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Limitations of dual-photopeak window scatter correction for brain imaging
R E Zimmerman1, B B Williams, K H Chan
1Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Unlabelled:
A method for performing scatter corrections that would directly use the photopeak information and would be straightforward for use in clinical practice would be attractive in SPECT imaging. The dual-photopeak window method may be such a method. It relates the scatter fraction to the ratio of the lower to the total parts of a split-photopeak window. We investigated the use of this scatter correction method on a dedicated brain camera.
Methods:
Calibration curves for the Ceraspect, a dedicated brain imaging camera, were obtained for four split-window combinations using point sources in air and water. Simulations of the Ceraspect calibration curves at several energy resolution values were obtained using a Monte Carlo simulation of the instrument.
Results:
The calibration curves, experimental and simulated, revealed an ambiguous and unstable relationship between lower-to-total ratio and scatter fraction.
Conclusion:
The unsatisfactory calibration curves can be attributed to the limited scatter produced in a brain-sized phantom during the calibration process and inherent stability problems in the calibration process. The dual-photopeak window method is not usable for small-field imaging systems and may even be unstable for larger-field systems.