Basic principles of computed axial tomography

Journal Article · Thu Mar 31 23:00:00 EST 1977 · Semin. Nucl. Med.; (United States)

DOI:https://doi.org/10.1016/S0001-2998(77)80013-5· OSTI ID:7212867

Ter-Pogossian, M M

Computer tomography (CT) is a radiological imaging method which yields transverse tomographic images reflecting with high accuracy the spatial distribution of x-ray attenuation in the part examined. The contrast resolution achieved by CT permits the visualization of soft tissue structure heretofore invisible with conventional radiographic procedure. The CT image is reconstructed by a computer applied algorithm, from a series of x-ray attenuation measurements obtained at different angles around the subject, by means of radiation detectors. The signal to noise ratio for these measurements is optimized by reducing the contribution of scattered radiation and of system noise. The CT principle of image reconstruction is also applicable in nuclear medicine imaging, with the goal of achieving contrast improvement and quantitative assessment of radionuclide distribution over conventional ''projection'' techniques. A mathematically rigorous tomographic reconstruction which would account for variables is unavailable for gamma ray-emitting radionuclides, although approximate solutions of that problem have led to the satisfactory images of the head. Images of larger inhomogeneous organs are less quantitative. The detection of coincidence annihilation counting of positron-emitting radionuclides allows the accurate correction for the attenuation of that radiation in tissues and permits depth independent collimation which renders these radionuclides particularly suitable for their imaging by CT. A number of CT devices designed for the imaging of positron emitting radionuclides are yielding nuclear medicine images of quality and potential clinical usefulness unequaled by more conventional projection techniques.

• Research Organization: Washington Univ., St. Louis
• OSTI ID: 7212867
• Journal Information: Semin. Nucl. Med.; (United States), Journal Name: Semin. Nucl. Med.; (United States) Vol. 7:2; ISSN SMNMA
• 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
ALGORITHMS
COLLIMATORS
COMPUTERS
DIAGNOSTIC TECHNIQUES
ELECTROMAGNETIC RADIATION
GAMMA RADIATION
IMAGES
IONIZING RADIATIONS
ISOTOPES
MATHEMATICAL LOGIC
MEASURING INSTRUMENTS
RADIATION DETECTORS
RADIATIONS
RADIOISOTOPES
SPECIFICATIONS
TOMOGRAPHY
X RADIATION