A high resolution radiation imaging detector using a ceramic YGAG scintillator plate

Abstract

A: Ce doped (YGd) 3 (GaAl) 5 O 12 :Ce (YGAG) is a ceramic scintillator originally developed for X-ray computed tomography (CT). It has high light output and is also a promising candidate for high resolution event-by-event radiation imaging detectors. Thus we developed a radiation imaging detector using a YGAG plate combined with a position sensitive photomultiplier tube (PSPMT) and evaluated the performance. The spatial resolution for Am-241 alpha particles (5.5 MeV) was ∼ 0.4 mm FWHM and the energy resolution was 12 % FWHM. The spatial resolution for Sr-Y-90 beta particles, Am-241 gammas (60 keV) and Cs-137 X-ray (∼ 35 keV) was 0.8 mm FWHM, 1.6 mm FWHM and 2.0 mm FWHM, respectively. The decay time difference of YGAG between 5.5 MeV alpha particles and 662 keV Cs-137 gammas was 37 ns and the pulse shape spectra for 5.5 MeV alpha particles and 662 keV Cs-137 gammas were separated without overlap with the figure of merit (FOM) of 1.14. It was possible to separate the alpha particle and gamma photon images using pulse shape discrimination. Using pulse shape discrimination, it was also possible to separate the alpha particles and gamma photons in the electrostatically collected radon daughters on the imaging detector. We conclude that the developed YGAG imaging detector is useful for high resolution radiation detector with pulse shape discrimination capability to discriminate the different types of radiations. K: Detector design and construction technologies and materials; Dosimetry concepts and apparatus; Scintillators and scintillating fibres and light guides; Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators) 1Corresponding author.

Performance evaluation for a radiation imaging detector using single-crystal GPS (Ce) plate

“…We successfully developed a GPS (Ce) radiation imaging detector with which we achieved a spatial resolution of ∼ 0.5 mm FWHM for 5.5 MeV α particles. This spatial resolution was almost similar to the previously developed LaGPS imaging detector (∼ 0.3 mm FWHM) [12], PSPMT-based GGAG (∼ 0.5 mm FWHM) [19] and YGAG imaging detector (∼ 0.4 mm FWHM) [24].…”

“…PSPMT's output signals were fed to a data-acquisition system for the calculations of position, energy, and pulse-shape spectra. These were the same conditions as those for the previously developed radiation imaging detectors using GGAG [19]- [20], YGAG [24], YAP (Ce) [25] and LaGPS [12]. Our developed GPS (Ce) radiation imaging detector without Al Mylar is shown in figure 2A.…”

“…With these advantages of alpha radionuclide therapy, alpha emitting radionuclides have been investigated with alpha particle imaging systems [16]- [18]. If its pulse-shape discrimination were also similar to LaGPS [12], GGAG [19,20], GAGG [21]- [23] or YGAG [24], separate different types of radiation would be an additional advantage of the scintillator. Therefore, we measured the decay times of GPS (Ce) for α particles and γ photons and also tested whether the pulse-shape analysis could separate the images of α particles and γ photons.…”

Feasibility evaluation of a direct detection method of alpha particles in water using YGAG plate with pulse shape analysis

“…The measured decay times of the YGAG measured with PMT were 107 ns for alpha particles and 70 ns for the beta particles and gamma photons. The 5.5 MeV alpha particles and the 662 keV gamma photons were separated in the pulse shape spectra without overlap with a figure of merit (FOM) of 1.14 with pulse shape spectra calculated by the dual integration method [15]. However, such excellent separation of the pulse shape spectra was for the direct coupling of the YGAG plate with a PSPMT [15].…”

“…The 5.5 MeV alpha particles and the 662 keV gamma photons were separated in the pulse shape spectra without overlap with a figure of merit (FOM) of 1.14 with pulse shape spectra calculated by the dual integration method [15]. However, such excellent separation of the pulse shape spectra was for the direct coupling of the YGAG plate with a PSPMT [15]. With the tested direct detection method of alpha particles in water, the fraction of the light collection was lowered, and the separation of the pulse shape spectra worsened.…”