Performance demonstration of a hybrid Compton camera with an active pinhole for wide-band X-ray and gamma-ray imaging

Abstract

X-ray and gamma-ray imaging are technologies with several applications in nuclear medicine, homeland security, and high-energy astrophysics. However, it is generally difficult to realize simultaneous wide-band imaging ranging from a few tens of keV to MeV because different interactions between photons and the detector material occur, depending on the photon energies. For instance, photoabsorption occurs below 100 keV, whereas Compton scattering dominates above a few hundreds of keV. Moreover, radioactive sources generally emit both X-ray and gamma-ray photons. In this study, we develop a “hybrid” Compton camera that can simultaneously achieve X-ray and gamma-ray imaging by combining features of “Compton” and “pinhole” cameras in a single detector system. Similar to conventional Compton cameras, the detector consists of two layers of scintillator arrays with the forward layer acting as a scatterer for high-energy photons (> 200 keV) and an active pinhole for low-energy photons (< 200 keV). The experimental results on the performance of the hybrid camera were consistent with those from the Geant4 simulation. We simultaneously imaged Am (60 keV) and Cs (662 keV) in the same field of view, achieving an angular resolution of 10 (FWHM) for both sources. In addition, imaging of At was conducted for the application in future nuclear medicine, particularly radionuclide therapy. The initial demonstrative images of the At phantom were reconstructed using the pinhole mode (using 79 keV) and Compton mode (using 570 keV), exhibiting significant similarities in source-position localization. We also verified that a mouse injected with 1 MBq of At can be imaged via pinhole-mode measurement in an hour.

Multi-modal 3D imaging of radionuclides using multiple hybrid Compton cameras

“…We developed a novel system consisting of four HCCs. Each camera in the system is similar to that reported by Omata et al 33 except for the size of the pinhole. As shown in Fig.…”

“…Yoshida et al (2020) described whole gamma imaging (WGI) as a combination of a PET scanner and Compton camera 32 . In our previous study, we proposed a hybrid Compton camera (HCC) that realizes simultaneous wide-band imaging that combines the advantages of a Compton camera and pinhole camera in a single detector system 33 . However, a simple imaging system that encompasses photons emitted by radionuclides from a few keV to several MeV is still challenging.…”

Design and Fabrication of CLYC-Based Rotational Modulation Collimator (RMC) System for Gamma-Ray/Neutron Dual-Particle Imager

“…Based on the measured modulation patterns, 2D radiation images will be reconstructed and the imaging performance of the CLYC-based RMC system will be evaluated. Maximum-likelihood expectation-maximization (MLEM) algorithm-based image reconstruction methods have been extensively studied and utilized in the field of radiation imaging because of their inherent excellence in low-count high-noise problems [7,[11][12][13][14][15][16][17]. We have been developing techniques which can further improve the efficiency and performance of the MLEM-based image reconstruction algorithm, by stabilizing inherent statistical noise contributions from the radiation counting [18][19][20].…”

Shape-controlled crystal growth of Y$_3$Al$_5$O$_{12}$:Ce single crystals with application of micro-pulling-down method and Mo crucibles, and their scintillation properties

“…Inorganic scintillator have been applied as radiation imaging sensors in many fields [1,2,3]. Some studies have developed imaging techniques that use scintillator arrays as collimators [4,5]. A tube-shaped single-crystal scintillator was required in these studies to achieve a high image quality.…”