Revision of the calculation accuracy of radiopharmaceutical uptake applied to radioiodine 131I therapy of differentiated thyroid cancer

Puprose: To develop new criteria for precise evaluation of 131I uptake value in thyroid remnants, based on activity determination in region of interest, which would not depend on gastrointestinal and urinary tracts radiopharmaceutical uptake. Calibration curve was developed means of various samples of known 131I-sources for activity in the residual thyroid tissue from events registered with gamma camera was derived. The traditional method based on calculation of 131I uptake percentage did not allow to assess activity in the remnant thyroid tissue, even after exclusion of physiologic uptake. The new criteria for evaluation of the thyroid remnants size with no dependence on physiological uptake of I131 by gastrointestinal and urinary tracts is offered.