Sci-PM Thurs - 02: Spatial resolution in PET and the effect of gamma-ray interaction depth in block detectors

2005 ◽  
Vol 32 (7Part1) ◽  
pp. 2408-2408
Author(s):  
S St. James ◽  
C Thompson
Keyword(s):  
Spatial Resolution ◽  
Gamma Ray ◽  
Interaction Depth

Development of a simultaneous imaging system to measure the optical and gamma ray images of Ir-192 source for high-dose-rate brachytherapy

2021 ◽  
Vol 16 (12) ◽  
pp. T12005
Author(s):  
J. Nagata ◽  
S. Yamamoto ◽  
Y. Noguchi ◽  
T. Nakaya ◽  
K. Okudaira ◽  
...  
Keyword(s):  
Dose Rate ◽  
Spatial Resolution ◽  
Gamma Camera ◽  
Gamma Ray ◽  
Imaging System ◽  
High Dose Rate ◽  
High Dose ◽  
Cmos Camera ◽  
Absolute Position ◽  
The Absolute

Abstract In high-dose-rate (HDR) brachytherapy, verification of the Ir-192 source's position during treatment is needed because such a source is extremely radioactive. One of the methods used to measure the source position is based on imaging the gamma rays from the source, but the absolute position in a patient cannot be confirmed. To confirm the absolute position, it is necessary to acquire an optical image in addition to the gamma ray image at the same time as well as the same position. To simultaneously image the gamma ray and optical images, we developed an imaging system composed of a low-sensitivity, high-resolution gamma camera integrated with a CMOS camera. The gamma camera has a 1-mm-thick cerium-doped yttrium aluminum perovskite (YAIO3: YAP(Ce)) scintillator plate optically coupled to a position-sensitive photomultiplier (PSPMT), and a 0.1-mm-diameter pinhole collimator was mounted in front of the camera to improve spatial resolution and reduce sensitivity. We employed the concept of a periscope by placing two mirrors tilted at 45 degrees facing each other in front of the gamma camera to image the same field of view (FOV) for the gamma camera and the CMOS camera. The spatial resolution of the imaging system without the mirrors at 100 mm from the Ir-192 source was 3.2 mm FWHM, and the sensitivity was 0.283 cps/MBq. There was almost no performance degradation observed when the mirrors were positioned in front of the gamma camera. The developed system could measure the Ir-192 source positions in optical and gamma ray images. We conclude that the developed imaging system has the potential to measure the absolute position of an Ir-192 source in real-time clinical measurements.

Mapping iron abundances on the surface of Mercury: Predicted spatial resolution of the MESSENGER Gamma-Ray Spectrometer

2011 ◽  
Vol 59 (13) ◽  
pp. 1654-1658 ◽  
Author(s):  
Patrick N. Peplowski ◽  
David T. Blewett ◽  
Brett W. Denevi ◽  
Larry G. Evans ◽  
David J. Lawrence ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Gamma Ray ◽  
Gamma Ray Spectrometer

scholarly journals Design and Optimisation of a Three Layers Thermal Neutron, Fast Neutron and Gamma-Ray Imaging System

2020 ◽  
Vol 225 ◽  
pp. 07002
Author(s):  
H. Al Hamrashdi ◽  
S. D. Monk ◽  
D. Cheneler
Keyword(s):  
Spatial Resolution ◽  
Gamma Ray ◽  
Imaging System ◽  
Detection System ◽  
Fast Neutrons ◽  
Silicon Photomultiplier ◽  
Current Configuration ◽  
Lithium Glass ◽  
Gamma Ray Imaging ◽  
Small Form Factor

