Ultracompact Compton camera for innovative gamma-ray imaging (original) (raw)
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Electron-tracking Compton gamma-ray camera for small animal and phantom imaging
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2010
We have developed an electron-tracking Compton camera (ETCC) for medical use. Our ETCC has a wide energy dynamic range (200-1300 keV) and wide field of view (3 steradian), and thus has potential for advanced medical use. To evaluate the ETCC, we imaged the head (brain) and bladder of mice that had been administered with F-18-FDG. We also imaged the head and thyroid gland of mice using double tracers of F-18-FDG and I-131 ion.
Physics in medicine and biology, 2016
In proton therapy, the prompt-γ (PG) radiation produced by the interactions between protons and matter is related to the range of the beam in the patient. Tomographic Compton imaging is currently studied to establish a PG image and verify the treatment. However the quality of the reconstructed images depends on a number of factors such as the volume attenuation, the spatial and energy resolutions of the detectors, incomplete absorptions of high energy photons and noise from other particles reaching the camera. The impact of all these factors was not assessed in details. In this paper we investigate the influence of the PG energy spectrum on the reconstructed images. To this aim, we describe the process from the Monte Carlo simulation of the proton irradiation, through the Compton imaging of the PG distribution, up to the image reconstruction with a statistical MLEM method. We identify specific PG energy windows that are more relevant to detect discrepancies with the treatment plan. ...
Potential of a Compton camera for high performance scintimammography
Physics in Medicine and Biology, 2004
In this paper, we present a novel approach to scintimammography that is based on the Compton camera principle. We analyse the performance of our scheme using Monte Carlo simulations. In particular, we evaluate the detection efficiency, spatial resolution and lesion visibility of the system at several gamma photon energies. The simulation results show that the proposed technique achieves an absolute detection efficiency of 0.03 and a full width at half maximum resolution of 3.8 mm at 141 keV photon energy for point sources 2.5 cm deep in a 5 cm thick breast phantom using 5 mm thick silicon detectors. Furthermore, our approach shows good performance in lesion detection, especially at high gamma photon energies, where mechanically collimated systems perform poorly due to severe septal penetration. With total collected counts of 1.35 million, equivalent to a 30 s acquisition time for an activity concentration level of 3.7 kBq ml −1 (100 nCi cm −3) in normal breast tissue, and a tumour-to-background ratio of 8:1, our system can clearly reveal an 8 mm diameter tumour that is located 2.5 cm deep in a 500 ml breast phantom. We also present a simulation-based quantitative performance comparison between the proposed scintimammographic system and the compact collimated scintimammographic system in the task of lesion detection under a clinical imaging situation using a non-prewhitening matched filter observer model. Our comparison demonstrates that for the same imaging time, the two systems have a comparable performance in detecting an 8 mm tumour at 141 keV, with the proposed system performing marginally better. However, the proposed scintimammographic system clearly outperforms the compact collimated counterpart in the detection of a 5 mm tumour. We also investigate the contribution of scatter and direct radiation from adjacent organs. We find that the background contribution of liver to the right breast is 30% at 141 keV, which can be reduced to 4.8% with shielding.
Design and performance tests of the calorimetric tract of a Compton Camera for small-animals imaging
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011
The bio-distribution and targeting capability of pharmaceuticals may be assessed in small animals by imaging gamma-rays emitted from radio-isotope markers. Detectors that exploit the Compton concept allow higher gamma-ray efficiency compared to conventional Anger cameras employing collimators, and feature sub-millimeter spatial resolution and compact geometry.
Optimization of the Compton camera for measuring prompt gamma rays in boron neutron capture therapy
A B S T R A C T Optimization of the Compton camera for measuring prompt gamma rays (0.478 MeV) emitted during boron neutron capture therapy (BNCT) was performed with Geant4. The parameters of the Compton camera were determined as follows: 3 cm thick – 10 cm wide scatter detector (Silicon), 10 cm thick – 10 cm wide absorber detector (Germanium), and 1 cm distance between the scatter and absorber detectors. For a typical brain tumor treatment, the overall detection efficiency of the optimized Compton camera was approximately 0.1425% using the Snyder's head phantom with a sphere tumor (4 cm diameter and ~1 cm depth).
