With the availability of MRI linacs, online adaptive intensity modulated radiotherapy (IMRT) has become a treatment option for liver cancer patients, often combined with hypofractionation. Intensity modulated proton therapy (IMPT) has the potential to reduce the dose to healthy tissue, but it is particularly sensitive to changes in the beam path and might therefore benefit from online adaptation. This study compares the normal tissue complication probabilities (NTCPs) for liver and duodenal toxicity for adaptive and non-adaptive IMRT and IMPT treatments of liver cancer patients. Adaptive and non-adaptive IMRT and IMPT plans were optimized to 50 Gy (RBE = 1.1 for IMPT) in five fractions for 10 liver cancer patients, using the original MRI linac images and physician-drawn structures. Three liver NTCP models were used to predict radiation-induced liver disease, an increase in albumin-bilirubin level, and a Child–Pugh score increase of more than 2. Additionally, three duodenal NTCP models were used to predict gastric bleeding, gastrointestinal (GI) toxicity with grades >3, and duodenal toxicity grades 2–4. NTCPs were calculated for adaptive and non-adaptive IMRT and IMPT treatments. In general, IMRT showed higher NTCP values than IMPT and the differences were often significant. However, the differences between adaptive and non-adaptive treatment schemes were not significant, indicating that the NTCP benefit of adaptive treatment regimens is expected to be smaller than the expected difference between IMRT and IMPT.
随着磁共振直线加速器的应用，在线自适应调强放疗已成为肝癌患者的治疗选择，常与大分割方案联合使用。调强质子治疗具有降低正常组织受照剂量的潜力，但其对射束路径变化尤为敏感，因此可能受益于在线自适应技术。本研究比较了肝癌患者接受自适应与非自适应调强放疗及调强质子治疗后，肝脏与十二指肠毒性的正常组织并发症发生概率。基于10例肝癌患者的原始磁共振加速器影像及医师勾画结构，分别设计五分割50 Gy（调强质子治疗采用相对生物学效应值1.1）的自适应与非自适应调强放疗及调强质子治疗计划。采用三种肝脏正常组织并发症概率模型预测放射性肝病、白蛋白-胆红素水平升高及Child-Pugh评分增加超过2分的情况；同时采用三种十二指肠正常组织并发症概率模型预测胃出血、3级以上胃肠道毒性及2-4级十二指肠毒性。计算结果显示，调强放疗的正常组织并发症概率普遍高于调强质子治疗，且差异多具统计学意义。然而自适应与非自适应治疗方案间的差异并不显著，表明自适应治疗方案在降低正常组织并发症概率方面的获益预期小于调强放疗与调强质子治疗间的差异。
肿瘤(癌症)患者之家