Effect of Patient Gender on the Calculation of Time-Integrated Activity Coefficient in Radionuclide Therapy: A Study Using the Non-Linear Mixed-Effects Model Assyifa Rahman Hakim (a), Fira Dwi Ananda (a), Rien Ritawidya (b), Deni Hardiansyah (a*)
(a) Medical Physics and Biophysics, Physics Department, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok, Indonesia
* denihardiansyah[at]sci.ui.ac.id
(b) Research Center for Radioisotope, Radiopharmaceutical, and Biodosimetry Technology, National Research and Innovation Agency (BRIN), Tangerang Selatan 15314, Indonesia
Abstract
Purpose:
This study investigates the influence of patient gender on the calculation of the Time-Integrated Activity Coefficient (TIAC) in radionuclide therapy.
Methods:
Kidney biokinetic data from 10 patients (6 males, 4 females) treated with [177Lu]Lu-DOTATATE were analyzed [1]. A bi-exponential function was used to model both the uptake and clearance phases. The reference TIAC (rTIAC) was determined by fitting bi-exponential parameters to the complete dataset using a Non-Linear Mixed-Effects Model (NLMEM). To assess gender impact, separate NLMEM fittings for male and female subgroups yielded estimated TIACs (eTIACs). rTIAC and eTIAC values were compared using Relative Deviation (RD) and Root-Mean-Square Error (RMSE). Gender was deemed impactful if RD or RMSE exceeded 10%.
Results:
The RMSE was 7.2% for males and 8.8% for females. Among male patients, two individuals showed RD values exceeding 10% (i.e. 10.9% and -13.3%). Similarly, two female patients exhibited RD values beyond this threshold (i.e. -13.0% and 12.3%).
Conclusion:
For [177Lu]Lu-DOTATATE therapy in this study^s tested biokinetic data, gender does not appear to be a major determinant in TIAC calculation, as deviations remain within an acceptable range for most patients.
Reference:
[1] Devasia TP, Dewaraja YK, Frey KA, Wong KK, Schipper MJ. J Nucl Med 2021-62:1118-25.
