Design and assessment of a novel SPECT system for desktop open‐gantry imaging of small animals: A simulation study. Issue 5 (29th April 2016)

• Record Type: Journal Article
• Authors: Zeraatkar, Navid; Farahani, Mohammad Hossein; Rahmim, Arman; Sarkar, Saeed; Ay, Mohammad Reza
• Is Part Of: Medical physics. Volume 43:Issue 5(2016)
• Page Start: 2581
• Page End: 2597
• Publication Date: 2016-04-29
• Subjects: collimators -- image denoising -- image reconstruction -- image resolution -- iterative methods -- medical image processing -- Monte Carlo methods -- phantoms -- single photon emission computed tomography; Single photon emission computed tomography (SPECT) -- Monte Carlo simulations -- Spatial resolution -- Noise -- Reconstruction; Biological material, e.g. blood, urine; Haemocytometers -- Digital computing or data processing equipment or methods, specially adapted for specific applications -- Image data processing or generation, in general -- Image enhancement or restoration, e.g. from bit‐mapped to bit‐mapped creating a similar image -- Using diaphragms, collimators -- Scintigraphy -- Measuring radioactive content of objects, e.g. contamination (whole‐body counters G01T011/63); SPECT -- tomography -- small‐animal imaging -- pinhole -- tilted detector; Image reconstruction -- Spatial resolution -- Monte Carlo methods -- Single photon emission computed tomography -- Collimators -- Image sensors -- Medical image reconstruction -- Image detection systems -- Data acquisition; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4947127
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: Given increasing efforts in biomedical research utilizing molecular imaging methods, development of dedicated high‐performance small‐animal SPECT systems has been growing rapidly in the last decade. In the present work, we propose and assess an alternative concept for SPECT imaging enabling desktop open‐gantry imaging of small animals. Methods: The system, PERSPECT, consists of an imaging desk, with a set of tilted detector and pinhole collimator placed beneath it. The object to be imaged is simply placed on the desk. Monte Carlo (MC) and analytical simulations were utilized to accurately model and evaluate the proposed concept and design. Furthermore, a dedicated image reconstruction algorithm, finite‐aperture‐based circular projections (FABCP), was developed and validated for the system, enabling more accurate modeling of the system and higher quality reconstructed images. Image quality was quantified as a function of different tilt angles in the acquisition and number of iterations in the reconstruction algorithm. Furthermore, more complex phantoms including Derenzo, Defrise, and mouse whole body were simulated and studied. Results: The sensitivity of the PERSPECT was 207 cps/MBq. It was quantitatively demonstrated that for a tilt angle of 30°, comparable image qualities were obtained in terms of normalized squared error, contrast, uniformity, noise, and spatial resolution measurements, the latter at ∼0.6 mm. Furthermore, quantitative analyses demonstrated that 3 iterations of FABCP image reconstruction (16 subsets/iteration) led to optimally reconstructed images. Conclusions: The PERSPECT, using a novel imaging protocol, can achieve comparable image quality performance in comparison with a conventional pinhole SPECT with the same configuration. The dedicated FABCP algorithm, which was developed for reconstruction of data from the PERSPECT system, can produce high quality images for small‐animal imaging via accurate modeling of the system as incorporated in the forward‐ and back‐projection steps. Meanwhile, the developed MC model and the analytical simulator of the system can be applied for further studies on development and evaluation of the system.