**Exhibit 10.22a****ADDENDUM****TO LEASE AGREEMENT FOR A GAMMA KNIFE UNIT**     This ADDENDUM TO LEASE AGREEMENT FOR A GAMMA KNIFE UNIT (the “Addendum”) is effective April 1,2005, and is entered into between NEW ENGLAND MEDICAL CENTER HOSPITALS, INC., a Massachusettscorporation (“Medical Center”), and GK FINANCING, LLC, a California limited liability company(“GKF”).**RECITALS**     WHEREAS, on October 5, 1998, GKF and Medical Center executed a Lease Agreement for a GammaKnife Unit (the “Lease”); and     WHEREAS, the parties desire to 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 herein shallhave the same meanings set forth in the Lease.     2. **Extension of Lease Term.**The Term of the Lease as set forth in Section 6 of the Lease ishereby extended for an additional six (6) years, plus the period of time that the Equipmentis unavailable to perform procedures due to the Equipment upgrade and cobalt reload processdescribed herein (collectively, the “Extension”). The Extension shall commence on the expiration ofthe initial Term of the Lease. Notwithstanding the foregoing, if the Term (as extended by theExtension) expires on a date that is prior to September 30 of any calendar year, then, the Term (asextended by the Extension) shall not expire until, and shall be further extended to, September 30of such calendar year. All references in the Lease to the “Term” shall be deemed to refer to theTerm as extended hereby.     3. **Upgrade and Cobalt Reload of the Equipment.**Section 15 (including Sections 15.1, 15.2 and15.3) of the Lease are hereby deleted in their entirety and replaced with the following:     15.1 Subject to the terms and conditions set forth below, GKF, at GKF’s cost andexpense, shall upgrade the Equipment to a Leksell Gamma Knife Model 4C (the “Model 4C”) andreload the Equipment (as upgraded) with new cobalt-60 (the “Upgrade and Reload”), whichUpgrade and Reload shall be performed at the Site and shall include any requiredinstallation and rigging. In connection with the Upgrade and
1

 
Reload, Medical Center, at Medical Center’s cost and expense, shall provide GKF withMedical Center personnel (including Medical Center physicists) and services upon requestand as required by GKF, among other things, to oversee, supervise and assist withconstruction and compliance with local, state and federal regulatory requirements and withnuclear regulatory compliance issues and the calibration of the Model 4C. Subject toMedical Center’s compliance with Section 15.2 below, it is anticipated but not guaranteedthat the Upgrade and Reload will be performed in or around fourth quarter 2005 or firstquarter 2006.     15.2 Notwithstanding the foregoing, the Upgrade and Reload shall be performed by GKFonly after all licenses, permits, approvals, consents and authorizations necessary andappropriate for the Upgrade and Reload, including, without limitation, the proper handlingof the cobalt-60 (collectively, the “Permits”), have been obtained by Medical Center atMedical Center’s sole cost and expense (other than any filing or registration fees whichshall be paid for by GKF). The timing and procedure for such Upgrade and Reload shall be asmutually agreed upon between the parties. All references in the Lease to (i) “Installation”shall be deemed to refer to the Upgrade and Reload, and (ii) “Equipment” shall be deemed,immediately following its upgrade, to mean the Model 4C. Notwithstanding the foregoing, GKFmakes no representation or warranty to Medical Center concerning the Upgrade and Reload, andGKF shall have no obligation to pay any damages to Medical Center resulting therefrom.     15.3 Unless Medical Center notifies GKF at least ninety (90) days prior to theexpiration of the Term (as extended) that Medical Center wishes to purchase the Model 4C incash at its fair market value (based upon the “in use” value of the Model 4C) as determinedby an appraiser mutually agreed upon between the parties, GKF shall remove the Model 4C, atits sole expense, within ninety (90) days after the expiration of the Term (as extended).     4. **Per Procedure Payment.**In consideration for and as compensation to GKF for the Upgrade andReload and the additional services to be provided by GKF hereunder, effective as of the date ofthis Addendum, Exhibit 2 of the Lease shall be deleted and replaced with Exhibit 2 attached hereto.     5. **Services Performed by GKF.**In addition to GKF’s responsibilities under the Lease, GKF shallprovide marketing support and research funding assistance as follows. Within ninety (90) days afterthe date of this Addendum and each succeeding anniversary date hereof during the extended Term, GKFand Medical Center shall jointly develop an annual marketing plan, budget and timeline, which shallbe implemented by Medical Center with the support of GKF based on the approved budget and timeline.Medical Center’s approval of such plan, budget and timeline shall not be unreasonably withheld ordelayed. If Medical Center has not approved or disapproved the same within thirty (30)
2

