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Reduction of the unnecessary dose from the over-range area with a spiral dynamic z-collimator: comparison of beam pitch and detector coverage with 128-detector row CT

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Abstract

Our purpose in this study was to assess the radiation dose reduction and the actual exposed scan length of over-range areas using a spiral dynamic z-collimator at different beam pitches and detector coverage. Using glass rod dosimeters, we measured the unilateral over-range scan dose between the beginning of the planned scan range and the beginning of the actual exposed scan range. Scanning was performed at detector coverage of 80.0 and 40.0 mm, with and without the spiral dynamic z-collimator. The dose-saving ratio was calculated as the ratio of the unnecessary over-range dose, with and without the spiral dynamic z-collimator. In 80.0 mm detector coverage without the spiral dynamic z-collimator, the actual exposed scan length for the over-range area was 108, 120, and 126 mm, corresponding to a beam pitch of 0.60, 0.80, and 0.99, respectively. With the spiral dynamic z-collimator, the actual exposed scan length for the over-range area was 48, 66, and 84 mm with a beam pitch of 0.60, 0.80, and 0.99, respectively. The dose-saving ratios with and without the spiral dynamic z-collimator for a beam pitch of 0.60, 0.80, and 0.99 were 35.07, 24.76, and 13.51%, respectively. With 40.0 mm detector coverage, the dose-saving ratios with and without the spiral dynamic z-collimator had the highest value of 27.23% with a low beam pitch of 0.60. The spiral dynamic z-collimator is important for a reduction in the unnecessary over-range dose and makes it possible to reduce the unnecessary dose by means of a lower beam pitch.

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References

  1. Tzedakis A, Damilakis J, Perisinakis K, Stratakis J, Gourtsoyiannis N. The effect of z overscanning on patient effective dose from multidetector helical computed tomography examinations. Med Phys. 2005;32:1621–9.

    Article  PubMed  CAS  Google Scholar 

  2. Nicholson R, Fetherston S. Primary radiation outside the imaged volume of a multislice helical CT scan. Br J Radiol. 2002;75:518–22.

    PubMed  CAS  Google Scholar 

  3. Theocharopoulos N, Damilakis J, Perisinakis K, Gourtsoyiannis N. Energy imparted-based estimates of the effect of z overscanning on adult and pediatric patient effective doses from multi-slice computed tomography. Med Phys. 2007;34:1139–52.

    Article  PubMed  Google Scholar 

  4. Tzedakis A, Damilakis J, Perisinakis K, Karantanas A, Karabekios S, Gourtsoyiannis N. Influence of z overscanning on normalized effective doses calculated for pediatric patients undergoing multidetector CT examinations. Med Phys. 2007;34:1163–75.

    Article  PubMed  Google Scholar 

  5. van der Molen AJ, Geleijns J. Overranging in multisection CT: quantification and relative contribution to dose—comparison of four 16-section CT scanners. Radiology. 2007;242:208–16.

    Article  PubMed  Google Scholar 

  6. Cohnen M, Poll LJ, Puettmann C, Ewen K, Saleh A, Modder U. Effective doses in standard protocols for multi-slice CT scanning. Eur Radiol. 2003;13:1148–53.

    PubMed  Google Scholar 

  7. Flohr TG, Schaller S, Stierstorfer K, Bruder H, Ohnesorge BM, Schoepf UJ. Multi-detector row CT systems and image-reconstruction techniques. Radiology. 2005;235:756–73.

    Article  PubMed  Google Scholar 

  8. Taguchi K, Aradate H. Algorithm for image reconstruction in multi-slice helical CT. Med Phys. 1998;25:550–61.

    Article  PubMed  CAS  Google Scholar 

  9. Christner JA, Zavaletta VA, Eusemann CD, Walz-Flannigan AI, McCollough CH. Dose reduction in helical CT: dynamically adjustable z-axis X-ray beam collimation. AJR Am J Roentgenol. 2010;194:W49–55.

    Article  PubMed  Google Scholar 

  10. Walker MJ, Olszewski ME, Desai MY, Halliburton SS, Flamm SD. New radiation dose saving technologies for 256-slice cardiac computed tomography angiography. Int J Cardiovasc Imaging. 2009;25:189–99.

    Article  Google Scholar 

  11. Mahesh M, Scatarige JC, Cooper J, Fishman EK. Dose and pitch relationship for a particular multislice CT scanner. AJR Am J Roentgenol. 2001;177:1273–5.

