Filling the gap in central shielding: three-dimensional analysis of the EQD2 dose in radiotherapy for cervical cancer with the central shielding technique.
Filling the gap in central shielding: three-dimensional analysis of the EQD2 dose in radiotherapy for cervical cancer with the central shielding technique.
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DOI：
10.1093/jrr/rrv029
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发表时间：
2015-09
影响因子：
2
通讯作者：
Nakano T
中科院分区：
文献类型：
--
作者：
Tamaki T;Ohno T;Noda SE;Kato S;Nakano T
本研究旨在通过分析体外放射治疗(EBRT) +腔内近距离放射治疗（ICBT）复合三维EQD2剂量分布，提供中心屏蔽技术治疗宫颈癌放射治疗的准确剂量分布曲线。在假体上，创建了全骨盆照射（WP）（4场）、骨盆中央屏蔽技术照射（CS）[前-后/后-前（AP-PA场），屏蔽宽度为3或4 cm]和使用a点处方的ICBT的四种组合模式：30 Gy/15分数+ 20 Gy/10分数+ 24 Gy/4分数[计划（30 + 20 + 24）]，40 Gy/20分数+ 10 Gy/5分数+ 18 Gy/3分数[计划（40 + 10 + 18）]，40 Gy/20分数+ 10 Gy/5分数+ 24 Gy/4分数[计划（40 + 10 + 24）]和45 Gy/25分数+ 0 Gy + 28 Gy/4分数[计划（45 + 0 + 28）]。分析了完整处理后EQD2的复合剂量分布。Plan（30 + 20 + 24）、Plan（40 + 10 + 18）、Plan（40 + 10 + 24）和Plan（45 + 0 + 28）的a点剂量分别为78.0 Gy (cs3cm)/71.8 Gy （cs4cm）、72.1 Gy (cs3cm)/69.0 Gy （cs4cm）、80.1 Gy (cs3cm)/77.0 Gy （cs4cm）和84.1 Gy，而此前报道的剂量分别为62 Gy、64 Gy、72 Gy和84 Gy。在所有CS治疗方案中，在左右方向上均实现了60 Gy （EQD2）的等效或更广的覆盖，而在前后方向上，CS治疗方案的覆盖范围有所下降。在中心目标周围没有不规则的“冷”区域。CS在宫颈癌放射治疗中的应用使肿瘤在侧方向上覆盖，剂量高于先前报道的a点剂量。
This study aimed to provide accurate dose distribution profiles of radiotherapy for cervical cancer when treated with the central shielding technique by analysing the composite 3D EQD2 dose distribution of external beam radiotherapy (EBRT) plus intracavitary brachytherapy (ICBT). On a phantom, four patterns of the combinations of whole pelvis irradiation (WP) (4 fields), pelvis irradiation with central shielding technique (CS) [anterior–posterior/posterior–anterior (AP-PA fields), shielding width of 3 or 4 cm] and ICBT using Point-A prescription were created: 30 Gy/15 fractions + 20 Gy/10 fractions + 24 Gy/4 fractions [Plan (30 + 20 + 24)], 40 Gy/20 fractions + 10 Gy/5 fractions + 18 Gy/3 fractions [Plan (40 + 10 + 18)], 40 Gy/20 fractions + 10 Gy/5 fractions + 24 Gy/4 fractions [Plan (40 + 10 + 24)] and 45 Gy/25 fractions + 0 Gy + 28 Gy/4 fractions [Plan (45 + 0 + 28)]. The composite EQD2 dose distributions of the complete treatment were analysed. The Point-A dose of Plan (30 + 20 + 24), Plan (40 + 10 + 18), Plan (40 + 10 + 24) and Plan (45 + 0 + 28) were 78.0 Gy (CS 3 cm)/71.8 Gy (CS 4 cm), 72.1 Gy (CS 3 cm)/69.0 Gy (CS 4 cm), 80.1 Gy (CS 3 cm)/77.0 Gy (CS 4 cm) and 84.1 Gy, whereas it has been previously reported to be 62 Gy, 64 Gy, 72 Gy and 84 Gy, respectively. For all the treatment plans with CS, equivalent or wider coverage of 60 Gy (EQD2) was achieved in the right–left direction, while coverage in the anterior–posterior direction decreased in plans with CS. There were no irregularly ‘cold’ regions around the central target. The use of CS in radiotherapy for cervical cancer resulted in tumor coverage in the lateral direction with doses higher than the previously reported Point-A doses.