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                                                                  EXHIBIT 10.52

         $ 313,573.59                                   Fort Myers, Florida
                                                        Dated: September 1, 2002

                                 PROMISSORY NOTE

         For value received (which, under the original Promissory Note referred
to below, was 313,215 shares of common stock of Radiation Therapy Services, Inc.
at $3.50 per share), Graciela R. Garton, M.D. ("Debtor") promises to pay to the
order of Radiation Therapy Services, Inc. ("Payee"), a Florida corporation, at
2234 Colonial Blvd., Fort Myers, Florida, 33907, or at such other place as Payee
may from time to time designate in writing, the principal sum of Three Hundred
Thirteen Thousand Five Hundred Seventy Three Dollars and Fifty Nine Cents
($313,573.59). Beginning on September 1, 2002, interest shall accrue at the
Prime Rate (as hereinafter defined) that is in effect on the date of this Note
and each annual anniversary thereafter that any outstanding principal amount
remains owing on this Note. This Note, when executed by Debtor, shall replace
that previous Note dated August 14, 1998 in the amount of $1,096,252.50 which
is attached hereto as Exhibit A, and that previous Note shall then be cancelled.

         Beginning on October 1, 2002, Debtor shall pay to Payee principal and
interest, per the attached payment schedule, on a monthly basis in arrears on
the first day of the month of this Note until all principal and interest owing
pursuant to this Note is paid in full. All unpaid principal and all accrued and
unpaid interest on this Note, unless sooner due and payable upon the occurrence
of an event of default hereunder, shall be due and payable in full on September
1, 2017.

         "Prime Rate" as used herein means the prime rate published in the Wall
Street Journal, Eastern Edition on the date of this Note and each annual
anniversary thereafter that any outstanding principal remains owing on this
Note; provided, however, in the event that the Wall Street Journal, Eastern
Edition does not publish the prime rate on the date of this Note or the
applicable annual anniversary, then "prime rate" shall mean, as applicable, the
prime rate published on the immediately next business day after the date of this
Note or the applicable annual anniversary that the Wall Street Journal, Eastern
Edition publishes such rate.

         Debtor will be provided with a revised payment schedule prior to each
anniversary date if there has been any change in the prime rate.

         Debtor may make prepayments of principal on this Note without penalty.

         This Note shall be with full recourse to Debtor. Further, to secure
full and timely payment of this Note, Debtor hereby pledges to Payee, and grants
to Payee, a security interest in 313,215 shares of Radiation Therapy Services,
Inc. together with all substitutions therefor (whether by conversion, stock
split, recapitalization, reorganization, exercise of rights, other corporate act
or otherwise), all proceeds thereof and all distributions (whether from
liquidation, dissolution, winding up or otherwise) with respect thereto (the
"Pledged Stock"). On the

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occurrence of an event of default, Payee shall have all of the rights and
remedies of a secured creditor with respect to the Pledged Stock, as well as all
rights and remedies otherwise available at law or in equity.

         Failure of Debtor to make any payment of interest or principal when due
shall be deemed to be an event of default. It shall also be an event of default
if Debtor files a petition seeking relief, or consents to the filing or
instituting of proceedings against him, under any federal or state bankruptcy
law or other similar law, or causes, permits or consents to the appointment of,
or taking possession by, a receiver or similar official of all or substantially
all of Debtor's property. On the occurrence of an event of default, Payee may
declare the entire amount due hereunder immediately due and payable (except that
in the case of an event of default described in the immediately preceding
sentence, the entire amount due hereunder automatically shall become due and
payable), and the interest rate hereunder shall be increased from and after such
default to twelve percent (12%) per annum (but in no event in excess of the
maximum rate permitted by Florida law).

         This Note shall be binding upon Debtor and Debtor's legal
representatives, heirs and assigns. Presentation for payment, notice of
dishonor, protest and notice of protest are hereby waived.

         Debtor agrees to pay and shall pay all documentary stamp taxes due on
this Note.

         In the event of any litigation arising under this Note, the
non-prevailing party shall pay the prevailing party's attorneys' fees and costs
incurred in litigation.

         This Note shall be governed by the laws of the State of Florida and may
not be changed or terminated orally.

Dated this 1st day of September 2002.

                                       DEBTOR:

                                       /s/ Graciela R. Garton
                                       -----------------------------------------
                                       Graciela R. Garton, M.D.

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