Air-kerma strength determination of a new directional 103Pd source

摘要

Purpose:A new directional ¹⁰³Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing ¹⁰³Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active ¹⁰³Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normally used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (SK) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring SK to a well-type ionization chamber.