Surgical probe design for a coincidence imaging system without a collimator

J. R. Saffer, H. H. Barrett, H. B. Barber, J. M. Woolfenden

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Surgical probes used in nuclear medicine can be maneuvered close to a suspected tumor site, thereby achieving higher resolution and sensitivity than external gamma cameras. Tomography with handheld probes is not possible, however, so it is difficult to determine whether an increase in the photon count rate is caused by features near the probe or by variations in the distant background radiation. Our group has experimented with several probe designs that address this problem. This paper describes a probe that images nearby objects without a collimator, and which is insensitive to inhomogeneities in the distant background level. The probe, which is used with a radionuclide that emits multiple photons per decay, such as 111 In, consists of a collimatorless array of gamma-ray detectors connected by coincidence circuitry. We used a Monte Carlo routine to simulate data collection from such a system and reconstructed the images using the pseudoinverse obtained by singular value decomposition. The images show a significant suppression of distant sources when compared to a probe equipped with a conventional parallel-hole collimator.

Original languageEnglish (US)
Pages (from-to)333-341
Number of pages9
JournalImage and Vision Computing
Issue number6
StatePublished - 1992
Externally publishedYes


  • Monte Carlo
  • gamma rays
  • nuclear medicine
  • singular value decomposition (SVD)
  • surgical probes

ASJC Scopus subject areas

  • Signal Processing
  • Computer Vision and Pattern Recognition


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