PT - JOURNAL ARTICLE AU - Hakjae Lee AU - Eungi Min AU - Young-Jun Jung AU - Hyemi Cha AU - Seungbin Bae AU - Kyeong Min Kim AU - Kisung Lee TI - Development of a target-oriented SPECT using a variable pinhole collimator DP - 2016 May 01 TA - Journal of Nuclear Medicine PG - 1943--1943 VI - 57 IP - supplement 2 4099 - http://jnm.snmjournals.org/content/57/supplement_2/1943.short 4100 - http://jnm.snmjournals.org/content/57/supplement_2/1943.full SO - J Nucl Med2016 May 01; 57 AB - 1943Objectives The two primary factors that determine the quality of single photon emission computed tomography (SPECT) are its spatial resolution and sensitivity. Usually, a pinhole collimator is used when high-resolution imaging is required. However, pinhole collimator-based imaging is time-consuming and involves higher radiation compared with other types of collimators, owing to its intrinsically low sensitivity. For improving the SPECT performance, we proposed a novel pinhole collimator with adjustable shape for real-time optimization of regions of interest (ROI). In this study, we implemented a prototype SPECT that utilizes the proposed variable pinhole collimator. The initial performance of this system was tested in a pilot study with a phantom.Methods The proposed variable pinhole collimator was modeled based on a conventional pinhole by piling 7 tungsten layers of different apertures. These apertures were drilled into 0.5-mm-thick tungsten sheets and the movement of each tungsten sheet was controlled by a dedicated motor driving unit, for aligning the optimal aperture of each layer with the pinhole center. A compact, wide area and high spatial resolution gamma camera has been developed with CsI(Tl) discrete scintillator and 4 multi-pixel photon counter (S12642-0808PB-50) arrays. The three axes of bed positioning, head movement, 7 layers of variable pinhole collimator driving, detector movement and gantry rotation were controlled by using a micro-controller (ATmega2560) that was connected to an integral operation system. The spatial resolution of the proposed SPECT device has been measured by using an ultra-micro hot spot phantom in a water-filled cylinder containing 11.1 mCi of a Tc-99m source. Using the cluster system (COCOMON project), a fully 3D (128×128×128 matrix) maximum likelihood-expectation maximization (ML-EM) reconstruction was performed.Results The active area of the developed gamma camera was 46.3×46.3 mm2 and its spatial resolution was 0.9 mm. The measured full width at half maximum was 3.4 mm for a 3-mm-diameter reconstructed image of a Co-57 point source. In the ultra-micro hot spot phantom study, 1.35-mm-diameter hot rods were clearly resolved.Conclusions In this study, we realized a prototype SPECT with a variable pinhole collimator. For implementing the proposed SPECT, we developed a novel collimator, a compact gamma camera, a gantry, a 3-axis positioning bed, an integral operation system and a 3D reconstruction algorithm. A pilot study with a phantom was conducted for measuring the initial image quality, and 1.35-mm-diameter hot rods were clearly resolved. $$graphic_7A9CF747-D608-43FC-9F00-E41F4B16E943$$