Transcript CT Dose indices of all multi-detector row CT scanners

Dianna Cody, Ph.D.
Professor
University of Texas M.D. Anderson
Cancer Center
Houston, TX
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LSS
Fred Larke
 Randell Kruger
 Mike Flynn
 Xizeng Wu
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ACRIN
Dianna Cody
 Chris Cagnon
 Mike McNitt-Gray
 Tony Seibert
 Phil Judy
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Subject of Cagnon, et al paper (Acad Radiol
2006: 1431-1441.)
Certification for each CT scanner (entry)
Annual physics tests – DOSE measurement
Over course of trial, collected 221 dose
measurements for 96 CT scanners
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CT Dose Index
10cm Pencil Ion Chamber
 Electrometer
 PMMA phantom
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 16cm Diameter
 32cm Diameter
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CTDI/mAs
Removes site-to-site variability (patient size)
Reflects MACHINE OUTPUT
All about the SCANNERS
Does NOT reflect patient dose
Does NOT reflect patient exposure
Does NOT reflect how sites operated scanners
Statistically significant differences in CTDI by vendor?
YES
Statistically significant differences in CTDI by
scanner models within a vendor?
YES (3 out of 4)
Statistically significant differences in CTDI among
all models and all vendors?
YES
Statistically significant differences in CTDI
by level of technology?
YES
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CT dose material presented at RSNA (2007)
Submitted manuscript to Radiology
summarizing effective dose estimates from
NLST chest CT exams (RSNA 2008)
Chest x-ray dose manuscript in preparation
(RSNA 2010)
Hope to estimate radiation dose to NLST
population from both CXR & CT exams