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CT brain perfusion: A static phantom study of contrast‐to‐noise ratio and radiation dose
Author(s) -
Midgley Stewart M,
Stella Damien L,
Campbell Bruce CV,
Langenberg Francesca,
Einsiedel Paul F
Publication year - 2017
Publication title -
journal of medical imaging and radiation oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.31
H-Index - 43
eISSN - 1754-9485
pISSN - 1754-9477
DOI - 10.1111/1754-9485.12561
Subject(s) - medicine , imaging phantom , contrast (vision) , nuclear medicine , perfusion scanning , perfusion , radiation exposure , radiation dose , radiation , radiology , optics , physics
Computed tomography perfusion ( CTP ) is increasingly employed in the diagnosis and management of ischaemic stroke but radiation dose can be significant and optimising contrast‐to‐noise ratio ( CNR ) is challenging. This study aimed to quantify and optimise the balance between CNR as a surrogate for image quality and radiation dose. Methods A perspex head phantom with vials of dilute contrast agent was scanned using a Siemens Definition Flash 128‐slice scanner. The CTP protocol exposure parameters were adjusted over 70–120 kV p and 150–285 mA s. Measurements were obtained for the average dose per slice, Hounsfield Units ( HU ) for iodinated contrast agent, and the image noise for background regions of perspex. The CNR was measured as a function of the volumetric CT dose index ( CTDI vol) and kV p. Results A change from 120 to 80 kV p, achieved the same CNR with 60% reduction in dose. Alternatively, for the same dose, the change from 120 to 80 kV p improved CNR by +58%. A change from 80 to 70 kV p while operating at the same CNR , led to 13% reduction in dose. Alternatively, maintaining the same dose while changing from 80 to 70 kV p improved the CNR by +7%. Conclusion Lower beam energies achieved the same CNR with less dose, or improved CNR at the same dose. A reduction from 80 kV p to 70 kV p may be clinically useful to optimise CTP acquisitions.