Basic characteristics of a newly developed Si/CdTe Compton camera for medical imaging

Kawachi, Naoki; Watanabe, Shigeki; Sato, Takahiro; Arakawa, Kazuo; Takeda, Shinichiro*; Ishikawa, Shinnosuke*; Aono, Hiroyuki*; Watanabe, Shin*; Yamaguchi, Mitsutaka*; Takahashi, Tadayuki*; Shimada, Hirofumi*; Yoshida, Yukari*; Suzuki, Yoshiyuki*; Sakurai, Hideyuki*; Nakano, Takashi*

The Compton camera is a very promising medical imaging system when we consider multiple radionuclide imaging and its sensitivity, portability and compactness. We have developed a Compton camera by using Si and CdTe semiconductors for medical imaging. The prototype Compton camera head consists of a double-sided Si strip detector (DSSD) module as the scatter detector and four layered 16 CdTe pixel detector modules as the absorber detector. The DSSD has an area of 2.562.56 cm, a thickness of 500 m and a strip pitch of 400 m. The CdTe pixel detector has an area of 1.351.35 cm, a thickness of 500 m and a pixel size of 1.35 mm. The high-energy resolution detectors (DSSD: E/E2.5%, CdTe: E/E1%) enable detect the Compton scatter events of the incident -rays, in consequence image radioactive multi-nuclide tracer. We evaluated distributions of sensitivity and spatial resolution, and rat study was performed with three tracers (In, I, Cu) concurrently-administered. As results, lines of point-source data indicated 4 mm spatial resolution in the center of field of view (FOV) in this experimental design, and a characteristic manner of the distributions in the Compton camera FOV was shown. The nuclides in the rat body were distinguished by the -ray energies, each tracer imaged separately in vivo, and the difference in distribution among the nuclide was visualized successfully.