Giacometti Valentina, King Raymond B, McCreery Craig, Buchanan Fraser, Jeevanandam Prakash, Jain Suneil, Hounsell Alan R, McGarry Conor K
Patrick G. Johnston Centre for Cancer Research, Queen's University, Belfast, United Kingdom.
Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, United Kingdom.
Phys Med. 2021 Nov 22;92:8-14. doi: 10.1016/j.ejmp.2021.10.018.
Developing and assessing the feasibility of using a three-dimensional (3D) printed patient-specific anthropomorphic pelvis phantom for dose calculation and verification for stereotactic ablative radiation therapy (SABR) with dose escalation to the dominant intraprostatic lesions.
A 3D-printed pelvis phantom, including bone-mimicking material, was fabricated based on the computed tomography (CT) images of a prostate cancer patient. To compare the extent to which patient and phantom body and bones overlapped, the similarity Dice coefficient was calculated. Modular cylindrical inserts were created to encapsulate radiochromic films and ionization chamber for absolute dosimetry measurements at the location of prostate and at the boost region. Gamma analysis evaluation with 2%/2mm criteria was performed to compare treatment planning system calculations and measured dose when delivering a 10 flattening filter free (FFF) SABR plan and a 10FFF boost SABR plan.
Dice coefficients of 0.98 and 0.91 were measured for body and bones, respectively, demonstrating agreement between patient and phantom outlines. For the boost plans the gamma analysis yielded 97.0% of pixels passing 2%/2mm criteria and these results were supported by the chamber average dose difference of 0.47 ± 0.03%. These results were further improved when overriding the bone relative electron density: 97.3% for the 2%/2mm gamma analysis, and 0.05 ± 0.03% for the ionization chamber average dose difference.
The modular patient-specific 3D-printed pelvis phantom has proven to be a highly attractive and versatile tool to validate prostate SABR boost plans using multiple detectors.
开发并评估使用三维（3D）打印的患者特异性拟人化骨盆体模进行剂量计算和验证的可行性，用于立体定向消融放疗（SABR）并增加对前列腺内主要病灶的剂量。
基于一名前列腺癌患者的计算机断层扫描（CT）图像制作了一个包含仿骨材料的3D打印骨盆体模。为了比较患者与体模的身体和骨骼重叠程度，计算了相似性Dice系数。制作了模块化圆柱形插入物，用于封装放射变色胶片和电离室，以便在前列腺位置和增敏区域进行绝对剂量测量。在实施10兆伏无均整器（FFF）SABR计划和10FFF增敏SABR计划时，采用2%/2毫米标准进行伽马分析评估，以比较治疗计划系统的计算结果和测量剂量。
身体和骨骼的Dice系数分别为0.98和0.91，表明患者与体模轮廓相符。对于增敏计划，伽马分析显示97.0%的像素通过2%/2毫米标准，电离室平均剂量差异为0.47±0.03%，这些结果支持了上述结论。当忽略骨相对电子密度时，这些结果进一步得到改善：2%/2毫米伽马分析为97.3%，电离室平均剂量差异为0.05±0.03%。
模块化的患者特异性3D打印骨盆体模已被证明是一种极具吸引力且用途广泛的工具，可使用多个探测器来验证前列腺SABR增敏计划。
