TITLE:
Preliminary Monte Carlo Investigation of Using Ir-192 as the Source for Real Time Imaging Purpose
AUTHORS:
Chengyu Shi, Brian Wang
KEYWORDS:
Monte Carlo, Ir-192, HDR, Imaging
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.6 No.1,
January
12,
2017
ABSTRACT: The purpose
of this study is to investigate the potential use of Ir-192 as the source for
real time imaging during HDR (High Dose Rate) brachytherapy treatment. Phantom
measurement was performed to determine outside of the body dose. Monte Carlo
code, EGSnrcMP egs_inprz, was used for the simulation to calculate the outside
of the body x-ray signal for CT reconstruction. Matlab code was developed to
reconstruct the Ir-192 source and for 3D visualization in order to assess
reconstructed CT resolution, signal-to-noise ratio, and imaging dose
information. The measured dose was 0.67 ± 0.04 cGy, which was comparable to the
Monte Carlo simulation result 0.71 ± 0.20 cGy. The reconstructed source
diameter dimension was 1.3 mm compared with 1.1 mm for the real source dimension.
The signal-to-noise ratio was 19.91 db following de-noising. Source position
was within a 1 mm difference between programmed and simulated results. Although
the Ir-192 signal is weak for CT imaging, it is possible to use it as a CT
imaging x-ray source for HDR treatment localization, verification and dosimetry
purposes. Further study is needed for the detailed design of an outside of the
body CT-like device for use in brachytherapy imaging.