Department of Radiation Oncology, Dalhousie University, Halifax, Canada; Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Canada; Nova Scotia Health Authority, Halifax, Canada.
Nova Scotia Health Authority, Halifax, Canada.
Pract Radiat Oncol. 2018 Jul-Aug;8(4):221-229. doi: 10.1016/j.prro.2017.12.008. Epub 2017 Dec 24.
This patient study evaluated the use of 3-dimensional (3D) printed bolus for chest wall radiation therapy compared with standard sheet bolus with regard to accuracy of fit, surface dose measured in vivo, and efficiency of patient setup. By alternating bolus type over the course of therapy, each patient served as her own control.
For 16 patients undergoing chest wall radiation therapy, a custom 5.0 mm thick bolus was designed based on the treatment planning computed tomography scan and 3D printed using polylactic acid. Cone beam computed tomography scanning was used to image and quantify the accuracy of fit of the 2 bolus types with regard to air gaps between the bolus and skin. As a quality assurance measure for the 3D printed bolus, optically stimulated luminescent dosimetry provided in vivo comparison of surface dose at 7 points on the chest wall. Durations of patient setup and image guidance were recorded and compared.
In 13 of 16 patients, the bolus was printed without user intervention, and the median print time was 12.6 hours. The accuracy of fit of the bolus to the chest wall was improved significantly relative to standard sheet bolus, with the frequency of air gaps 5 mm or greater reduced from 30% to 13% (P < .001) and maximum air gap dimension diminished from 0.5 ± 0.3 to 0.3 ± 0.3 mm on average. Surface dose was within 3% for both standard sheet and 3D printed bolus. On average, the use of 3D printed bolus reduced the setup time from 104 to 76 seconds.
This study demonstrates 3D printed bolus in postmastectomy radiation therapy improves fit of the bolus and reduces patient setup time marginally compared with standard vinyl gel sheet bolus. The time savings on patient setup must be weighed against the considerable time needed for the 3D printing process.
本患者研究评估了与标准片状布块相比，在胸壁放射治疗中使用三维（3D）打印布块在贴合准确性、体内测量的表面剂量和患者摆位效率方面的情况。通过在治疗过程中交替使用布块类型，每位患者自身互为对照。
对 16 例接受胸壁放射治疗的患者，根据治疗计划 CT 扫描设计定制 5.0 毫米厚的布块，并使用聚乳酸进行 3D 打印。使用锥形束 CT 扫描对 2 种布块类型的贴合准确性进行成像和定量，以评估布块与皮肤之间的气隙。作为 3D 打印布块质量保证措施，光激励发光剂量测量提供了 7 个胸壁点的体内表面剂量比较。记录并比较了患者摆位和图像引导的时间。
在 16 例患者中，有 13 例患者的布块在无用户干预的情况下打印，中位打印时间为 12.6 小时。布块贴合胸壁的准确性与标准片状布块相比有显著提高，气隙 5 毫米或更大的频率从 30%降低到 13%（P<.001），最大气隙尺寸从平均 0.5±0.3 毫米减小到 0.3±0.3 毫米。标准片状布块和 3D 打印布块的表面剂量均在 3%以内。平均而言，使用 3D 打印布块可将摆位时间从 104 秒减少到 76 秒。
本研究表明，在乳腺癌根治术后放射治疗中，与标准乙烯基凝胶片状布块相比，3D 打印布块可改善布块贴合度，略微减少患者摆位时间。在患者摆位方面节省的时间必须与 3D 打印过程所需的大量时间相权衡。
