Xu ZhengZheng, Traughber Bryan J, Harris Eleanor, Podder Tarun K
Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH, USA.
School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
J Contemp Brachytherapy. 2022 Apr;14(2):176-182. doi: 10.5114/jcb.2022.114929. Epub 2022 Mar 24.
The volume of Venezia applicator with vaginal caps can be relatively large compared to target volumes. This study investigated the dosimetric and radiobiological effects of applicator volume removal for cervical cancer patients treated with Venezia (VZ) and tandem and split-ring (TSR) applicators used in the clinic.
A total of 40 patients (101 plans) with stage IIA-IIIC cervical cancer were retrospectively reviewed. Thirty patients were treated with VZ and ten patients were treated with TSR. Applicators were contoured on planning CTs where target contours were involved. Applicator contours were subtracted from the target contours. External beam radiation therapy (EBRT) and brachytherapy doses were calculated in biologically equivalent doses in 2 Gy fractions (EQD) and combined using full parameter addition for dose-volume histogram (DVH) parameters of composited dose. D, D, V, V, V, and tumor control probability (TCP) were evaluated and compared for targets after applicator exclusion.
The average volume changes in gross tumor volume (GTV), high-risk clinical target volume (HR-CTV), and intermediate-risk clinical target volume (IR-CTV) after VZ applicator exclusion were 1.4 ±1.5 cm, 15.7 ±6.6 cm, and 33.8 ±15.1 cm, respectively. VZ exclusion resulted in significant changes ( < 0.05) in small volume parameters (D) and high-dose parameters (V and V) for HR-CTV and IR-CTV. Dosimetric impact of TSR exclusion on targets was not significant. There was no significant change in TCP after applicator exclusion.
Venezia applicator with vaginal caps has significant impact on small volume and high-dose DVH parameters of the target. Applicator contour exclusion is recommended for dosimetric evaluation when Venezia applicator is used.
与靶区体积相比，带有阴道帽的威尼斯施源器体积可能相对较大。本研究调查了在临床中使用威尼斯（VZ）施源器以及串联和裂环（TSR）施源器治疗的宫颈癌患者去除施源器体积后的剂量学和放射生物学效应。
回顾性分析了40例IIA-IIIC期宫颈癌患者（101个计划）。30例患者接受VZ治疗，10例患者接受TSR治疗。在涉及靶区轮廓的计划CT上对施源器进行轮廓勾画。从靶区轮廓中减去施源器轮廓。外照射放疗（EBRT）和近距离放疗剂量以2Gy分次的生物等效剂量（EQD）计算，并使用全参数相加法对合成剂量的剂量体积直方图（DVH）参数进行组合。在排除施源器后，对靶区的D、D、V、V、V和肿瘤控制概率（TCP）进行评估和比较。
排除VZ施源器后，大体肿瘤体积（GTV）、高危临床靶区体积（HR-CTV）和中危临床靶区体积（IR-CTV）的平均体积变化分别为1.4±1.5cm³、15.7±6.6cm³和33.8±15.1cm³。排除VZ导致HR-CTV和IR-CTV的小体积参数（D）和高剂量参数（V和V）发生显著变化（P<0.05）。排除TSR对靶区的剂量学影响不显著。排除施源器后TCP无显著变化。
带有阴道帽的威尼斯施源器对靶区的小体积和高剂量DVH参数有显著影响。当使用威尼斯施源器时，建议在剂量学评估中排除施源器轮廓。
