Kawahara Daisuke, Ozawa Shuichi, Kimura Tomoki, Saito Akito, Nishio Teiji, Nakashima Takeo, Ohno Yoshimi, Murakami Yuji, Nagata Yasushi
Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
J Radiat Res. 2017 Jan;58(1):149-154. doi: 10.1093/jrr/rrw096. Epub 2016 Oct 19.
A new randomized Phase III trial, the Japan Clinical Oncology Group (JCOG) 1408, which compares two dose fractionations (JCOG 0403 and JCOG 0702) for medically inoperable Stage IA NSCLC or small lung lesions clinically diagnosed as primary lung cancer, involves the introduction of a prescribed dose to the D of the planning target volume (PTV) using a superposition/convolution algorithm. Therefore, we must determine the prescribed dose in the D prescribing method to begin JCOG1408. JCOG 0702 uses density correction and the D prescribing method. However, JCOG 0403 uses no density correction and isocenter- prescribing method. The purpose of this study was to evaluate the prescribed dose to the D of the PTV equivalent to a dose of 48 Gy to the isocenter (JCOG 0403) using a superposition algorithm. The peripheral isodose line, which has the highest conformity index, and the D of the PTV were analyzed by considering the weighting factor, i.e. the inverse of the difference between the doses obtained using the superposition and Clarkson algorithms. The average dose at the isodose line of the highest conformity index and the D of the PTV were 41.5 ± 0.3 and 42.0 ± 0.3 Gy, respectively. The D of the PTV had a small correlation with the target volume (r = 0.0022) and with the distance between the scatterer and tumor volumes (r = 0.19). Thus, the prescribed dose of 48 Gy using the Clarkson algorithm (JCOG0403) was found to be equivalent to the prescribed dose of 42 Gy to the D of the PTV using the superposition algorithm.
一项新的随机III期试验——日本临床肿瘤学组（JCOG）1408，比较了两种剂量分割方案（JCOG 0403和JCOG 0702）用于医学上无法手术的IA期非小细胞肺癌或临床诊断为原发性肺癌的小肺病变，该试验涉及使用叠加/卷积算法将处方剂量引入计划靶体积（PTV）的D。因此，我们必须确定D处方方法中的处方剂量以启动JCOG1408。JCOG 0702使用密度校正和D处方方法。然而，JCOG 0403不使用密度校正，而是采用等中心处方方法。本研究的目的是使用叠加算法评估与等中心剂量48 Gy（JCOG 0403）等效的PTV的D的处方剂量。通过考虑加权因子，即使用叠加算法和克拉克森算法获得的剂量之差的倒数，分析了具有最高适形指数的外周等剂量线和PTV的D。最高适形指数的等剂量线处的平均剂量和PTV的D分别为41.5±0.3和42.0±0.3 Gy。PTV的D与靶体积（r = 0.0022）以及散射体与肿瘤体积之间的距离（r = 0.19）的相关性较小。因此，发现使用克拉克森算法（JCOG0403）的48 Gy处方剂量与使用叠加算法的PTV的D的42 Gy处方剂量等效。
