螺旋断层治疗用于全骨髓照射的初步结果

Preliminary results of helical tomotherapy for total marrow irradiation

目的：评估全骨髓照射作为异基因外周血干细胞移植（ Allo－PBSCT）前预处理方式的疗效及安全性。方法2014—2015年6例患者Allo－PBSCT前均采用HT联合环磷酰胺（60 mg／kg1次／d共2 d）的预处理方式。采用HT技术实施。结果6例患者中位年龄18．5岁。处方剂量（12 Gy分3次3 d完成）精确覆盖全部骨骼区域，OAR受量较全身照射降低13％～60％。头颈、胸腹、盆腔部位剂量验证通过率分别为（95．8±1．2）％、（96．2±1．1）％、（98．9±0．8）％。上、下部分的HI和平均治疗时间分别为1．18、1．17和39．2、14．3 min。放疗期间5例患者出现1—2级恶心、呕吐，2例患者出现1—2级疼痛，1例患者出现1级腹泻，1例患者出现2级肠炎。所有患者均未出现3—4级非血液学不良反应，并且成功植入骨髓。结论 HT技术应用于全骨髓照射是可行的，靶区适形度高，剂量均匀性好，安全性高且不良反应较传统TBI明显减低，可作为新的骨髓移植前预处理方式。

Objective To evaluate the efficacy and safety of total marrow irradiation （TMI） as the pretreatment before allogeneic peripheral blood stem cell transplantation （Allo-PBSCT）.Methods From 2014 to 2015, six patients undergoing TMI combined with cyclophosphamide （ 60 mg/kg, once a day for 2 days） as the pretreatment before Allo-PBSCT were enrolled as subjects.The pretreatment was performed by helical tomotherapy （ HT） .Results The median age of the six patients was 18.5 years.The prescribed dose （ 12 Gy in 3 fractions for 3 days ） accurately covered all bone regions.Compared with the total body irradiation, the dose to organs at risk was reduced by 13%to 60%in TMI.The passing rates for the doses to head-neck, chest-abdomen, and pelvic cavity were （95.8±1.2）%,（96.2±1.1）%, and （99.0±0.5）%, respectively.The homogeneity indices for the upper and lower parts were 1.18 and 1.17, respectively, while the average treatment durations for the upper and lower parts were 39.2 and 14.3 min, respectively.During radiotherapy, five patients had grade 1-2 nausea and vomiting, two grade 1-2 pain, one grade 1 diarrhea, and one grade 2 enteritis.There was no grade 3-4 non-hematological toxicity in patients.Bone marrow was successfully implanted in all patients.Conclusions HT is a feasible approach for TMI, with satisfactory dose homogeneity, high conformity to the target volume, high safety, and substantially reduced toxicities compared with total body irradiation.HT can be used as a novel method for the pretreatment before bone marrow transplantation.