Andic Fundagul, Ors Yasemin, Davutoglu Rima, Baz Cifci Sule, Ispir Emine Burcin, Erturk Mehmet Ertugrul
Department of Radiation Oncology, Faculty of Medicine, Gaziantep University, Gaziantep, Turkey.
J Exp Clin Cancer Res. 2009 Mar 24;28(1):41. doi: 10.1186/1756-9966-28-41.
The study aimed to calculate chest-wall skin dose associated with different frequencies of bolus applications in post-mastectomy three-dimensional conformal radiotherapy (3D-CRT) and to provide detailed information in the selection of an appropriate bolus regimen in this clinical setting.
CT-Simulation scans of 22 post-mastectomy patients were used. Chest wall for clinical target volume (CTV) and a volume including 2-mm surface thickness of the chest wall for skin structures were delineated. Precise PLAN 2.11 treatment planning system (TPS) was used for 3D-CRT planning. 50 Gy in 25 fractions were prescribed using tangential fields and 6-MV photons. Six different frequencies of bolus applications (0, 5, 10, 15, 20, and 25) were administered. Cumulative dose-volume histograms were generated for each bolus regimen. The minimum, maximum and mean skin doses associated with the bolus regimens were compared. To test the accuracy of TPS dose calculations, experimental measurements were performed using EBT gafchromic films.
The mean, minimum and maximum skin doses were significantly increased with increasing days of bolus applications (p < 0.001). The minimum skin doses for 0, 5, 10, 15, 20, and 25 days of bolus applications were 73.0% +/- 2.0%, 78.2% +/- 2.0%, 83.3% +/- 1.7%, 88.3% +/- 1.6%, 92.2% +/- 1.7%, and 93.8% +/- 1.8%, respectively. The minimum skin dose increments between 20 and 25 (1.6% +/- 1.0%), and 15 and 20 (4.0% +/- 1.0%) days of bolus applications were significantly lower than the dose increments between 0 and 5 (5.2% +/- 0.6%), 5 and 10 (5.1% +/- 0.8%), and 10 and 15 (4.9% +/- 0.8%) days of bolus applications (p < 0.001). The maximum skin doses for 0, 5, 10, 15, 20, and 25 days of bolus applications were 110.1% +/- 1.1%, 110.3% +/- 1.1%, 110.5% +/- 1.2%, 110.8% +/- 1.3%, 111.2% +/- 1.5%, and 112.2% +/- 1.7%, respectively. The maximum skin dose increments between 20 and 25 (1.0% +/- 0.6%), and 15 and 20 (0.4% +/- 0.3%) days of bolus applications were significantly higher than the dose increments between 0 and 5 (0.2% +/- 0.2%), 5 and 10 (0.2% +/- 0.2%), and 10 and 15 (0.2% +/- 0.2%) days of bolus applications (p < or = 0.003). The TPS overestimated the near-surface dose 10.8% at 2-mm below the skin surface.
In post-mastectomy 3D-CRT, using a 1-cm thick bolus in up to 15 of the total 25 fractions increased minimum skin doses with a tolerable increase in maximum doses.
本研究旨在计算乳房切除术后三维适形放疗（3D-CRT）中不同敷贴频率下胸壁皮肤剂量，并为该临床情况下选择合适的敷贴方案提供详细信息。
使用22例乳房切除术后患者的CT模拟扫描图像。勾勒出临床靶区（CTV）的胸壁以及包含胸壁表面2毫米厚度的皮肤结构体积。使用Precise PLAN 2.11治疗计划系统（TPS）进行3D-CRT计划。采用切线野和6兆伏光子，处方剂量为25次分割照射共50 Gy。给予六种不同的敷贴频率（0、5、10、15、20和25次）。为每种敷贴方案生成累积剂量体积直方图。比较与敷贴方案相关的最小、最大和平均皮肤剂量。为测试TPS剂量计算的准确性，使用EBT变色胶片进行实验测量。
随着敷贴天数增加，平均、最小和最大皮肤剂量显著增加（p < 0.001）。敷贴0、5、10、15、20和25天的最小皮肤剂量分别为73.0%±2.0%、78.2%±2.0%、83.3%±1.7%、88.3%±1.6%、92.2%±1.7%和93.8%±1.8%。敷贴20至25天（1.6%±1.0%）和15至20天（4.0%±1.0%）之间的最小皮肤剂量增量显著低于敷贴0至5天（5.2%±0.6%）、5至10天（5.1%±0.8%）和10至15天（4.9%±0.8%）之间的剂量增量（p < 0.001）。敷贴0、5、10、15、20和25天的最大皮肤剂量分别为110.1%±1.1%、110.3%±1.1%、110.5%±1.2%、110.8%±1.3%、111.2%±1.5%和112.2%±1.7%。敷贴20至25天（1.0%±0.6%）和15至20天（0.4%±0.3%）之间的最大皮肤剂量增量显著高于敷贴0至5天（0.2%±0.2%）、5至10天（0.2%±0.2%）和10至15天（0.2%±0.2%）之间的剂量增量（p≤0.003）。TPS在皮肤表面下方2毫米处高估近表面剂量10.8%。
在乳房切除术后3D-CRT中，在总共25次分割照射中最多15次使用1厘米厚的敷贴可增加最小皮肤剂量，同时最大剂量的增加在可耐受范围内。
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