用于宫颈癌基于逆向优化的腔内近距离放疗的两种不同施源器和直肠回缩方法的剂量学比较
Dosimetric comparison of two different applicators and rectal retraction methods used in inverse optimization-based intracavitary brachytherapy for cervical cancer.
作者信息
Biltekin Fatih, Gultekin Melis, Yilmaz Melek Tugce, Yildiz Ferah
机构信息
Department of Radiation Oncology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
出版信息
J Contemp Brachytherapy. 2020 Feb;12(1):35-43. doi: 10.5114/jcb.2020.92699. Epub 2020 Feb 28.
PURPOSE
The purpose of this study was to evaluate the dosimetric differences between two different applicators and rectal-retraction methods used in image-guided brachytherapy (IGBT) for locally advanced cervical cancer (LACC).
MATERIAL AND METHODS
Ten patients with LACC treated with definitive chemoradiotherapy and inverse optimization-based IGBT were included in this study. In each patient, at least one fraction of IGBT was performed using tandem-ovoids (TO) with vaginal gauze packing (VGP) or tandem-ring (TR) with rectal-retractor (RR). High-risk clinical target volume (CTV) and intermediate-risk CTV (CTV) were defined as CTVs, and bladder, rectum, sigmoid, small bowel, urethra, and vaginal mucosa were defined as organs at risk (OARs). All patients received 50.4 Gy external beam radiotherapy (EBRT) in 28 fractions. After EBRT, 28 Gy high-dose-rate (HDR) IGBT in 4 fractions was delivered to central disease. A plan comparison was performed using dose-volume histogram (DVH) and treatment planning parameters for CTVs and OARs.
RESULTS
There were no significant differences in D values of CTV. In terms of rectum dose, TR with RR was found to be significantly better than TO with VGP ( < 0.0001 for D and < 0.013 for V). Although, there were no statistically significant differences in D value of bladder, sigmoid, small bowel, upper vaginal mucosa, and urethra, mean value of D for all defined OARs were found lower in TR than in TO. Bladder V, upper vaginal mucosa V, middle and lower vaginal mucosa D values were all found to be significantly lower for TR than for TO ( < 0.035). CTV and CTV volumes contoured in TR were approximately 11% and 9% smaller than TO, respectively.
CONCLUSIONS
The results showed that there were no statistically differences in D value of CTV and CTV. However, all DVH parameters for OARs in TR with RR were found to be better than in TO with VGP.
目的
本研究旨在评估两种不同施源器及直肠退缩方法在局部晚期宫颈癌（LACC）图像引导近距离放疗（IGBT）中的剂量学差异。
材料与方法
本研究纳入10例接受根治性放化疗及基于逆向优化的IGBT治疗的LACC患者。在每位患者中，至少有一个IGBT分次使用带阴道纱布填塞（VGP）的串珠-卵圆体（TO）或带直肠牵开器（RR）的串珠-环（TR）进行。将高危临床靶区（CTV）和中危CTV定义为CTV，将膀胱、直肠、乙状结肠、小肠、尿道和阴道黏膜定义为危及器官（OARs）。所有患者接受28次分割的50.4 Gy外照射放疗（EBRT）。EBRT后，分4次给予中央病灶28 Gy高剂量率（HDR）IGBT。使用剂量体积直方图（DVH）以及CTV和OARs的治疗计划参数进行计划比较。
结果
CTV的D值无显著差异。在直肠剂量方面，发现带RR的TR明显优于带VGP的TO（D的P<0.0001，V的P<0.013）。虽然膀胱、乙状结肠、小肠、阴道上段黏膜和尿道的D值无统计学显著差异，但发现所有定义的OARs的D平均值TR低于TO。发现TR的膀胱V、阴道上段黏膜V、阴道中下段黏膜D值均显著低于TO（P<0.035）。TR中勾勒出的CTV和CTV体积分别比TO小约11%和9%。
结论
结果表明，CTV和CTV的D值无统计学差异。然而，发现带RR的TR中OARs的所有DVH参数均优于带VGP的TO。
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