Exhibit 10.6

THIRD ADDENDUM TO MANAGEMENT SERVICES AGREEMENT

This Third Addendum (the “Addendum”) is entered into as of August 1, 2007, by
and between CALIFORNIA RADIATION THERAPY MANAGEMENT SERVICES, INC., a California
corporation (“Manager”) and 21ST CENTURY ONCOLOGY OF CALIFORNIA A MEDICAL
CORPORATION, a California medical corporation (“Medical Group”). This Addendum
amends Sections 1.(a) of the Management Services Agreement dated May 1, 2006, as
set forth below.

From and after the date here of,

 

  (i) Section 1.(a) shall be amended to read as follows:

“(a) Management. The Manager will be responsible for general management and
administration operations of the Office locations, excluding the provision of
medical services, set forth on Exhibit B hereto. The Manager shall not engage in
the practice of medicine.”

 

Accepted:

  CALIFORNIA RADIATION THERAPY MANAGEMENT SERVICES, INC.   By:  

/s/ David N.T. Watson

    David N.T. Watson     Vice President

Accepted:

  21ST CENTURY ONCOLOGY OF CALIFORNIA, A MEDICAL CORPORATION   By:  

/s/ Daniel E. Dosoretz

    Daniel E. Dosoretz, M.D.     Vice President

--------------------------------------------------------------------------------

EXHIBIT B

THIRD ADDENDUM TO MANAGEMENT SERVICES AGREEMENT

Office Locations and Manager Compensation

 

Office Location

  

Manager

Compensation

as a % of Net

Collected Dollars

Palm Desert

77840 Flora Road

Palm Desert, CA 92211

   77%

Santa Monica

2428 Santa Monica Boulevard

Suite 103

Santa Monica, CA 90404

   77%

Beverly Hills Radiation Oncology

150 N. Robertson Blvd.

Suite 160

Beverly Hills, CA 90221

   77%

Vidya S. Bobba, M.D., Inc.

963 Butte Street

Redding, CA 96001

   77%