JPNM Physics

A World Wide Web-Based Resource for the Physical Evaluation of 511 keV-Collimated Imaging


1996 Journal of Nuclear Medicine; Volume 37(5) 305P.

Document created June 6, 1996

Wagenaar DJ, Van den Abbeele AD, Kolodny GM, Hill TC, Zimmerman RE.

Joint Program in Nuclear Medicine and New England Deaconess Hospital, Harvard Medical School, Boston, Massachusetts

Imaging 511 keV gamma-rays with collimated cameras raises unique problems which have not been completely solved. This exhibit addresses these problems and is designed to be a comprehensive resource for those who are planning to work with positron emitters using standard gamma cameras.

The fundamental physics of the interactions of 511 keV photons with patient, collimator, detector, and shielding materials are described. Early work in 511 keV imaging is reviewed. Basic collimator parameters and their effect on system performance are described. The sensitivity and spatial resolution of these colimated cameras are compared to coincidence PET systems, and applications of these collimators in the clinic are summarized.

Acceptance tests and measurements performed on our four dual-head systems (ADAC, Elscint, Park, and Siemens) are reported. Intrinsic measurements include pulse height linearity and energy resolution. System penetration, gantry stability and multi-head registration (i.e., COR), planar and SPECT spatial resolution, contrast resolution, and system sensitivity with attention to penetration and scatter. Contrast measurements with an axially-extended medium and 68Ge filled spheres of varying sizes in an 18F filled water phantom are described in detail.

Recommendations for acceptance tests are regular quality control checks are offered to supplement those which have been published for imaging at lower energies. This online, WWW project will continue to evolve and be linked to similar resources as they are developed.

Douglas J. Wagenaar, Ph.D.,