Abstract

Objective: Radioisotopes are administered in varying amounts to patients orally and intravenously for treatment and diagnostic procedures in nuclear medicine. It is an established fact that radionuclides have both therapeutic and harmful effects on humans. Hence, the need for individual patient dosimetry is an important factor in optimizing patient-specific doses. The study objective is to estimate the internal radiation doses to the selected patients undergoing Tc99m - MIBI scan using computer codes.
Material and Methods: Technetium 99m MIBI was administered to the ten randomly selected patients for the 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, Islamabad. The injected activity ranged from 821 to 993 MBq. The absorbed and effective doses for all selected patients are measured using OLINDA/EXM version 2.0 and IDAC DOSE VERSION 2.1 computer codes.
Results: The obtained results show that this is the highest mean absorbed dose received by kidneys and intestine using Olinda/exm and idac dose, respectively. The mean effective dose for Tc99m-MIBI from Olinda/exm for selected patients was found to be 5.52 µSv/MBq and 6.8 µSv/MBq assessed for idac dose software. The results from both the codes are compared to ICRP 128 publication and show a significant correlation within the recommended limits with ICRP dose guidelines. These results are considered key to greater accuracy in internal dose calculation and very useful for patients, education, and research studies.

Key words: Olinda, idac-dose, technetium 99m MIBI, internal dosimetry, nuclear medicine, SPECT/CT. OLINDA/EXM, IDAC-DOSE.