    PubMed  CAS  Google Scholar 

  12. Rah J-E, Hong J-Y, Kim G-Y, Kim Y-L, Shin D-O, Suh T-S. A comparison of the dosimetric characteristics of a glass rod dosimeter and a thermoluminescent dosimeter for mailed dosimeter. Radiat Meas. 2009;44:18–22.

    Article  CAS  Google Scholar 

  13. Baron RL. Understanding and optimizing use of contrast material for CT of the liver. AJR Am J Roentgenol. 1994;163:323–31.

    PubMed  CAS  Google Scholar 

  14. Awai K, Takada K, Onishi H, Hori S. Aortic and hepatic enhancement and tumor-to-liver contrast: analysis of the effect of different concentrations of contrast material at multi-detector row helical CT. Radiology. 2002;224:757–63.

    Article  PubMed  Google Scholar 

  15. Hurwitz LM, Yoshizumi TT, Reiman RE, Paulson EK, Frush DP, Nguyen GT, Toncheva GI, Goodman PC. Radiation dose to the female breast from 16-MDCT body protocols. AJR Am J Roentgenol. 2006;186:1718–22.

    Article  PubMed  Google Scholar 

  16. Hohl C, Mahnken AH, Klotz E, Das M, Stargardt A, Muhlenbruch G, Schmidt T, Gunther RW, Wildberger JE. Radiation dose reduction to the male gonads during MDCT: the effectiveness of a lead shield. AJR Am J Roentgenol. 2005;184:128–30.

    PubMed  Google Scholar 

  17. Lee SS, Kim TK, Byun JH, Ha HK, Kim PN, Kim AY, Lee SG, Lee MG. Hepatic arteries in potential donors for living related liver transplantation: evaluation with multi-detector row CT angiography. Radiology. 2003;227:391–9.

    Article  PubMed  Google Scholar 

  18. Schroeder T, Nadalin S, Stattaus J, Debatin JF, Malago M, Ruehm SG. Potential living liver donors: evaluation with an all-in-one protocol with multi-detector row CT. Radiology. 2002;224:586–91.

    Article  PubMed  Google Scholar 

  19. Frederick MG, McElaney BL, Singer A, Park KS, Paulson EK, McGee SG, Nelson RC. Timing of parenchymal enhancement on dual-phase dynamic helical CT of the liver: how long does the hepatic arterial phase predominate? AJR Am J Roentgenol. 1996;166:1305–10.

    PubMed  CAS  Google Scholar 

  20. Awai K, Hiraishi K, Hori S. Effect of contrast material injection duration and rate on aortic peak time and peak enhancement at dynamic CT involving injection protocol with dose tailored to patient weight. Radiology. 2004;230:142–50.

    Article  PubMed  Google Scholar 

  21. Goshima S, Kanematsu M, Kondo H, Yokoyama R, Miyoshi T, Nishibori H, Kato H, Hoshi H, Onozuka M, Moriyama N. MDCT of the liver and hypervascular hepatocellular carcinomas: optimizing scan delays for bolus-tracking techniques of hepatic arterial and portal venous phases. AJR Am J Roentgenol. 2006;187:W25–32.

    Article  PubMed  Google Scholar 

  22. Barrett JF, Keat N. Artifacts in CT: recognition and avoidance. Radiographics. 2004;24:1679–91.

    Article  PubMed  Google Scholar 

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Authors and Affiliations

  1. Department of Radiological Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka, 812-8582, Japan

    Takashi Shirasaka, Mutsukazu Hayashi, Shinichi Awamoto, Masatoshi Kondo & Yasuhiko Nakamura

  2. Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto, 862-0976, Japan

    Yoshinori Funama

  3. Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka, 812-8582, Japan

    Masamitsu Hatakenaka & Hiroshi Honda

Authors
  1. Takashi Shirasaka
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  2. Yoshinori Funama
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  3. Mutsukazu Hayashi
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  4. Shinichi Awamoto
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  5. Masatoshi Kondo
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  6. Yasuhiko Nakamura
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  7. Masamitsu Hatakenaka
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  8. Hiroshi Honda
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Correspondence to Takashi Shirasaka.

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Shirasaka, T., Funama, Y., Hayashi, M. et al. Reduction of the unnecessary dose from the over-range area with a spiral dynamic z-collimator: comparison of beam pitch and detector coverage with 128-detector row CT. Radiol Phys Technol 5, 53–58 (2012). https://doi.org/10.1007/s12194-011-0135-0

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  • DOI: https://doi.org/10.1007/s12194-011-0135-0

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