title: Quantitative assessment of crystal material and size on the performance of rotating dual head small animal PET scanners using Monte Carlo modeling.
abstract: In this work, among different proposed designs we have studied dual-head coincidence detectors (DHC) with pixelated crystals in order to optimize the design of detector systems of small animal PET scanners. Monte Carlo simulations and different detector components and materials, under different imaging conditions and geant 4 application for tomographic emission (GATE) were used for all simulations. Crystal length and inter material space on system performance were studied modeling several pixel sizes, ranging from 0.5 x 0.5mm² to 3.0 x 3.0mm² by increment of 0.5mm and using epoxy intermaterial with pitch of 0.1, 0.2 and 0.3mm. Three types of scintillator crystals:bismuth germinate orthosilicate, cerium-doped lutetium orthosilicate and gadolinium orthosilicate were simulated with thicknesses of 10mm and 15 mm. For all measurements a point source with the activity of 1MBq was placed at the center of field of view. The above simulation revealed that by increasing pixel size and crystal length in scintillator material of a pixelated array, sensitivity can be raised from 1% to 7%. However, spatial resolution becomes worse when pixel size increases from 0.6mm to 2.6mm. In addition, photons mispositioned events decrease from 76%to 45%. Crystal length decrease, significantly reduces the percentage of mispositioned events from 89% to 59%. Moreover increase in crystal length from 10mm to 15 mm changes sensitivity from 2% to 6% and spatial resolution from 0.6mm to 3.5mm. In conclusion, it was shown that pixel size 2mm with 10mm crystal thickness can provide the best dimensions in order to optimize system performance. These results confirmed the value of GATE Monte Carlo code, as being a useful tool for optimizing nuclear medicine imaging systems performance, for small animal PET studies.
authors.affiliation: Department of Medical Physics and Biomedical Engineering, Research Center for Science and Technology in Medicine, Tehran University of Medical Sciences, Iran.
authors.forename: Nafise
authors.initials: N
authors.lastname: Ghazanfari
authors.forename: Saeed
authors.initials: S
authors.lastname: Sarkar
authors.forename: George
authors.initials: G
authors.lastname: Loudos
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Ay
mesh_terms: D000818:Animals; D003460:Crystallization; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008420:Manufactured Materials; D009010:Monte Carlo Method; D049268:Positron-Emission Tomography / Q000295:instrumentation* / Q000662:veterinary*; D012399:Rotation; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D014159:Transducers / Q000662:veterinary*