**Exhibit 10.19b****ASSIGNMENT, ASSUMPTION AND AMENDMENT OF****LEASE AGREEMENT FOR A GAMMA KNIFE UNIT**     This ASSIGNMENT, ASSUMPTION AND AMENDMENT OF LEASE AGREEMENT FOR A GAMMA KNIFE UNIT (this“Amendment”) is made effective as of the close of business on June 30, 2006 (the “AmendmentEffective Date”) and is entered into by and among **Yale-New Haven Ambulatory Services Corporation**,a Connecticut corporation (“ASC”), **Yale-New Haven Hospital, Inc. a/k/a Yale-New Haven Hospital,**aConnecticut corporation (“YNHH”) and **GK Financing, LLC,**a California limited liability company(“GKF”).**RECITALS**     WHEREAS, on April 10, 1997 GKF and ASC entered into a Lease Agreement For A Gamma Knife Unit(the “Lease”), which Lease was amended pursuant to an Addendum dated as of October 25, 2005 (the“Addendum”) (the Lease, as amended by the Addendum, is hereinafter referred to as the “AmendedLease”);     WHEREAS, YNHH is an affiliate of ASC, and ASC desires to transfer and assign its interest inthe Amended Lease (as further amended hereby) to YNHH; and     WHEREAS, ASC, YNHH and GKF desire to further amend the Amended Lease with respect toreimbursement paid to GKF and certain other provisions and to effect such transfer and assignment.     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: 1. Definitions. All capitalized terms used but not defined herein have themeanings given thereto in the Amended Lease. The lease arrangement as amended and assignedto YNHH hereby is referred to as the “Assigned Lease.”  2. Additional Amendments to the Amended Lease. GKF and ASC agree to amend theAmended Lease as follows: a. As of the Amendment Effective Date, Section 7 of the Lease (captioned“Reimbursement to GKF”) and Section 4 of the Addendum (captioned “Lease Payment toGKF”) are deleted and of no further force or effect.  b. From and after the Amendment Effective Date, YNHH shall pay to GKF themonthly “Lease Payments” (as defined below), plus, if applicable, the“Additional Payments” (as defined below). The Lease Payments shall be payablewithin thirty (30) days after the conclusion of each calendar month in which theapplicable procedures were performed. In addition to the Lease Payments and theAdditional Payments, YNHH shall pay to GKF quarterly payments in an amount equal toone quarter of YNHH’s reasonable projection of the total * due on the Equipment andpaid by GKF for each “Contract Year” (as defined below). Within thirty (30) daysafter the end of each Contract Year, the sum of such quarterly projected paymentsmade by YNHH shall be reconciled against the actual amounts of such expenses, andYNHH or GKF shall, within thirty (30) days thereafter, make a “true up” payment tothe other as appropriate. Through the term of the AssignedLease, and thereafter until final settlement of all amounts owed to or claimed byeither party under the Assigned Lease, each party shall have the right at reasonabletimes and upon reasonable advance notice to inspect, audit and copy the otherparty’s books and 
- 1 -

 
   records which relate to scheduling and billing of, andreimbursement for, Gamma Knife procedures, the Lease Payments and AdditionalPayments, and the * associated with the Equipment. Notwithstanding the foregoing,the compensation payable to GKF pertaining to procedures performed prior to theAmendment Effective Date shall be calculated and paid by ASC in accordance withSection 4 of the Amended Lease. i. As used herein: (A) “Lease Payment” shall mean and be equal to *multiplied by each and every procedure performed after the AmendmentEffective Date during the applicable calendar month using theEquipment, irrespective of (1) whether the procedure is performed byYNHH, its representatives or affiliates, or any other person or entity;or (2) the actual amounts billed or collected, if any, pertaining tosuch procedures.  (B) “Affiliate” shall mean as to any YNHH and/orASC, (1) any Person which, directly or indirectly, is in control of, iscontrolled by, or is under common control with such YNHH and/or ASC, or(2) any Person who is a director or officer (aa) of YNHH and/or ASC,(bb) of any subsidiary of YNHH and/or ASC, or (cc) of any Persondescribed in clause (1) above. For purposes of this definition,control of a Person shall mean the power, direct or indirect, to director cause the direction of the management and policies of such Personwhether through ownership of voting securities, by contract orotherwise.    Without limiting the generality of the foregoing, “Affiliate” shallexpressly include the Yale-New Haven Delivery Network and all of itsconstituent entities, including, without limitation, Yale-New HavenHospital, Yale-New Haven Children’s Hospital, Yale-New HavenPsychiatric Hospital, Yale-New Haven Ambulatory Services Corp (TempleMedical Center), Yale-New Haven Independent Practice Association(IPA), Yale-New Haven Physician Hospital Organization (PHO), andMedical Center Pharmacy.    Notwithstanding the foregoing, “Affiliate” shall expressly exclude(aaa) the Bridgeport Delivery Network, comprised of BridgeportHospital, Ahlbin Rehabilitation Centers, United Visiting NurseAssociation and Bridgeport Hospital Foundation, and (bbb) theGreenwich Delivery Network comprised of Greenwich Hospital, GreenwichPhysicians Association, Inc., and Greenwich Hospital Hospiceservices.  (C) “Contract Year” shall mean each successivetwelve (12) month period commencing from the First Procedure Date.  (D) “Person” shall mean any individual,partnership, corporation, business trust, joint stock company, trust,unincorporated association, joint venture, or other entity of whatevernature. ii. If (A) at any time, YNHH, ASC and/or any of theirrespective Affiliates purchases, leases or otherwise acquires, directlyor indirectly, an ownership or other interest in one or more additionalLeksell Gamma Knife units (each, an “Additional Unit”) for use oroperation within the State of Connecticut in 
- 2 -

