Kharouta Michael, Malin Martha, Son Christina, Al-Hallaq Hania, Hasan Yasmin
Department of Radiation and Cellular Oncology, University of Chicago Medical Center, Chicago, USA.
J Contemp Brachytherapy. 2018 Jun;10(3):218-224. doi: 10.5114/jcb.2018.76522. Epub 2018 Jun 20.
Interstitial brachytherapy implemented for locally advanced gynecologic cancer can result in toxicity due to the proximity of organs at risk (OAR). We report our experience using superflab bolus as vaginal packing to displace OAR during interstitial brachytherapy.
Twelve patients with stage IB-IVA gynecologic cancer were treated with definitive chemoradiation including interstitial brachytherapy. A Syed template was used for a computed tomography (CT)-based pre-plan with magnetic resonance imaging (MRI) fusion. A 1-2 cm superflab bolus was cut and sterilized. The tandem and obturator were placed, and superflab was then inserted into the vagina. Interstitial needles were then placed through the template and superflab as per the pre-plan under transabdominal ultrasound guidance. Prescription doses ranged from 85-90 Gy EQD including external beam radiation therapy (EBRT). 5-6 Gy per fraction was delivered biologically effective dose (BID) over 2-3 days in 1-2 implants. Toxicities were evaluated post-treatment, 1 month, and 3 months.
The rectum, bladder, and sigmoid had significant average displacement from the prescription isodose line. The average reduction in D between pre- and post-implant was 5.19 Gy per fraction ( < 0.0001), 7.19 Gy ( < 0.0004), and 1.78 Gy ( < 0.003) for the rectum, bladder, and sigmoid, respectively. The high-risk target volume (HR-TV) received a median D of 104% (range, 58-122%) of the prescription dose, and 92% (range, 71-131%) in the pre-/post-implant plans, respectively ( = 0.4).
Our initial experience with superflab as vaginal packing demonstrates technical feasibility and dosimetric improvement for OAR.
对于局部晚期妇科癌症实施的间质近距离放射治疗，由于危及器官（OAR）位置临近，可能会导致毒性反应。我们报告了使用超厚填充物作为阴道填塞物在间质近距离放射治疗期间移位危及器官的经验。
12例IB-IVA期妇科癌症患者接受了包括间质近距离放射治疗在内的根治性放化疗。使用Syed模板进行基于计算机断层扫描（CT）的磁共振成像（MRI）融合的预计划。将1-2厘米厚的超厚填充物裁剪并消毒。放置阴道施源器和闭孔器，然后将超厚填充物插入阴道。然后在经腹超声引导下，按照预计划通过模板和超厚填充物放置间质针。处方剂量范围为85-90 Gy等效剂量，包括外照射放疗（EBRT）。在1-2次植入中，分2-3天给予每分次5-6 Gy的生物有效剂量（BID）。治疗后、1个月和3个月评估毒性反应。
直肠、膀胱和乙状结肠与处方等剂量线的平均位移显著。植入前后直肠、膀胱和乙状结肠每分次的D平均降低分别为5.19 Gy（<0.0001）、7.19 Gy（<0.0004）和1.78 Gy（<0.003）。高危靶区（HR-TV）接受的中位D分别为处方剂量的104%（范围58-122%）和植入前/后计划中的92%（范围71-131%）（P = 0.4）。
我们使用超厚填充物作为阴道填塞物的初步经验证明了其在技术上的可行性以及对危及器官的剂量学改善。
