Limitations of dual-photopeak window scatter correction for brain imaging.
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.


CONCLUSIONS
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.
Zimmerman
R E
RE
Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Williams
B B
BB
Chan
K H
KH
Moore
S C
SC
Kijewski
M F
MF
D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging*; D002138:Calibration; D003198:Computer Simulation; D015902:Gamma Cameras; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D012542:Scattering, Radiation; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation / Q000379:methods*