质子束在肝细胞肝癌治疗中的剂量分布

Dose distributions of proton beam therapy for hepotacellular carcinoma： a comparative study of treatment planning with 3D-conformal radiation therapy or intensity-modulated radiation therapy

目的对质子束治疗（PBT）与x线三维适形放射治疗（3D—CRT）及调强放射治疗（IMRT）在肝细胞肝癌患者治疗时的剂量分布进行对比研究，以评价PBT的潜在优势。方法选用Ⅰ期肝癌患者10例（肿瘤直径≤5．0om），总剂量为66Gy和86Gy，ⅡA期肝癌患者12例（肿瘤直径5．1～10．0cm），总剂量为60Gy和72Gy，分别设计3D—CRT、IMRT和PBT治疗计划，通过剂量体积直方图（DVH）比较其正常肝脏和危及器官（OARs）的剂量分布差异。结果Ⅰ期肝癌患者3D—CRT的总剂量为66Gy时，其肝脏平均剂量（Dmean）为13．01Gy，其V10、V20和V30分别为51．89％、36．13％和21．24％，而PBT总剂量为66Gy时，其Dmean、V10、V20和V30则分别为6．34Gy、30．23％、17．86％和10，66％（P〈0．002）。当总剂量提高至86Gy时，3D—CRT的Dmean、V10、V20和V30分别为16．91Gy、67．51％、46．84％和27．61％；而PBT的Dmean、V10、V20和V30则分别为8．26Gy、39．31％、23．22％和13．86％（P〈0．002）。与3D-CRT总剂量为66Gy时相比，PBT在总剂量提升至86Gy时，其Dmean、V10、V20和V30仍明显低于3D—CRT（P〈0．042）。ⅡA期患者3D—CRT总剂量为60Gy时，其Dmean、V10、V20和V30分别为29．18Gy、72．25％、58．17％和44．01％；IMRT的Dmean、V10、V20和V30分别为24．92Gy、73．32％、56．15％和37．75％，而PBT则分别为16．28Gy、43．93％、33．54％和22．78％（P〈0．002）。当总剂量提高至72Gy时，3D-CRT的Dmean、V10、V20和V30分别为35．02Gy、86．70％、69．80％和52．8l％；IMRT的Dmean、V10、V20和V30分别为29．90Gy，87．98％，67．74％and45．30％，而PBT的Dmean、V10、V20和V30分别为19．54Gy、52．72％、40．25％和27．34％（P〈0．002）。与3D—CRT总剂量为60Gy时相比，PBT在总剂量提升至72Gy时，其Dmean、V10、V20和V30仍明显低于3D—CRT和IMRT（P〈0．05）。22例患者采用PBT可使肝外OARs（脊髓、右侧。肾脏和胃）的照射剂量明显低于3D—CRT（P〈0．002）。与IMRT相比，PBT降低了右侧肾脏和胃的受量（P〈0．05），脊髓的受量两者差异无统计学意义（P〉0．05）。结论与3D—CRT相比，PBT可使肝脏的平均剂量和肝外OARs的照射剂量明显降低。当PBT的总剂量较3D—CRT提升20．0％-30．3％时，其肝脏的平均剂量仍明显低于3D—CRT。与IMRT相比，PBT使ⅡA期患者的Dmean、V10、V20、V30、右侧肾脏和胃的受量明显降低，脊髓的受量两者无显著性差异。

Objective A comparative dose distribution study has been undertaken between proton beam therapy （PBT）, 3-dimensional conformal radiation therapy （3D-CRT） and intensity-modulated radiation therapy（IMRT） in the treatment of hepatocellular carcinoma（ HCC）, so as to assess the potential advantages of PBT. Methods Dose volume histograms（DVHs） were compared between PBT and 3D-CRT or IMRT planning at total dose of 66 Gy and 86 Gy in stage I patients （n = 10, diameter ≤5 cm） , 60 Gy and 72 Gy in stage II A patients （n = 12, diameter = 5.1-10 cm）. Results For patients with stage I , the mean liver dose（ Dmean）, V10, V20 and V30 were 13.01 Gy, 51.89%, 36. 13% and 21.24% for 3D- CRT,whereas they were 6. 34 Gy, 30. 23% , 17.86% and 10. 66% , respectively, for PBT （ P 〈 0. 002）.With dose escalation to 86 Gy, the Dmean, V10,V20 and V30 were 16.91 Gy,67.51% ,46.84% and 27.61% for 3D-CRT, whereas they were 8.26 Gy, 39. 31% , 23.22% and 13.86% , respectively, for PBT （P 〈0. 002）. Compared with 3D-CRT with dose of 66 Gy, PBT reduced the Dmean, V10, V20 and V30 even with dose escalation to 86 Gy（P 〈0. 042）. For patients with stage Ⅱ A, the Dmean, V10,V20 and V30 were 29. 18 Gy, 72. 25%, 58. 17% , 44.01% and 24. 92 Gy, 73.32%, 56. 15%, 37. 75% for 3D- CRT and IMRT, respectively, with dose of 60 Gy, whereas they were 16. 28 Gy, 43.93% ,33.54% and 22. 78%, respectively, for PBT（ P 〈 0. 002）. With dose escalation to 72 Gy, the Dmean, V10, V20, V30 were 35. 02 Gy, 86. 70%, 69. 80%, 52. 81% and 29. 90 Gy, 87.98%, 67.74% and 45. 30% for 3D-CRT and IMRT, respectively, whereas they were 19. 54 Gy, 52.72%, 40. 25% and 27. 34% , respectively, for PBT （P 〈 0. 002）. Compared with 3D-CRT and IMRT with total dose of 60 Gy, PBT reduced the Dmean, V10,V20 and V30 even with dose escalation to 72 Gy（P 〈0. 05）. In all of the 22 cases, compared with 3D-CRT, PBT reduced the doses to the nonliver OARs（ organs at risks）including spinal cord, fight kidney and stomach（P 〈0. 002）. Compared with IMRT, PBT also reduced the dose to the fight kidney and stomach significantly, while no significant difference was found respect to the dose to spinal cord （ P 〉 0. 05 ）. Conclusion Compared with 3D-CRT, PBT reduced the dose to the normal liver tissues and nordiver OARs significantly, even with 20 to 30. 3 percent of dose escalation. Compared with IMRT, PBT reduced the dose to the normal liver tissues significantly, even with 20 to 30. 3 percent of dose escalation. PBT reduced the dose to the right kidney and stomach significantly. No significant difference was observed respect to the dose to spinal cord.