Download PDF
CC BY-NC-ND 4.0 · World J Nucl Med 2016; 15(02): 114-123
DOI: 10.4103/1450-1147.174700
Original article

A 3D Monte Carlo method for estimation of patient-specific internal organs absorbed dose for 99m Tc-hynic-Tyr 3 -octreotide imaging

Mehdi Momennezhad
Department of Medical Physics, Faculty of Medicine, University of Medical Sciences, Mashhad
,
Shahrokh Nasseri
1   Department of Medical Physics, Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad
,
Seyed Zakavi
2   Department of Nuclear Medicine, Nuclear Medicine Research Center, Mashhad University of Medical Sciences, Mashhad
,
Ali Parach
3   Department of Medical Physics, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
,
Mahdi Ghorbani
Department of Medical Physics, Faculty of Medicine, University of Medical Sciences, Mashhad
,
Ruhollah Asl
Department of Medical Physics, Faculty of Medicine, University of Medical Sciences, Mashhad
› Author Affiliations
› Further Information
Also available at
  PDF Download Permissions and Reprints

Single-photon emission computed tomography (SPECT)-based tracers are easily available and more widely used than positron emission tomography (PET)-based tracers, and SPECT imaging still remains the most prevalent nuclear medicine imaging modality worldwide. The aim of this study is to implement an image-based Monte Carlo method for patient-specific three-dimensional (3D) absorbed dose calculation in patients after injection of 99m Tc-hydrazinonicotinamide (hynic)-Tyr 3 -octreotide as a SPECT radiotracer. 99m Tc patient-specific S values and the absorbed doses were calculated with GATE code for each source-target organ pair in four patients who were imaged for suspected neuroendocrine tumors. Each patient underwent multiple whole-body planar scans as well as SPECT imaging over a period of 1-24 h after intravenous injection of 99m hynic-Tyr 3 -octreotide. The patient-specific S values calculated by GATE Monte Carlo code and the corresponding S values obtained by MIRDOSE program differed within 4.3% on an average for self-irradiation, and differed within 69.6% on an average for cross-irradiation. However, the agreement between total organ doses calculated by GATE code and MIRDOSE program for all patients was reasonably well (percentage difference was about 4.6% on an average). Normal and tumor absorbed doses calculated with GATE were slightly higher than those calculated with MIRDOSE program. The average ratio of GATE absorbed doses to MIRDOSE was 1.07 ± 0.11 (ranging from 0.94 to 1.36). According to the results, it is proposed that when cross-organ irradiation is dominant, a comprehensive approach such as GATE Monte Carlo dosimetry be used since it provides more reliable dosimetric results.

Keywords

GATE Monte Carlo package - MIRDOSE - patient-specific dosimetry - S value


Publication History

Article published online:
19 May 2022

© 2016. Sociedade Brasileira de Neurocirurgia. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commecial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

Thieme Medical and Scientific Publishers Pvt. Ltd.
A-12, 2nd Floor, Sector 2, Noida-201301 UP, India