Medical Physics

Volume 35, Issue 8 p. 3501-3510

Radiation protection physics

On the uncertainties in effective dose estimates of adult CT head scans

Kent J. Gregory,

Kent J. Gregory

Department of Medical Physics, Royal Adelaide Hospital, Adelaide, S.A. 5000, Australia and School of Electrical and Information Engineering (Applied Physics), University of South Australia, Mawson Lakes, S.A. 5095, Australia

Author to whom correspondence should be addressed. Present address: Department of Medical Physics, Royal Adelaide Hospital, Adelaide, S.A. 5000, Australia. Telephone: 61 8 8222 5539; Fax: 61 8 8222 5937. Electronic mail: [email protected]

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Giovanni Bibbo,

Giovanni Bibbo

Division of Medical Imaging, Women's and Children's Hospital, North Adelaide, S.A. 5006, Australia and School of Electrical and Information Engineering (Applied Physics), University of South Australia, Mawson Lakes, S.A. 5095, Australia

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John E. Pattison,

John E. Pattison

School of Electrical and Information Engineering (Applied Physics), University of South Australia, Mawson Lakes, S.A. 5095, Australia

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Kent J. Gregory,

Kent J. Gregory

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Giovanni Bibbo,

Giovanni Bibbo

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John E. Pattison,

John E. Pattison

School of Electrical and Information Engineering (Applied Physics), University of South Australia, Mawson Lakes, S.A. 5095, Australia

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First published: 08 July 2008

https://doi.org/10.1118/1.2952359

Citations: 12

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Abstract

Estimates of the effective dose to adult patients from computed tomography (CT) head scanning can be calculated using a number of different methods. These estimates can be used for a variety of purposes, such as improving scanning protocols, comparing different CT imaging centers, and weighing the benefits of the scan against the risk of radiation-induced cancer. The question arises: What is the uncertainty in these effective dose estimates? This study calculates the uncertainty of effective dose estimates produced by three computer programs (CT-EXPO, CTDosimetry, and ImpactDose) and one method that makes use of dose-length product (DLP) values. Uncertainties were calculated in accordance with an internationally recognized uncertainty analysis guide. For each of the four methods, the smallest and largest overall uncertainties (stated at the 95% confidence interval) were: 20%–31% (CT-EXPO), 15%–28% (CTDosimetry), 20%–36% (ImpactDose), and 22%–32% (DLP), respectively. The overall uncertainties for each method vary due to differences in the uncertainties of factors used in each method. The smallest uncertainties apply when the CT dose index for the scanner has been measured using a calibrated pencil ionization chamber.

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Volume35, Issue8

August 2008

Pages 3501-3510

On the uncertainties in effective dose estimates of adult CT head scans

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On the uncertainties in effective dose estimates of adult CT head scans

Abstract

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