Increase in Superficial Dose in Whole-Breast Irradiation With Halcyon Straight-Through Linac Compared With Traditional C-arm Linac With Flattening Filter: In vivo Dosimetry and Planning Study
Increase in Superficial Dose in Whole-Breast Irradiation With Halcyon Straight-Through Linac Compared With Traditional C-arm Linac With Flattening Filter: In vivo Dosimetry and Planning Study
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DOI：
10.1016/j.adro.2019.07.011
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发表时间：
2020-01-01
影响因子：
2.3
通讯作者：
Li, Taoran
中科院分区：
文献类型：
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作者：
O'Grady, Fionnbarr;Barsky, Andrew R.;Li, Taoran
目的：乳腺癌放射治疗中，表观剂量是一个重要的参数。当用传统的直线加速器治疗时，通常应用推注来改善表面附近的目标覆盖，同时还管理严重皮肤反应和负面美容的风险。随着引进现代直线加速器与6倍平坦滤波器免费（FFF）光子束，表面剂量的影响和需要团必须evaluated.Methods和材料：在体内测量表面剂量的光激发光剂量计治疗的Halcyon 6倍FFF直线加速器（瓦里安医疗系统，帕洛阿尔托，加利福尼亚州）11例乳腺癌患者。此外，使用Halycon 6X FFF射束和带有平坦滤波器（FF）的6X射束对拟人化体模进行测量。进行了一项计划研究，其中14名在Halcyon上接受治疗的患者使用传统直线加速器重新计划，以确定治疗计划系统预测的表面剂量差异。结果：Halcyon 6X FFF射束的使用导致了比6X FF射束更高的表面剂量。体内测量结果显示平均表面剂量为83.8% +/-0.6%，与已发表的6X FF直线加速器测量结果相比，增加了约10%。体模测量中6X FF和6X FFF射束的表面剂量比较显示从70% +/- 1.3%增加到84% +/-1.3%，这与体内测量结果一致。计划比较显示，与带FF的标准C形臂直线加速器相比，Halcyon 6X FFF射束的浅表乳腺组织的V70% Rx从62% +/- 4.4%增加到81% +/- 2.2%。结论：Halcyon 6X FFF射束的使用与较高的浅表剂量相关，这可能导致团注的使用。(C)2019作者由爱思唯尔公司出版代表美国放射肿瘤学会。
Purpose: Superficial dose is an important parameter in breast cancer radiation therapy. When treated with conventional linacs, bolus is commonly applied to improve target coverage near the surface while also managing the risk of severe skin reactions and negative cosmesis. With the introduction of modern linacs with 6X flattening filter free (FFF) photon beams, the effect on superficial dose and the need for bolus must be evaluated.Methods and Materials: In vivo measurements of superficial dose were made with optically stimulated luminescence dosimeters on 11 breast cancer patients treated with the Halcyon 6X FFF linac (Varian Medical Systems, Palo Alto, CA). Additionally, measurements were made with the Halycon 6X FFF beam and a 6X beam with flattening filter (FF) delivered to an anthropomorphic phantom. A planning study was carried out in which 14 patients treated on the Halcyon were replanned with a conventional linac to determine the difference in superficial dose predicted by the treatment planning system. Measures were taken to increase the accuracy of the treatment planning system superficial dose.Results: The use of the Halcyon 6X FFF beam led to higher superficial dose compared with 6X FF beams. The in vivo measurements show an average superficial dose of 83.8% +/- 0.6%, which is an increase of approximately 10% compared with published measurements for a 6X FF linac. Comparison of superficial dose for 6X FF and 6X FFF beams in the phantom measurements show an increase from 70% +/- 1.3% to 84% +/- 1.3%, which is consistent with the in vivo measurements. The planning comparison shows an increase in V70% Rx from 62% +/- 4.4% to 81% +/- 2.2% for the superficial breast tissue for the Halcyon 6X FFF beam compared with a standard C-arm linac with FF.Conclusions: The use of the Halcyon 6X FFF beam was associated with higher superficial dose which may obviate the use of bolus. (C) 2019 The Authors. Published by Elsevier Inc. on behalf of American Society for Radiation Oncology.