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CTDI
CTDI
vol
Now we have to take into account the fact that the table (for spiral
examinations) is actually moving. We define CTDI
vol
as:
CTDI
vol
reflects the dose that a 32 cm or 16 cm water phantom would absorb
with the specific scan settings.
Patient size plays an important role in estimating the effectively absorbed dose
and should be taken into account.
One way of doing it is to calculate the effective diameter of the patient and
estimate the aborbed dose via a proportion with the diameter of the phantom.
Effective dose is calculated as DLP*w, where the weight w depends on the
body region and the DLP is the CTDI multiplied by the scan lenght.