Pre-therapeutic (124)I PET(/CT) dosimetry confirms low average absorbed doses per administered (131)I activity to the salivary glands in radioiodine therapy of differentiated thyroid cancer.

Purpose: Salivary gland impairment following high activity radioiodine therapy of differentiated thyroid cancer (DTC) is a severe side effect. Dosimetric calculations using planar gamma camera scintigraphy (GCS) with (131)I and ultrasonography (US) provided evidence that the average organ dose per administered (131)I activity (ODpA) is too low to account for observed radiation damages to the salivary glands. The objective of this work was to re-estimate the ODpA using (124)I PET(/CT) as a more reliable approach than (131)I GCS/US.

Optimized 124I PET dosimetry protocol for radioiodine therapy of differentiated thyroid cancer.

Unlabelled: Iodine kinetics and lesion dose per administered 131I activity (LDpA) of differentiated thyroid cancer metastases were determined using 124I PET. These data were analyzed to derive an optimized dosimetry protocol.

Methods: We evaluated the time-activity-concentration curves of 37 lesions in 17 patients who had undergone thyroidectomies.