Evaluation of single time point dosimetry model for personalized radioiodine therapy in cancer patients

Abstract

This study aims to evaluate the performance of the single time-point (STP) dosimetry model in patients with differentiated thyroid cancer (DTC) or neuroendocrine tumors (NETs) undergoing radioiodine therapy. This approach facilitates personalized dosimetry and optimizes radioiodine therapy for these patients. The study enrolled 18 patients—9 with DTC and 9 with NETs. Each patient underwent three planar imaging sessions at 24, 72, and 168 h following the administration of the respective radioiodine compounds. The results from the STP evaluations for each time point were compared to the three-time-point dosimetry measurements to determine the accuracy of the STP model. In DTC patients, using the STP dosimetry at 72 h provided integrated activity estimates for all organs with less than 10% error compared to the reference three-time-point dosimetry, except in the thyroid, where the activity estimation error was 14%. The 168-h STP evaluation yielded an integrated activity estimation in the thyroid remnants with only a 7% error. In NET patients treated with ¹³¹I-MIBG, applying the STP dosimetry at 72 h led to at most a 10% underestimation of activity across all tissues. Additionally, the 168 h STP produced integrated activity estimates in different tissues within a range of +15% to −14% compared to the reference model. The STP dosimetry model demonstrated reliable accuracy for quantifying absorbed doses in various tissues and NET lesions. These findings support the potential of this approach for routine personalized dosimetry in radioiodine therapy.