Wootton Landon, Kudchadker Rajat, Lee Andrew, Beddar Sam
Department of Radiation Physics, The University of Texas M D Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX, USA.
Phys Med Biol. 2014 Feb 7;59(3):647-60. doi: 10.1088/0031-9155/59/3/647. Epub 2014 Jan 17.
We designed and constructed an in vivo dosimetry system using plastic scintillation detectors (PSDs) to monitor dose to the rectal wall in patients undergoing intensity-modulated radiation therapy for prostate cancer. Five patients were enrolled in an Institutional Review Board-approved protocol for twice weekly in vivo dose monitoring with our system, resulting in a total of 142 in vivo dose measurements. PSDs were attached to the surface of endorectal balloons used for prostate immobilization to place the PSDs in contact with the rectal wall. Absorbed dose was measured in real time and the total measured dose was compared with the dose calculated by the treatment planning system on the daily computed tomographic image dataset. The mean difference between measured and calculated doses for the entire patient population was -0.4% (standard deviation 2.8%). The mean difference between daily measured and calculated doses for each patient ranged from -3.3% to 3.3% (standard deviation ranged from 5.6% to 7.1% for four patients and was 14.0% for the last, for whom optimal positioning of the detector was difficult owing to the patient's large size). Patients tolerated the detectors well and the treatment workflow was not compromised. Overall, PSDs performed well as in vivo dosimeters, providing excellent accuracy, real-time measurement and reusability.
我们设计并构建了一种使用塑料闪烁探测器（PSD）的体内剂量测定系统，用于监测接受前列腺癌调强放射治疗患者直肠壁的剂量。五名患者参加了一项经机构审查委员会批准的方案，使用我们的系统每周进行两次体内剂量监测，共进行了142次体内剂量测量。PSD附着在用于前列腺固定的直肠内气囊表面，使PSD与直肠壁接触。实时测量吸收剂量，并将总测量剂量与治疗计划系统根据每日计算机断层扫描图像数据集计算的剂量进行比较。整个人群测量剂量与计算剂量之间的平均差异为-0.4%（标准差2.8%）。每位患者每日测量剂量与计算剂量之间的平均差异范围为-3.3%至3.3%（四名患者的标准差范围为5.6%至7.1%，最后一名患者的标准差为14.0%，因其体型较大，探测器难以实现最佳定位）。患者对探测器耐受性良好，治疗流程未受影响。总体而言，PSD作为体内剂量计表现良好，具有出色的准确性、实时测量能力和可重复使用性。
