University of Utah.
J Appl Clin Med Phys. 2011 May 22;12(3):3516. doi: 10.1120/jacmp.v12i3.3516.
This study investigates the dosimetric benefits of designing patient-specific margins for prostate cancer patients based on 4D localization and tracking. Ten prostate patients, each implanted with three radiofrequency transponders, were localized and tracked for 40 fractions. "Conventional margin" (CM) planning target volumes (PTV) and PTVs resulting from uniform margins of 5 mm (5M) and 7 mm (7M) were explored. Through retrospective review of each patient's tracking data, an individualized margin (IM) design for each patient was determined. IMRT treatment plans with identical constraints were generated for all four margin strategies and compared. The IM plans generally created the smallest PTV volumes. For similar PTV coverage, the IM plans had a lower mean bladder (rectal) dose by an average of 3.9% (2.5%), 8.5% (5.7%) and 16.2 % (9.8%) compared to 5M, 7M and CM plans, respectively. The IM plan had the lowest gEUD value of 23.8 Gy for bladder, compared to 35.1, 28.4 and 25.7, for CM, 7M and 5M, respectively. Likewise, the IM plan had the lowest NTCP value for rectum of 0.04, compared to 0.07, 0.06 and 0.05 for CM, 7M and 5M, respectively. Individualized margins can lead to significantly reduced PTV volumes and critical structure doses, while still ensuring a minimum delivered CTV dose equal to 95% of the prescribed dose.
本研究旨在探讨基于 4D 定位和跟踪设计前列腺癌患者个体化边缘的剂量学优势。对十位植入三个射频应答器的前列腺癌患者进行了 40 次分割的定位和跟踪。分别探讨了常规边缘（CM）计划靶区（PTV）和 5mm（5M）和 7mm（7M）均匀边缘的 PTV。通过回顾每位患者的跟踪数据，为每位患者确定了个体化边缘（IM）设计。对所有四种边缘策略生成了具有相同约束的 IMRT 治疗计划，并进行了比较。IM 计划通常会创建最小的 PTV 体积。对于相似的 PTV 覆盖，IM 计划的平均膀胱（直肠）剂量分别比 5M、7M 和 CM 计划低 3.9%（2.5%）、8.5%（5.7%）和 16.2%（9.8%）。与 CM、7M 和 5M 计划相比，IM 计划的膀胱 gEUD 值最低，为 23.8Gy。同样，IM 计划的直肠 NTCP 值最低，为 0.04，而 CM、7M 和 5M 计划分别为 0.07、0.06 和 0.05。个体化边缘可以显著降低 PTV 体积和危及器官剂量，同时仍能确保 CTV 剂量达到处方剂量的 95%。
