Instrumentation and reconstruction aspects of imaging single photon emitters with electronic collimation

Conference · Wed May 01 04:00:00 EDT 1985 · J. Nucl. Med.; (United States)

OSTI ID:6919450

Singh, M; Brechner, R; Doria, D; Inayat, M A; Tai, W M

To overcome limitations of mechanical collimation in single photon imaging, a prototype electronically collimated gamma camera has been implemented by replacing the lead collimator with a unique 4x4 germanium detector. Coincident counts are recorded between the germanium detector and the uncollimated scintillation camera (Model Pho/gamma HP), stored in ''list'' mode and sorted as a function of position and energy within the germanium array. Each coincident count multiplexes activity on a conical surface through the object. As a first step to SPECT, demultiplexing is carried out to produce multiple-view pin-hole images of the object. In a new approach to demultiplexing, the planar distribution of coincident counts is mapped onto a spherical surface, thereby producing data which represent a convolution of the pin-hole projection with a circular point spread function on a spherical surface. Deconvolution is subsequently achieved either by iterative methods or a Fourier-filtering approach. Using these methods, pin-hole images have been obtained with point, line and uniformly distributed planar (8.8 cm diam) sources of Tc-99m, and a point source of Cs-137 (662 keV). The pin-hole image of a centrally located point source of Tc-99m produced a spatial resolution of 8.9 +- 1.2mm at a distance of 6cm from the germanium detector. Also, using the prototype system, the sensitivity of a 32x32 germanium detector based camera was deduced to be a factor of 70 higher than a conventionally collimated camera for imaging Tc-99m distributed in a 5cm diam cylinder at equivalent resolution. Thus, electronic collimation increases sensitivity, enables imaging at high energies and facilitates dynamic SPECT.

• Research Organization: Univ. of Southern California, Los Angeles, CA
• OSTI ID: 6919450
• Report Number(s): CONF-850611-
• Conference Information: Journal Name: J. Nucl. Med.; (United States) Journal Volume: 26:5
• Country of Publication: United States
• Language: English

Related Subjects

440101* -- Radiation Instrumentation-- General Detectors or Monitors & Radiometric Instruments
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
550601 -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ALKALI METAL ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CAMERAS
CESIUM 137
CESIUM ISOTOPES
COINCIDENCE METHODS
COLLIMATORS
COMPUTERIZED TOMOGRAPHY
COUNTING TECHNIQUES
DESIGN
DIAGNOSTIC TECHNIQUES
EMISSION COMPUTED TOMOGRAPHY
FUNCTIONS
GAMMA CAMERAS
GE SEMICONDUCTOR DETECTORS
HOURS LIVING RADIOISOTOPES
IMAGE PROCESSING
IMAGES
IMPLEMENTATION
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
ITERATIVE METHODS
MEASURING INSTRUMENTS
NUCLEI
ODD-EVEN NUCLEI
OPERATION
PERFORMANCE
PROCESSING
RADIATION DETECTORS
RADIOISOTOPES
RESOLUTION
SEMICONDUCTOR DETECTORS
SENSITIVITY
SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY
SPATIAL RESOLUTION
TECHNETIUM 99
TECHNETIUM ISOTOPES
TOMOGRAPHY
YEARS LIVING RADIOISOTOPES