Open AccessA comparative study of NaI(Tl), CeBr3, and CZT for use in a real-time simultaneous nuclear and fluoroscopic dual-layer detector
Author(s) -
Wilco J C Koppert,
Martijn M A Dietze,
Sandra van der Velden,
J H Leo Steenbergen,
Hugo W. A. M. de Jong
Publication year - 2019
Publication title -
physics in medicine and biology/physics in medicine and biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.312
H-Index - 191
eISSN - 1361-6560
pISSN - 0031-9155
DOI - 10.1088/1361-6560/ab267c
Subject(s) - detector , physics , gamma ray , optics , gamma camera , nuclear medicine , afterglow , flat panel detector , x ray detector , particle detector , scintillator , materials science , nuclear physics , medicine , gamma ray burst , astronomy
Simultaneous acquisition of nuclear and fluoroscopic projections could be of benefit for image-guided radionuclide administration. A gamma camera positioned behind an x-ray flat panel detector can accomplish such simultaneous acquisition, but the gamma camera performance suffers from the intense x-ray dose. A regular NaI(Tl)-based camera has nominal performance up to 0.02 nGy dose per pulse, whereas 10 nGy dose is expected for our foreseen applications. We evaluated the performance of CeBr 3 - and CZT-based detectors and investigated a cost-effective improvement of a regular NaI(Tl)-based camera by the introduction of a high-pass filter and shorting circuit. A CeBr 3 -based detector was exposed to 5 mGy x-ray dose and the resulting light emission was measured over time to quantify the crystal afterglow, allowing comparison with a previously measured NaI(Tl)-based detector. The NaI(Tl)-, CeBr 3 - and CZT-based detectors were exposed to x-ray pulse sequences with dose from 0.06 to 60 nGy, while being irradiated with a gamma source. The mean gamma energy and energy resolution in between the x-ray pulses were measured as a reference of the detector performance. The afterglow signal after 3 ms was 14.1% for the NaI(Tl)-based detector, whereas for the CeBr 3 -based detector it was only 0.1%. The limits for a proper functioning detectors are 0.32 nGy for the NaI(Tl)-based detector with high-pass filter and shorting circuit and 18.94 nGy for the one with CeBr 3 . No energy degradation was observed for the CZT module in the studied dose range. The performance of regular NaI(Tl)-based gamma cameras deteriorates when exposed to high x-ray doses. CeBr 3 and CZT are much better suited for introduction into a dual-layer detector but have high associated costs. Addition of a high-pass filter and shorting circuit into the PMT of a NaI(Tl)-based detector is a cost-effective solution that works well for low dose levels.