Development of a tweezers-type coincidence imaging detector.
OBJECTIVE
When employing F-18-fluorodeoxyglucose (FDG)-guided surgery to detect positron accumulation in isolated small organs, sampling these organs from opposite directions is a useful way of determining a tumor's position, similar to sampling a small organ with tweezers. The coincidence method is suitable for this purpose because only the positrons between two detectors can be detected. For this purpose, we developed a tweezers-type coincidence imaging detector.


METHODS
The detector employs two depth-of-interaction (DOI) detectors positioned at the tip of the tweezers and images the positron distribution between them using the coincidence method. The DOI detector consists of a 4 x 3 Gd(2)SiO(5):Ce (GSO) array optically coupled to a one-dimensionally arranged quad-photomultiplier tube. These GSOs were arranged to form a DOI detector using the Anger principle. The useful field of view is 20 mm x 15 mm. With these configurations, we could resolve 4 x 3 GSO arrays on a position histogram.


RESULTS
Because the imaging detectors were positioned at the tip of the tweezers, one could easily sample the target part manually from opposed sides. A real-time image in coincidence between these two DOI detectors could be obtained. The point spread functions were approximately 3-mm full width at half-maximum (FWHM) parallel to the tweezers and 4-mm FWHM perpendicular to them. The sensitivity was approximately 1% when the two imaging detectors were 10 mm apart.


CONCLUSIONS
With these results, we conclude that the developed tweezers-type imaging detector has a potential to be a new instrument in nuclear medicine.
Yamamoto
Seiichi
S
Kobe City College of Technology, 8-3 Gakuen-Higashi-machi, Nishi-ku, Kobe 651-2194, Japan. s-yama@kobe-kosen.ac.jp
Sakamoto
Yusuke
Y
Matsumoto
Keiichi
K
Senda
Michio
M
D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers