Second Affiliated Hospital of Fujian Medical University, NO 950, Donghai Street, Fengze District, Quanzhou, 362000, Fujian, China.
BMC Cancer. 2021 Apr 9;21(1):384. doi: 10.1186/s12885-021-08119-6.
The dose perturbation effect of immobilization devices is often overlooked in intensity-modulated radiation therapy (IMRT) for breast cancer (BC). This retrospective study assessed the dosimetric effects of supine immobilization devices on the skin using a commercial treatment planning system.
Forty women with BC were divided into four groups according to the type of primary surgery: groups A and B included patients with left and right BC, respectively, who received 50 Gy radiotherapy in 25 fractions after radical mastectomy, while groups C and D included patients with left and right BC, respectively, who received breast-conservation surgery (BCS) and 40.05 Gy in 15 fractions as well as a tumor bed simultaneous integrated boost to 45 Gy. A 0.2-cm thick skin contour and two sets of body contours were outlined for each patient. Dose calculations were conducted for the two sets of contours using the same plan. The dose differences were assessed by comparing the dose-volume histogram parameter results and by plan subtraction.
The supine immobilization devices for BC resulted in significantly increased skin doses, which may ultimately lead to skin toxicity. The mean dose increased by approximately 0.5 and 0.45 Gy in groups A and B after radical mastectomy and by 2.7 and 3.25 Gy in groups C and D after BCS; in groups A-D, the percentages of total normal skin volume receiving equal to or greater than 5 Gy (V) increased by 0.54, 1.15, 2.67, and 1.94%, respectively, while the V increased by 1.27, 1.83, 1.36, and 2.88%; the V by 0.85, 1.87, 2.76, and 4.86%; the V by 1.3, 1.24, 10.58, and 11.91%; and the V by 1.29, 0.65, 10, and 10.51%. The dose encompassing the planning target volume and other organs at risk, showed little distinction between IMRT plans without and with consideration of immobilization devices.
The supine immobilization devices significantly increased the dose to the skin, especially for patients with BCS. Thus, immobilization devices should be included in the external contour to account for dose attenuation and skin dose increment.
This study does not report on interventions in human health care.
在乳腺癌（BC）调强放疗（IMRT）中，常忽略固定装置的剂量干扰效应。本回顾性研究使用商业治疗计划系统评估了仰卧位固定装置对皮肤的剂量学影响。
40 名 BC 女性患者根据主要手术类型分为 4 组：A 组和 B 组分别为接受根治性乳房切除术的左、右侧 BC 患者，接受 50Gy 放疗，共 25 次；C 组和 D 组分别为接受保乳手术（BCS）和 40.05Gy 放疗，共 15 次，肿瘤床同步整合加量至 45Gy 的左、右侧 BC 患者。每位患者分别勾画 0.2cm 厚的皮肤轮廓和两组体廓。使用相同的计划为两组轮廓进行剂量计算。通过比较剂量-体积直方图参数结果和计划减影评估剂量差异。
BC 的仰卧位固定装置导致皮肤剂量显著增加，这可能最终导致皮肤毒性。根治性乳房切除术后，A 组和 B 组的平均剂量分别增加约 0.5 和 0.45Gy，BCS 后 C 组和 D 组分别增加 2.7 和 3.25Gy；A-D 组总正常皮肤体积接受等于或大于 5Gy（V）的百分比分别增加 0.54、1.15、2.67 和 1.94%，V 分别增加 1.27、1.83、1.36 和 2.88%；V 分别增加 1.3、1.24、10.58 和 11.91%；V 分别增加 1.29、0.65、10 和 10.51%。包含计划靶区和其他危及器官的剂量，无和有固定装置的 IMRT 计划之间差异不大。
仰卧位固定装置显著增加了皮肤剂量，特别是对于接受 BCS 的患者。因此，应将固定装置纳入外部轮廓，以考虑剂量衰减和皮肤剂量增加。
本研究未报告对人体保健的干预措施。
