Dosimetry in MARS spectral CT: TOPAS Monte Carlo simulations and ion chamber measurements

• DOI: 10.1007/s13246-017-0532-8
• Publication Date: 2017-02-20T05:56:04Z
• Authors: Gray Lu; Steven Marsh; Jerome Damet; Pierre Carbonez; John Laban; Christopher Bateman; Anthony Butler; Phil Butler
• Keywords: Medipix; spectral computed tomography; TOPAS; Radiation Dosage; Phantoms; Imaging; ANZSRC::4003 Biomedical engineering; Mice; 03 medical and health sciences; 0302 clinical medicine; ionization chamber; ANZSRC::5105 Medical and biological physics; Animals; Humans; Polymethyl Methacrylate; Computer Simulation; Radiometry; Tomography; Monte Carlo simulation; Ions; dosimetry; Phantoms, Imaging; X-Rays; MARS; ANZSRC::110320 Radiology and Organ Imaging; X-Ray Computed; Tomography, X-Ray Computed; Monte Carlo Method

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.