Feasibility of gamma camera system with CdWO4 detector for quantitation of yttrium-90 bremsstrahlung imaging: Monte Carlo simulation study

Abstract

Yttrium-90 (Y-90) has attracted great attention as a therapeutic radionuclide because of higher emitted particle energy and pure beta emitter. In Y-90 bremsstrahlung imaging, NaI(Tl) and GSO detectors are widely used in detecting photon but these detectors cannot be easily applied to this imaging because of relatively low sensitivity. Among detector candidates, cadmium tungstate (CdWO4) can acquire high detection efficiency due to the high density and good light yield. The purpose of this study was to evaluate the feasibility of gamma camera system with CdWO4 detector for quantitation of Y-90 bremsstrahlung imaging using a Geant4 Application for Tomographic Emission (GATE). To evaluate performance of the imaging system, a Y-90 point source was designed in GATE simulation. These detectors using CdWO4, NaI(Tl), and GSO were equipped with low energy general purpose (LEGP), medium energy general purpose (MEGP), and high energy general purpose (HEGP) parallel-hole collimators. According to the results, the average sensitivities of the CdWO4 detector with LEGP, MEGP, and HEGP were 43.76, 37.16, and 28.22cps/MBq, respectively. In addition, the sensitivity was higher for CdWO4 detector system than for NaI(Tl) or GSO detector systems for all parallel-hole collimator system with 55–285keV energy window. However, differences of scatter fraction for three detectors were very similar. Our results showed that the effect and feasibility of CdWO4 detector for Y-90 bremsstrahlung imaging can be investigated by a GATE simulation. In conclusion, the results of this study suggest that CdWO4 detector can be achieved improved performance of Y-90 bremsstrahlung imaging.