Paliwal B R, Ritter M A, McNutt T R, Mackie T R, Thomadsen B R, Purdy J A, Kinsella T J
Department of Medical Physics, University of Wisconsin, Madison, USA.
Int J Radiat Oncol Biol Phys. 1998 Aug 1;42(1):205-11. doi: 10.1016/s0360-3016(98)00187-4.
With increased interest in 3-D conformal radiation therapy and dose escalation, it is necessary to provide advanced techniques to assure quality in treatment delivery. Multi-institutional trials for these newer treatment techniques require methods of verifying the consistency of treatments between the participating institutions. For this reason, a phantom was designed to address the quality and consistency of Radiation Therapy Oncology Group (RTOG) 3-D prostate treatment protocol.
A solid water pelvic and prostate phantom for imaging, volume rendering, treatment planning, and dosimetry applications for performing comprehensive quality assurance has been designed and fabricated. Its configuration was based upon CT slices obtained from a patient study. Individual slices were machined with corresponding contours of the prostate, bladder, rectum, and the left and right femurs. Most of the phantom is made of solid water (Gammex/RMI, Middleton, WI), while the femurs are made of bone-equivalent material. The CT numbers from patient images were used to adjust the solid water composition within the organ volumes, providing image contrast from the remainder of the phantom. Cylindrical insertion grooves are machined in the phantom to allow placement of ionization chambers and thermal luminal dosimeters (TLDs) for dosimetry applications. During imaging, the cavities are filled with rods fabricated from solid water material.
The phantom is being used to evaluate the consistency of a range of processes in radiation therapy simulation, planning, and delivery of 3-D-based treatments for prostate cancer.
The ultimate study objective is to use the phantom to evaluate the accuracy and consistency of treatments delivered by institutions participating in national collaborative clinical trials involving 3-D conformal dose escalation.
随着人们对三维适形放射治疗和剂量递增的兴趣增加，有必要提供先进技术以确保治疗实施的质量。针对这些更新的治疗技术开展的多机构试验需要有方法来验证参与机构之间治疗的一致性。因此，设计了一种体模，以解决放射治疗肿瘤学组（RTOG）三维前列腺治疗方案的质量和一致性问题。
已设计并制造出一种用于成像、容积再现、治疗计划和剂量测定应用的固体水盆腔和前列腺体模，用于进行全面的质量保证。其构造基于从一项患者研究中获得的CT切片。对各个切片进行加工，使其具有前列腺、膀胱、直肠以及左右股骨的相应轮廓。体模的大部分由固体水（Gammex/RMI，威斯康星州米德尔顿）制成，而股骨由等效骨材料制成。利用患者图像中的CT值来调整器官体积内的固体水成分，从而与体模的其余部分形成图像对比度。在体模上加工出圆柱形插入槽，以便放置电离室和热释光剂量仪（TLD）用于剂量测定应用。在成像过程中，这些腔室填充由固体水材料制成的棒。
该体模正用于评估放射治疗模拟、计划以及前列腺癌三维治疗实施等一系列过程的一致性。
最终的研究目标是利用该体模评估参与涉及三维适形剂量递增的国家协作临床试验的机构所实施治疗的准确性和一致性。
