Half-cone beam collimation for triple-camera SPECT systems.
Cone-beam collimators provide increased sensitivity at similar resolution compared to other collimators. The use of cone-beam collimators for brain imaging with triple-camera SPECT systems, however, results in truncation of the base of the brain because of clearance of the shoulders. A half-cone beam collimator does not have the problem of truncation. The objective of this study was to compare the performance characteristics of half-cone beam with parallel-beam and fan-beam collimators with similar resolution characteristics for SPECT imaging of the brain.


METHODS
A half-cone beam collimator with the focal point located towards the base of the brain was built for a triple-camera SPECT system. Spatial resolutions and sensitivities of three collimators were measured.


RESULTS
When 10-cm from the collimator surface, the planar spatial resolutions FWHM in mm (point source sensitivities in cps-MBq) for half-cone beam, fan-beam and parallel-beam collimators were 5.2 (85.6), 5.1 (55.6) and 5.9 (39.7), respectively. Image quality was evaluated using a three-dimensional Hoffman brain phantom and patient data. The deeper gray matter were more clearly visualized in the half-cone beam scans.


CONCLUSIONS
Half-cone beam collimation provides higher sensitivity and offers the potential for improved brain imaging compared with parallel-beam and fan-beam collimation when used with a triple-camera SPECT system.
Li
J
J
Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Jaszczak
R J
RJ
Van Mullekom
A
A
Scarfone
C
C
Greer
K L
KL
Coleman
R E
RE
D001921:Brain / Q000000981:diagnostic imaging*; D005260:Female; D015902:Gamma Cameras; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation* / Q000379:methods*