Huić D, Medvedec M, Dodig D, Popović S, Ivancević D, Pavlinovic Z, Zuvic M
Department of Nuclear Medicine and Radiation Protection, University Hospital Rebro, Zagreb, Croatia.
Nucl Med Commun. 1996 Oct;17(10):839-42.
The aim of this study was to investigate the influence of the diagnostic administration of 74 MBq 131I on subsequent uptake of therapeutic radioiodine in thyroid cancer patients. Retention measurements were performed using a whole-body counter in 24 patients 6 weeks after total thyroidectomy. Profile scans were performed 2, 24, 48 and 72 h after the administration of the diagnostic dose and 72 h after the administration of the ablation-therapeutic dose (4.4 GBq). The mean ( +/- S.D.) effective half-life of the diagnostic dose in thyroid remnants was 40.3 +/- 23.0 h. The uptake in the thyroid remnants of the subsequent ablation dose 72 h after administration was 30.4 +/- 19.8% of that predicted from the diagnostic study. The greater reduction in uptake was associated with the longer half-life of iodine and higher uptake in the thyroid remnants at 24 h, with a longer interval between surgery and administration of the diagnostic dose and a shorter period between administration of the diagnostic and ablation doses. Our results show that a diagnostic dose of 74 MBq 131I markedly reduces thyroid uptake of an ablation dose of 131I. This should be taken into account during radiation dose planning whenever a quantitative dosimetric study is to be performed.
本研究的目的是调查74 MBq 131I诊断性给药对甲状腺癌患者后续治疗性放射性碘摄取的影响。在24例患者全甲状腺切除术后6周，使用全身计数器进行滞留测量。在诊断剂量给药后2、24、48和72小时以及消融治疗剂量（4.4 GBq）给药后72小时进行轮廓扫描。甲状腺残余组织中诊断剂量的平均（±标准差）有效半衰期为40.3±23.0小时。给药后72小时，后续消融剂量在甲状腺残余组织中的摄取量为诊断研究预测值的30.4±19.8%。摄取量的更大减少与碘的半衰期更长、24小时时甲状腺残余组织中的摄取量更高、手术与诊断剂量给药之间的间隔更长以及诊断剂量与消融剂量给药之间的时间更短有关。我们的结果表明，74 MBq 131I的诊断剂量显著降低了131I消融剂量在甲状腺中的摄取。每当要进行定量剂量学研究时，在辐射剂量规划过程中都应考虑到这一点。
