Determination of the Dosimetric Characteristics of BATAN’s 125I Source for Brachytherapy: An Experimental Study

125I brachytherapy sources with low photon energies have been widely used in
treating tumors. According to American Association of Physicists in Medicine
Task Group No. 43 (AAPM TG-43) recommendations, dosimetric characteristic of
the new brachytherapy sources should be determined before clinical use. In this
study, dosimetric characteristic of 125
I manufactured by BATAN have been
determined through measurement by using Thermoluminescent Dosemeter (TLD)
and gafchromic XR- QA2 film. The radial dose function measurements were
performed at distances ranging from 0.5 to 10 cm from the source center. The
anisotropy functions were measured at distances of 2, 3, and 5 cm from the source
center for angles ranging from 0 to 90 degree in all quadrants. The results indicated
that a dose rate constants measured with TLD and film are 1.05  8 % cGy.h
-1
.U
-1
and 1.01  8 % cGy.h
-1
.U
-1
, respectively. The radial dose function decreases along
with the increasing distance from source and meets the 5
th
order polynomial
equation. The anisotropy function result shows that the anisotropy in dose
distribution increases along the source axis. This measurement data are in agreement
with the previous study on EGSnrc Monte Carlo result and have a similar pattern
with IsoAid and GMS BT-125 commercial 125I source.