Abstract-The Purpose of this study is to investigate the performance of a dual head SPECT system having an array of pinholes as a collimator. Several analytical methods are used to evaluate the performance of the given pinhole array detector module design. Monte Carlo simulation studies using Geant4 Application for Tomographic Emission (GATE) validate the performance of this novel dual head SPECT where a cylindrical water phantom is imaged. We are proposing a pinhole array detector module with 48mm by 48mm of active area behind an array of 100 pinholes laid out in a 10 by 10 lattice. This configuration allows high detection efficiency and excellent sensitivity in SPECT imaging. The system is based on a pixelated array of NaI crystals (100 × 100 × 10mm elements) coupled with an array of position sensitive photomultiplier tubes (PSPMTs). The basic characteristics of this system were evaluated with pinhole apertures of 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm and 3mm respectively. A conventional filtered back projection algorithm was used to reconstruct the images. Performance evaluation of this system indicates that high quality images can be obtained for in vivo imaging.Index Terms-Dual head SPECT, SPECT instrumentation, pinhole SPECT and GATE.
I. INTRODUCTIONIn the past several years, SPECT has developed significantly and is now considered to be an imperative modality in the nuclear emission field. SPECT is a physiological imaging tool that is commonly used for visualizing or measuring the function of specific organs. There are definite advantages for improved SPECT devices [1]. Higher sensitivity and resolution are necessary for small animal imaging than for human imaging to achieve a level of anatomic detail that is comparable to human studies. Dedicated small animal imaging systems are being developed in several modalities. In spite of the requirement for higher spatial resolution, SPECT is most often based on the Anger camera principle: a collimator is placed in front of a NaI (Tl) scintillation crystal associated with a set of photomultipliers. Conventional collimators used for SPECT imaging cannot provide better detection efficiency and result in poor image quality. SPECT is a rapidly changing field, and the past several years have produced new developments in both hardware technology and image processing algorithms [2]. At the component level, there have been improvements in scintillators and photon transducers as well as in the greater availability of semiconductor technology. The current Manuscript received September 10, 2014; revised November 25, 2014 state-of-the-art of SPECT has been developing from many fronts and there is still scope to see improvements in instrumentation and innovative image reconstruction algorithms. Despite the readily available isotopes, unlike PET, SPECT suffers from low detection efficiency and low resolution; therefore, many investigations have focused on increasing its sensitivity without degrading spatial resolution [3]- [5]. A pinhole approach for SPECT is envisaged for superior spa...
