| Tang Minmin,Liu Jianzhong,Wu Zhifang,Lu Keyi,Li Sijin,Gao Yongju,Wu Xinyu,Xu Junling.Estimation of residual activity in patients with differentiated thyroid cancer after administration of 131I for therapy[J].Chinese Journal of Radiological Medicine and Protection,2015,35(4):299-302 |
| Estimation of residual activity in patients with differentiated thyroid cancer after administration of 131I for therapy |
| Received:July 26, 2014 |
| DOI：10.3760/cma.j.issn.0254-5098.2015.04.016 |
| KeyWords:Differentiated thyroid cancer 131I Radioactivity Urine Equivalent dose rate |
| FundProject: |
| Author Name | Affiliation | E-mail | | Tang Minmin | Department of Nuclear Medicine, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou 450003, China | | | Liu Jianzhong | 山西医科大学第一医院核医学科 | 43833031@qq.com | | Wu Zhifang | 山西医科大学第一医院核医学科 | | | Lu Keyi | 山西医科大学第一医院核医学科 | | | Li Sijin | 山西医科大学第一医院核医学科 | | | Gao Yongju | Department of Nuclear Medicine, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou 450003, China | | | Wu Xinyu | Department of Nuclear Medicine, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou 450003, China | | | Xu Junling | Department of Nuclear Medicine, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou 450003, China | |
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| Abstract:: |
| Objective To estimate the residual activity in patients with differentiated thyroid cancer (DTC) after administration of 131I for post-operative therapy. Methods Forty-nine DTC patients were divided into two groups (thyroid remnant 131I ablation therapy group and group with 131I treatment for recurrent and metastatic lesions). Urine excretion of 49 patients with differentiated thyroid cancer after 131I therapy was collected every time, with the activity of urine excretion and total activity calculated, and then residual activity in patients estimated. The determination of equivalent dose rate at 1 meter point were performed to estimate multi-temporal residual activity in each patient at 2, 6, 24, 48, and 72 h after administration of therapeutic doses of 131I, respectively. The equivalent dose rate at 1 meter point was indirectly estimated when the residual activity reach to 400 MBq. Correlation and regression were used to evaluate the relationship between residual activity and the equivalent dose rate at 1 m. Results The percentage of residual activity at 2, 6, 24, 48, and 72 h after administration of 131I, was, respectively, 99%, 72%, 25%, 15% and 7% in patients who have undergone thyroid remnant 131I ablation, and 99%, 71%, 18%, 7% and 3% in those who have undergone 131I treatment for metastatic lesions. The equivalent dose rate at 1 m point was, respectively, 157, 120, 35, 11 and 9 μSv/h in the former and 232, 182, 48, 11 and 2 μSv/h in the latter. There is a positive correlation between residual activity and equivalent dose rate at 1 m (r=0.94, P<0.001). The residual activity at 48-72 h after administration of 131I was, respectively, 548-259 MBq in the former and 451-248 MBq in the latter. The corresponding equivalent dose rate at 1 m ranged from 8 to 10 μSv/h. Conclusions The in vivo residual activity reaches the national standard of 400 MBq (10.8 mCi) in patients with differentiated thyroid cancer during 48-72 h after administration of 131I and the equivalent dose rate at 1 m ranged from 8 to 10 μSv/h. At this time, radiation isolation could be released. |
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