Journal of the Korean Physical Society

, Volume 67, Issue 1, pp 82–88 | Cite as

Operating characteristics of tube-current-modulation techniques when scanning simple-shaped phantoms

  • Kosuke Matsubara
  • Kichiro Koshida
  • Pei-Jan Paul Lin
  • Atsushi Fukuda
Article

Abstract

Our objective was to investigate the operating characteristics of tube current modulation (TCM) in computed tomography (CT) when scanning two types of simple-shaped phantoms. A tissueequivalent elliptical phantom and a homogeneous cylindrical step phantom comprising 16-, 24-, and 32-cm-diameter polymethyl methacrylate (PMMA) phantoms were scanned by using an automatic exposure control system with longitudinal (z-) and angular-longitudinal (xyz-) TCM and with a fixed tube current. The axial dose distribution throughout the elliptical phantom and the longitudinal dose distribution at the center of the cylindrical step phantom were measured by using a solid-state detector. Image noise was quantitatively measured at eight regions in the elliptical phantom and at 90 central regions in contiguous images over the full z extent of the cylindrical step phantom. The mean absorbed doses and the standard deviations in the elliptical phantom with z- and xyz-TCM were 12.3’ 3.7 and 11.3’ 3.5 mGy, respectively. When TCM was activated, some differences were observed in the absorbed doses of the left and the right measurement points. The average image noises in Hounsfield units (HU) and the standard deviations were 15.2’ 2.4 and 15.9’ 2.4 HU when using z- and xyz-TCM, respectively. With respect to the cylindrical step phantom under z-TCM, there were sudden decreases followed by increases in image noise at the interfaces with the 24- and 16-cm-diameter phantoms. The image noise of the 24-cm-diameter phantom was, relatively speaking, higher than those of the 16- and 32-cm-diameter phantoms. The simple-shaped phantoms used in this study can be employed to investigate the operating characteristics of automatic exposure control systems when specialized phantoms designed for that purpose are not available.

Keywords

Computed tomography Tube current modulation Dose Phantom Image noise 

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References

  1. [1]
    F. A. Mettler, Jr., B. R. Thomadsen, M. Bhargavan, D. B. Gilley, J. E. Gray, J. A. Lipoti, J. McCrohan, T. T. Yoshizumi and M. Mahesh. Health Phys. 95, 502 (2008).CrossRefGoogle Scholar
  2. [2]
    National Council on Radiation Protection and Measurements (NCRP), NCRP Report No. 160, 2009.Google Scholar
  3. [3]
    D. Tack, V. De Maertelaer and P. A. Gevenois. AJR Am. J. Roentgenol. 181, 331 (2003).CrossRefGoogle Scholar
  4. [4]
    M. Kalra, M. Maher, T. Toth, R. Kamath, E. Halpern and S. Saini. Radiology 232, 347 (2004).CrossRefGoogle Scholar
  5. [5]
    E. Angel et al., AJR Am. J. Roentgenol. 193, 1340 (2009).CrossRefGoogle Scholar
  6. [6]
    Y. Muramatsu, S. Ikeda, K. Osawa, R. Sekine, N. Niwa, M. Terada, N. Keat and S. Miyazaki, Nippon Hoshasen Gijutsu Gakkai Zasshi 63, 534 (2007).CrossRefGoogle Scholar
  7. [7]
    A. E. Papadakis, K. Perisinakis and J. Damilakis. Med. Phys. 35, 4567 (2008).CrossRefGoogle Scholar
  8. [8]
    M. Söderberg and M. Gunnarsson. Acta Radiol. 51, 625 (2010).CrossRefGoogle Scholar
  9. [9]
    O. Rampado, F. Marchisio, A. Izzo, E. Garelli, C. C. Bianchi, G. Gandini and R. Ropolo, Eur. J. Radiol. 72, 181 (2009).CrossRefGoogle Scholar
  10. [10]
    K. Matsubara, P. J. Lin, A. Fukuda and K. Koshida, Radiol. Phys. Technol. 7, 316 (2014).CrossRefGoogle Scholar
  11. [11]
    I. A. Tsalafoutas, A. Varsamidis, S. Thalassinou and E. P. Efstathopoulos. Med. Phys. 40, 111918 (2013).CrossRefGoogle Scholar
  12. [12]
    S. Sookpeng, C. J.Martin and D. J. Gentle. Radiat. Prot. Dosimetry 163, 521 (2015).CrossRefGoogle Scholar
  13. [13]
    C. H. McCollough, M. R. Bruesewitz and J. M. Kofler, Jr., Radiographics 26, 503 (2006).CrossRefMATHGoogle Scholar
  14. [14]
    Discovery CT750 HD Technical Reference Manual, 5317222-1EN, Rev. 5, GE Healthcare (Waukesha, WI, USA, 2009).Google Scholar
  15. [15]
    L. Herrnsdorf, M. Björk, B. Cederquist, C. G. Mattsson, G. Thungström and C. Fröjdh, Nucl. Instrum. Meth. Phys. Res. Sect. A 607, 223 (2009).ADSCrossRefGoogle Scholar
  16. [16]
    J. H. Hubbell and S. M. Seltzer, Tables of X-ray mass attenuation coefficients and mass energy-absorption coefficients from 1 keV to 20 MeV for elements Z = 1 to 92 and 48 additional substances of dosimetric interest, Report NISTIR 5632. National Institute of Standards and Technology, Gaithersburg, MD, USA, 1996.Google Scholar
  17. [17]
    International Commission on Radiation Units and Measurements (ICRU), ICRP Report No. 44, 1989.Google Scholar
  18. [18]
    K. Matsubara, K. Koshida, M. Suzuki, H. Tsujii, T. Yamamoto and O. Matsui, Radiat. Prot. Dosimetry 128, 106 (2008).Google Scholar
  19. [19]
    M. Söderberg and M. Gunnarsson, Acta. Radiol. 51, 625 (2010).CrossRefGoogle Scholar

Copyright information

© The Korean Physical Society 2015

Authors and Affiliations

  • Kosuke Matsubara
    • 1
  • Kichiro Koshida
    • 1
  • Pei-Jan Paul Lin
    • 2
    • 3
  • Atsushi Fukuda
    • 1
    • 4
  1. 1.Department of Quantum Medical TechnologyKanazawa UniversityKanazawaJapan
  2. 2.Department of RadiologyBeth Israel Deaconess Medical CenterBostonUSA
  3. 3.Department of RadiologyVirginia Commonwealth University Medical CenterVirginiaUSA
  4. 4.Department of RadiologyShiga Medical Center for ChildrenMoriyamaJapan
  5. 5.Department of RadiologyVirginia Commonwealth University Medical CenterVirginiaUSA

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