Independent software for dose verification in cervical cancer brachytherapy

Abstract

An independent software is used to verify the radiation dose of Oncentra software at point doses in high-dose–rate (HDR) brachytherapy. MuCheck is a software tool to validate the dose from the treatment planning calculation, performed by AAPM TG-43 algorithm with the same equation as Oncentra treatment planning system. The purpose of this study is to verify the dose at the reference points in HDR brachytherapy for the cervical cancer patients calculated by Oncentra treatment planning system with the MuCheck independent software. Source calibration was performed with the well chamber. The result showed 0.2% error from the source certification with less than 5% dose criteria. Furthermore, software verification was implemented with EBT2 film that showed -2.69±4.45% and -2.37±4.65% dose difference from Oncentra and MuCheck, respectively. According to the 253 cervical cancer treatment plans, the results revealed that the dose difference between Oncentra and MuCheck depended slightly on the applicator types. The MR compatible Flecther applicator remained the dose discrepancy that was 0.18±0.91%, -0.24±0.97%, 0.49±0.52%, 0.44±0.86% at point A, point B, bladder and rectum, respectively. The needles combined with Utrecht applicator resulted in 0.34±0.58%, 0.37±0.25%, 0.62±0.54%, 0.75±0.91% of the dose difference at point A, point B, bladder and rectum, respectively. The vaginal cylinder applicator showed the dose difference that was 0.52±0.76%, 0.25±0.51%, 0.55±0.43%, 0.58±0.44% at point A, point B, bladder and rectum, respectively. The needles presented the highest discrepancy due to more complex plans. Another factor for the dose varying was the position of the mark points. Additionally for 253 cases, the % frequency that obtained the dose difference within 1% were 81.82%, 87.74%, 90.12%, and 82.21% at point A, point B, bladder and rectum, respectively. Point A showed lower %pass at 1% compared with point B because it located in the high dose gradient point. The maximum percent dose difference was within 3% according to AAPM TG-59. Thus, MuCheck is an accuracy and precision independent approach, which is suitable to perform the patient specific quality assurance for HDR brachytherapy promptly and expediently.