The design and configuration of a multi-layered imaging system with the ability to detect thermal neutrons, fast neutrons and gamma rays has been developed and its efficacy demonstrated. The work presented here numerically determines the systems efficiency and spatial resolution, using 252Cf and 137Cs as a case study. The novelty of this detection system lies in the use of small form factor detectors in a three-layer design, which utilises neutron elastic scattering and Compton scattering simultaneously. The current configuration consists of 10 mm thick natural lithium glass (GS10) scintillator integrated with a 20 mm thick plastic scintillator (EJ-204) in the first layer, a 15 mm thick lithium glass (GS10) scintillator in the second and a 30 mm thick CsI(Tl) scintillator forming the final layer. Each of these layers is backed with an 8 x 8 silicon photomultiplier diode (SiPM) array. The overall size of the imaging system is 27 mm x 27 mm x 135 mm. MCNPv6.1 and Geant4-10.04 were alternatively used to optimise the overall configuration and to investigate detection modalities. Results show promising performance with high precision source localisation and characterization abilities. Measurements were virtually obtained of two gamma-ray sources within steel enclosures at angles of 15°, 30° and 50° separation in order to test spatial resolution ability of the system. With the current active size of the system and the 8x8 SiPM configuration, the results estimate the spatial resolution to be close to 30°. The ability of the system to characterise and identify sources based on the type and energy of the radiation emitted, has been investigated and results show that for all radiation types the system can identify the source energy within the energy range of typical reported sources in literature.

High-speed UV imaging of elves and lightning from space: first simultaneous detections from the Mini-EUSO and ASIM instruments

2020 ◽  
Author(s):  
Matteo Battisti ◽  
Enrico Arnone ◽  
Mario Bertaina ◽  
Marco Casolino ◽  
Olivier Chanrion ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Speed ◽  
Multispectral Imaging ◽  
Gamma Ray ◽  
Single Photon ◽  
Uv Light ◽  
Photon Counting ◽  
Space Station ◽  
Wide Field ◽  
First Time

<p>The search for the physical mechanisms of lightning, transient luminous events and terrestrial gamma-ray flashes is receiving an extraordinary support by new space observations that have recently become available. Next to lightning detectors on geostationary satellites, new low orbit experiments are giving an unprecedented insight in the very source of these processes. Looking at the physics behind these new observations requires however to have a variety of different instruments covering the same event, and this is proving extremely challenging. Here, we present observations of UV emissions of elves and lightning taken for the first time simultaneously from the two instruments Mini-EUSO and ASIM operating on the international space station. Mini-EUSO was designed to perform observations of the UV-light night emission from Earth. It is a wide field of view telescope (44°x44° square FOV) installed for the first time on October 2019 inside the Zvezda Module of the ISS, looking nadir through a UV transparent window. Its optical system consists of two Fresnel lenses for light collection. The light is focused onto an array of 36 multi-anode photomultiplier tubes (MAPMT), for a total of 2304 pixels. Each pixel has a footprint on ground of ~5.5 km. The instrument is capable of single-photon counting on three different timescales: a 2.5 microsecond (D1) and a 320 microsecond (D2) timescale with a dedicated trigger system, and a 40.96ms timescale (D3) used to produce a continuous monitoring of the UV emission from the Earth. ASIM is an experiment dedicated to lightning and atmospheric processes. Its Modular Multispectral Imaging Array (MMIA) is made of an array of 3 high speed photometers probing different wavelength sampling at rates up to 100 kHz, and 2 Electron Multiplication Charge Coupled Devices (EM-CCDs) with a sub-km spatial resolution with an 80° FOV and recording up to 12 frames per second. Mini-EUSO detected several bright atmospheric events like lightning and elves, with a few km spatial resolution and different time resolutions, probing therefore different stages of the electromagnetic phenomena. Observations from Mini-EUSO were simultaneously captured by ASIM instruments, allowing for the first time to compare and complement the capabilities of the two instruments with a time inter-calibration based on unambiguous series of lightning detections.</p>

scholarly journals Gamma-Ray Precursors of Solar Flares

1994 ◽  
Vol 142 ◽  
pp. 645-648
Author(s):  
E. Rieger
Keyword(s):  
Spatial Resolution ◽  
Gamma Rays ◽  
Solar Flares ◽  
Gamma Ray ◽  
High Energy ◽  
X Rays ◽  
High Energy Gamma ◽  
Gamma Ray Spectrometer ◽  
Energy Gamma ◽  
Negligible Contribution

