Multi-pinhole collimator design for small-object imaging with SiliSPECT: a high-resolution SPECT

Abstract

We have designed a multi-pinhole collimator for a dual-headed, stationary SPECT system that incorporates high-resolution silicon double-sided strip detectors. The compact camera design of our system enables imaging at source-collimator distances between 20 and 30 mm. Our analytical calculations show that using knife-edge pinholes with small-opening angles or cylindrically shaped pinholes in a focused, multi-pinhole configuration in combination with this camera geometry can generate narrow sensitivity profiles across the field of view that can be useful for imaging small objects at high sensitivity and resolution. The current prototype system uses two collimators each containing 127 cylindrically shaped pinholes that are focused toward a target volume. Our goal is imaging objects such as a mouse brain, which could find potential applications in molecular imaging.

The effects of object activity distribution on multiplexing multi-pinhole SPECT

“…Suggestions made by the researchers for alleviating the multiplexing artifacts include complete blockage of overlapping using physical septa (Vunckx et al 2008, Beekman et al 2005, Van der Have et al 2009), and mixing the multiplexing data with non-multiplexing data for reconstructions (Mahmood et al 2010), which shows promising results in artifact reduction. Another solution is to acquire projections at a number of imaging distances, known as synthetic collimator, so that the amount of multiplexing varies and provides more information for reconstruction (Wilson et al 2000, Shokouhi et al 2009). …”

An enhanced high-resolution EMCCD-based gamma camera using SiPM side detection

“…Rogulski et al (1993), Beekman and Vastenhouw (2004), Meng et al (2006), Rentmeester et al (2007), Shokouhi et al (2009) and Goorden et al (2009); recent work by Meng et al (2009a) validates the efficacy of high-resolution detectors in small-animal SPECT applications. High-resolution gamma-ray detectors have been developed for applications ranging from astronomy and particle physics to biomedical imaging.…”

Evaluation of image reconstruction for mouse brain imaging with synthetic collimation from highly multiplexed SiliSPECT projections

“…A ij geom is given as an intersection between the perimeters of the pinhole openings on the collimator’s front and back planes projected from the source point j onto the detector surface. A detailed description of A ij geom can be found in our previous work (25). The sensitivity for each point source j through aperture i into K number of detector pixels is given by: $${\mathit{\text{Sens}}}_{ij}=\sum _{k=1}^K{\mathit{\text{Sens}}}_{ijk}=\frac{{{\mathrm{italicA}}^{ij}}_{\mathit{\text{geom}}}{\text{cos}}^3\theta }{4\pi H_j^2}$$ H j is the perpendicular distance between the point source j and collimator (back) plane and θ is the angle between the pinhole axis and the line connecting the center of the pinhole to the source position.…”