title: Dosimetry in MARS spectral CT: TOPAS Monte Carlo simulations and ion chamber measurements.
abstract: Spectral computed tomography (CT) is an up and coming imaging modality which shows great promise in revealing unique diagnostic information. Because this imaging modality is based on X-ray CT, it is of utmost importance to study the radiation dose aspects of its use. This study reports on the implementation and evaluation of a Monte Carlo simulation tool using TOPAS for estimating dose in a pre-clinical spectral CT scanner known as the MARS scanner. Simulated estimates were compared with measurements from an ionization chamber. For a typical MARS scan, TOPAS estimated for a 30 mm diameter cylindrical phantom a CT dose index (CTDI) of 29.7 mGy; CTDI was measured by ion chamber to within 3% of TOPAS estimates. Although further development is required, our investigation of TOPAS for estimating MARS scan dosimetry has shown its potential for further study of spectral scanning protocols and dose to scanned objects.
authors.affiliation: University of Canterbury, Christchurch, New Zealand. gsl29@uclive.ac.nz.
authors.forename: Gray
authors.identifier: http://orcid.org/0000-0003-3455-0257
authors.initials: G
authors.lastname: Lu
authors.affiliation: University of Canterbury, Christchurch, New Zealand.
authors.forename: Steven
authors.initials: S
authors.lastname: Marsh
authors.affiliation: CERN, Geneva, Switzerland.|Institute of Radiation Physics, Lausanne University Hospital, Lausanne, Switzerland.|Department of Radiology, University of Otago, Christchurch, New Zealand.
authors.forename: Jerome
authors.initials: J
authors.lastname: Damet
authors.affiliation: CERN, Geneva, Switzerland.|Department of Radiology, University of Otago, Christchurch, New Zealand.
authors.forename: Pierre
authors.initials: P
authors.lastname: Carbonez
authors.affiliation: National Centre for Radiation Science, Christchurch, New Zealand.
authors.forename: John
authors.initials: J
authors.lastname: Laban
authors.affiliation: University of Canterbury, Christchurch, New Zealand.|Department of Radiology, University of Otago, Christchurch, New Zealand.|MARS Bioimaging Ltd, Christchurch, New Zealand.
authors.forename: Christopher
authors.initials: C
authors.lastname: Bateman
authors.affiliation: Department of Radiology, University of Otago, Christchurch, New Zealand.|MARS Bioimaging Ltd, Christchurch, New Zealand.
authors.forename: Anthony
authors.initials: A
authors.lastname: Butler
authors.affiliation: University of Canterbury, Christchurch, New Zealand.|MARS Bioimaging Ltd, Christchurch, New Zealand.
authors.forename: Phil
authors.initials: P
authors.lastname: Butler
mesh_terms: D000818:Animals; D003198:Computer Simulation; D006801:Humans; D007477:Ions; D051379:Mice; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*; D014965:X-Rays
chemical_list: D007477:Ions; D019904:Polymethyl Methacrylate
keywords: Dosimetry; Ionization chamber; MARS; Medipix; Monte Carlo simulation; Spectral computed tomography; TOPAS