https://www.theragnostics.no/en/author/satyajit-ghosh/ Satyajit Ghosh Hugo Blox Builder (https://hugoblox.com)en-usWed, 13 Nov 2024 00:00:00 +0000 https://www.theragnostics.no/media/icon_hu14557955862192370321.png https://www.theragnostics.no/en/author/satyajit-ghosh/ https://www.theragnostics.no/en/publications/cosmi-2024-twisted/ Wed, 13 Nov 2024 00:00:00 +0000 https://www.theragnostics.no/en/publications/cosmi-2024-twisted/ <hr> <p><em>Objective.<em>Advanced pinhole collimation geometries optimized for preclinical high-energy</em>ɣ</em>imaging facilitate applications such as<em>ɑ</em>and<em>ß</em>emitter imaging, simultaneous multi-isotope PET and PET/SPECT, and positron range-free PET. These geometries replace each pinhole with a group of clustered pinholes (CPs) featuring smaller individual pinhole opening angles (POAs), enabling sub-mm resolution imaging up to ∼1 MeV. Further narrowing POAs while retaining field-of-view (FOV) may enhance high-energy imaging but faces geometrical constraints. Here, we detail how the novel twisted CPs (TCPs) address this challenge.*Approach.*We compared TCP and CP collimator sensitivity at equal system resolution (SR) and SR at matched sensitivity by tuning pinhole diameters for¹⁸F (511 keV) and⁸⁹Zr (909 keV). Additionally, simulated Derenzo phantoms at low activity (LA: 12 MBq ml^-1) and high activity (HA: 190 MBq ml^-1) levels, along with uniformity images, were compared to assess image resolution and uniformity.*Main results.*At equal SR, TCP increased average central FOV sensitivity by 15.6% for¹⁸F and 29.4% for⁸⁹Zr compared to CP. Image resolution was comparable, except for⁸⁹Zr at LA, where TCP resolved 0.80 mm diameter rods compared to 0.90 mm for CP. Image uniformity was equivalent for¹⁸F, while for⁸⁹Zr TCP granted a 10.4% improvement. For collimators with matched sensitivity, TCP improved SR by 6.6% for¹⁸F and 17.7% for⁸⁹Zr while also enhancing image resolution; for¹⁸F, rods distinguished were 0.65 mm (CP) and 0.60 mm (TCP) for HA, and 0.70 mm (CP and TCP) for LA. For⁸⁹Zr, image resolutions were 0.75 mm (CP) and 0.65 mm (TCP) for HA, and 0.90 mm (CP) and 0.80 mm (TCP) for LA. Image uniformity with TCP decreased by 18.3% for¹⁸F but improved by 20.1% for⁸⁹Zr.<em>Significance.<em>This study suggests that the TCP design has potential to improve high-energy</em>ɣ</em>imaging.</p>