High-resolution brain SPECT imaging by combination of parallel and tilted detector heads
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ORIGINAL ARTICLE
High-resolution brain SPECT imaging by combination of parallel and tilted detector heads Atsuro Suzuki1 • Wataru Takeuchi1 • Takafumi Ishitsu1 • Yuichi Morimoto1 Keiji Kobashi1 • Yuichiro Ueno1
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Received: 30 March 2015 / Accepted: 12 June 2015 / Published online: 23 June 2015 Ó The Japanese Society of Nuclear Medicine 2015
Abstract Objective To improve the spatial resolution of brain single-photon emission computed tomography (SPECT), we propose a new brain SPECT system in which the detector heads are tilted towards the rotation axis so that they are closer to the brain. In addition, parallel detector heads are used to obtain the complete projection data set. We evaluated this parallel and tilted detector head system (PT-SPECT) in simulations. Methods In the simulation study, the tilt angle of the detector heads relative to the axis was 45°. The distance from the collimator surface of the parallel detector heads to the axis was 130 mm. The distance from the collimator surface of the tilted detector heads to the origin on the axis was 110 mm. A CdTe semiconductor panel with a 1.4 mm detector pitch and a parallel-hole collimator were employed in both types of detector head. A line source phantom, cold-rod brain-shaped phantom, and cerebral blood flow phantom were evaluated. The projection data & Atsuro Suzuki [email protected] Wataru Takeuchi [email protected]
were generated by forward-projection of the phantom images using physics models, and Poisson noise at clinical levels was applied to the projection data. The orderedsubsets expectation maximization algorithm with physics models was used. We also evaluated conventional SPECT using four parallel detector heads for the sake of comparison. Results The evaluation of the line source phantom showed that the transaxial FWHM in the central slice for conventional SPECT ranged from 6.1 to 8.5 mm, while that for PT-SPECT ranged from 5.3 to 6.9 mm. The coldrod brain-shaped phantom image showed that conventional SPECT could visualize up to 8-mm-diameter rods. By contrast, PT-SPECT could visualize up to 6-mm-diameter rods in upper slices of a cerebrum. The cerebral blood flow phantom image showed that the PT-SPECT system provided higher resolution at the thalamus and caudate nucleus as well as at the longitudinal fissure of the cerebrum compared with conventional SPECT. Conclusion PT-SPECT provides improved image resolution at not only upper but also at central slices of the cerebrum. Keywords Brain SPECT Cadmium telluride (CdTe) detector Collimator
Takafumi Ishitsu [email protected] Yuichi Morimoto [email protected]
Introduction
Keiji Kobashi [email protected]
Scintillation detectors have been widely used for clinical single-photon emission computed tomography (SPECT) imaging. For improved detector spatial resolution and energy resolution, pixellated semiconductor detectors such as cadmium telluride (CdTe) and cadmium zinc telluride (CZT) have been developed. Our previous study [1]
Yu
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