Computed tomography (CT) technology has changed considerably in recent years
with the introduction of increasing numbers of multiple detector arrays. There are several
parameters specific to multi-detector computed tomography (MDCT) scanners that increase
or decrease patient dose systematically compared to older single detector computed
tomography (SDCT) scanners. This document briefly reviews the MDCT technology,
radiation dose in MDCT, including differences from SDCT and factors that affect dose,
radiation risks, and the responsibilities for patient dose management. The document
recommends that users need to understand the relationship between patient dose and image
quality and be aware that image quality in CT is often higher than that necessary for
diagnostic confidence. Automatic exposure control (AEC) does not totally free the operator
from selection of scan parameters, and awareness of individual systems is important. Scanning
protocols cannot simply be transferred between scanners from different manufacturers and
should be determined for each MDCT. If the image quality is appropriately specified by the
user, and suited to the clinical task, there will be a reduction in patient dose for most patients.
Understanding of some parameters is not intuitive and the selection of image quality
parameter values in AEC systems is not straightforward. Examples of some clinical situations
have been included to demonstrate dose management, e.g. CT examinations of the chest, the
heart for coronary calcium quantification and non-invasive coronary angiography,
colonography, the urinary tract, children, pregnant patients, trauma cases, and CT guided
interventions. CT is increasingly being used to replace conventional x-ray studies and it is
important that patient dose is given careful consideration, particularly with repeated or
multiple examinations.
Computed tomography (CT) technology has changed considerably in recent years
with the introduction of increasing numbers of multiple detector arrays. There are several
parameters specific to multi-detector computed tomography (MDCT) scanners that increase
or decrease patient dose systematically compared to older single detector computed
tomography (SDCT) scanners. This document briefly reviews the MDCT technology,
radiation dose in MDCT, including differences from SDCT and factors that affect dose,
radiation risks, and the responsibilities for patient dose management. The document
recommends that users need to understand the relationship between patient dose and image
quality and be aware that image quality in CT is often higher than that necessary for
diagnostic confidence. Automatic exposure control (AEC) does not totally free the operator
from selection of scan parameters, and awareness of individual systems is important. Scanning
protocols cannot simply be transferred between scanners from different manufacturers and
should be determined for each MDCT. If the image quality is appropriately specified by the
user, and suited to the clinical task, there will be a reduction in patient dose for most patients.
Understanding of some parameters is not intuitive and the selection of image quality
parameter values in AEC systems is not straightforward. Examples of some clinical situations
have been included to demonstrate dose management, e.g. CT examinations of the chest, the
heart for coronary calcium quantification and non-invasive coronary angiography,
colonography, the urinary tract, children, pregnant patients, trauma cases, and CT guided
interventions. CT is increasingly being used to replace conventional x-ray studies and it is
important that patient dose is given careful consideration, particularly with repeated or
multiple examinations.
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