The Effect of the Uncertainty of the Biokinetic Data to the Time-integrated Activity in Thyroid Disease
Jaja Muhamad Jabar, Ade Riana, Deni Hardiansyah, Freddy Haryanto, Idam Arief

Institut Teknologi Bandung

Abstract

Accurate calculation of individual time-integrated activity (TIA) is desirable in 131I therapy for thyroid disease. TIA is determined by fitting a mathematical model to the biokinetic data of 131I. This study aimed to investigate the influence of varying levels of uncertainty in the biokinetic data on the accuracy of TIA in thyroid disease. Biokinetic data of 131I in the thyroid was obtained from the publication in (1). were fitted to the biokinetic data in thyroid to obtain reference TIAs (rTIAs). Three uncertainty levels, expressed as fractional standard deviation (FSD), were simulated fifty times and were added to the biokinetic data. The parameters of the exponential function were then re-fitted to the simulated noisy biokinetic data to obtain calculated TIAs (cTIAs). Relative deviations (RD) between cTIAs and rTIAs were calculated to explore the relationship between biokinetic data uncertainty and TIA uncertainty. The uncertainty of biokinetic data positively correlates with the uncertainty of TIA. These findings emphasize the importance of incorporating uncertainty analysis in the calculation of TIAs (and subsequently radiation-absorbed doses) in molecular radiotherapy.

Keywords: Time-integrated activity, Thyroid, uncertainty

Topic: Biophysics and Medical Physics