Primary, scatter, and penetration characterizations of parallel-hole and pinhole collimators for I-123 SPECT
Authors
Konik, ArdaAuer, Benjamin
De Beenhouwer, Jan
Kalluri, Kesava S.
Zeraatkar, Navid
Furenlid, Lars R.
King, Michael A.
UMass Chan Affiliations
Department of RadiologyDocument Type
Journal ArticlePublication Date
2019-12-13
Metadata
Show full item recordAbstract
Multi-pinhole (MPH) collimators are known to provide better trade-off between sensitivity and resolution for preclinical, as well as for smaller regions in clinical SPECT imaging compared to conventional collimators. In addition to this geometric advantage, MPH plates typically offer better stopping power for penetration than the conventional collimators, which is especially relevant for I-123 imaging. The I-123 emits a series of high-energy ( > 300 keV, ~2.5% abundance) gamma photons in addition to the primary emission (159 keV, 83% abundance). Despite their low abundance, high-energy photons penetrate through a low-energy parallel-hole (LEHR) collimator much more readily than the 159 keV photons, resulting in large downscatter in the photopeak window. In this work, we investigate the primary, scatter, and penetration characteristics of a single pinhole collimator that is commonly used for I-123 thyroid imaging and our two MPH collimators designed for I-123 DaTscan imaging for Parkinson's Disease, in comparison to three different parallel-hole collimators through a series of experiments and Monte Carlo simulations. The simulations of a point source and a digital human phantom with DaTscan activity distribution showed that our MPH collimators provide superior count performance in terms of high primary counts, low penetration, and low scatter counts compared to the parallel-hole and single pinhole collimators. For example, total scatter, multiple scatter, and collimator penetration events for the LEHR were 2.5, 7.6 and 14 times more than that of MPH within the 15% photopeak window. The total scatter fraction for LEHR was 56% where the largest contribution came from the high-energy scatter from the back compartments (31%). For the same energy window, the total scatter for MPH was 21% with only 1% scatter from the back compartments. We therefore anticipate that using MPH collimators, higher quality reconstructions can be obtained in a substantially shorter acquisition time for I-123 DaTscan and thyroid imaging.Source
Phys Med Biol. 2019 Dec 13;64(24):245001. doi: 10.1088/1361-6560/ab58fe. Link to article on publisher's site
DOI
10.1088/1361-6560/ab58fePermanent Link to this Item
http://hdl.handle.net/20.500.14038/48407PubMed ID
31746783Related Resources
ae974a485f413a2113503eed53cd6c53
10.1088/1361-6560/ab58fe