M El-Doushy Asmaa, Attalla Ehab Marouf, Ibrahim I H, El-Sayed S M, Saadeldin Ayat M
Department of Clinical Oncology and Nuclear Medicine, Faculty of Medicine, Ain Shams University, Cairo, Egypt.
National Cancer Institute, Cairo University, Cairo, Egypt.
J Cancer Res Clin Oncol. 2025 Sep 9;151(9):247. doi: 10.1007/s00432-025-06280-0.
High-dose-rate (HDR) brachytherapy is essential in the treatment of locally advanced cervical cancer. While Iridium-192 (Ir-192) is commonly used, its short half-life imposes logistical and financial constraints, particularly in low- and middle-income countries (LMICs). Cobalt-60 (Co-60), with a longer half-life and lower operational costs, is a viable alternative. This study aims to evaluate the dosimetric performance and planning uncertainties associated with Co-60 HDR brachytherapy.
A retrospective dosimetric analysis was conducted on 30 patients with FIGO stage IIB-IIIB cervical cancer, eligable for Brachytherapy, were treated using CT-guided intracavitary HDR brachytherapy with Co-60 sources. Treatment plans were assessed for high-risk clinical target volume (HR-CTV) coverage (D90, D80), dose-volume histogram parameters, and organ-at-risk (OAR) doses (D2cc for bladder, rectum, and sigmoid). Plan quality indices including conformity index (COIN), dose homogeneity index (DHI), and dose non-uniformity ratio (DNR) were calculated. Uncertainty analyses accounted for treatment planning system (TPS) variability and applicator positioning.
The mean HR-CTV D90 was 6.97 Gy, achieving 99.6% of the prescription dose. The mean D2cc values were 5.73 Gy for bladder (81.9%Rx), 4.72 Gy for rectum (67.4%Rx), and 3.23 Gy for sigmoid, all within acceptable tolerance limits. The mean COIN was 0.292, DHI 0.31, and DNR 0.69, indicating moderate dose conformity and acceptable inhomogeneity. TPS and applicator uncertainties contributed to estimated dose deviations of ± 2% and ± 1 mm, respectively.
Cobalt-60 HDR brachytherapy provides clinically acceptable dose coverage and OAR sparing, with dosimetric outcomes comparable to Ir-192. Its longer half-life offers practical advantages for LMICs. Optimization of dose distribution and further validation through Monte Carlo simulations and prospective clinical studies are recommended.
高剂量率（HDR）近距离放射治疗在局部晚期宫颈癌的治疗中至关重要。虽然铱-192（Ir-192）被广泛使用，但其半衰期短带来了后勤和经济方面的限制，特别是在低收入和中等收入国家（LMICs）。钴-60（Co-60）半衰期更长且运营成本更低，是一种可行的替代方案。本研究旨在评估Co-60 HDR近距离放射治疗的剂量学性能和计划不确定性。
对30例国际妇产科联盟（FIGO）IIB-IIIB期宫颈癌患者进行回顾性剂量学分析，这些患者符合近距离放射治疗条件，采用CT引导下的腔内HDR近距离放射治疗，使用Co-60源。评估治疗计划的高危临床靶区（HR-CTV）覆盖情况（D90、D80）、剂量体积直方图参数以及危及器官（OAR）剂量（膀胱、直肠和乙状结肠的D2cc）。计算包括适形指数（COIN）、剂量均匀性指数（DHI）和剂量不均匀率（DNR）在内的计划质量指标。不确定性分析考虑了治疗计划系统（TPS）的变异性和施源器定位。
HR-CTV的平均D90为6.97 Gy，达到处方剂量的99.6%。膀胱的平均D2cc值为5.73 Gy（81.9%Rx），直肠为4.72 Gy（67.4%Rx），乙状结肠为3.23 Gy，均在可接受的耐受范围内。平均COIN为0.292，DHI为0.31，DNR为0.69，表明剂量适形性中等且不均匀性可接受。TPS和施源器不确定性分别导致估计剂量偏差为±2%和±1 mm。
钴-60 HDR近距离放射治疗提供了临床上可接受的剂量覆盖和对危及器官的保护，剂量学结果与铱-192相当。其较长的半衰期为低收入和中等收入国家带来了实际优势。建议通过蒙特卡洛模拟和前瞻性临床研究优化剂量分布并进一步验证。
