PubMed Health⌕ Search

Biomedical subjects

R R Fulton

Publications and source records attributed to R R Fulton.

3 recordsLinked to original sources
PubMed1989

Dynamic geometric mean studies using a single headed rotating gamma camera.

A technique for acquiring dynamic geometric mean studies utilizing a single-headed rotating gamma camera has been developed. The camera head is repeatedly rotated between opposed views under computer control. A single data set results, from which a dynamic sequence of geometric mean images can be produced. Software has been developed to accomplish data acquisition and the reformatting required. The accuracy of the geometric mean data formed using this technique has been studied experimentally, and compared with results obtained from anterior and posterior sequences. In a simple clearance experiment of a 1-I volume with a known clearance of 20 ml.min-1, the geometric mean data resulted in estimates of volume remaining in the container with a mean error or +2.0 ml (s.d. = 5.7 ml, range -4.5 +/- 15.3 ml), while the anterior and posterior images yielded volume estimates with mean errors of -10.1 ml (s.d. = 16.6 ml, range -47.4 +/- 10.5 ml) and +35.5 ml (s.d. = 22.6 ml, range -3.2 +/- 51.6, ml), respectively. The technique is easy to implement and does not require modification of existing hardware. An application of the technique to a clinical study of gastric emptying is also included.

Gamma Cameras↗
PubMed1987

Artefact reduction in dual-radionuclide subtraction studies.

A method is proposed which significantly reduces the artefacts commonly experienced in dual radionuclide subtraction studies. Images of two radionuclides recorded simultaneously differ in resolution, sensitivity and attenuation. Also, one image will include scatter from the second higher-energy radionuclide. As a result severe artefacts are likely to occur when the two images are subtracted. In order to minimise the depth dependence of resolution, attenuation and scatter, the geometric mean of conjugate views was considered. From experimental work with activity placed in a depth of water it was demonstrated that the number and spatial distribution of scattered photons recorded in any energy window could be accurately predicted from the geometric mean image recorded in the photopeak. This prediction was accurate, independent of the depth of the source in water for a range of phantom dimensions. Differences in the instrument sensitivity and resolution at different energies can also be readily compensated for by using geometric mean images, as can differences due to the variation in attenuation. In practice three factors can be experimentally determined for any pair of radionuclides: a scatter ratio, a scatter function and a resolution compensation function. These data are then used to improve the dual-radionuclide subtraction analysis. The ability of the technique to significantly reduce subtraction artefacts has been demonstrated in phantom studies.

Humans↗