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Dose and image quality for a cone‐beam C‐arm CT system
Author(s) -
Fahrig Rebecca,
Dixon Robert,
Payne Thomas,
Morin Richard L.,
Ganguly Arundhuti,
Strobel Norbert
Publication year - 2006
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2370508
Subject(s) - image quality , imaging phantom , dosimetry , cone beam computed tomography , medical imaging , nuclear medicine , scanner , voltage , image noise , hounsfield scale , optics , tube (container) , contrast (vision) , beam (structure) , computed tomography , materials science , physics , medicine , computer science , image (mathematics) , radiology , artificial intelligence , quantum mechanics , composite material
We assess dose and image quality of a state‐of‐the‐art angiographic C‐arm system (Axiom Artis dTA, Siemens Medical Solutions, Forchheim, Germany) for three‐dimensional neuro‐imaging at various dose levels and tube voltages and an associated measurement method. Unlike conventional CT, the beam length covers the entire phantom, hence, the concept of computed tomography dose index (CTDI) is not the metric of choice, and one can revert to conventional dosimetry methods by directly measuring the dose at various points using a small ion chamber. This method allows us to define and compute a new dose metric that is appropriate for a direct comparison with the familiar CTDI W of conventional CT. A perception study involving the CATPHAN 600 indicates that one can expect to see at least the 9 mm inset with 0.5% nominal contrast at the recommended head‐scan dose ( 60 mGy ) when using tube voltages ranging from 70 kVp to 125 kVp . When analyzing the impact of tube voltage on image quality at a fixed dose, we found that lower tube voltages gave improved low contrast detectability for small‐diameter objects. The relationships between kVp, image noise, dose, and contrast perception are discussed.

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