University of Florida Proton Therapy Institute, Jacksonsville, FL, USA.
Int J Radiat Oncol Biol Phys. 2012 May 1;83(1):158-63. doi: 10.1016/j.ijrobp.2011.05.045. Epub 2012 Jan 13.
To determine the potential role for adjuvant proton-based radiotherapy (PT) for resected pancreatic head cancer.
Between June 2008 and November 2008, 8 consecutive patients with resected pancreatic head cancers underwent optimized intensity-modulated radiotherapy (IMRT) treatment planning. IMRT plans used between 10 and 18 fields and delivered 45 Gy to the initial planning target volume (PTV) and a 5.4 Gy boost to a reduced PTV. PTVs were defined according to the Radiation Therapy Oncology Group 9704 radiotherapy guidelines. Ninety-five percent of PTVs received 100% of the target dose and 100% of the PTVs received 95% of the target dose. Normal tissue constraints were as follows: right kidney V18 Gy to <70%; left kidney V18 Gy to <30%; small bowel/stomach V20 Gy to <50%, V45 Gy to <15%, V50 Gy to <10%, and V54 Gy to <5%; liver V30 Gy to <60%; and spinal cord maximum to 46 Gy. Optimized two- to three-field three-dimensional conformal proton plans were retrospectively generated on the same patients. The team generating the proton plans was blinded to the dose distributions achieved by the IMRT plans. The IMRT and proton plans were then compared. A Wilcoxon paired t-test was performed to compare various dosimetric points between the two plans for each patient.
All proton plans met all normal tissue constraints and were isoeffective with the corresponding IMRT plans in terms of PTV coverage. The proton plans offered significantly reduced normal-tissue exposure over the IMRT plans with respect to the following: median small bowel V20 Gy, 15.4% with protons versus 47.0% with IMRT (p = 0.0156); median gastric V20 Gy, 2.3% with protons versus 20.0% with IMRT (p = 0.0313); and median right kidney V18 Gy, 27.3% with protons versus 50.5% with IMRT (p = 0.0156).
By reducing small bowel and stomach exposure, protons have the potential to reduce the acute and late toxicities of postoperative chemoradiation in this setting.
确定辅助质子放疗（PT）在切除的胰头癌中的潜在作用。
2008 年 6 月至 2008 年 11 月，连续 8 例切除的胰头癌患者接受了优化的调强放疗（IMRT）治疗计划。IMRT 计划使用 10 至 18 个射野，初始计划靶区（PTV）给予 45 Gy 剂量，缩小的 PTV 给予 5.4 Gy 的 boost。PTV 根据放射治疗肿瘤学组 9704 放疗指南定义。95%的 PTV 接受了 100%的目标剂量，100%的 PTV 接受了 95%的目标剂量。正常组织约束如下：右侧肾脏 V18 Gy <70%；左侧肾脏 V18 Gy <30%；小肠/胃 V20 Gy <50%，V45 Gy <15%，V50 Gy <10%，V54 Gy <5%；肝脏 V30 Gy <60%；脊髓最大剂量为 46 Gy。在同一患者上回顾性生成了优化的两到三野三维适形质子计划。生成质子计划的团队对 IMRT 计划的剂量分布一无所知。然后对 IMRT 和质子计划进行了比较。对每位患者的两种计划的各种剂量学点进行了 Wilcoxon 配对 t 检验。
所有质子计划均满足所有正常组织约束，并且在 PTV 覆盖方面与相应的 IMRT 计划具有等效性。与 IMRT 计划相比，质子计划在以下方面显著降低了正常组织的暴露：小肠 V20 Gy 的中位数，质子治疗为 15.4%，IMRT 治疗为 47.0%（p = 0.0156）；胃 V20 Gy 的中位数，质子治疗为 2.3%，IMRT 治疗为 20.0%（p = 0.0313）；右肾 V18 Gy 的中位数，质子治疗为 27.3%，IMRT 治疗为 50.5%（p = 0.0156）。
通过降低小肠和胃的暴露，质子治疗有可能降低该情况下术后放化疗的急性和迟发性毒性。
