Moreno Amy C, Gunther Jillian R, Milgrom Sarah, Fuller C David, Williamson Tyler, Liu Amy, Wu Richard, Zhu X Ronald, Dabaja Bouthaina S, Pinnix Chelsea C
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Department of Radiation Oncology at the University of Colorado, Denver, Colorado.
Adv Radiat Oncol. 2020 Aug 25;5(6):1255-1266. doi: 10.1016/j.adro.2020.08.004. eCollection 2020 Nov-Dec.
Intensity modulated radiation therapy delivered with deep-inspiration breath hold (IMRT-BH) provides favorable normal tissue dosimetric profiles when treating patients with mediastinal lymphoma. However, it is unclear if IMRT-BH plans are comparable to free breathing (FB) proton plans. We performed a retrospective, comparative dosimetric study between IMRT-BH and FB passive scatter proton therapy (P-FB) or intensity modulated proton therapy (IMPT-FB). Hypothesizing that BH would provide superior normal tissue sparing when added to proton therapy, we also compared plans to passive scatter BH (P-BH).
For 15 patients who received involved-site RT with "butterfly" IMRT-BH, 3 additional proton plans (P-FB, IMPT-FB, P-BH) were optimized to deliver 30.6 Gy/Gy relative biological effectiveness. Dosimetric variables (mean dose, V30, V25, V15, and V5) for organs at risk (OARs) were calculated and compared using nonparametric Wilcoxon signed-rank tests.
Of 57 studied OAR parameters, IMRT-BH plans were comparable in 37 (65%) parameters with P-FB plans, 32 (56%) of IMPT-FB parameters, and 30 (53%) of P-BH parameters. Doses to breasts were generally equivalent among plans while esophageal dosing was worse with IMRT-BH. Mean doses and V5 of the total lung and heart were the highest with IMRT-BH; however, IMRT-BH resulted in comparable coronary and superior lung V30 relative to proton plans. The addition of BH with proton therapy resulted in the greatest lung sparing, with mean lung dose reductions of 11% to 38%.
The use of BH with IMRT reduces the disparity in OAR doses with equivalence achieved in nearly two-thirds of OAR metrics compared with P-FB and 50% compared with IMPT-BH. Because each modality exhibited unique benefits, personalization of modality selection is recommended. Proton therapy via BH provides additional benefits in heart and lung sparing.
在治疗纵隔淋巴瘤患者时，采用深吸气屏气技术的调强放射治疗（IMRT - BH）能提供良好的正常组织剂量分布。然而，IMRT - BH计划是否与自由呼吸（FB）质子计划相当尚不清楚。我们对IMRT - BH与FB被动散射质子治疗（P - FB）或调强质子治疗（IMPT - FB）进行了一项回顾性、比较剂量学研究。假设屏气技术在质子治疗中能提供更好的正常组织保护，我们还将这些计划与被动散射屏气（P - BH）计划进行了比较。
对于15例接受“蝴蝶”IMRT - BH累及野放疗的患者，另外优化了3个质子计划（P - FB、IMPT - FB、P - BH），以给予30.6 Gy/相对生物效应剂量（Gy）。使用非参数Wilcoxon符号秩检验计算并比较危及器官（OARs）的剂量学变量（平均剂量、V30、V25、V15和V5）。
在57个研究的OAR参数中，IMRT - BH计划在37个（65%）参数上与P - FB计划相当，在32个（56%）IMPT - FB参数上相当，在30个（53%）P - BH参数上相当。各计划中乳房的剂量总体相当，而IMRT - BH的食管剂量更高。IMRT - BH的全肺和心脏平均剂量及V5最高；然而，相对于质子计划，IMRT - BH的冠状动脉剂量相当，肺V30更好。质子治疗中加入屏气技术能最大程度地保护肺，平均肺剂量降低11%至38%。
与P - FB相比，IMRT联合屏气技术使用减少了OAR剂量差异，在近三分之二的OAR指标上实现了等效，与IMPT - BH相比为50%。由于每种治疗方式都有独特的优势，建议根据个体情况选择治疗方式。屏气技术的质子治疗在保护心脏和肺方面有额外的益处。
