Answer(s):

    III.A.8.     Assume that a scan of one CT slice produces an average dose of 3 rad to the tissue in the slice.     If 10 contiguous slices are scanned with the same factors:

    a.     The average dose to the tissue within the slice will increase by at least a factor of 10.    No

    b.     The integral dose (imparted energy) will increase by at least a factor of 10.    Yes

    c.     The risk to the patient will be increased.    Yes

    d.     Scattered radiation contributes to the dose.    Yes

   Discussion:    The dose to a previously scanned slice does not increase in proportion to the number of additional contiguous slices. There will be some scatter contribution (perhaps 10-20%) to adjacent slices.

   Reference:    Physical Principles of Medical Imaging, 2nd Edition. p. 48


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