Relative biological effectiveness of proton medical beam at Moscow synchrotron determined by the Chinese hamster cells assay.
OBJECTIVE
Assessment of relative biological effectiveness (RBE) of the proton medical beam at Moscow synchrotron.


METHODS
The study was performed at Moscow proton medical facility (Institute for Theoretical and Experimental Physics). Relative biological effectiveness of the synchrotron proton beam was assessed at the entry of the unmodulated 179 MeV beam and in the center of spread out Bragg peak (SOBP), from measurements of the survival of Chinese hamster cells (clone 431). Gamma-radiation of 60Co was used as a reference source.


RESULTS
According to the linear regression model, mean RBE values at 37% survival level were found to be 1.10 +/- 0.04 at the beam entry and 1.14 +/- 0.05 in the center of SOBP. Values of RBE obtained using the linear-quadratic model for 10% and 37% survival levels were 1.09 and 1.07, respectively, at the beam entry and 1.07 and 1.08, respectively, in the center of SOBP.


CONCLUSIONS
The data obtained indicate that (a) the RBE values at the entry of the unmodulated beam and at the center of the SOBP are in close agreement, with an average of about 1.10; (b) protons are radiobiologically somewhat more effective than 60Co gamma rays; and, (c) high pulse dose rate of the medical beam does not significantly affect biological effects of the beam.
Institute of Biophysics, Moscow, Russia.
P N
PN
Yashkin
D I
DI
Silin
V A
VA
Zolotov
V I
VI
Kostjuchenko
D F
DF
Nichiporov
T P
TP
Feoktistova
K S
KS
Martirosov
Y I
YI
Minakova
V S
VS
Khoroshkov
P B
PB
Polonski
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D061766:Proton Therapy; D011879:Radiotherapy Dosage; D012062:Relative Biological Effectiveness; D017356:Synchrotrons; D011522:Protons
D011522:Protons