Collimation and surface counting in haematology

Abstract

syNopsis The effect on the results obtained in surface counting investigations of using a dual detector counting system and multihole collimators has been investigated. The use of the additional detector results in smoother curves for the uptake of the radionuclide and the use of multihole collimators increases the discrimination of the counting system against the effects of radioactivity outside the region of interest. In a clinical trial to compare multihole collimation with conventional single hole collimation it was found that increased excess counts were obtained over the spleen with the multihole collimators in eight of ten cases.

Platelet dynamics in chronic liver disease with special reference to the role of the spleen.

“…Much depends on the techniques of scanning, both in collimation and organ geometry (Bowring and Glass, 1974). With normal or mildly enlarged spleens posterior scanning may well be more accurate and may reveal degrees of splenic sequestration unsuspected on anterior scanning (Ries and Price, 1974).…”

An improved uptake probe designed for a large crystal rectilinear scanner

“…I n this respect the focused probe presented here would also perform better than recently designed stationary detectors with parallel multihole collimators (Bowring and Glass 1974). In these systems the field of view is not well defined as the isocount contours, although parallel, are separated by much larger distances.…”

“…Recent attempts to overcome these problems have employed opposed detectors with multiple parallel hole collimators. These produce a constant field of view, but sensitivity variations within the field are significant, leading to a response which depends on size and location (Bowring and Glass 1974). The radiation scattered within the body may be used to provide an index of organ depth, and this approach has also been used to improve quantification of activity measurements (Eversden et ab.…”