Carlier Thomas, Salaun Pierre-Yves, Cavarec Marie-Béatrice, Valette Frédéric, Turzo Alexandre, Bardiès Manuel, Bizais Yves, Couturier Olivier
Nuclear Medicine Department, Nantes University Hospital, France.
Nucl Med Commun. 2006 Jul;27(7):559-66. doi: 10.1097/00006231-200607000-00003.
(131)I therapy is increasingly used for Graves' hyperthyroidism. Debate remains about the best method for calculating the activity to administer, as well as about the potential benefit of such computed activity. Several arguments plead, nevertheless, in favour of a personalized computation, such as inter-individual variations of thyroid volume and biokinetics.
A MIRD-based dosimetric approach, with an additional extension that takes into account the variation of thyroid mass during the treatment, has been developed. This approach includes the benefits of a personalized determination of biokinetics. Results were compared with those of six methods widely used in routine practice. Forty-one patients were enrolled (34 women, seven men; mean age +/-SD: 48.11 +/- 6.4 years). (131)I uptakes were measured at 4, 24 and 96 h (36.2 +/- 14.6%, 42.8 +/- 9.7% and 27.6 +/- 6.8%, respectively), following administration of the tracer. The kinetics of iodine in the thyroid were evaluated using a two-compartment model (effective half-life of 5.1 +/- 1.6 days). Computations of activities to deliver the doses prescribed by the physician were done with the eight formalisms.
There was no statistical difference between results of the two MIRD-based formalisms (227 +/- 148 MBq and 213 +/- 124 MBq), which were also not significantly different from those obtained with the majority of the other methods (from 128 +/- 95 MBq to 275 +/- 223 MBq). However, a large intra-individual difference up to a factor of 2 between two given methods was found.
The formalism developed appears to be a good compromise between all the common formalisms already used in many institutions. Furthermore, it allows the exposures of target volumes and non-target volumes to be planned individually and practical individual radiation protection recommendations to be implemented.
（131）I治疗越来越多地用于格雷夫斯甲亢。关于计算给药活度的最佳方法以及这种计算活度的潜在益处仍存在争议。然而，有几个论据支持个性化计算，比如甲状腺体积和生物动力学的个体间差异。
已开发出一种基于医学内照射剂量学（MIRD）的剂量测定方法，并额外扩展以考虑治疗期间甲状腺质量的变化。该方法包括个性化确定生物动力学的益处。将结果与常规实践中广泛使用的六种方法的结果进行比较。纳入了41例患者（34名女性，7名男性；平均年龄±标准差：48.11±6.4岁）。给予示踪剂后，在4小时、24小时和96小时测量（131）I摄取率（分别为36.2±14.6%、42.8±9.7%和27.6±6.8%）。使用双室模型评估甲状腺中碘的动力学（有效半衰期为5.1±1.6天）。用八种方法计算给予医生规定剂量所需的活度。
两种基于MIRD的方法的结果之间无统计学差异（分别为227±148MBq和213±124MBq），且与大多数其他方法获得的结果也无显著差异（从128±95MBq到275±223MBq）。然而，发现两种给定方法之间个体内差异高达2倍。
所开发的方法似乎是许多机构已经使用的所有常用方法之间的良好折衷。此外，它允许分别规划靶区和非靶区的照射，并实施切实可行的个体辐射防护建议。
