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


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.

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  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).

    Article  Google Scholar 

  2. [2]

    National Council on Radiation Protection and Measurements (NCRP), NCRP Report No. 160, 2009.

  3. [3]

    D. Tack, V. De Maertelaer and P. A. Gevenois. AJR Am. J. Roentgenol. 181, 331 (2003).

    Article  Google Scholar 

  4. [4]

    M. Kalra, M. Maher, T. Toth, R. Kamath, E. Halpern and S. Saini. Radiology 232, 347 (2004).

    Article  Google Scholar 

  5. [5]

    E. Angel et al., AJR Am. J. Roentgenol. 193, 1340 (2009).

    Article  Google 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).

    Article  Google Scholar 

  7. [7]

    A. E. Papadakis, K. Perisinakis and J. Damilakis. Med. Phys. 35, 4567 (2008).

    Article  Google Scholar 

  8. [8]

    M. Söderberg and M. Gunnarsson. Acta Radiol. 51, 625 (2010).

    Article  Google 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).

    Article  Google Scholar 

  10. [10]

    K. Matsubara, P. J. Lin, A. Fukuda and K. Koshida, Radiol. Phys. Technol. 7, 316 (2014).

    Article  Google Scholar 

  11. [11]

    I. A. Tsalafoutas, A. Varsamidis, S. Thalassinou and E. P. Efstathopoulos. Med. Phys. 40, 111918 (2013).

    Article  Google Scholar 

  12. [12]

    S. Sookpeng, C. J.Martin and D. J. Gentle. Radiat. Prot. Dosimetry 163, 521 (2015).

    Article  Google Scholar 

  13. [13]

    C. H. McCollough, M. R. Bruesewitz and J. M. Kofler, Jr., Radiographics 26, 503 (2006).

    Article  MATH  Google Scholar 

  14. [14]

    Discovery CT750 HD Technical Reference Manual, 5317222-1EN, Rev. 5, GE Healthcare (Waukesha, WI, USA, 2009).

  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).

    ADS  Article  Google 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.

  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).

    Article  Google Scholar 

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Correspondence to Kosuke Matsubara.

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Matsubara, K., Koshida, K., Lin, PJ.P. et al. Operating characteristics of tube-current-modulation techniques when scanning simple-shaped phantoms. Journal of the Korean Physical Society 67, 82–88 (2015). https://doi.org/10.3938/jkps.67.82

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  • Computed tomography
  • Tube current modulation
  • Dose
  • Phantom
  • Image noise