Abstract
Multihead camera inspection usually examines only head alignment with parallel-hole collimators, therefore, fanbeam collimators are not analyzed. We demonstrate that acceptance testing should include evaluating fanbeam collimator alignment.
Methods: Two sets of low-energy ultra-high resolution (LEUHR) fanbeam collimators, Sets A (misaligned) and B (aligned), were examined. SPECT acquisitions were acquired for the three point sources aligned in the Z and Y directions, offset in the X direction and a three-dimensional Hoffman brain phantom.
Results: Cinematic display of the raw data revealed artifactual motion in the Y direction for collimator Set A (misaligned), a SPECT spatial resolution (FWHM) increase of 4 mm in the Y direction and 1 mm in the X direction for Set A compared to Set B. Reconstructed images from the three-dimensional Hoffman brain phantom resulted in no clinical discernible differences.
Conclusion: We recommend testing fanbeam collimators during acceptance testing, before patient data is assumed to be reliable.