**Exhibit 10.55****ADDENDUM THREE****TO LEASE AGREEMENT FOR A GAMMA KNIFE UNIT**     This ADDENDUM THREE TO LEASE AGREEMENT FOR A GAMMA KNIFE UNIT (this “Addendum”) is datedeffective as of June 20, 2007, and is entered into between (i) GK FINANCING, LLC, a Californialimited liability company (“GKF”), and (ii) SUNRISE HOSPITAL AND MEDICAL CENTER, LLC, a Delawarelimited liability company that is qualified to do business in the State of Nevada, d/b/a/ SunriseHospital and Medical Center (“Medical Center”), with reference to the following recitals:**Recitals****:**     A. Medical Center owns and operates an acute care hospital facility located at 3186 SouthMaryland Parkway, Las Vegas, NV 89109.     B. On June 3, 1999, GKF and Medical Center executed a Lease Agreement for a Gamma Knife Unit,which Lease Agreement was amended by a certain Addendum dated effective December 1, 1998, and acertain Addendum Two (“Addendum Two”) dated effective January 17, 2007 (as amended, the “Lease”).     C. The parties desire to further amend the terms and provisions of the Lease as set forthherein.     NOW THEREFORE, in consideration of the mutual covenants and agreements set forth herein, andfor other good and valuable consideration, the receipt and sufficiency of which are herebyacknowledged, the parties agree as follows:**Agreement****:**     1. **Defined Terms****.**Unless otherwise defined herein, the capitalized terms used hereinshall have the same meanings set forth in the Lease.     2. **Cobalt Reload of the Equipment****.**          a. Cobalt Reload. Pursuant to Section 14 of the Lease, and subject to the terms andconditions set forth below, (i) GKF, at GKF’s cost and expense, shall reload the Equipment with newcobalt-60 (the “Reload”), which Reload shall be performed at the Site and shall include anyrequired installation and rigging; and (ii) GKF shall use its commercially reasonable efforts toperform the Reload prior to December 31, 2007. It is anticipated that the Equipment will beunavailable to perform procedures for approximately three to four weeks due to the Reload process.          b. Medical Center Support. In connection with the Reload, Medical Center, at MedicalCenter’s cost and expense, shall provide GKF with Medical Center personnel (including MedicalCenter physicists) and services upon request and as required by GKF, among other things, tooversee, supervise and assist with construction and compliance with local, state and federalregulatory requirements and with nuclear regulatory compliance issues.
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          c. Permits. Notwithstanding the foregoing, the Reload shall be performed by GKF onlyafter all necessary and appropriate licenses, permits, approvals, consents and authorizations,including, without limitation, the proper handling of the cobalt-60 (collectively, the “Permits”),have been obtained by Medical Center at Medical Center’s sole cost and expense. The timing andprocedure for the Reload shall be as mutually agreed upon between the parties. Notwithstandinganything to the contrary contained in the Lease and/or this Addendum, GKF makes no representationor warranty to Medical Center concerning the Reload, and GKF shall have no obligation or liabilityto pay any damages to Medical Center resulting therefrom, including, without limitation, any lostrevenues or profits during the period of time that the Equipment is unavailable to performprocedures due to the Reload process     3. **Per Procedure Payment****.**          Notwithstanding anything to the contrary contained in the Lease, for each of the “IncreasedRent Procedures” (as defined below), the per procedure payment set forth in Section 6 of the Leaseshall be increased to * per procedure. Immediately following the completion of the last IncreasedRent Procedure, the per procedure payment shall return to * per procedure. As used herein, (i) theterm, “Increased Rent Procedures” shall mean * procedures performed from and after the completionof the Reload; and (ii) the term “procedure” shall mean each individual treatment session(fraction) that involves stereotactic, external, single fraction, conformal radiation, commonlycalled radiosurgery, that may include one or more isocenters during the patient treatment session,delivered to any site(s) superior to the foramen magnum, whether performed on an inpatient oroutpatient basis, using the Equipment and/or any other equipment or devices that are used in lieuof, or as an alternative to, the Equipment. It is acknowledged by the parties that the IncreasedRent Procedures are intended to allow GKF to recover its costs to perform the Reload. Nothing setforth herein shall affect the per case reimbursement rates for medical radiation physicist servicespayable to GKF pursuant to Addendum Two.     4. **No Responsibility for Additional Reloading****.**It is understood by the parties thatGKF is not responsible for any additional cobalt reloading, except as expressly agreed upon inwriting by Medical Center and GKF. However, if Medical Center and GKF mutually agree in writing toanother cobalt reloading of the Equipment, then, the costs for such reloading shall be sharedequally between Medical Center and GKF.     5. **Captions****.**The captions and paragraph headings used herein are for convenience onlyand shall not be used in construing or interpreting this Addendum.     6. **Full Force and Effect****.**Except as amended by this Addendum, all of the terms andprovisions of the Lease shall remain in full force and effect.     7. **Assignment****.**Pursuant to Section 24 of the Lease, GKF shall be permitted at anytime to assign any and all of its rights and obligations under the Lease to its wholly-ownedsubsidiary, provided that such all of such assigned obligations shall be guaranteed by GKF.     IN WITNESS WHEREOF, the parties have executed this Addendum effective as of the date firstwritten above.           **GK FINANCING, LLC**   **SUNRISE HOSPITAL AND MEDICAL**