Assessment of Adult Patient Radiation Dose and Image Quality in CT Examinations Performed Using Automatic Exposure Control and Fixed Tube Current Techniques: A Phantom Case Study

Authors(7) :-Hamza Sulemana, Stephen Inkoom, , Cyril Schandorf , Edem Sosu, , Dominic Yaotse Kaka

The aim of the study was to compare radiation dose and image quality for adult routine medical CT examinations performed with automatic exposure control (AEC) and fixed tube current (FTC) techniques. Head and body dosimetry CT phantoms were used to mimic an adult head and torso region for routine adult CT examinations (head, chest, abdomen and pelvis). The same acquisition parameters were used, except with varying tube current time product (mAs) for the FTC technique. Dose measurements were performed using a CT dose Profiler probe connected to an electrometer. Image quality was assessed in terms of spatial resolution, low contrast resolution and contrast to noise ratio (CNR) using the Catphan 700 phantom. For AEC activated scans, the estimated CTDIvol were; 32.8, 6.7, 14.3, and 11.7 mGy for head CT, chest CT, abdomen CT and pelvis CT examinations respectively. Scans performed with FTC ranged from 32.9 - 53.0 mGy (head CT), 9.5 - 26.2 mGy (chest CT), 9.5 - 24.2 mGy (abdomen CT) and 9.5 - 26.0 mGy (pelvis CT). For the DLP, scans with AEC activated were; 593, 108, 240, and 190 mGy.cm for head, chest, abdomen and pelvis CT examinations respectively. That of FTC technique ranged from 571 - 946 mGy.cm (head CT), 284 - 780 mGy.cm (chest CT), 165 - 543 mGy.cm (abdomen CT), and 250 - 690 mGy.cm (pelvis CT). The use of AEC resulted in up to 19.4% and 18.2% mean dose reduction in CTDIvol and DLP for head CT and a mean reduction of 12% - 59.4% in CTDIvol and 7.1% - 78.3% in DLP for chest CT, abdomen CT and pelvis CT. The overall image quality test for spatial resolution was 4.20 and 4.40, and low contrast detectability score of 11.20 and 14.60 for the supra slice contrast level and 9.40 and 6.0 for the sub-slice contrast level for the two scan techniques respectively, with no significant differences (P >0.05). However a difference of significance was noted in the contrast to noise ratio score (P=0.014). Thus, CT scans performed using the AEC system reduces the radiation doses with no compromise in image quality compared with FTC technique.

Authors and Affiliations

Hamza Sulemana
Department of Medical Physics, Graduate School of Nuclear and Allied Science, University of Ghana, Accra - Ghana, West Africa
Stephen Inkoom
Radiation Protection Institute, Ghana Atomic Energy Commission, Accra – Ghana, West Africa

Department of Medical Physics, Graduate School of Nuclear and Allied Science, University of Ghana, Accra - Ghana, West Africa
Cyril Schandorf
Radiological and Medical Sciences Research Institute, Ghana Atomic Energy Commission, Accra – Ghana, West Africa
Edem Sosu
Department of Medical Physics, Graduate School of Nuclear and Allied Science, University of Ghana, Accra - Ghana, West Africa


Dominic Yaotse Kaka

Radiation dose; Computed tomography; Image quality; Automatic exposure control; Fixed tube current; Catphan phantom; CT dose Profiler.

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Publication Details

Published in : Volume 4 | Issue 5 | March-April 2018
Date of Publication : 2018-04-30
License:  This work is licensed under a Creative Commons Attribution 4.0 International License.
Page(s) : 1285-1289
Manuscript Number : IJSRST1845313
Publisher : Technoscience Academy

Print ISSN : 2395-6011, Online ISSN : 2395-602X

Cite This Article :

Hamza Sulemana, Stephen Inkoom, , Cyril Schandorf , Edem Sosu, , Dominic Yaotse Kaka, " Assessment of Adult Patient Radiation Dose and Image Quality in CT Examinations Performed Using Automatic Exposure Control and Fixed Tube Current Techniques: A Phantom Case Study", International Journal of Scientific Research in Science and Technology(IJSRST), Print ISSN : 2395-6011, Online ISSN : 2395-602X, Volume 4, Issue 5, pp.1285-1289, March-April-2018.
Journal URL : https://ijsrst.com/IJSRST1845313
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