Radiation Exposure; Radiation Exposure Sensitivity; Dose Reporting Considerations - GE Revolution CT User Manual

2 Radiation Exposure

2.1 Radiation exposure sensitivity

Radiation exposure is a concern in both adults and children. However, children are more
sensitive to radiation than adults and have a longer life expectancy. Radiation risk is higher in
young patients, as they have more rapidly dividing cells than adults. The younger the patient,
the more sensitive they are. Using the same exposure parameters on a child as used on an
adult may result in larger doses to the child. There is no need for these larger doses to children,
and CT settings can be adjusted to reduce dose significantly while maintaining diagnostic image
quality.
The National Cancer Institute and The Society for Pediatric Radiology developed a brochure,
Radiation Risks and Pediatric Computed Tomography: A Guide for Health Care Providers , and
the FDA issued a Public Health Notification,
Tomography for Pediatric and Small Adult Patients dated November 2, 2001, that discuss the
value of CT and the importance of minimizing the radiation dose, especially in children. These
documents can be accessed at http://www.fda.gov.

2.2 Dose reporting considerations

It is widely understood and accepted that adult techniques should never be applied to small
patients or pediatrics since smaller objects have higher dose at the same technique. The chart
below illustrates the sharp increases in relative dose as the part scanned gets smaller in size
using the same technique.
Illustration 1: Relationship between dose and phantom size for head and body filters at 120 kV.
Another consideration about dose is since it is not possible to characterize dose given to
individual patients, the CT dose indices are provided to help make relative comparisons. These
dose index values can be used to compare CT systems and to help select appropriate operating
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Similar curves are obtained for the 70, 80, 100, and 140 kVs.
Direction 5480385-1EN, Revision 1
Reducing Radiation Risk from Computed
Revolution CT User Manual
2 Radiation Exposure