 
days following its receipt, Medical Center shall be deemed to have approved the same. GKF shall beresponsible for any actual out-of-pocket marketing expenses paid to unrelated third parties thatare included in the marketing plan budget in an approximate amount of *. This section shall notreduce or alter Medical Center’s obligations pursuant to Section 9.5 of the Lease.     6. **No Responsibility for Additional Upgrades or Reloading.**It is understood by the partiesthat GKF is not responsible for any additional upgrades, hardware, cobalt reloading, softwarechanges and/or other modifications to the Model 4C except as expressly set forth herein orotherwise agreed upon in writing by Medical Center and GKF.     7. **Captions.**The captions and paragraph headings used herein are for convenience only andshall not be used in construing or interpreting this Addendum.     8. **Full Force and Effect.**Except as amended by this Addendum, all of the terms and provisionsof the Lease shall remain in full force and effect.     IN WITNESS WHEREOF, the parties have executed this Addendum effective as of the date firstwritten above.           **GK FINANCING, LLC**   **NEW ENGLAND MEDICAL CENTER HOSPITALS, INC.**           By: /s/ Craig K. Tagawa   By: /s/ Michael T. Burke             Name: Craig K. Tagawa   Name: Michael T. Burke  Title: Chief Executive Officer   Title: Senior Vice President and CFO
3

 
Exhibit 2PER PROCEDURE PAYMENTS             **Year** **Annual Procedures Performed**      **Fee Per Procedure** 1-4      *   *        *   *        *   *        *   *              5-10      *   *        *   *        *   *        *   *              11-16      *   *        *   *        *   *        *   * Notwithstanding anything to the contrary set forth herein, (a) for purposes of determining the perprocedure payment, the number of annual procedures performed shall be reset to zero (0) at thecommencement of each fiscal year of Medical Center (i.e., on October 1 of each year); (b)the per procedure payment shall not be affected or adjusted due to any upgrading and/or cobaltreloading of the Equipment; and (c) there shall be no retroactive adjustment of the per procedurepayment irrespective of whether the number of procedures performed during any fiscal year reaches alower per procedure payment level. For example, if * procedures are performed during the * year,Medical Center would pay * for each of the first * procedures, and * for each of the next *procedures (i.e., for procedures *). The parties acknowledge that, for purposes of determining theper procedure payment, October 1, 2005 shall mark the commencement of year seven (7) of the Lease.**Compliance with Safe Harbor.**GKF and Medical Center intend that the reductions to the fee per procedure set forth above shallsatisfy the requirements of the anti-kickback safe harbor applicable to discounts contained in 42C.F.R. § 1001.952(h). In furtherance of the foregoing:
4

 
1. The discount shall be earned and computed based on total number of procedures performedwithin a single fiscal year of Medical Center ending September 30 of each year. 2. Medical Center must claim the benefit of the discount in the fiscal year in which thediscount is earned. 3. Medical Center must fully and accurately report the discount in its applicable cost report orin its separate claims for payment with the Department of Health and Human Services or a Stateagency. 4. Medical Center must provide, upon request by the Secretary of the Department of Health andHuman Services or a State agency, the information provided by GKF as specified below. 5. GKF shall fully and accurately report the existence of the discount on the invoices orstatements submitted to Medical Center. GKF hereby informs Medical Center of its obligation toreport such discount as stipulated in subparagraphs 3 and 4 above. When the value of thediscount becomes known for each fiscal year, GKF shall provide Medical Center withdocumentation of the calculation of the discount identifying the number of procedures to whichthe discount will be applied.
5