Abstract
Objective: Radioisotopes of the different amount administered to patients orally and intravenously for treatment and diagnostic procedures in nuclear medicine. It is an established fact that radionuclides are beneficial as well as harmful to the human being. Hence, the need for individual patient dosimetry is an important factor to optimize patient-specific doses. The study aims to estimate the internal radiation doses to the randomly selected patients undergoing Tc99m-MIBI scan using computer codes.

Material and Methods: Technetium 99m MIBI administered to the ten randomly selected patients for rest study. Whole-body planar scintigraphy at a different time was performed on a dual-head gamma camera. SPECT-CT gamma camera is installed in the nuclear medicine department at Nuclear Medicine, Oncology and Radiotherapy Institute (NORI), Islamabad. The injected activity to relevant selected patients was in the ranged from 821 to 993 MBq. Computer code OLINDA/EXM version 2.0and IDAC DOSE VERSION 2.1 used to estimate the absorbed doses for each organ and effective doses for all selected patients.
Results: The mean absorbed dose received by kidneys is 14.18 ±5.8 µGy/MBq and 27.53± 7.0 µGy/MBq using Olinda /exm and idac dose respectively. Similarly, the estimated mean absorbed dose for intestine found to be 23.96 ± 3.7 µGy/MBq and 17 ± 4.5 µGy/MBq for Olinda/exm and Idac dose software, respectively. The mean effective dose for Tc99m-MIBI from Olinda/exm for selected patients was found to be 5.52 µSy/MBq and 6.8 µSy/MBq assessed for idac dose software.

Key words: Olinda, Idac-dose, Technetium 99m MIBI, Internal Dosimetry, Nuclear Medicine, SPECT/CT. OLINDA/EXM, IDAC-DOSE,