FIRST AMENDMENT TO PURCHASED SERVICES AGREEMENT

Exhibit 10.57a

FIRST AMENDMENT TO PURCHASED SERVICES AGREEMENT

     This FIRST AMENDMENT TO PURCHASED SERVICES AGREEMENT (this “First Amendment”) is effective as of the 1st day of April, 2009, and is entered into by and between GK FINANCING, LLC, a California limited liability company (“GKF”), or its wholly owned subsidiary whose obligations hereunder shall be guaranteed by GKF, and UNIVERSITY OF SOUTHERN CALIFORNIA, a California nonprofit public benefit corporation (“Hospital”).

Recitals :

     A. On March 5, 2008, GKF and USC University Hospital, Inc. (“USC University Hospital”), entered into a certain Purchased Services Agreement.

     B. Pursuant to a certain letter dated effective as of March 31, 2009, GKF agreed to the transfer and assignment to Hospital of all of USC University Hospital’s right, title and interest in, under and to the Purchased Services Agreement. The Purchased Services Agreement, as assigned to and assumed by Hospital, is referred to herein as the “Agreement.”

     C. GKF and Hospital desire to amend the Agreement as set forth herein.

     NOW THEREFORE, for valuable consideration, the receipt and sufficiency of which are acknowledged, the parties hereby amend the Agreement as follows:

Agreement :

     1.  Defined Terms . Unless otherwise defined herein, the capitalized terms used herein shall have the same meanings set forth in the Agreement.

     2.  Amendment to Section 7 . Section 7 of the Agreement (Marketing Support) is hereby deleted in its entirety and replaced with the following:

“7. Marketing . Hospital shall determine whether and how to market the services provided using the Equipment. The parties shall discuss and mutually agree on marketing activities that promote the Equipment and the Hospital services related to the Equipment to the mutual benefit of both parties. If such joint marketing is undertaken, the parties will determine an appropriate allocation of the costs of the marketing based on the relative benefit each receives.”

     3.  Amendment to Section 8(b) . Section 8(b) of the Agreement is hereby deleted in its entirety and replaced with the following:

“(b) In consideration for and as compensation to GKF for deinstallation and removal of the Model C, the preparation, construction and improvement of the Site, installation of the Equipment and the other additional services to be provided by GKF under this Agreement, Hospital shall pay to GKF, on a monthly basis, the applicable per Procedure payments set forth in Exhibit 8 of this Agreement (the “Purchased

Services Payments”) for each “Procedure” that is performed using the Equipment at the Site, whether on an inpatient or outpatient basis, and irrespective of the actual amounts billed or collected, if any, pertaining to such procedures. As used herein, a “Procedure” means any treatment that involves stereotactic, external, single fraction, conformal radiation, commonly called radiosurgery, that may include one or more isocenters during the patient treatment session, delivered to any site(s) superior to the foramen magnum.”

     4.  New Section 9.5 . The following is hereby added as a new Section 9.5 to the Agreement:

“(a) At all times during the term of the Agreement subsequent to the effective date of this First Amendment, Hospital represents and warrants that any and all Procedures performed or to be performed within the “Southern California Region” (as defined below) by Hospital, its representatives and/or affiliates (including, without limitation, USC/Norris Comprehensive Cancer Center), whether on an inpatient or outpatient basis, shall be performed using the Equipment at the Site, except that the foregoing representation and warranty shall not apply (i) to the performance of any Procedures using the existing Cyberknife equipment, as presently configured, upgraded or replaced (the “Cyberknife”), so long as the Procedures using such Cyberknife are performed at the USC/Norris Comprehensive Cancer Center; (ii) to the performance of any Procedures outside the Southern California Region; (iii) to the activities of Hospital-affiliated physicians at facilities not owned or operated by Hospital or its affiliates; or (iv) if the Equipment ceases to represent the prevailing standard of care for Procedures, as determined in accordance with Section 9.5(c) below (the “Equipment Use Representation”). As used herein, the “Southern Califor