Design of an ultra-near-field system for planar coded aperture nuclear medicine imaging

D. M. Starfield, D. M. Rubin, T. Marwala

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

3 Citations (Scopus)


Collimators are typically used for the acquisition of nuclear medicine images. Coded apertures provide an alternative means of acquisition, and under specific conditions are associated with a signal-to-noise-ratio advantage. However, under the near-field conditions of nuclear medicine, the point spread function is no longer ideal, and near-field artifacts result. Our previous work has highlighted three potential advances, but in each case, application results in the loss of count statistics. An array of limited-field-of-view coded apertures reduces near-field artifacts, but decreases the number of counts of radioactivity that are acquired. A thin and highly transparent coded aperture allows for ease of manufacture, a potential increase in resolution, and a reduction of thickness artifacts. A greater number of counts must be acquired if the signal-to-noise-ratio is to be maintained. Coded aperture resolution can be enhanced without modification of either the open fraction of the material or the field-of-view of the system. The size of each element in the array is decreased, and the total number of elements in the coded aperture pattern is increased. However, a smaller pattern element collects fewer counts of radioactivity. The design of an ultra-near-field system is proposed, which increases counting efficiency, provided that gamma camera sensitivity is able to follow suit. The design is tested by means of a ray-tracing computer simulator, which utilizes a two-dimensional digital Shepp-Logan phantom as a distributed source. Simulation results are presented for the prior state-of-the-art, and for the proposed design, under both near-field and ultra-near-field geometries. Severe artifacts arise under ultra-near-field conditions. Nevertheless, results show that the proposed design leads to both artifact reduction and an enhancement of resolution, relative to the state-of-the-art and without adjustment of either dose or acquisition time.

Original languageEnglish
Title of host publication14th Nordic-Baltic Conference on Biomedical Engineering and Medical Physics, NBC 2008
PublisherSpringer Verlag
Number of pages4
ISBN (Print)9783540693666
Publication statusPublished - 2008
Externally publishedYes

Publication series

NameIFMBE Proceedings
Volume20 IFMBE
ISSN (Print)1680-0737


  • Artifact reduction
  • Coded apertures
  • Count statistics
  • Nuclear medicine imaging
  • Ultra-near-field system

ASJC Scopus subject areas

  • Bioengineering
  • Biomedical Engineering


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