Feasibility Study of a Lens-Based SPECT With a Tiled Lens and Detector Geometry for Animal Research: Simulation Results

The considerable potential of gamma cameras in Nuclear Medicine Imaging has sparked attention. They facilitate early cancer screening and several investigations. By leveraging recent advances in high-energy astrophysics, focusing X-ray and gamma-ray optics enables us to break the paradigm of low resolution and demonstrate a methodology for imaging small organisms with high resolution. This work aims to develop a method for imaging small animals with gamma rays that does not require parallel collimators nor pinholes and conducts a first of its kind Monte Carlo analysis of its aspects. In the present work, we introduce and elaborate upon our efforts to develop a high-resolution SPECT system augmented with a Laue lens [1] for small-animal/organ imaging and tumour detection. We examine the performance parameters of a Multi Lens-Based SPECT system equipped with modular partially curved detectors and Laue lens arrays. The Laue lenses and their detectors are placed in tilted planes in a modular fashion such that their fields of view converge. A tracking Monte Carlo (MC) simulation was used in the SPECT gamma camera environment to determine the distribution of diffracted high energy photons. The developed environment compensates for potential absorption and attenuation events by incorporating physical interactions. We explore the resolution and possibilities that the proposed device can offer to obtain real-time images of tumours in the sub-millimetre range. For this purpose, we have simulated a phantom sphere of 0.03 mm radius with a total activity of 0.1 mCi. The simulation results demonstrated the modular SPECT’s capacity to discriminate between two adjacent volumes as small as 0.00013 cc placed at 0.1 mm offsets from centre to centre, which is significantly better than any existing SPECT or PET system. In terms of system resolution and sensitivity, the resulting performance factors are correlated to those of the previously proposed single lens-based SPECT [1] and the conventional LEHR SPECT. The modular Lens-Based SPECT has shown a superior resolution in the submillimeter range and a comparable sensitivity compared to existing LEHR. Moreover, the sensitivity was boosted with the modified geometry compared to the single lens-based SPECT and to LEHR with three hits detected per 42 source photons, corresponding to a sensitivity of 81 cps/MBq. The system's novelty relies on the ability to view the data from every lens separately to capture a specific view of the object, or it can be integrated to generate a three-dimensional image from the three modules, including exact information about the object's size and location.