Feasibility of adjustable-gantry PET system using advanced DOI method

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2020-02, Vol.953, p.163087, Article 163087
• Main Authors: Song, Hankyeol, Lee, Seung-Jae, Park, Chanwoo, Kang, In Soo, Kim, Kyu Bom, Chung, Yong Hyun
• Format: Article
• Language: English
• Subjects: Adjustable gantry; DOI PET detector; Small-animal PET system
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2019.163087

Small-animal positron emission tomography (PET) systems are useful functional imaging systems for pathology and pharmacology research. However, conventional small-animal PET systems show degradation with regard to spatial resolution and sensitivity when small objects are image with a scanner having large diameter. In this study, to overcome this limitation, we propose a small-animal PET using an adjustable gantry and a depth-of-interaction (DOI) detector. The adjustable gantry allows the field of view (FOV) to be changed depending on object size to increase the solid-angle coverage and improve sensitivity. In addition, detector modules are arranged in a square shape to fill gaps between the detector module as well as in the corners to achieve higher sensitivity. To overcome the parallax error that occurs in the square-shaped gantry with long and thin crystal elements, a DOI detector is employed using a depth-dependent reflector pattern. The adjustable-gantry PET (AGPET) system is designed by GATE Monte Carlo simulation and evaluated by comparison with conventional small-animal PET systems, such as Inveon and PETbox, in terms of spatial resolution and sensitivity. The DOI detector blocks were composed of two 8 × 8 SiPM arrays coupled to two blocks of 12 × 12 lutetium-yttrium oxyorthosilicate (LYSO) crystals of size 2.1 ×2.1× 20 mm3. The signals of the detector blocks are fed to a data acquisition system based on field-programmable gate array, and the position, energy, and time information were recorded. The detector module performance is analyzed by the peak-to-valley ratio (PVR), distance-to-width ratio (DWR), energy resolution, and timing resolution. The results demonstrate that the proposed AGPET potentially provide higher sensitivity and resolution for small animal imaging. •Development of small animal PET system with adjustable gantry.•Investigation of the depth of interaction method using depth-dependent reflector.•Evaluation of small animal PET system using Monte Carlo simulation.