【摘要】 目的:定量分析剂量计算网格尺寸(DCGS)对宫颈癌放疗中物理剂量和生物剂量的影响。方法:选取Pinnacle~3治疗计划系统中宫颈癌的治疗方案12例,取默认值DCGS=4.0 mm的计算网格,优化调整宫颈癌治疗方案,再改变DCGS(1.0～7.0 mm),重新计算靶区和危及器官(OAR)的剂量,探讨靶区和OAR的物理剂量和生物剂量随DCGS的变化情况。结果:靶区和OAR的物理剂量随DCGS的变大而减小,在体积剂量直方图上表现出曲线整体向低剂量区平移。除左右股骨头外,靶区的肿瘤控制概率(TCP)和OAR的正常组织并发症概率(NTCP)也随DCGS增大而缓慢降低。PGTVnd的TCP下降率约为0.7%/mm,PTV的TCP下降率约为0.6%/mm,而膀胱和直肠的NTCP下降速度相对较快,膀胱NTCP下降率最大值为15.0%,直肠NTCP下降率最大值为13.5%。结论:宫颈癌放疗中物理剂量和生物剂量随DCGS变大而减少,靶区和OAR的物理剂量在体积剂量直方图上表现出整体向低剂量区平移,这种变化趋势会诱导研究者低估靶区的TCP及OAR的NTCP。更多还原

【Abstract】 Objective To quantitatively investigate the effects of dose calculation grid size(DCGS) on the physical dose and biological dose in radiotherapy for cervical cancer. Methods Twelve treatment plans of cervical cancer designed in Pinnacle~3 treatment planning system were selected and then optimized with the default DCGS of 4.0 mm. As the DCGS were changed from 1.0 mm to 7.0 mm, the doses of target areas and organs-at-risk(OAR) were recalculated to explore the changes of physical dose and biological dose of target and OAR with different DCGS. Results The physical doses of target areas and OAR were decreased with the increase of DCGS, and the dose-volume curves showed an overall shift to the lower dose region in dose-volume histogram.Except for the NTCP of femoral heads, both the tumor control probability(TCP) of target areas and the normal tissue complication probability(NTCP) of OAR were slowly decreased with the increase of DCGS. The decline rate of TCP of PGTVndwas about 0.7%/mm, and that of TCP of PTV was about 0.6%/mm. However, the decrease rates of NTCP of the bladder and the rectum were relatively faster, and the maximum decrease rate of NTCP was 15.0% for the bladder and 13.5% for the rectum. Conclusion The physical dose and biological dose in radiotherapy for cervical cancer are decreased with the increase of DCGS, and the dose-volume curves of target areas and OAR show an overall shift to the lower dose region in dosevolume histogram, which will induce the underestimations of the TCP of target areas and the NTCP of OAR.更多还原