AbstractBursts have been observed by the gamma-ray spectrometer on SMM at medium- and high-energy gamma-rays that precede the flare maximum. The negligible contribution of nuclear lines in the spectra of these events and their impulsive appearance suggests that they are hard-electron-dominated events superposed on the flares. Spatial resolution at gamma-ray energies will be necessary to decide whether this kind of bursts is cospatial with the flares or whether they occur in the flares’ vicinity.Subject headings: Sun: flares — Sun: X-rays, gamma rays

scholarly journals Centaurus A at Hard X-Rays and Soft Gamma-Rays

2010 ◽  
Vol 27 (4) ◽  
pp. 431-438 ◽  
Author(s):  
H. Steinle
Keyword(s):  
Energy Range ◽  
Spatial Resolution ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
X Rays ◽  
Satellite Mission ◽  
X Ray

AbstractCen A, at a distance of less than 4 Mpc, is the nearest radio-loud AGN. Its emission is detected from radio to very-high energy gamma-rays. Despite the fact that Cen A is one of the best studied extragalactic objects the origin of its hard X-ray and soft gamma-ray emission (100 keV <E< 50 MeV) is still uncertain. Observations with high spatial resolution in the adjacent soft X-ray and hard gamma-ray regimes suggest that several distinct components such as a Seyfert-like nucleus, relativistic jets, and even luminous X-ray binaries within Cen A may contribute to the total emission in the MeV regime that has been detected with low spatial resolution. As the Spectral Energy Distribution of Cen A has its second maximum around 1 MeV, this energy range plays an important role in modeling the emission of (this) AGN. As there will be no satellite mission in the near future that will cover this energies with higher spatial resolution and better sensitivity, an overview of all existing hard X-ray and soft gamma-ray measurements of Cen A is presented here defining the present knowledge on Cen A in the MeV energy range.

Deconvolution and spatial resolution of airborne gamma‐ray surveys

Geophysics ◽  
2003 ◽  
Vol 68 (4) ◽  
pp. 1257-1266 ◽  
Author(s):  
Stephen D. Billings ◽  
Brian R. Minty ◽  
Garry N. Newsam
Keyword(s):  
Spatial Resolution ◽  
Gamma Ray ◽  
Signal To Noise Ratio ◽  
Wiener Filter ◽  
Flying Height ◽  
Autocorrelation Functions ◽  
Thorium Concentration ◽  
Propagation Analysis ◽  
Error Propagation Analysis ◽  
Averaged Power Spectrum

The first part of the paper presents a method for frequency domain deconvolution of airborne gamma‐ray surveys using a Wiener filter. A geometrical detector model is used to model gamma‐ray detection, with aircraft movement simply incorporated by a multiplicative term. The method requires estimation of the autocorrelation functions governing both signal and noise. The former is estimated through the radially averaged power spectrum of the survey data, whereas an error propagation analysis is used to estimate the latter, which is assumed white. Slight manual adjustments to the noise level are used to tune the reconstruction. The technique is applied to a low‐altitude radiometric survey collected along closely spaced transects. Results are good for thorium, but are poor for both potassium and uranium. This can be attributed to the high noise levels in the potassium and uranium estimates, principally due to scattered gamma‐rays from high thorium concentration. Much better results are obtained when the method is applied to a survey with more typical radioelement concentrations. The reconstructions are improved significantly if an adaptive 2D Lee filter is applied prior to deconvolution. The second part of the paper addresses how noise in the data and attenuation of signal due to the flying height limit the spatial resolution. The autocorrelation functions of signal and noise, along with the gamma‐ray model, can be used to determine how signal‐to‐noise ratio degrades with increasing height. The frequency where signal and noise are present in equal quantity can be used as an estimate of the spatial resolution. Predicted critical sampling rates range from 30 m at 20 m elevation to 60 m at 60 m elevation and 90 m at 120 m elevation.

A modeling method to calibrate the interaction depth in 3-D position sensitive CdZnTe gamma-ray spectrometers

2000 ◽  
Vol 47 (3) ◽  
pp. 890-894 ◽  
Author(s):  
W. Li ◽  
Z. He ◽  
G.F. Knoll ◽  
D.K. Wehe ◽  
Y.F. Du
Keyword(s):  
Gamma Ray ◽  
Modeling Method ◽  
Position Sensitive ◽  
Interaction Depth
Sign in / Sign up

Export Citation Format

Share Document