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Analysis of effective and organ dose estimation in CT when using mA modulation : a single scanner pilot study

Tootell, AK; Szczepura, K; Hogg, P

Analysis of effective and organ dose estimation in CT when using mA modulation : a single scanner pilot study Thumbnail


Authors

AK Tootell



Abstract

Effective dose (ED) estimation in CT examinations can be obtained by combining dose length product (DLP) with published ED per DLP coefficients or performed using software. These methods do not account for tube current (mA) modulation which is influenced by patient size.
Aim
To compare different methods of organ and ED estimation to measured values when using mA modulation in CT chest, abdomen and pelvis examinations.
Method
Organ doses from CT of the chest, abdomen and pelvis were measured using digital dosimeters and a dosimetry phantom. ED was calculated. Six methods of estimating ED accounting for mA modulation were performed using ImPACT CTDosimetry and Dose Length Product to ED coefficients. Corrections for the phantom mass were applied resulting in 12 estimation methods. Estimated organ doses from ImPACT CTDosimtery were compared to measured values.
Results
Calculated EDs were; chest 12.35 mSv (±1.48 mSv); abdomen 8.74 mSv (±1.36 mSv) and pelvis 4.68 mSv (±0.75 mSv). There was over estimation in all three anatomical regions. Correcting for phantom mass improved agreement between measured and estimated ED. Organ doses showed overestimation of dose inside the scan range and underestimation outside the scan range.
Conclusion
Reasonable estimation of effective dose for CT of the chest and abdomen can be obtained using ImPACT CTDosimetry software or k-coefficients. Further work is required to improve the accuracy of ED estimation from CT of the pelvis. Accuracy of organ dose estimation has been shown to depend on the inclusion or exclusion of the organ from the scan range.

Citation

Tootell, A., Szczepura, K., & Hogg, P. (2017). Analysis of effective and organ dose estimation in CT when using mA modulation : a single scanner pilot study. Radiography, 23(2), 159-166. https://doi.org/10.1016/j.radi.2017.02.006

Journal Article Type Article
Acceptance Date Feb 14, 2017
Online Publication Date Mar 2, 2017
Publication Date May 1, 2017
Deposit Date Feb 27, 2017
Publicly Available Date Mar 2, 2018
Journal Radiography
Print ISSN 1078-8174
Publisher Elsevier
Volume 23
Issue 2
Pages 159-166
DOI https://doi.org/10.1016/j.radi.2017.02.006
Publisher URL http://dx.doi.org/10.1016/j.radi.2017.02.006
Related Public URLs https://www.journals.elsevier.com/radiography

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