26 September 2013 Preliminary investigation fo the non-linear response of image intensifiers used for gamma-ray imaging
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Image intensifiers combined with columnar scintillators have found application in x-ray and gamma-ray, biomedical imaging and other fields. In scintillator imaging, hundreds or thousands of optical photons can illuminate the faceplate of the image intensifier in a small area, essentially simultaneously. This is a situation not found in the typical design application for an image intensifier, night vision or low-light-level imaging. Microchannel plates (MCPs) are known to exhibit gain saturation that could result in non-linear signal response in scintillator imaging, limiting quantitative measurement capabilities. A calibrated LED photon source was developed that can provide a known average number of photons per unit area in a small spot size, similar to that seen due to a gamma-ray interaction in a BazookaSPECT imager. A BazookaSPECT imager is composed of a columnar scintillator and an image intensifier, with output light optically imaged onto a CCD camera. The calibrated source was used to investigate gain-saturation effects for two Proxivision, GmbH image intensifiers, a single-stage BV 2583 EZ and a two stage BV 2583 QZ-V 100N in a BazookaSPECT imaging configuration. No gain saturation was found for the single-stage image intensifier up to more than 100 optical photons per microchannel, but significant gain-saturation non-linearities were measured in the two-stage image intensifier at high gains for >12 optical photons per microchannel. Implications for scintillator imaging using such systems are discussed.
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David Fastje, David Fastje, H. Bradford Barber, H. Bradford Barber, Vaibhav Bora, Vaibhav Bora, Daniel Lemieux, Daniel Lemieux, Brian Miller, Brian Miller, Gary P. Grim, Gary P. Grim, "Preliminary investigation fo the non-linear response of image intensifiers used for gamma-ray imaging", Proc. SPIE 8854, Penetrating Radiation Systems and Applications XIV, 88540J (26 September 2013); doi: 10.1117/12.2030175; https://doi.org/10.1117/12.2030175

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