SPECT instrumentation: performance, lesion detection, and recent innovations

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · Semin. Nucl. Med.; (United States)

DOI:https://doi.org/10.1016/S0001-2998(87)80033-8· OSTI ID:5977124

Heller, S L; Goodwin, P N

The use of a gamma camera for single photon emission computed tomography (SPECT) imaging places greater demand on camera performance than does planar imaging, since camera specifications that are adequate for planar imaging may produce serious image artifacts in SPECT. Manufacturers have responded to the challenge with improvements in both hardware and software, but the user must pay careful attention to quality control procedures. Field nonuniformity is caused mainly by spatial distortion, which may vary during rotation; some cameras incorporate a means of automatically correcting for angular changes. The purpose of performing SPECT is to improve lesion detection, ie, to improve contrast, which is influenced by many factors. Attenuation corrections may be applied either before or after reconstruction. For Tc-99m an attenuation coefficient less than that for water, ie, either 0.11 or 0.12, would appear to give better results; the visual appearance is improved but the effect on contrast is minimal. Scattered photons are the major cause of loss of contrast in SPECT images. Recent developments in on-line energy corrections allow the use of narrower photopeak windows as well as asymmetric energy windows. Offpeak energy windows have demonstrated significant improvements in contrast; however, the increase in nonuniformity can cause artifacts which may limit their use. Simultaneous collection of separate images, one in the photopeak region and the other in the scatter region (92 to 125 keV) may enable a transaxial scatter image to be subtracted from the transaxial photopeak image. This may permit quantification of the true radioactivity distribution. 67 references.

• Research Organization: Albert Einstein College of Medicine, Bronx, NY
• OSTI ID: 5977124
• Journal Information: Semin. Nucl. Med.; (United States), Journal Name: Semin. Nucl. Med.; (United States) Vol. 17:3; ISSN SMNMA
• Country of Publication: United States
• Language: English

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62 RADIOLOGY AND NUCLEAR MEDICINE
CAMERAS
COMPUTERIZED TOMOGRAPHY
CONTROL
DIAGNOSTIC TECHNIQUES
EMISSION COMPUTED TOMOGRAPHY
GAMMA CAMERAS
PERFORMANCE
QUALITY CONTROL
SCATTERING
SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY
TOMOGRAPHY