甲癌患者^(131)I治疗后手及颈部剂量当量率的监测与临床意义

Monitoring and analysis of dose equivalent rate to hands and neck of the patients with thyroid cancer after iodine-131 therapy

为监测分化型甲癌(differentiated thyroid carcinoma,DTC)患者^(131)I治疗后手及颈部近距离剂量当量率变化情况,指导患者如何进行最优化的辐射防护。以100例DTC患者按治疗次数分为两组,每组各50例,组1为首次行^(131)I清甲治疗患者(服用131I剂量3 700~4 440 MBq),组2为再次行131I清灶治疗患者(服用^(131)I剂量6 660~8 140 MBq),采用Inspector Alertγ射线检测仪分别对两组患者于131I治疗后出院时、出院后1周、2周、1个月及2个月进行双手及颈前部剂量当量率测量,测量距离包括颈前部、手掌部30 cm处及紧贴皮肤处。结果表明,(1)随着时间的延后,各监测时间点剂量当量率逐渐降低。患者出院后1个月距患者颈部、手掌部30 cm处剂量当量率、出院后2个月各监测部位剂量当量率均值均在天然本底范围内(0.25μSv/h)。(2)^(131)I治疗出院时,患者颈部剂量当量率均值均大于手掌部位,但出院后1周、2周及1个月,患者手掌部位剂量当量率均大于颈部。(3)出院后1个月内,一疗程患者颈部各时间点剂量当量率均值均大于二疗程(p<0.05),二疗程患者紧贴手部各时间点剂量当量率均值明显大于一疗程(p<0.05)。^(131)I治疗患者刚出院时,各监测部位剂量当量率均较高(>20μSv/h),建议患者出院后1周内避免与他人亲密接触,2周内避免长时间超亲密接触,避免与特殊人群(如婴幼儿、孕妇等)零距离接触(如拥抱、亲吻等),出院后1个月距离患者≥30 cm的社交活动和出院后2个月的社交活动可完全不受限制。患者手部容易被污染导致剂量当量率较高,尤其是二疗程患者,应做好辐射防护隔离措施。

In order to optimize the protective measures for patients with differentiated thyroid carcinoma（ DTC）after iodine-131 therapy,the variation of dose equivalent rate to hands and necks of the patients was monitored at short distance. 100 DTC patients were divided into two groups with 50 cases in each group. Group 1 was thyroid remnant 131I ablation therapy group（ dose from 3 700 to 4 440 MBq）,and Group 2 with 131I treatment for recurrent and metastatic lesions（ dose from 6 660 to 8 140 MBq）. To determine dose equivalent rate to hands and necks,an Inspector Alert gamma detector was used to measure the dose rate on discharge,and at one week,two weeks,one month and two months after discharge. The detector was placed 30 cm away from the necks and palms,and closely contacted skin,respectively. The results showed that：（ 1） All the measured dose rates were high at the time of discharge after iodine-131 therapy,and the dose rates gradually decreased over time. The dose equivalent rates measured 30 cm away from the necks and palms one month after discharge and all the results for two months after discharge were lower than 0. 25 μSv/h.（ 2） At the time of discharge,average dose equivalent rates to the necks were higher than those to the hands（ p 〈 0. 05）,while at the time of one week,two weeks,one month after discharge（ p 〈 0. 05）,the average dose equivalent rates to the hands were higher than those to the necks.（ 3） Dose equivalent rates for Group 1 in front of the neck at the time of discharge and at one week,two weeks,one month after discharge were higher than the results of Group 2（ p 〈0. 05）,while dose equivalent rates for Group 2 measured by closely contacting the hands were lower than those for Group 1 at the same time（ p 〈 0. 05）. As all the results for the DTC patients measured at the time of discharge were higher than 20 μSv/h,we recommend that the patients should avoid intimate contact with others within a week after discharge and also avoid long-time contacts within two weeks after discharge. The DTC patients can have normal social activities with other people around one month after a large doses of 131I therapy,but in accordance with the principle of optimization of radiation protection,they should avoid intimate contact with vulnerable groups（ such as infants,young children and pregnant women,etc.）. Two months after therapy,as dose equivalent rates would have dropped to the background level,there is no need to take any radiological protection measures. As dose equivalent dose rates to the hands could be high due to contamination,patients particularly with the second course of treatment should take radiological protection measures.