Royal Marsden NHS Foundation Trust, Sutton, UK.
Radiother Oncol. 2011 Aug;100(2):221-6. doi: 10.1016/j.radonc.2010.11.005. Epub 2010 Dec 13.
To test a prone position against the international-standard supine position in women undergoing whole-breast-radiotherapy (WBRT) after wide-local-excision (WLE) of early breast cancer (BC) in terms of feasibility, set-up errors, and respiratory motion.
Following WLE of BC with insertion of tumour-bed clips, patients underwent 4D-CT for WBRT-planning in supine and prone positions (the latter using an in-house-designed platform). Patients were randomised to undergo WBRT fractions 1-7 in one position, switching to the alternate position for fractions 8-15 (40Gy/15-fractions total). Cone-beam CT-images (CBCT) were acquired prior to fractions 1, 4, 7, 8, 11 and 14. CBCT data were matched to planning-CT data using (i) chest-wall and (ii) clips. Systematic and random errors were calculated. Maximal displacement of chest-wall and clips with respiration was measured on 4D-CT. Clinical- to planning-target-volume (CTV-PTV) margins were calculated. Patient-comfort-scores and treatment-times were evaluated.
Twenty-five patients were randomized. 192/192 (100%) planned supine fractions and 173/192 (90%) prone fractions were completed. 3D population systematic errors were 1.3-1.9mm (supine) and 3.1-4.3mm (prone) (p=0.02) and random errors 2.6-3.2mm (supine) and 3.8-5.4mm (prone) (p=0.02). Prone positioning reduced chest-wall and clip motion (0.5±0.2mm (prone) versus 2.7±0.5mm (supine) (p<0.001)) with respiration. Calculated CTV-PTV margins were greater for prone (12-16mm) than for supine treatment (10mm). Patient-comfort-scores and treatment times were comparable (p=0.06).
Set-up errors were greater using our prone technique than for our standard supine technique, resulting in the need for larger CTV-PTV margins in the prone position. Further work is required to optimize the prone treatment-platform and technique before it can become a standard treatment option at our institution.
在早期乳腺癌（BC）广泛局部切除（WLE）后行全乳放疗（WBRT）的女性中，通过比较俯卧位和国际标准仰卧位，测试俯卧位在可行性、摆位误差和呼吸运动方面的优劣。
在 BC 行 WLE 并插入肿瘤床夹后，患者行 4D-CT 进行仰卧位和俯卧位 WBRT 计划（后者使用内部设计的平台）。患者随机接受 1-7 个分次的 WBRT 治疗，第 8-15 个分次切换到另一侧（总剂量 40Gy/15 分次）。在第 1、4、7、8、11 和 14 个分次治疗前进行锥形束 CT 图像（CBCT）采集。使用（i）胸壁和（ii）夹，将 CBCT 数据与计划 CT 数据进行匹配。计算系统误差和随机误差。在 4D-CT 上测量呼吸时胸壁和夹的最大位移。计算临床靶区到计划靶区（CTV-PTV）的边界。评估患者舒适度评分和治疗时间。
25 例患者随机分组。192/192（100%）计划仰卧位分次和 173/192（90%）俯卧位分次完成。3D 人群系统误差为 1.3-1.9mm（仰卧位）和 3.1-4.3mm（俯卧位）（p=0.02），随机误差为 2.6-3.2mm（仰卧位）和 3.8-5.4mm（俯卧位）（p=0.02）。俯卧位定位减少了胸壁和夹的运动（0.5±0.2mm（俯卧位）比 2.7±0.5mm（仰卧位）（p<0.001））。计算的 CTV-PTV 边界在俯卧位（12-16mm）比仰卧位（10mm）更大。患者舒适度评分和治疗时间相当（p=0.06）。
与我们的标准仰卧位技术相比，我们的俯卧位技术摆位误差更大，导致俯卧位需要更大的 CTV-PTV 边界。在我们的机构将俯卧位治疗平台和技术优化为标准治疗选择之前，还需要进一步的工作。
