AbstractID: 7262 Title: A Computed Tomography Dose Index For Infants and Young Children
CT system manufacturers have recently implemented a display of dose ( CTDIw ) on their
system’s operating consoles in accordance with IEC Standard-60601-2-44. This dose
display feature provides a reference dose to CTDI head and body phantoms for any
selected head or body scan protocol. However the actual dose delivered to infants and
young children up to the age of two is always underestimated by the displayed CTDIw
reference dose. In order to estimate the magnitude of this underestimation, a smaller
diameter ( 10 cm ) CTDI phantom, which better represents the x-ray attenuation of an
infant or young child, has been fabricated which other than diameter mimics the regular
CTDI phantoms. Using a Marconi MX8000 CT system, CTDI100 dose measurements
were made on this smaller 10 cm diameter CTDI phantom and compared to the same
measurements made on the standard CTDI head ( 16 cm diameter ) and body ( 32 cm
diameter ) phantoms. The measurement results indicate that the CTDIw dose to the
smaller phantom is 1.2 times higher than to the standard CTDI head phantom for the
standard head protocol ( 120 kV, 250 mAs ). Likewise, the CTDIw dose to this infant
phantom is 2.5 times higher than to the CTDI body phantom for the same standard body
protocol. CTDIw dose measured on a 10 cm diameter CTDI phantom would provide a
more meaningful reference dose for infants and young children than what is displayed
today.