胸上段食管癌调强放疗两种优化算法的剂量学比较研究

Study on Two Optimization Algorithms for the Dosimetric of Upper Thoracic Esophageal Carcinoma in IMRT

摘要: 目的：探讨并行优化(parallel optimization, PO)算法在胸上段食管癌调强放射治疗中的剂量学优势。方法：随机选取15例已接受调强放射治疗的胸上段食管癌病例，其治疗计划均基于剂量–体积(dose-volume, DV)优化方法得到，将治疗计划中肺的优化方法改为PO优化，保持其他优化条件不变，重新优化该治疗计划。比较新旧治疗计划的剂量学差异。结果：两组治疗计划均能满足临床要求，PO优化比DV优化对靶区均匀性好(0.07 ± 0.02 : 0.07 ± 0.01, t = 4.14, p = 0.001)，对危及器官PO优化明显降低了全肺V5、V10、V20、V30、V40、V50和Dmean (P < 0.05)，心脏D33和Dmean受量PO优化较DV优化高(P < 0.05)，脊髓受量两组计划无统计学差异(P > 0.05)。结论：胸上段食管癌调强放疗运用PO优化能有效降低全肺受照剂量，不仅能降低发生放射治疗并发症的概率，同时也为进一步提高肿瘤靶区剂量预留了空间，为提高肿瘤局部控制率提供了可能。

Abstract: Objective: To investigate the dosimetric advantage of the parallel optimization (PO) algorithm on upper thoracic esophageal carcinoma in IMRT. Methods: 15 upper thoracic esophageal carcinoma cases were randomly selected which had accepted IMRT and their treatment plans were based on the dose-volume optimization method. Keeping the other optimization conditions unchanged, re-optimizing the treatment plan after changing the optimization method of the lung to PO and comparing the dosimetric difference between old and new treatment plans. Results: Two groups of treatment plans can meet the clinical requirements. PO is better than dose-volume optimization on the uniformity of target (0.07 ± 0.02: 0.07 ± 0.01, t = 4.14, p = 0.001). For organ at risk, PO sig-nificantly reduces V5, V10, V20, V30, V40, V50 and Dmean (P < 0.05) of whole lung, D33 and Dmean of heart optimized with PO are higher than dose-volume optimization(P < 0.05), and dose of the spinal cord has no statistical difference between two groups of plans(P > 0.05). Conclusion: Esophageal cancer optimized by PO can effectively reduce the dose of whole lung in IMRT, not only to reduce the probability of radiotherapy complications, but also to reserve space to further im-prove the dose of tumor target. So it provides the possibility to improve local tumor control rate.