Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 32119
Effective Dose and Size Specific Dose Estimation with and without Tube Current Modulation for Thoracic Computed Tomography Examinations: A Phantom Study

Authors: S. Gharbi, S. Labidi, M. Mars, M. Chelli, F. Ladeb


The purpose of this study is to reduce radiation dose for chest CT examination by including Tube Current Modulation (TCM) to a standard CT protocol. A scan of an anthropomorphic male Alderson phantom was performed on a 128-slice scanner. The estimation of effective dose (ED) in both scans with and without mAs modulation was done via multiplication of Dose Length Product (DLP) to a conversion factor. Results were compared to those measured with a CT-Expo software. The size specific dose estimation (SSDE) values were obtained by multiplication of the volume CT dose index (CTDIvol) with a conversion size factor related to the phantom’s effective diameter. Objective assessment of image quality was performed with Signal to Noise Ratio (SNR) measurements in phantom. SPSS software was used for data analysis. Results showed including CARE Dose 4D; ED was lowered by 48.35% and 51.51% using DLP and CT-expo, respectively. In addition, ED ranges between 7.01 mSv and 6.6 mSv in case of standard protocol, while it ranges between 3.62 mSv and 3.2 mSv with TCM. Similar results are found for SSDE; dose was higher without TCM of 16.25 mGy and was lower by 48.8% including TCM. The SNR values calculated were significantly different (p=0.03<0.05). The highest one is measured on images acquired with TCM and reconstructed with Filtered back projection (FBP). In conclusion, this study proves the potential of TCM technique in SSDE and ED reduction and in conserving image quality with high diagnostic reference level for thoracic CT examinations.

Keywords: Anthropomorphic phantom, computed tomography, CT-expo, radiation dose.

Digital Object Identifier (DOI):

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1107


[1] D.J Brenner, J. David, Brenner, D. Carl, Elliston, J. Eric, Hall, E. Walter, Berdon, “Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CT,” AJR, vol. 176, pp.289–296, Feb 2001.
[2] K. Mannudeep, M. Michael, R. Stefania, K. David, S. J. Anne, “Shepard Radiation exposure from Thoracic CT: Issues and Strategies. Korean,” Med Sci, vol. 19, pp.159-66, Apr 2004.
[3] M. Kalra, M. Maher, T. Toth, L. Hamberg, M. Blake, J. Shepard, S. Saini, “Strategies for CT radiation dose optimization,” Radiology, vol .230, pp.619–28, Mar 2004.
[4] WA. Kalender, H. Wolf, C. Suess, “Dose reduction in CT by anatomically adapted tube current modulation. II. Phantom measurement,” Med. Phys, vol .26, pp.2248–2253, Nov 1999.
[5] J. Ludlow, C. Walker, “Assessment of phantom dosimetry and image quality of i-CAT FLX cone-beam computed tomography,” Am. J. Orthod. Dentofac Orthop, vol.144, pp.802–817, December 2013.
[6] A. Sabarudin, Z. Mustafa, K. Nassir, H. Hamid, Z. Sun, “Radiation dose reduction in thoracic and abdomen – pelvic CT using tube current modulation: a phantom study,” J. Appl. Clin. Med. Phys, vol.16, pp.319–328, September 2014.
[7] ICPR publication 103, “Recommendations of the International Commission on Radiological Protection,” Ann. ICPR 37, 2007.
[8] J.M. Boone, K.J. Strauss, D.D. Cody, C.H. McCollough, M.F. McNitt-gray, T.L. Toth, “Size specific dose estimates (SSDE) in pediatric and adult body CT examinations,” AAPM Report No. 204, 2011.
[9] G. Stamm, H. Nagel, “CT-expo–a novel program for dose evaluation in CT,” Rofo, vol.174, pp.1570–1576, Dec 2002.
[10] I. Cunningham, R. Shaw, “Signal-to-noise optimization of medical imaging systems,” J. Opt. Soc. Am. A, vol. 16, pp.621-632, March 1999.
[11] H. Greess, H. Wolf, U. Baum, M. Lell, M. Pirkl, W. Kalender, W. Bautz, “Dose Reduction in Computed Tomography by Attenuation-Based Online Modulation of Tube Current: Evaluation of Six Anatomical Regions,” ER, vol.10, pp.391–394, 2000.
[12] S. Alibek, M. Brand, C. Suess, W. Wuest, M. Uder, H. Greess, “Dose Reduction in Pediatric Computed Tomography with Automated Exposure Control,” Acad Radiol, vol.18, pp. 690–693,Jun 2011.
[13] AE. Papadakis, K. Perisinakis, J. Damilakis, “Automatic exposure control in pediatric and adult multidetector CT examinations: a phantom study on dose reduction and image quality,” Med Phys,Vol.35, pp.4567–76, October 2008.
[14] M. Soderberg, M. Gunnarsson, “Automatic exposure control in computed tomography an evaluation of systems from different manufacturers,” Acta Radiol, vol.51, pp.625-634, July 2010.
[15] A. Sabarudin, Z. Mustafa, K.M. Nassir, H.A. Hamid, Z. Sun, “Radiation dose reduction in thoracic and abdomen–pelvic CT using tube current modulation: A phantom study,” JACMP, Vol.16, Jan 2014.
[16] X. L. Rendon, H. Bosmans, R. Oyen, F. Zanca, “Effective dose and organ doses estimation taking tube current modulation into account with a commercial software package,” Eur Radiol, vol.25, pp.1919–1925, Jul 2015.
[17] J. A. Brink, R.L Morin, “Size specific dose estimation for CT: how should it be used and what does it mean?” Radiology, vol. 265, pp.666–68, December 2012.
[18] J. A. Christner, N. N. Braun, M. C. Jacobsen, R. E. Carter, J. M. Kofler, C. H. McCollough, “Size specific dose estimates for adult patients at CT of the torso,” Radiology, vol.265, pp.841–47, December 2012.
[19] C. H. McCollough, Quality and safety in Radiology, Radiology, vol.6, pp.237:755, 2005.