Investigation of the Effect of Changing the Tolerated Dose for Kidney and Spleen on the Predicted Distribution of 212Pb-DOTAMTATE and Its Daughters in Alpha Therapy
Rohma Novitasari (a), Asyifa Khoerunnisa (a), Deni Hardiansyah (a*)

(a) Medical Physics and Biophysics, Physics Department, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok, Indonesia.
*denihardiansyah[at]ui.ac.id

Abstract

Background:
Targeted radionuclide therapy with 212Pb-SSTA is a potentially effective approach for treating neuroendocrine cancers. Evaluating biodistribution and dosimetry in non-target organs like kidney and spleen, this study aims to minimize toxicity and improve therapeutic safety.
Methods:
A multicompartment model developed using SAAM II was used to analyze the kinetics of 212Pb-SSTA and its decay products (Bi-212, Tl-208, Pb-208) in kidney and spleen at graded doses of 1-6 Gy. This represents the fractional dose absorbed per cycle based on a total renal dose limit of 23 Gy over four treatment cycles. Area under the curve (AUC) calculated from the activity-time curves in each compartment, were used to assess radionuclide accumulation.
Results:
AUC analysis showed that Pb-212 contributed dominantly in most compartments. The highest activity in the kidney was found in the proximal tubule and excretory compartment. Using 6 Gy as a reference, the average relative deviation (RD) values of using the tolerated dose for kidneys of 1-5 Gy were 83%, 66%, 50%, 33%, and 16%, respectively. RD values at each dose showed a decrease with increasing dose. RD values did not show significant differences between radionuclide compartments.
Conclusion:
The radionuclide distribution has been analyzed, the effect of varying the maximum tolerated dose affects the AUC distribution in each compartment.

Keywords: PBPK model, 212Pb-SSTA, compartment model

Topic: Medical Physics and Biophysics