The Design of an Audit Test for ۶۰Co Brachytherapy Treatment Planning System

Background: Auditing the treatment planning system (TPS) software for a radiotherapy unit is of paramount importance in any radiation therapy department. A Plexiglas phantom was proposed to measure the ionization of ۶۰Co high dose rate (HDR) source and compare dose points in the planning system for auditing and verifying TPS. Methods: Auditing was performed using a Plexiglas phantom in an end‑to‑end test, and relative dose points were detected by a farmer‑type ionization chamber and compared with the relative dose of similar points in TPS. The audit results were determined as pass optimal level (<۳.۳%), pass action level (between ۳.۳% and ۵%), and out of tolerance (>۵%). Results: The comparison of the collected data revealed that ۸۰% of the measured values were ≤۵% in the pass level, and ۲۰% of the points were out of tolerance (between ۵% and ۶.۹۹%). Conclusion: This study documented the appropriateness of the dosimetry audit test and this phantom design for the HDR brachytherapy TPS.