^131I-美妥昔单抗联合动脉内化疗栓塞治疗原发性肝癌的内照射吸收剂量估算

目的对^131I-美妥昔单克隆抗体（简称单抗）联合动脉内化疗栓塞（TACE）治疗原发性肝癌患者器官的内照射吸收剂量进行估算。方法21例患者肝动脉内按体质量注入^131I-美妥昔单抗（27．75MBq／kg）和混合化疗药物的碘化油乳剂。用1计数仪测量5min和0．5，2，4，24，48，72，120，168h血样和尿样的放射性。用SPECT仪行4或5次全身扫描。用感兴趣区图像处理法计算主要器官和全身放射性活度占给予放射性活度的百分数（％ID），SPSS12．0软件拟合时间-％ID曲线，计算累积活度，依据医学内照射辐射剂量学（MIRD）方法和血液间接法计算器官和红骨髓的内照射吸收剂量，计算肿瘤／非肿瘤放射性比值。结果^131I-美妥昔单抗的平均剂量为1．89（1．47～223）GBq／次。显像示放射性主要浓聚于肝区肿瘤组织，随时间延长，甲状腺后期有放射性浓聚，体内其他组织未见明显放射性分布。器官吸收剂量（12例）：肝（3．19±1．01）Gy，脾（3．65±2．41）Gy，甲状腺（3．61±2．40）Gy，肺（0．97±0．23）Gy，肾（0．96±0．35）Gy，全身（0．57±1．55）Gy，红骨髓（0．55±0．09）Gy（7例）。肿瘤／肝放射陛比值（7例）：3h为2．88±1．11，64h为2．15±0．53，120h为1．81±0．39，168h为1．64±0．39。结论依据MIRD方法计算获得了主要器官、红骨髓和全身内照射吸收剂量，这对更好评价疗效、不良反应和制订个体化方案有重要意义。

Dosimetry of 131I labeled metuximab and transarterial chemoembolization for treatment of hepatocellular carcinoma

Objective Metuximab is a specific monoclonal antibody F(ab')fragment targeted to the hepatocellular carcinoma(HCC)associated antigen of HAb18G/CD147.131I labeled metuximab has shown to be effective response on HCC in phase Ⅰ/Ⅱtrails.To evaluate the feasibility of 131I-metuximab combined with transarterial chemoembolization(TACE)is the treatment of HCC,the anthors estimated the radiation absorbed dose to organs.Methods 131I-metuximab(27.75 MBq/kg)and the mixture of anticancer drug and Lipiodol with interval 20 min later were administered to 21 patients with HCC via a transfemoral catheter.The pharmacokinetie and desimetric data were collected by means of venous blood samples.urine collections,and 4 or 5 γ-scintigraphies (SPECT) over7 d.The total amount of activity in percent of iniected activity (%ID)of main organ and the total body were calculated by regions of interest(ROI).The cumulated activities were determined from integration of the time-%ID curves using the SPSS 12.0 software.Absorbed doses to organ and red marrow were estimated according to the medical internal radiation dose (MIRD) formalism and blood-based marrow estimation with a red marrow-to-blood activity concentration ratio.The tumorto-no tumor ratio was calculated as well.Results A mean administered aetivity was 1.89 GBq per session (range 1.47-2.23 GBq).SPECT scans showed the significant accumulation of the radioconjugate in liver tumor and faint uptake in other organs until 14 d.Organ absorbed dose(n=12):the total absorbed dose to liver,spleen,thyroid,lungs,kidney and total-body was(3.19±1.01),(3.65±2.41),(3.61±2.40),(0.97±0.23),(0.96±0.35)and(0.57±1.55)Gy,with(0.55±0.09)Gy to the red marrow(n=7),respectively.From 2.88±1.11 to 1.64±0.39 were observed in tumor-to-liver ratio at 3 h to 168 h.Conclusion Internal absorbed dose estimation based on MIRD formalism is not only to establish reliable dose-response relationships for target tissue and dose-toxicity relationships for normal tissue but also to improve treatment planning in individual patient.