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PubMed · 10716331

Angulation errors in parallel-hole and fanbeam collimators: computer controlled quality control and acceptance testing procedure.

M Eckholt·H Bergmann
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Abstract

UNLABELLED: Angulation errors in collimators of 1 degrees or even less can seriously diminish the resolution of SPECT images. We have developed a computer-controlled quality control procedure that can be used for acceptance testing and regular routine checks. METHODS: Using a marker point source and a computer-controlled x-y positioning table, we investigated 7 parallel-hole and 3 fanbeam collimators. The results are presented as collimator surface maps, which are easy to interpret visually. RESULTS: The measurement accuracy for absolute angulation errors was better than 0.32 degrees. Regional variations in channel tilt could be detected with an accuracy better than 0.16 degrees. Six parallel-hole collimators were found acceptable for high-resolution SPECT imaging. For a parallel-hole collimator that had to be replaced because of nonoptimal image quality, our measurements clearly identified regions of directionally uniform angulation errors. Two fanbeam collimators showed slight concavities. CONCLUSION: Automation of the measurement and evaluation process make this procedure suitable for both acceptance tests and routine quality control checks. It can be applied to parallel-hole, fanbeam, converging, and diverging collimators, regardless of their individual geometry. No technical collimator specifications are needed. Our results reveal subtle mechanical deformations of collimators. They also show that for a detailed investigation, angulation error surface maps should be used to discover regional preferences in channel orientation.

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Equipment DesignHumansQuality ControlTomography, Emission-Computed, Single-PhotonJournal Article

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M Eckholt, H Bergmann. 2000. Angulation errors in parallel-hole and fanbeam collimators: computer controlled quality control and acceptance testing procedure.. https://pubmed.ncbi.nlm.nih.gov/10716331/

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