Department of Radiation Oncology, Loyola University Medical Center, Maywood, IL, 60637 USA.
Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardine Cancer Center, Loyola University Chicago, Maywood, IL, 60637 USA.
Med Dosim. 2021;46(3):e10-e14. doi: 10.1016/j.meddos.2021.01.001. Epub 2021 Jan 31.
We investigated skin dose enhancements of brass mesh bolus (BMB) and a recently developed transparent polymer-gel bolus (PGB) for clinically relevant breast treatment delivery techniques. The dose enhancement of the breast surface with BMB and PGB were compared to that of tissue-equivalent bolus. Three breast treatment plans were generated on CT scans of an anthropomorphic chest phantom: tangential step-and-shoot 3D conformal (3DCRT) planned using Field-in-Field (FiF), tangential sliding-window 3DCRT using Electronic Compensator (EC), and volumetric modulated arc therapy (VMAT). All plans were created using 6 MV photons and a prescription dose (Rx) of 180 cGy per fraction. Skin doses of all 3 plans were measured with radiochromic films, separately delivered in triplicate. Each plan was delivered to the phantom without bolus, and then with BMB (1 or 2 layers; 3 or 10 mm tissue-equivalent), PGB, and Superflab (3, 5, and 10 mm tissue-equivalent). Doses were determined by reading the radiochromic films with a flatbed scanner, and analyzing the images using a calibration curve for each specific batch. For all bolus types and plans, surface doses averaged over the 3 measurements were between 88.4% and 107.4% of Rx. Without bolus, average measured skin doses were between 51.2% and 64.2% of Rx. Skin doses with BMB and PGB were comparable to that with tissue-equivalent bolus. Over all 3 treatment delivery techniques, using BMB resulted in average skin doses of 92.8% and 102.1% for 1- and 2 layers, respectively, and using PGB results in average skin doses of 94.8%, 98.2%, and 99.7% for 3, 5, and 10-mm tissue-equivalent, respectively. The average measured skin doses with BMB and PGB agreed within ± 3% compared to the tissue-equivalent thickness bolus. We concluded that BMB and PGB are clinically equivalent in skin dose enhancement for breast treatment as the 3, 5, and 10 mm tissue-equivalent bolus.
我们研究了 brass mesh bolus（BMB）和最近开发的透明聚合物凝胶 bolus（PGB）在临床相关乳房治疗中的表面剂量增强效果。比较了 BMB 和 PGB 与组织等效 bolus 在乳房表面的剂量增强效果。在人体胸部模体的 CT 扫描上生成了三种乳房治疗计划：使用 Field-in-Field（FiF）的切线步进式 3D 适形（3DCRT）计划、使用电子补偿器（EC）的切线滑动窗口 3DCRT 计划和容积调强弧形治疗（VMAT）计划。所有计划均使用 6 MV 光子和 180 cGy/分次的处方剂量（Rx）创建。使用 radiochromic films 分别独立重复测量三次来测量所有 3 种计划的皮肤剂量。没有 bolus 的情况下，将每个计划单独输送到模体，然后使用 BMB（1 或 2 层；3 或 10 mm 组织等效）、PGB 和 Superflab（3、5 和 10 mm 组织等效）。使用特定批次的校准曲线，通过平板扫描仪读取 radiochromic films 并分析图像来确定剂量。对于所有 bolus 类型和计划，三次测量的平均表面剂量均为 Rx 的 88.4%至 107.4%之间。没有 bolus 的情况下，平均测量的皮肤剂量在 Rx 的 51.2%至 64.2%之间。BMB 和 PGB 的皮肤剂量与组织等效 bolus 相当。在所有 3 种治疗输送技术中，使用 BMB 分别导致 1 层和 2 层的平均皮肤剂量为 92.8%和 102.1%，而使用 PGB 则分别导致 3、5 和 10-mm 组织等效的平均皮肤剂量为 94.8%、98.2%和 99.7%。与组织等效厚度 bolus 相比，BMB 和 PGB 的平均测量皮肤剂量相差在±3%以内。我们得出结论，BMB 和 PGB 在乳房治疗中的皮肤剂量增强效果与 3、5 和 10mm 组织等效 bolus 临床等效。
