MD, PhD, Department of Nuclear Medicine, University Hospital Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany.
J Clin Endocrinol Metab. 2013 Oct;98(10):3912-9. doi: 10.1210/jc.2013-2259.
Pediatric differentiated thyroid cancer (DTC) patients frequently present with lymph node and/or distant (lung) metastases. Such patients warrant an aggressive treatment consisting of surgical removal of all surgically accessible local metastases as well as further treatment with one or more courses of radioiodine therapy (RAI). It is still a subject of debate in literature how much I-131 should be administered to pediatric patients. Patients can either be given a fixed (possibly body weight adjusted) activity or a dosimetry based activity, which is often considerably higher.
Here, we will present a typical case of a pediatric patient who was treated using a dosimetric approach. Then we will discuss the basis of dosimetry and the procedures involved, followed by a discussion of when to use dosimetric RAI as well as the pros and cons of the various approaches in pediatric patients.
In general, two opposite approaches to dosimetry exist: either the activity that is as high as safely administrable (AHASA) is determined based on the radiation exposure to the critical organs at risk (in pediatric patients these are the bone marrow and, in patients with lung metastases, the lungs), or a lesion-based approach in which the activity that is required to deliver a certain radiation dose to the metastatic lesion(s) is determined.
Because the latter approach requires an accurate volumetry of the target lesion(s), which is not possible in children with disseminated pulmonary metastases, which are often not visible with morphologic imaging techniques, we advocate using the AHASA approach in children with extensive metastatic DTC.
儿科分化型甲状腺癌（DTC）患者常出现淋巴结和/或远处（肺）转移。此类患者需要进行积极治疗，包括手术切除所有可手术切除的局部转移灶，以及进一步接受一次或多次放射性碘治疗（RAI）。在文献中，对于儿科患者应给予多少碘-131 仍存在争议。患者可以接受固定（可能根据体重调整）剂量或基于剂量测定的剂量，后者通常要高得多。
本研究将介绍一例采用剂量测定方法治疗的儿科患者典型病例。然后，我们将讨论剂量测定的基础和所涉及的程序，随后讨论何时使用基于剂量测定的 RAI 以及在儿科患者中各种方法的优缺点。
一般来说，剂量测定有两种相反的方法：一种是根据危险器官（在儿科患者中为骨髓，在有肺转移的患者中为肺部）的辐射暴露，确定尽可能高的安全给药活性（AHASA）；另一种是基于病灶的方法，即确定达到转移病灶（多个病灶）一定辐射剂量所需的活性。
因为后一种方法需要对靶病灶（多个病灶）进行准确的体积测量，而在广泛转移的 DTC 儿童中，由于弥散性肺转移病灶往往无法通过形态学成像技术看到，因此无法进行测量，所以我们主张在广泛转移的 DTC 儿童中使用 AHASA 方法。
