Sikorska Katarzyna, Zolciak-Siwinska Agnieszka, Kowalczyk Adam, Bijok Michał, Michalski Wojciech, Gruszczynska Ewelina
Department of Medical Physics, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland.
Department of Gynecological Oncology, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland.
J Contemp Brachytherapy. 2020 Jun;12(3):248-251. doi: 10.5114/jcb.2020.96865. Epub 2020 Jun 30.
The aim of the study was to perform a prospective analysis of dosimetric consequences of rectal enema administration before vaginal cuff brachytherapy (VCB), the dose distribution in organs at risk (OARs), and the presence of air gaps (AGs) in patients with cervical or endometrial cancer.
In total, 75 patients treated in 2019 were randomly divided into two groups including 38 patients with and 37 without an enema before VCB. All patients received post-operative high-dose-rate (HDR). Single-channel vaginal cylinders with active length of 2.75 cm were used. Prescription dose was 7 Gy at 5 mm depth from the applicator surface in all directions. Treatment plans were based on computed tomography (CT).
Enema performed before cylinder insertion had no effect on rectosigmoid D or D. Rectosigmoid median V was 0.5 cm (range, 0-2.7 cm). V ≥ 1 cm in 22 and ≥ 2 cm in 6 patients, with D up to 19.7 Gy (282%) were observed. No effect of bladder volume in the range of 27-256 cm on D or D was found. The median bladder V was 0.1 cm (range, 0-1.4 cm). There were 62 (83%) patients with AGs, with 24% at the top of the vagina and 75% on the remaining length of the vagina. Most of the AGs were small (≤ 3 mm), but in 5 (8%) cases, they were bigger than 5 mm.
VCB planning with the use of CT is essential. CT can facilitate the selection of optimal cylinder size to reduce the occurrence of large AGs. A few percent of plans require correction of dose distribution because of hot spots in OARs and the presence of AGs. Enema before cylinder insertion does not influence rectosigmoid D and D. The analysis revealed no bladder volume effect on bladder doses D and D.
本研究旨在对宫颈癌或子宫内膜癌患者在阴道残端近距离放射治疗（VCB）前直肠灌肠给药的剂量学后果、危及器官（OARs）的剂量分布以及气隙（AGs）的存在情况进行前瞻性分析。
2019年接受治疗的75例患者被随机分为两组，其中38例在VCB前进行了灌肠，37例未进行灌肠。所有患者均接受术后高剂量率（HDR）治疗。使用活性长度为2.75 cm的单通道阴道施源器。处方剂量为在距施源器表面各方向5 mm深度处7 Gy。治疗计划基于计算机断层扫描（CT）。
在插入施源器前进行灌肠对直肠乙状结肠的D或D没有影响。直肠乙状结肠的中位V为0.5 cm（范围为0 - 2.7 cm）。观察到22例患者的V≥1 cm，6例患者的V≥2 cm，D高达19.7 Gy（282%）。未发现膀胱体积在27 - 256 cm范围内对D或D有影响。膀胱的中位V为0.1 cm（范围为0 - 1.4 cm）。有62例（83%）患者存在气隙，其中24%位于阴道顶部，75%位于阴道其余长度。大多数气隙较小（≤3 mm），但在5例（8%）情况下，气隙大于5 mm。
使用CT进行VCB计划至关重要。CT有助于选择最佳施源器尺寸以减少大气隙的发生。由于OARs中的热点和气隙的存在，少数计划需要校正剂量分布。在插入施源器前进行灌肠不会影响直肠乙状结肠的D和D。分析显示膀胱体积对膀胱剂量D和D没有影响。
