Characterization of an Iodinated Rectal Spacer for Prostate Photon and Proton Radiation Therapy
Characterization of an Iodinated Rectal Spacer for Prostate Photon and Proton Radiation Therapy
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DOI：
10.1016/j.prro.2021.09.009
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发表时间：
2022-03-02
影响因子：
3.3
通讯作者：
Efstathiou, Jason A.
中科院分区：
文献类型：
--
作者：
Kamran, Sophia C.;McClatchy, David M.;Efstathiou, Jason A.
目的：传统的直肠间隔器（非I-SP）在计算机断层扫描（CT）上的对比度较低，通常需要磁共振成像才能进行准确描绘。一种新的融合器配方（I-SP）包含碘，以改善射线不透性和CT可视化。我们的特点是放置，稳定性和计划质量的I-SPs相比，nonI-SPs.Methods和材料：患者与完整的前列腺癌（n = 50）与I-SPs和光子治疗进行了比较，随机选择的患者（n = 50）与nonI-SPs（光子或质子治疗）。在3个时间点（第一次、中间和最终治疗（n = 200次扫描））在计划CT和锥形束CT上勾画I-SP轮廓。在计划CT上比较每个队列之间的I-SP Hounsfield单位（HU）、体积、表面积（SA）、相对于前列腺质心的质心位置以及前列腺/直肠质心之间的距离。通过锥形束CT评估治疗过程中I-SP的变化。对计划质量和稳健性进行了剂量测定评价。I-SP在体模中进行测试，以表征其对质子的相对线性阻止能力。结果：与非I-SP相比，I-SP在计划CT上产生了明显的可见对比度（HU 138 vs 12，P <0.001），允许单独在CT上描绘。I-SP的勾画体积和SA小于非I-SP（体积8.9 vs 10.6mL，P <0.001; SA 28 vs 35 cm（2），P <0.001），但相对间隔器位置和前列腺-直肠分离相似（P = 0.79）。在治疗过程中，HU、体积、SA或ISPs水凝胶的相对位置没有发生显著变化（所有P > 0.1）。剂量测定分析得出结论，与非I-SP相比，I-SP的计划质量或稳健性没有显著变化。I-SP的相对线性阻止功率为1.018，需要HU覆盖质子planning.Conclusions：I-SP提供了一个明显的CT对比，允许规划CT单独划定没有必要的磁共振成像。I-SP的不透射线性，大小和相对位置保持稳定的治疗过程中，从28至44分。比较I-SP和非I-SP，未观察到计划质量或稳健性发生变化。(C)2021年美国放射肿瘤学会。爱思唯尔公司出版All rights reserved.
Purpose: Conventional rectal spacers (nonI-SPs) are low-contrast on computed tomography (CT), often necessitating magnetic resonance imaging for accurate delineation. A new formulation of spacers (I-SPs) incorporates iodine to improve radiopacity and CT visualization. We characterized placement, stability, and plan quality of I-SPs compared to nonI-SPs.Methods and Materials: Patients with intact prostate cancer (n = 50) treated with I-SPs and photons were compared to randomly selected patients (n = 50) with nonI-SPs (photon or proton therapy). The I-SP was contoured on the planning CT and cone beam CTs at 3 timepoints: first, middle, and final treatment (n = 200 scans). I-SPs Hounsfield units (HU), volume, surface area (SA), centroid position relative to prostate centroid, and distance between prostate/rectum centroids were compared on the planning CTs between each cohort. I-SP changes were evaluated on cone beam CTs over courses of treatment. Dosimetric evaluations of plan quality and robustness were performed. I-SP was tested in a phantom to characterize its relative linear stopping power for protons.Results: I-SPs yielded a distinct visible contrast on planning CTs compared to nonI-SPs (HU 138 vs 12, P < .001), allowing delineation on CT alone. The delineated volume and SA of I-SPs were smaller than nonI-SPs (volume 8.9 vs 10.6mL, P < .001; SA28 vs 35 cm(2), P < .001), yet relative spacer position and prostate-rectal separation were similar (P = .79). No significant change in HU, volume, SA, or relative position of the ISPs hydrogel occurred over courses of treatment (all P > .1). Dosimetric analysis concluded there were no significant changes in plan quality or robustness for I-SPs compared to nonI-SPs. The I-SP relative linear stopping power was 1.018, necessitating HU override for proton planning.Conclusions: I-SPs provide a manifest CT contrast, allowing for delineation on planning CT alone with no magnetic resonance imaging necessary. I-SPs radiopacity, size, and relative position remained stable over courses of treatment from 28 to 44 fractions. No changes in plan quality or robustness were seen comparing I-SPs and nonI-SPs. (C) 2021 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.