PT  - JOURNAL ARTICLE
AU  - Mao, Yanfei
AU  - Yu, Zhicong
AU  - Zeng, Gengsheng Lawrence
TI  - Geometric Calibration and Image Reconstruction for a Segmented Slant-Hole Stationary Cardiac SPECT System
AID  - 10.2967/jnmt.114.153668
DP  - 2015 May 01
TA  - Journal of Nuclear Medicine Technology
PG  - jnmt.114.153668
4099  - http://tech.snmjournals.org/content/early/2015/05/06/jnmt.114.153668.short
4100  - http://tech.snmjournals.org/content/early/2015/05/06/jnmt.114.153668.full
AB  - Objective: A dedicated stationary cardiac SPECT system is developed with a novel segmented-slant-hole collimator. The goal of this paper is to calibrate this new imaging geometry with a point source. Methods: Unlike the commercially available dedicated cardiac SPECT systems, which are specialized and can only be used to image the heart, our proposed cardiac system is based on a conventional SPECT system, but the collimator is replaced with a segmented-slant-hole collimator. For a dual-head SPECT system, two segmented collimators, each with seven sections, are arranged in an L-shaped configuration such that it can produce a complete cardiac SPECT image with only one gantry position. A calibration method is developed to estimate the geometric parameters of each collimator section as well as the detector rotation radius, under the assumption that the point source location is calculated using the central-section data. With a point source located off the rotation axis, geometric parameters for each collimator section can be estimated independently. The parameters estimated individually are further improved by a joint objective function that uses all collimator sections simultaneously and incorporates the collimator symmetry information. Results: Estimation results and images reconstructed from estimated parameters are presented for both simulated as well as real data acquired from a prototype collimator. The calibration accuracy was validated by computer simulations with an error of ~ 0.1 degree for the slant angles and ~ 1 mm for the rotation radius. Reconstructions of a heart insert phantom did not show any image artifacts of inaccurate geometric parameters. Conclusion: Compared to the detector's intrinsic resolution, the estimation error is small and ignorable. Therefore, the accuracy of the calibration is sufficient for the cardiac SPECT imaging.