Monte carlo simulation of multi-head Si/CdTe Compton camera for medical imaging

Yamaguchi, Mitsutaka*; Kawachi, Naoki; Watanabe, Shin*; Odaka, Hirokazu*; Takeda, Shinichiro*; Ishikawa, Shinnosuke*; Aono, Hiroyuki*; Takahashi, Tadayuki*; Arakawa, Kazuo; Nakano, Takashi*

We evaluated the position resolutions of single- and double-head Compton camera by using Monte Carlo simulation. A -ray source was placed at the origin of rectangular coordinates. For single-head camera, one head was placed as its center axis was corresponding to the z-axis. For double-head camera, two heads were placed as those center axes were corresponding to the z- and y-axis, respectively. Monte Carlo simulations were performed by using the Geant4 toolkit on ANL PLUS framework. The energy of rays was set at 364.5 keV, which correspond to radiation of iodine-131. After these simulations, two hit Compton event was selected. And then back-projection and image reconstruction were performed in 3D-space. Image reconstructions were performed by using the List-Mode Most- Likelihood Expectation-Maximizing, LM-ML-EM, algorithm. Consequently, the position resolution (FWHM) of the z-axis was about 4.4 mm for double-head camera whereas about 15 mm for single-head camera. These values are consistent with the values roughly estimated by using angular resolution measure (ARM). These results indicate that the position resolution is improved and clear 3D-image is taken by using multi-head Compton camera.