Silicon detector for a Compton camera in nuclear medical imaging
IEEE Transactions on Nuclear Science, 2002
Electronically collimated gamma cameras based on Compton scattering in silicon pad sensors may improve imaging in nuclear medicine and bio-medical research. The work described here concentrates on the silicon pad detector developed for a prototype Compton camera. The silicon pad sensors are read out using low noise VLSI CMOS chips and novel fast triggering chips. Depending on the application a light weight and dense packaging of sensors and its readout electronics on a hybrid is required. We describe the silicon pad sensor and their readout with the newly designed hybrid. We also describe a modular and lowcost data acquisition system (CCDAQ) based on a digital signal processor which is interfaced to the EPP port of personal computers. Using the CCDAQ and the hybrids energy spectra of gamma-ray photons from technetium (99m 43 Tc) and americium (241 95 Am) were acquired with an energy resolution of 2.45 keV FWHM for the 140.5 keV photo-absorption line of 99m 43 Tc. For all pads the discrimination threshold in the trigger chip was between (15 and 25) keV.
First coincidences in pre-clinical Compton camera prototype for medical imaging
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2004
Compton collimated imaging may improve the detection of gamma rays emitted by radioisotopes used in single photon emission computed tomography (SPECT). We present a crude prototype consisting of a single 500 mm thick, 256 pad silicon detector with pad size of 1:4 Â 1:4 mm 2 ; combined with a 15 Â 15 Â 1 cm 3 NaI scintillator crystal coupled to a set of 20 photo multipliers. Emphasis is placed on the performance of the silicon detector and the associated read-out electronics, which has so far proved to be the most challenging part of the set-up. Results were obtained using the VATAGP3, 128 channel low-noise self-triggering ASIC as the silicon detector's front-end. The noise distribution ðsÞ of the spectroscopic outputs gave an equivalent noise charge (ENC) with a mean value of /sS ¼ 137 e with a spread of 10 e; corresponding to an energy resolution of 1:15 keV FWHM for the scattered electron energy. Threshold settings above 8:2 keV were required for stable operation of the trigger. Coincident Compton scatter events in both modules were observed for photons emitted by 57 Co source with principal gamma ray energies of 122 and 136 keV: r 2004 Published by Elsevier B.V. Fig. 13. Drawing of the envisaged prostate probe. Left: External detector (scintillator-PM module) and a patient table. Right: Internal probe-densely packed scatterer array of silicon with lead shielding. A. Studen et al. / Nuclear Instruments and Methods in Physics Research A ] (]]]]) ]]]-]]] 7 NIMA : 21769
Physics in Medicine and Biology, 2008
In radionuclide treatment, tumor cells are primarily destroyed by charged particles emitted by the compound while associated higher energy photons are used to image the tumor in order to determine radiation dose and monitor shrinkage. However, the higher energy photons are difficult to image with conventional collimated Anger cameras, since a tradeoff exists between resolution and sensitivity, and the collimator septal penetration and scattering is increased due to the high energy photons. This research compares imaging performance of the conventional Anger camera to a Compton imaging system that can have improved spatial resolution and sensitivity for high energy photons because this tradeoff is decoupled, and the effect of Doppler broadening at higher gamma energies is decreased. System performance is analyzed by the modified uniform Cramer-Rao bound (M-UCRB) algorithms based on the developed system modeling. The bound shows that the effect of Doppler broadening is the limiting factor for Compton camera performance for imaging 364.4 keV photons emitted from 131 I. According to the bound, the Compton camera outperforms the collimated system for an equal number of detected events when the desired spatial resolution for a 26 cm diameter uniform disk object is better than 12 mm FWHM. For a 3D cylindrical phantom, the lower bound on variance for the collimated camera is greater than for the Compton imaginer over the resolution range from 0.5 to 2 cm FWHM. Furthermore, the detection sensitivity of the proposed Compton imaging system is about 15-20 times higher than that of the collimated Anger camera.