Clinical Engineering and Clinical Dosimetry in Patients with Differentiated Thyroid Cancer Undergoing Thyroid Remnant Ablation with Radioiodine-131

摘要

Differentiated thyroid cancer (DTC) is a malignant disease with increasing incidence worldwide. Croatia is among the top European countries regarding a high incidence rate of DTC, whereas DTC is among the top fifteen primary cancer sites in Croatian population. The objective of this work is to present the practical impact of clinical engineering in supporting and advancing care in patient with DTC by applying engineering and managerial skills to nuclear medicine technology. The final goal of this work was to harmonize radioactive iodine-131 (1-131) ablation of thyroid remnant with a desired clinical outcome, radiation protection and safety, quality of patient's life and the costs of treatment. This study included 269 DTC patients. The first part of the study dealt with dosimetric measurements and analysis in 49 patients after thyroidectomy and administration of diagnostic and therapeutic 1-131. Serial in vivo measurements of 1-131 activity in thyroid remnant and whole body were performed by a conventional probe system and beta-gamma exposure rate meter during the first week after 1-131 administrations. The mass of thyroid remnant was determined from two orthogonal pinhole gamma camera images assuming an ellipsoidal shape. The radiation absorbed dose was calculated according to the Medical Internal Radiation Dose (MIRD) formalism. In the second part of the study, 220 low risk DTC patients had been post-surgically given only 900 MBq of therapeutic 1-131 and were followed up for five years. Clinical engineering efforts integrated into a novel clinical dosimetry-based approach applied to our DTC patients undergoing 1-131 thyroid remnant ablation decreased overall patient's procedure time and costs two-folds and the amount of radioactivity five-folds. The quality of patient's life and radiation protection and safety have been significantly improved. Simultaneously, the high success rate of thyroid remnant ablation with 1-131 has been preserved.