 
   addition to the Equipment;and (B) at any time or from time-to-time thereafter, the number ofprocedures performed using the Equipment during any Contract Year is *shall be prorated if the Contract Year is less than 365 days (a“Shortfall Contract Year”), then, in addition to the Lease Paymentspayable to GKF for procedures performed using the Equipment, YNHH shallpay to GKF an additional amount (each, an “Additional Payment”) equal tothe sum of * multiplied by each procedure performed using the AdditionalUnit(s) during the corresponding Shortfall Contract Year, up to anaggregate of * (prorated if the subject Contract Year is less than 365days) combined between procedures performed using the Equipment andprocedures performed using the Additional Unit(s), irrespective of (1)whether such procedures are performed by YNHH, its representatives oraffiliates, or any other person or entity; or (2) the actual amountsbilled or collected, if any, pertaining to any such procedures. TheAdditional Payments shall be paid by YNHH to GKF quarterly in an amountequal to one quarter of YNHH’s reasonable projection of the aggregateAdditional Payment for the then-current Contract Year. Within thirty(30) days after the end of each Contract Year, the sum of such quarterlyprojected payments made by YNHH shall be reconciled against the actualAdditional Payment payable for the subject Contract Year, and YNHH or GKFshall, within thirty (30) days thereafter, make a “true up” payment tothe other as appropriate. Nothing set forth herein shall limit or placea ceiling on the number of procedures that may be performed using theEquipment or on the Lease Payment that is payable in connection withprocedures performed using the Equipment. iii. For example, if Additional Unit(s) have beenacquired: 1. Assuming * procedures are performed usingthe Equipment during a Contract Year and another * procedures areperformed in the same Contract Year using the Additional Unit(s),then, the aggregate Lease Payments for that Contract Year wouldequal *, and the Additional Payment for that Contract Year wouldequal *.  2. Assuming * procedures are performed usingthe Equipment during a Contract Year and another * procedures areperformed in the same Contract Year using the Additional Unit(s),then, the aggregate Lease Payments for that Contract Year wouldequal *, and the Additional Payment for that Contract Year wouldequal *.  3. Assuming * procedures are performed usingthe Equipment during a Contract Year and * procedures are performedin the same Contract Year using the Additional Unit(s), then, theaggregate Lease Payments for that Contract Year would equal *, andthe Additional Payment for that Contract Year would equal *.  4. Assuming * procedures are performed usingthe Equipment during a Contract Year and * procedures are performedin the same Contract Year using the Additional Unit(s), then, theaggregate Lease Payments for thatContract Year would equal *, and the Additional Payment for thatContract Year would equal *.
- 3 -

 
 c. Section 11.1 (captioned “Right of First Refusal”) of the Lease ishereby deleted and of no further force or effect.  d. YNHH and GKF agree to implement Section 6 (captioned “MarketingSupport”) of the Lease in accordance with the following paragraph:    Marketing Support. YNHH shall provide reasonable and customary marketingmaterials (i.e. brochures, announcements, etc.), marketing support, andadministrative and physician support for this clinical service (i.e. seminars byneurosurgeons and radiation oncologists to interested physicians and the like). Notless than ninety (90) days prior to each anniversary of the Amendment EffectiveDate, GKF and YNHH shall develop a mutually agreed upon marketing budget and planfor the clinical service to be supported by the Equipment for the succeeding twelve(12) month period of the Term. Once mutually approved, the marketing budget andplan shall be implemented in accordance with its terms. As funds are expended byYNHH in accordance with the marketing budget and plan, YNHH shall submit invoices(together with documentary evidence supporting the invoices) for its expendituresand, promptly following the receipt of such invoices, GKF shall reimburse YNHH for *of the expenditures up to an annual maximum reimbursement by GKF of *. It isacknowledged by GKF and YNHH that the expenses to be reimbursed by GKF as providedin this Section have been reflected in the calculation of the per procedure paymentto be paid to GKF by YNHH pursuant to the first sentence of Section 2.b of thisAmendment, and shall not be taken into account in calculating any obligations of GKFor YNHH in connection with the payments for property tax, the service and supportagreement and insurance obligations contemplated by such Section 2.b. 3. Assignment and Assumption. a. ASC hereby (i) transfers, sells, assigns and sets over to YNHH all ofASC’s right, title and interest in, under and to the Assigned Lease to YNHH, itssuccessors and assigns, from and after the Amendment Effective Date for the entirebalance of the term of the Assigned Lease, subject to the terms, covenants andconditions therein contained; and (ii) agrees to keep, carry out and perform of allof the terms, covenants and conditions of the Amended Lease to be performed by“Yale” thereunder and arising or accruing at any time prior to the AmendmentEffective Date.  b. ASC hereby agrees to defend, indemnify and hold YNHH harmless from andagainst any loss, cost, damage or expense arising out of or in connection with theAmended Lease accruing up through the Amendment Effective Date.  c. YNHH hereby (i) accepts such assignment, assumes the Assigned Lease,and agrees to keep, carry out and perform of all of the terms, covenants andconditions of the Assigned Lease to be performed by “Yale” thereunder and arisingor accruing from and after the Amendment Effective Date, and (ii) agrees to defend,indemnify and hold ASC harmless from and against any loss, cost, damage or expensearising out of or in connection with the Assigned Lease accruing from and after theAmendment Effective Date.  d. GKF hereby (i) consents to such assignment of the Assigned Lease andthe assumption of the Assigned Lease by YNHH; and (ii) agrees to release ASC fromany claim under the Amended Lease or the Assigned Lease first accruing from andafter the Amendment Effective Date.
- 4 -

 
 4. Address of YNHH for Notices. For the purposes of any notices required by theAssigned Lease, YNHH’s address and contact shall be:Yale-New Haven Hospital