To evaluate the possibility of dose escalation and reduction of fraction number in cervical brachytherapy using a gel spacer. Twenty patients with uterine cervical cancer treated with image-guided adaptive brachytherapy (IGABT) were selected. Hyaluronic acid gel injection (HGI) was performed in the rectovaginal and vesicouterine septum for 10 patients. The other ten patients were not with HGI. Both groups were treated with IGABT involving tandem/ovoid or cylindrical applicators along with additional interstitial needles. Dose distributions approved by radiation oncologists were retrospectively analyzed, and a dose summation of 45 Gy/25 of external beam radiation therapy and IGABT was performed. Dose constraints for D of bladder, rectum, and sigmoid were 80, 70, and 70 Gy, respectively. Equivalent dose in 2-Gy fractions calculations used α/β = 10 Gy for high-risk clinical target volume (CTV) D and α/β = 3 Gy for organs at risks (OARs). As a planning study, dose distribution rescaling was conducted to deliver as much dose to CTV D as possible within the dose constraint limitation for OARs when IGABT was performed for four, three, and two fractions in both groups. The median CTV D was >80 Gy in the non-HGI group and >85 Gy in the HGI group for virtual two and three fractions. Rectum D was significantly lower in the HGI group for three fractions ( < 0.01). In the HGI group, adequate dose delivery to CTV could be achieved with a reduced IGABT fraction number while meeting the dose constraints of OARs.

中文翻译：

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在直肠阴道和膀胱子宫隔中使用凝胶垫片进行宫颈近距离放射治疗的安全剂量递增和分数减少：一项规划研究

评估使用凝胶垫片进行颈部近距离放射治疗时剂量递增和分数减少的可能性。选择了 20 名接受图像引导适应性近距离放射治疗 (IGABT) 治疗的宫颈癌患者。 10 名患者在直肠阴道和膀胱子宫间隔处进行了透明质酸凝胶注射 (HGI)。其他十名患者没有患有 HGI。两组均接受 IGABT 治疗，涉及串联/卵形或圆柱形施药器以及额外的间质针。回顾性分析了放射肿瘤学家批准的剂量分布，并进行了 45 Gy/25 的外照射放射治疗和 IGABT 的剂量总和。膀胱、直肠和乙状结肠 D 的剂量限制分别为 80、70 和 70 Gy。 2 Gy 分数计算中的等效剂量对于高风险临床靶体积 (CTV) D 使用 α/β = 10 Gy，对于风险器官 (OAR) 使用 α/β = 3 Gy。作为一项规划研究，当两组均进行四次、三次和两次 IGABT 治疗时，进行了剂量分布重新调整，以便在 OAR 的剂量限制范围内向 CTV D 提供尽可能多的剂量。对于虚拟两次和三次分割，非 HGI 组的中位 CTV D 为 >80 Gy，HGI 组的中位 CTV D 为 >85 Gy。 HGI 组的三个分数的直肠 D 显着较低 ( < 0.01)。在 HGI 组中，可以通过减少 IGABT 分数来实现向 CTV 提供足够的剂量，同时满足 OAR 的剂量限制。