Publication Details

Rozenfeld, AB, Lerch, MLF, Chan, M, Inwood, D, Takacs, GJ, Lee, B, Gektin, AF & Perevertaylo, V, A dual scintillator - dual silicon photodiode detector module for intraoperative gamma\beta probe and portable anti-compton spectrometer, Journal of Nuclear Science and Technology, S5, 2008, 458-461.


A new approach has been investigated for the miniaturization and simplification of intraoperative gamma and beta probes that have recently found application in radioguided surgery and sentinel lymph node biopsy. The probe design that is based on dual annular scintillators coupled to specially designed silicon concentric dual photodiode (CDPD). This approach allows us to avoid fiber optics coupling and PMTs. Two channels readout front-end electronics including shaper amplifier attached directly to the back of the detector module has been proposed. Two geometries of Si dual photodiodes coupled to CsI(Tl) annular scintillators with light masking between them were fabricated and investigated. CDPDs have size 10 and 6 mm as well as 6 and 3 mm outer and inner diameters respectively. The spectroscopy properties of CDPD separately and coupled to CsI(Tl) dual scintillator were investigated on I-125, Co- 57 and Na-22 photon sources. Both detectors have demonstrated acceptable energy resolution (10% for 511-keV) for the proposed application with FDG isotopes. In the smaller detector the amplitude of the 511 keV photopeak from outer detector was less than in inner and is related to the light collection in the current geometry. When used in coincidence mode operation we observe a significant reduction in the measured Compton continuum level relative to the photopeak which is not significantly attenuated. The spatial resolution of detector module measured in the horizontal plane was 2-mm FWHM using a 0.5-mm collimated Tc-99m source.

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