Yi ByongYong, Mossahebi Sina, Modiri Arezoo, Nichols Elizabeth M, Guerrero Mariana, Lamichhane Narottam, Mohindra Pranshu
Department of Radiation Oncology, University of Maryland School of Medicine, MD, USA.
Proton Treatment Center, Baltimore, MD, USA.
Int J Part Ther. 2022 Jun 28;9(2):31-39. doi: 10.14338/IJPT-22-00013.1. eCollection 2022 Fall.
To investigate whether volumetric-modulated proton arc therapy (VPAT) plans generate comparable doses to organs at risk (OARs) compared with interstitial high-dose-rate (iHDR) brachytherapy for patients with gynecologic cancer with disease extension to parametrial/pelvic side wall, who are not eligible for the aggressive procedure.
VPAT delivers proton arc beams by modulated energies at the beam nozzle while maintaining the same incident energy to the gantry during the arc rotation. Plans of 10 patients previously treated with iHDR brachytherapy for high-risk clinical treatment volumes (HRCTV; 31.8-110.6 cm; lateral dimensions, 4.2-5.6 cm) were selected and compared with VPAT plans. VPAT plans for each patient were designed using a 152- to 245-MeV range of energy-modulated proton beams.
HRCTV coverage of the VPAT plans was comparable to that of the iHDR plans, with V150% showing no statistical differences. On average, the V100% and V90% of VPAT plans were higher than those of the iHDR plans, 95.0% vs 91.9% ( = .02) and 98.6% vs 97.5% ( = .02), respectively. D100 was also 17% higher for the VPAT plans ( = .03). On average, the D of bladder, rectum, and small bowels in the VPAT plans were considerably lower than those in iHDR plans (by 17.4%, 35.2%, and 65.6%, respectively; .05 for all OARs).
VPAT-generated plans were dosimetrically superior to those with HDR brachytherapy with interstitial needles for locally advanced gynecologic cancer with parametrial/pelvic side wall disease extension. Dosimetrically, VPAT provides a noninvasive alternative to iHDR brachytherapy with a superior dosimetric profile.
探讨对于疾病已扩展至宫旁组织/盆腔侧壁、不符合激进手术条件的妇科癌症患者，容积调强质子弧形治疗（VPAT）计划与组织间高剂量率（iHDR）近距离放射治疗相比，对危及器官（OARs）产生的剂量是否相当。
VPAT通过在射束喷嘴处调制能量来输送质子弧形束，同时在弧形旋转过程中保持对机架的入射能量相同。选择10例先前接受iHDR近距离放射治疗的高危临床靶体积（HRCTV；31.8 - 110.6 cm³；横向尺寸，4.2 - 5.6 cm）患者的计划，并与VPAT计划进行比较。使用152至245 MeV能量调制质子束为每位患者设计VPAT计划。
VPAT计划的HRCTV覆盖情况与iHDR计划相当，V150%无统计学差异。平均而言，VPAT计划的V100%和V90%高于iHDR计划，分别为95.0%对91.9%（P = 0.02）和98.6%对97.5%（P = 0.02）。VPAT计划的D100也高17%（P = 0.03）。平均而言，VPAT计划中膀胱、直肠和小肠的Dmean明显低于iHDR计划（分别低17.4%、35.2%和65.6%；所有OARs的P < 0.05）。
对于宫旁组织/盆腔侧壁疾病扩展的局部晚期妇科癌症，VPAT生成的计划在剂量学上优于使用组织间针的HDR近距离放射治疗。在剂量学方面,VPAT为iHDR近距离放射治疗提供了一种无创替代方案，且剂量学特征更优。
