Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.
Medical Physics Unit, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
Phys Med. 2019 Mar;59:151-157. doi: 10.1016/j.ejmp.2019.03.001. Epub 2019 Mar 7.
The multichannel vaginal cylinder (MVC) applicator employed for gynecological high dose rate (HDR) brachytherapy increases dose delivery complexity, and thus makes the treatment more prone to errors. A quality assurance (QA) procedure tracking the source throughout dose delivery can detect dwell position and time errors in the multiple channels of the applicator. A new MVC system with integrated real time in vivo treatment delivery QA has been developed based on diodes embedded on the outer surface of the MVC. It has been pre-calibrated and verified using a non-clinical treatment plan with consecutive test positions and dwell times within each catheter, followed by the delivery of ten clinical plans of adjuvant vaginal cuff brachytherapy following hysterectomy for endometrial cancer. The non-clinical verification showed overall mean dwell position and time discrepancies between the nominal and measured treatment of -0.2 ± 0.5 mm and -0.1 ± 0.1 s (k = 1), respectively. The clinical plans showed mean positional discrepancies of 0.2 ± 0.4 and 0.0 ± 0.8 mm, for the central and peripheral catheters, respectively, and mean dwell time discrepancies of -0.1 ± 0.2 and -0.0 ± 0.1 s for central and peripheral catheters, respectively. The innovative prototype of the MVC system has shown the ability to track the source with sub-mm and sub-second accuracy, and demonstrated potential for its incorporation into the clinical routine.
多通道阴道圆柱（MVC）施源器用于妇科高剂量率（HDR）近距离治疗，增加了剂量传递的复杂性，因此使治疗更容易出错。一种质量保证（QA）程序可以在整个剂量传递过程中跟踪源，以检测施源器多个通道中的驻留位置和时间误差。一种新的 MVC 系统，具有集成的实时体内治疗输送 QA，已基于嵌入在 MVC 外表面的二极管开发。它已通过具有连续测试位置和每个导管内驻留时间的非临床治疗计划进行了预校准和验证，随后对十例子宫内膜癌子宫切除术后辅助阴道袖口近距离治疗的临床计划进行了治疗。非临床验证显示，名义治疗和测量治疗之间的总体平均驻留位置和时间差异分别为-0.2±0.5mm 和-0.1±0.1s（k=1）。临床计划显示，中央和外周导管的平均位置差异分别为 0.2±0.4mm 和 0.0±0.8mm，中央和外周导管的平均驻留时间差异分别为-0.1±0.2s 和-0.0±0.1s。MVC 系统的创新原型已显示出以亚毫米和亚秒级精度跟踪源的能力，并展示了将其纳入临床常规的潜力。
