Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage, Chiba, Japan.
J Radiat Res. 2011;52(1):69-74. doi: 10.1269/jrr.10066. Epub 2010 Dec 24.
The purpose of this work is to retrospectively analyze the effect of the inhomogeneity correction using clinically treated plan of stage III non-small-cell lung cancer within multiple institutions in Japan. Twenty-five patients among five facilities of radiation therapy were registered for this study. The isocenter dose or D(95) of PTV or other important values were compared with and without an inhomogeneity correction using model-based algorithm. The differences in isocenter dose were 4% average and 10% maximum for the first Anterior-Posterior opposed field plan to 40 Gy and 6% average and 11% maximum for the off-cord boost oblique field plan of 20 Gy. The differences in D(95) dose were 1% average and 9% maximum for the first plan and 1% average and 6% maximum for the boost plan. D(95) prescription seemed to be a superior method; however, its reliability depends on each clinical case. Additionally, maximum dose, minimum dose and mean dose for both the primary tumor and the metastatic lymph node were analyzed, and the minimum dose had the most impressive results. In some cases, the target volume had unintended underdose of more than 10%. Finally, an analysis of the organ at risk was added, and this showed no meaningful differences for the V(20) of the lung and the maximum dose of the spinal cord. These results provide a standard for the effects of the inhomogeneity correction.
本研究旨在回顾性分析日本多家医疗机构采用临床治疗计划对 III 期非小细胞肺癌进行不均匀性校正的效果。本研究共纳入 5 家放疗机构的 25 名患者。采用基于模型的算法，比较了校正前后 PTV 等重要靶区的等中心剂量或 D95 值与未校正时的差异。对于 40 Gy 的一前一后对置野首程计划，校正前后的等中心剂量差异平均为 4%，最大为 10%；对于 20 Gy 偏角楔形野的补充照射野计划，校正前后的等中心剂量差异平均为 6%，最大为 11%。对于首程计划，校正前后的 D95 剂量差异平均为 1%，最大为 9%；对于补充照射野计划，校正前后的 D95 剂量差异平均为 1%，最大为 6%。D95 处方似乎是一种更好的方法，但它的可靠性取决于每个临床病例。此外，还对原发肿瘤和转移淋巴结的最大、最小和平均剂量进行了分析，最小剂量的结果最为显著。在某些情况下，靶区的剂量不足 10%。最后，还对危及器官进行了分析，结果显示肺部 V20 和脊髓最大剂量无明显差异。这些结果为不均匀性校正的效果提供了标准。
