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Influence of 320-detector-row volume scanning and AAPM report 111 CT dosimetry metrics on size-specific dose estimate: a Monte Carlo study

Abstract

The American Association of Physicists in Medicine (AAPM) task group 204 has recommended the use of size-dependent conversion factors to calculate size-specific dose estimate (SSDE) values from volume computed tomography dose index (CTDIvol) values. However, these conversion factors do not consider the effects of 320-detector-row volume computed tomography (CT) examinations or the new CT dosimetry metrics proposed by AAPM task group 111. This study aims to investigate the influence of these examinations and metrics on the conversion factors reported by AAPM task group 204, using Monte Carlo simulations. Simulations were performed modelling a Toshiba Aquilion ONE CT scanner, in order to compute dose values in water for cylindrical phantoms with 8–40-cm diameters at 2-cm intervals for each scanning parameter (tube voltage, bow-tie filter, longitudinal beam width). Then, the conversion factors were obtained by applying exponential regression analysis between the dose values for a given phantom diameter and the phantom diameter combined with various scanning parameters. The conversion factors for each scanning method (helical, axial, or volume scanning) and CT dosimetry method (i.e., the CTDI100 method or the AAPM task group 111 method) were in agreement with those reported by AAPM task group 204, within a percentage error of 14.2 % for phantom diameters ≥11.2 cm. The results obtained in this study indicate that the conversion factors previously presented by AAPM task group 204 can be used to provide appropriate SSDE values for 320-detector-row volume CT examinations and the CT dosimetry metrics proposed by the AAPM task group 111.

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References

  1. Shope TB, Gagne RM, Johnson GC (1981) A method for describing the doses delivered by transmission X-ray computed tomography. Med Phys 8:488–495

    CAS  Article  PubMed  Google Scholar 

  2. AAPM task group 23 (2008) The measurement, reporting, and management of radiation dose in CT, AAPM report no. 96. AAPM, College Park

  3. McCollough CH, Leng S, Yu L, Cody DD, Boone JM, McNitt-Gray MF (2011) CT dose index and patient dose: they are not the same thing. Radiology 259:311–316

    Article  PubMed  PubMed Central  Google Scholar 

  4. AAPM task group 204 (2011) Size-specific dose estimates (SSDE) in pediatric and adult body CT examinations, AAPM report no. 204. AAPM, College Park

  5. Moore BM, Brady SL, Mirro AE, Kaufman RA (2014) Size-specific dose estimates (SSDE) provides a simple method to calculate organ dose for pediatric CT examinations. Med Phys 41:071917

    Article  PubMed  Google Scholar 

  6. Supanich M, Peck D (2012) Size-specific dose estimates as an indicator of absorbed organ dose in CT abdomen and pelvis studies. In: Radiological Society of North America 2012 Scientific Assembly and Annual Meeting. RSNA, Oak Brook

  7. Silverman JD, Paul NS, Siewerdsen JH (2003) Investigation of lung nodule detectability in low-dose 320-slice computed tomography. Med Phys 36:1700–1710

    Article  Google Scholar 

  8. Kroft LJ, Roelofs JJ, Geleijns J (2010) Scan time and patient dose for thoracic imaging in neonates and small children using axial volumetric 320-detector row CT compared to helical 64-, 32-, and 16-detector row CT acquisitions. Pediatr Radiol 40:294–300

    Article  PubMed  Google Scholar 

  9. Orrison WW, Snyder KV, Hopkins LN, Roach CJ, Ringdahl EN, Nazir R (2011) Whole-brain dynamic CT angiography and perfusion imaging. Clin Radiol 66:566–574

    Article  PubMed  Google Scholar 

  10. Kobayashi M, Koshida K, Suzuki S, Katada K (2012) Evaluation of patient dose and operator dose in swallowing CT studies performed with a 320-detector-row multislice CT scanner. Radiol Phys Technol 5:148–155

    Article  PubMed  Google Scholar 

  11. Halpenny D, Courtney K, Torreggiani WC (2012) Dynamic four dimensional 320 section CT and carpal bone injury: a description of a novel technique to diagnose scapholunate instability. Clin Radiol 67:185–187

    CAS  Article  PubMed  Google Scholar 

  12. Leitz W, Axelsson B, Szendro G (1995) Computed tomography dose assessment: a practical approach. Radiat Prot Dosim 57:377–380

    Google Scholar 

  13. Boone JM (2007) The trouble with CTDI100. Med Phys 34:1364–1371

    Article  PubMed  Google Scholar 

  14. Dixon RL (2003) A new look at CT dose measurement: beyond CTDI. Med Phys 30:1272–1280

    Article  PubMed  Google Scholar 

  15. Dixon RL, Ballard AC (2007) Experimental validation of a versatile system of CT dosimetry using a conventional ion chamber: beyond CTDI100. Med Phys 34:3399–3413

    Article  PubMed  Google Scholar 

  16. Perisinakis K, Damilakis J, Tzedakis A, Papadakis A, Theocharopoulos N, Gourtsoyiannis N (2007) Determination of the weighted CT dose index in modern multi-detector CT scanners. Phys Med Biol 52:6485–6495

    CAS  Article  PubMed  Google Scholar 

  17. AAPM Task Group 111 (2010) Comprehensive methodology for the evaluation of radiation dose in X-ray CT computed tomography, AAPM report no. 111. AAPM, College Park

  18. Hirayama H, Namito Y, Bielajew AF, Wilderman SJ, Nelson WR (2007) The EGS5 code system, SLAC report number: SLAC-R-730. SLAC, Stanford

  19. Turner AC et al (2009) A method to generate equivalent energy spectra and filtration models based on measurement for multidetector CT monte carlo dosimetry simulations. Med Phys 36:2154–2164

    Article  PubMed  PubMed Central  Google Scholar 

  20. Demarco JJ, Cagnon CH, Cody DD, Stevens DM, McCollough CH, Zankl M, Angel E, McNitt-Gray MF (2007) Estimating radiation doses from multidetector CT using monte carlo simulations: effects of different size voxelized patient models on magnitudes of organ and effective dose. Phys Med Biol 52:2583–2597

    CAS  Article  PubMed  Google Scholar 

  21. Zhang D, Savandi AS, Demarco JJ, Cagnon CH, Angel E, Turner AL, Cody DD (2009) Variablity of surface and center position radiation dose in MDCT: monte carlo simulation using CTDI and anthropomorphic phantoms. Med Phys 36:1025–1038

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  22. ICRU Report 74 (2005) Patient dosimetry for X-rays used in medical imaging. Oxford University Press, Oxford

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Correspondence to Tomonobu Haba.

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Haba, T., Koyama, S., Kinomura, Y. et al. Influence of 320-detector-row volume scanning and AAPM report 111 CT dosimetry metrics on size-specific dose estimate: a Monte Carlo study. Australas Phys Eng Sci Med 39, 697–703 (2016). https://doi.org/10.1007/s13246-016-0465-7

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  • DOI: https://doi.org/10.1007/s13246-016-0465-7

Keywords

  • Size-specific dose estimate
  • 320-detector-row volume CT
  • AAPM task group 111
  • Monte Carlo simulation