Meeting dose prescription is critical to control tumors in radiation therapy. Interfraction dose variations (IDVs) from the prescribed dose in high dose rate brachytherapy (HDR) would cause the target dose to deviate from the prescription but their clinical effect has not been widely discussed in the literature. Our previous study found that IDVs followed a left-skewed distribution. The clinical effect of the IDVs in 100 cervical cancer HDR patients will be addressed in this paper. An in-house Monte Carlo (MC) program was used to simulate clinical outcomes by convolving published tumor dose response curves with IDV distributions. The optimal dose and probability of risk-free local control (RFLC) were calculated using the utility model. The IDVs were well-fitted by the left-skewed Beta distribution, which caused a 3.99% decrease in local control probability and a 1.80% increase in treatment failure. Utility with respect to IDV uncertainty increased the RFLC probability by 6.70% and predicted an optimal dose range of 83 Gy–91 Gy EQD2. It was also found that a 10 Gy dose escalation would not affect toxicity. In conclusion, HRCTV IDV uncertainty reduced LC probabilities and increased treatment failure rates. A dose escalation may help mitigate such effects.
在放射治疗中，达到处方剂量对于控制肿瘤至关重要。高剂量率近距离放射治疗（HDR）中分次间剂量变化（IDVs）会导致靶区剂量偏离处方剂量，但其临床效应在文献中尚未得到广泛讨论。我们先前的研究发现IDVs呈左偏分布。本文旨在探讨100例宫颈癌HDR患者中IDVs的临床效应。通过将已发表的肿瘤剂量反应曲线与IDV分布进行卷积，采用自主研发的蒙特卡洛（MC）程序模拟临床结果。利用效用模型计算了无风险局部控制（RFLC）的最佳剂量和概率。IDVs能够很好地拟合为左偏Beta分布，该分布导致局部控制概率下降3.99%，治疗失败率增加1.80%。考虑IDV不确定性的效用模型使RFLC概率提高6.70%，并预测最佳剂量范围为83 Gy–91 Gy EQD2。研究还发现，10 Gy的剂量提升不会影响毒性反应。综上所述，HRCTV的IDV不确定性会降低局部控制概率并增加治疗失败率，而剂量提升可能有助于缓解这种影响。
肿瘤(癌症)患者之家