferred Stock " shall mean the Series A Preferred Stock of the Company, par value $1.00 per share.

2.13   " Series A Statement " shall mean the Statement of Designation Establishing Series A 8% Cumulative Convertible Redeemable Preferred Stock of Position Corporation, filed with the Texas Secretary of State on February 29, 1996.

2.14   " Series C Preferred Stock " shall mean the Series C Preferred Stock of the Company, par value $1.00 per share.

2.15   " Series C Statement " shall mean the Statement of Designation Establishing Series C Preferred Stock of Positron Corporation, filed with the Texas Secretary of State on May 21, 2004.

2.16   " Series D Preferred Stock " shall mean the Series D Preferred Stock of the Company, par value $1.00 per share.

2.17   " Series D Statement " shall mean the Statement of Designation Establishing Series D Preferred Stock of Positron Corporation, filed with the Texas Secretary of State on May 21, 2004.

2.18   " Series E Preferred Stock " shall mean the Series E Preferred Stock of the Company, par value $1.00 per share.

2.19   " Series E Statement " shall mean the Statement of Designation Establishing Series E Preferred Stock of Positron Corporation, to be filed with the Texas Secretary of State following the Closing.

2.20   " Series F Preferred Stock " shall mean the Series F Preferred Stock of the Company, par value $1.00 per share.

2.21   " Series F Statement " shall mean the Statement of Designation Establishing Series F Preferred Stock of Positron corporation to be filed with the Texas Secretary of State following the Closing.

2.22   " Subsidiary " shall mean any corporation, partnership or other entity, more than 50% of whose equity interests (measured by virtue of voting rights) in the aggregate is owned by the Company.

2.23   " Transactional Agreements " shall mean this Agreement, the Notes, and the Registration Rights Agreement.

The Company hereby represents and warrants to the Investor that:

3.1   Corporate Organization and Authority . The Company:

3.1.1   is a corporation duly organized, validly existing, authorized to exercise all its corporate powers, rights and privileges, and in good standing in the State of Texas;

3.1.2   has the corporate power and corporate authority to own and operate its properties and to carry on its business as now conducted and as proposed to be conducted;

3.1.3   has made available to the Investor or their counsel a copy of the minute books of the Company, and said copies are true, correct, and complete and contain all amendments and all minutes of meetings and actions taken by the shareholders and directors of the Company through the date of this Agreement.

3.2   Subsidiaries . The Company does not presently own, have any equity interest or investment in, or control, directly or indirectly, any other corporation, partnership or entity. The Company is not a participant in any joint venture or partnership.

3.3   SEC Filings; Financial Statements . The Company has filed (i) its Annual Report on Form 10-K for the fiscal year ended December 31, 2004 (the " Company Current 10-K "), and (ii) its Quarterly Reports on Form 10-Q for the fiscal quarters ended March 31, 2005 and June 30, 2005, (the " Company Current 10-Qs " and, together with the Company Current 10-K and the " Company SEC Reports "), all of which complied when filed in all material respects with all applicable requirements of the Securities Act and the Exchange Act of 1934, as amended. The audited financial statements and unaudited interim financial statements of the Company included or incorporated by reference in such Company SEC Reports were prepared in accordance with GAAP applied on a consistent basis during the periods involved (except as may be indicated in the notes thereto) and present fairly, in all material respects, the financial position and results of operations and cash flows of the Company at the respective dates and for the respective periods indicated (and in the case of all such financial statements that are interim financial statements, contain all adjustments so to present fairly). Except to the extent that information contained in any Company SEC Report was revised or superseded by a later filed report, none of the Company SEC Reports contained any untrue statement of a material fact or omitted to state any material fact required to be stated therein or necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading.

3.4   Corporate Power . The Company will have at the Closing Date all requisite legal and corporate power and authority to execute and deliver the Transactional Agreements, to sell and issue the Notes hereunder, to issue the Common Stock upon conversion of the Notes (subject to stockholder approval as set forth in Section 7.1 hereof), and to carry out and perform its obligations under the terms of the Transactional Agreements.

3.5   Authorization . All corporate action on the part of the Company, its officers, directors, and stockholders necessary for the authorization, execution, delivery, and performance of all obligations under the Transactional Agreements, and for the authorization, issuance, and delivery of the Notes, and of the Common Stock (subject to stockholder approval as set forth in Section 7.1 hereof) issuable upon conversion of the Notes has been taken. The Transactional Agreements constitute legally binding and valid obligations of the Company enforceable in accordance with their respective terms, except to the extent that such enforcement may be subject to applicable bankruptcy, insolvency, reorganization, moratorium, or other laws of general application relating to or affecting enforcement of creditors' rights and laws concerning equitable remedies.

3.6   Validity of Shares . Subject to stockholder approval, as set forth in Section 7.1 hereof, the Common Stock issuable upon conversion of the Notes has been duly and validly reserved and, assuming such Common Stock is issued in accordance with the Articles, will be duly and validly issued (including, without limitation, issued in compliance with applicable federal and state securities laws) and non-assessable and will be free of any liens or encumbrances other than any liens or encumbrances created by or imposed thereon by the holders; provided, however, that the Common Stock shall be subject to restrictions on transfer under state and/or federal securities laws. Except as set forth in the Articles and the Notes, the Common Stock issuable upon conversion of the Notes is not subject to any preemptive or other similar statutory or contractual rights and will not conflict with any provisions of any agreement or instrument to which the Company is a party or by which it is bound.

The Investor represents and warrants to the Company as follows:

4.1   Authorization . When executed and delivered by the Investor, and assuming execution and delivery by the Company, the Transactional Agreements will each constitute a valid obligation of the Investor, enforceable in accordance with its terms, except to the extent that such enforcement may be subject to applicable bankruptcy, insolvency, reorganization, moratorium, or other laws of general application relating to or affecting enforcement of creditors' rights and laws concerning equitable remedies.

4.2   Brokers and Finders . The Investor has not retained any investment banker, broker, or finder in connection with the transactions contemplated by this Agreement.

4.3   Investment . This Agreement is made with the Investor in reliance upon the Investor's representation to the Company, which by the Investor's execution of this Agreement the Investor hereby confirms, that the Notes (including capital stock issuable upon conversion thereof) to be received by the Investor will be acquired for investment for the Investor's own account, not as a nominee or agent, and not with a view to the sale or distribution of any part thereof, and that the Investor has no present intention of selling, granting any participation in, or otherwise distributing any of the Notes (including capital stock issuable upon conversion thereof). By executing this Agreement, the Investor further represents that it has no contract, undertaking, agreement, or a