Abstract
Abstract
The application of more and more low-energy, low-dose-rate
photon radiation seeds in brachytherapy. According to the TG43 report
and TG43-U1 report issued by the American Association of Physicists
in Medicine, both apparent activity and air kerma strength are
physical characterization parameters of brachytherapy seed
strength,which are needed to convert into water absorbed dose at the
depth of 1 cm. At present, the method of obtaining the water
absorbed dose is to convert the air kerma strength, the uncertainty
of results exceeds 5% (k = 1), which could reduce the cure rate
of the treatment. In order to address this issue ,the China
Institute of Atomic Energy has designed a device that can directly
replicate the water absorbed dose of 125I brachytherapy
seeds,which is an extrapolation chamber embedded with water
equivalent material. In order to evaluate the performance of the
extrapolation chamber, a series of experiments were carried out,
including partial pressure test, leakage current, saturation curve,
response linearity, collection area and zero point position. The
test results show that the performance parameters of the
extrapolation chamber meet the relevant requirements.