大体积脑转移瘤大分割后程缩野放疗的剂量学及临床疗效分析

Hypo-fractionated Adaptive Radiotherapy for Large Brain Metastasis:Dosimetric and Clinical Analysis

目的探讨大分割后程缩野放疗对大体积脑转移瘤患者的剂量学及其临床疗效分析。方法收集20例病灶体积6~20 cm^(3)、病灶数目1~4个且行大分割后程缩野放疗的脑转移瘤患者资料。脑部病灶处方剂量为52.5 Gy/3.5 Gy/15 f。治疗10次后复查颅脑增强MRI评估疗效、若肿瘤退缩明显重新勾画靶区完成后程放疗。评估不缩野放疗计划(Plan1)和后程缩野放疗计划下(Plan2)脑组织及其他危及器官剂量学参数变化、后程计划缩瘤率、近期疗效(疗后2~3个月评估近期疗效)。结果后程缩野放疗中脑组织及危及器官的辐射剂量都有下降。且后程缩野时平均缩瘤率为41.76%,3个月ORR为90.5%,6个月LCR为100%。结论大分割后程缩野放疗缩瘤率高,能有效减少正常组织剂量学参数值,对大体积病灶局部控制率好,近期疗效佳。

Objective To investigate the dosimetric and clinical analysis of hypo-fractionated adaptive radiotherapy in patients with large brain metastases.Methods A total of 20 patients with large brain metastases who were initially treated with hypo-fractionated adaptive radiotherapy and with lesion volume of 6 cm^(3) to 20 cm^(3) and the number of lesions 1 to 4 of radiotherapy were collected.The lesion was prescribed a dose of 52.5Gy/3.5Gy/15f,Patients were re-examined by MRI after 10 times treatment.The radiation field would be shrunk if the GTV was reduced,and complete the remaining dose of radiotherapy.Changes in dosimetric parameters of two segment planning brain and other organs at risk,rate of second segment planning tumor reduction,and recent efficacy were evaluated.Results The dosimetric parameters of brain tissue and organs at risk in plan2 were reduced to varying degrees.The average rate of tumor reduction during second segment field reduction was 41.76%,the 3-month ORR was 92.6%,and the 3-month,6-month LCR was 100%.Conclusion Hypo-fractionated adaptive radiotherapy has a high rate of tumor reduction,can effectively reduce the value of dosimetric parameters of normal brain tissue,and has a good local control rate for large-volume lesions,and best short-term results.