The non-uniformity correction factor for the cylindrical ionization chambers in dosimetry of an HDR¹⁹²Ir brachytherapy source

Abstract

The aim of this study is to derive the non-uniformity correction factor for the two therapy ionization chambers for the dose measurement near the brachytherapy source. The two ionization chambers of 0.6 cc and 0.1 cc volume were used. The measurement in air was performed for distances between 0.8 cm and 20 cm from the source in specially designed measurement jig. The non-uniformity correction factors were derived from the measured values. The experimentally derived factors were compared with the theoretically calculated non-uniformity correction factors and a close agreement was found between these two studies. The experimentally derived non-uniformity correction factor supports the anisotropic theory.

Comparative dosimetry of GammaMed Plus high-dose rate 192 Ir brachytherapy source

“…The detailed explanation about measurement jig and experimental procedure has been revealed in the publication. [ 27 ] The dimensions of water phantom were about 50 × 50 × 45 cm 3 , and the walls were made of acrylic. The jig was designed in such a way that it could be easily placed from air into water phantom (or vice versa) without any displacement of the chamber and the source applicator.…”

“…The values of nonuniformity correction factors ( N n ) used were 1.107, 1.033, 1.006 and 1.0044 for the source-to-chamber distances of 1.0, 2.0, 5.0 and 8.0 cm, respectively. [ 27 ]…”