First demonstration of multi-color 3-D in vivo imaging using ultra-compact Compton camera

Abstract

In the field of nuclear medicine, single photon emission tomography and positron emission tomography are the two most common techniques in molecular imaging, but the available radioactive tracers have been limited either by energy range or difficulties in production and delivery. Thus, the use of a Compton camera, which features gamma-ray imaging of arbitrary energies from a few hundred keV to more than MeV, is eagerly awaited along with potential new tracers which have never been used in current modalities. In this paper, we developed an ultra-compact Compton camera that weighs only 580 g. The camera consists of fine-pixelized Ce-doped Gd3Al2Ga3O12 scintillators coupled with multi-pixel photon counter arrays. We first investigated the 3-D imaging capability of our camera system for a diffuse source of a planar geometry, and then conducted small animal imaging as pre-clinical evaluation. For the first time, we successfully carried out the 3-D color imaging of a live mouse in just 2 h. By using tri-color gamma-ray fusion images, we confirmed that 131I, 85Sr, and 65Zn can be new tracers that concentrate in each target organ.

Recent Advances in Radioisotope Imaging Technology for Plant Science Research in Japan

“…This can allow simultaneous kinetic analysis of multiple elements in a test plant body. Several Compton cameras were developed as imaging devices for the environmental monitoring of 137 Cs after the Fukushima disaster [39][40][41][42][43]. The Compton imaging method is based on the idea of precisely measuring Compton scattering in the detector and obtaining the distribution of radioactive isotopes by estimating the direction of arrival of gamma rays ( Figure 6).…”

Precision imaging of 4.4 MeV gamma rays using a 3-D position sensitive Compton camera

“…Note that conventional dual-sided DOI detectors often use a crystal block consisting of uniform strip scintillators with no divisions in the DOI direction. In contrast, we constructed a crystal block with a polished surface consisting of multiple discrete scintillators to form a substantial gradient of output signals that depend on the DOI positions of the crystals 37 .…”

“…This was triggered by a nuclear accident in the Fukushima Daiichi Nuclear Plant in 2011. While the radioactive material distributed in the accident was mainly 137 Cs, which emits 662 keV gamma rays, various attempts were made to visualize sub-MeV to MeV gamma-rays quickly and accurately with the most recent detector technologies 33,[37][38][39][40][41][42] .…”

Enhancement of Compton camera images reconstructed by inversion of a conical Radon transform

“…Inversion methods that restrict the useful set of projections to cones with axes perpendicular on a manifold will generally neglect a large part of the acquired data and thus provide very noisy images. A particular case where they may be of interest is the one of small detectors that move around the patient (see e.g., [26]). Such detectors can anyway measure projections only for small values of α.…”