Optimal beam quality for chest flat panel detector system: realistic phantom study

  • Chie Kuwahara
  • Takatoshi AokiEmail author
  • Nobuhiro Oda
  • Jun Kawabata
  • Koichiro Sugimoto
  • Michiko Kobayashi
  • Masami Fujii
  • Yukunori Korogi



To investigate optimal beam quality for chest flat panel detector (FPD) system by semi-quantitatively assessment using a realistic lung phantom.

Materials and methods

Chest FPD radiographs were obtained on a realistic lung phantom with simulated lung opacities using various X-ray tube voltage levels (90–140 kV) with/without copper filter. Entrance skin dose was set to maintain identical for all images (0.1 mGy). Three chest radiologists unaware of the exposure settings independently evaluated the image quality of each simulated opacity and normal structure using a 5-point scale (+ 2: clearly superior to the standard; + 1: slightly superior to the standard; 0: equal to the standard; − 1: slightly inferior to the standard; − 2: clearly inferior to the standard). The traditional FPD image obtained at a tube voltage of 120 kV was used as the standard. The scores of image quality were statistically compared using the Wilcoxon rank test with Bonferroni correction.


FPD images using 90-kV shot with copper filter were superior to the traditional 120-kV shot without filter with respect to the visibility of vertebra, pulmonary vessels, and nodules overlapping diaphragm and heart (p < 0.05). There was no significant difference with respect to the visibility of all other simulated lung opacities (lung nodules except for overlying diaphragm/heart and honeycomb opacity) between each tube voltage level with/without copper filter and the traditional 120-kV shot without filter.


Image quality of FPD images using 90 kV with copper filtration is superior to that using standard tube voltage when dose is identical.

Key Points

• FPD image quality using 90 kV with filter is superior to that using traditional beam.

• Ninety-kilovolt shot with copper filter may be suitable for chest FPD image.

• Clinical study dealing with chest FPD beam optimization would be warranted.


Digital radiography Chest radiography Physics Dose Image quality 



Contrast-to-noise ratios


Computed radiography


Digital radiography


Entrance skin dose


Flat panel detector


Intraclass correlation coefficients


Polymethyl methacrylate



The authors state that this work has not received any funding.

Compliance with ethical standards


The scientific guarantor of this publication is Takatoshi Aoki.

Conflict of interest

The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.

Statistics and biometry

No complex statistical methods were necessary for this paper.

Informed consent

Informed consent was waived because of phantom study.

Ethical approval

Institutional Review Board approval was not required because of phantom study.


• experimental

• performed at one institution


  1. 1.
    Körner M, Weber CH, Wirth S, Pfeifer KJ, Reiser MF, Treitl M (2007) Advances in digital radiography: physical principles and system overview. Radiographics 27:675–686CrossRefGoogle Scholar
  2. 2.
    Vaño E, Fernández JM, Ten JI et al (2007) Transition from screen-film to digital radiography: evolution of patients radiation doses at projection radiography. Radiology 243:461–466CrossRefGoogle Scholar
  3. 3.
    American College of Radiology (2014) ACR–SPR–STR practice parameter for the performance of chest radiography. Available via Accessed 12 Oct 2017
  4. 4.
    Asada Y, Suzuki S, Kobayashi K et al (2012) Summary of results of the patients exposures in diagnostic radiography in 2011 questionnaire-focus on radiographic conditions. Nihon Hoshasen Gijutsu Gakkai Zasshi 68:1261–1268CrossRefGoogle Scholar
  5. 5.
    Matsunaga Y, Kawaguchi A, Kobayashi K et al (2017) Patients exposure during plain radiography and mammography in Japan in 1974-2014. Radiat Prot Dosim 176:347–353CrossRefGoogle Scholar
  6. 6.
    Oda N, Nakata H, Murakami S, Terada K, Nakamura K, Yoshida A (1996) Optimal beam quality for chest computed radiography. Invest Radiol 31:126–131CrossRefGoogle Scholar
  7. 7.
    Launders JH, Cowen AR, Bury RF, Hawkridge P (1998) A case study into the effect of radiographic factors on image quality and dose for a selenium based digital chest radiography system. Radiat Prot Dosim 80:279–282CrossRefGoogle Scholar
  8. 8.
    Chotas HG, Floyd CE Jr, Dobbins JT 3rd, Ravin CE (1993) Digital chest radiography with photostimulable storage phosphors: signal-to-noise ratio as a function of kilovoltage with matched exposure risk. Radiology 186:395–398CrossRefGoogle Scholar
  9. 9.
    Uffmann M, Neitzel U, Prokop M et al (2005) Flat-panel-detector chest radiography: effect of tube voltage on image quality. Radiology 235:642–650CrossRefGoogle Scholar
  10. 10.
    Ullman G, Sandborg M, Dance DR, Hunt RA, Alm Carlsson G (2006) Towards optimization in digital chest radiography using Monte Carlo modelling. Phys Med Biol 51:2729–2743CrossRefGoogle Scholar
  11. 11.
    Willemink MJ, Leiner T, Budde RP et al (2012) Systematic error in lung nodule volumetry: effect of iterative reconstruction versus filtered back projection at different CT parameters. AJR Am J Roentgenol 199:1241–1246CrossRefGoogle Scholar
  12. 12.
    Xueqian X, Zhao Y, Snijder RA et al (2013) Sensitivity and accuracy of volumetry of pulmonary nodules on low-dose 16- and 64-row multi-detector CT: an anthropomorphic phantom study. Eur Radiol 23:139–147CrossRefGoogle Scholar
  13. 13.
    Hashemi S, Mehrez H, Cobbold RS, Paul NS (2014) Optimal image reconstruction for detection and characterization of small pulmonary nodules during low-dose CT. Eur Radiol 24:1239–1250Google Scholar
  14. 14.
    Koyama S, Aoyama T, Oda N, Yamauchi-Kawaura C (2010) Radiation dose evaluation in tomosynthesis and C-arm cone-beam CT examinations with an anthropomorphic phantom. Med Phys 37:4298–4306CrossRefGoogle Scholar
  15. 15.
    Hubbell JH, Seltzer SM (1995) “Tables of X-ray mass attenuation coefficients and mass energy-absorption coefficients 1 keV to 20 MeV for elements Z=1 to 92 and 48 additional substances of dosimetric interest,” NISTIR 5632 National Institute of Standards and Technology, Gaithersdurg, MDGoogle Scholar
  16. 16.
    Landis JR, Koch GG (1977) The measurement of observer agreement for categorical data. Biometrics 33:159–174CrossRefGoogle Scholar
  17. 17.
    Dobbins JT 3rd, Samei E, Chotas HG et al (2003) Chest radiography: optimization of x-ray spectrum for cesium iodide–amorphous silicon flat-panel detector. Radiology 226:221–230CrossRefGoogle Scholar
  18. 18.
    ICRP (1991) 1990 Recommendations of the International Commission on Radiological Protection. ICRP Publication 60. Ann ICRP 21 1–3Google Scholar
  19. 19.
    Hamer OW, Sirlin CB, Strotzer M et al (2005) Chest radiography with a flat-panel detector: image quality with dose reduction after copper filtration. Radiology 237:691–700CrossRefGoogle Scholar

Copyright information

© European Society of Radiology 2019

Authors and Affiliations

  • Chie Kuwahara
    • 1
  • Takatoshi Aoki
    • 1
    Email author
  • Nobuhiro Oda
    • 2
  • Jun Kawabata
    • 1
  • Koichiro Sugimoto
    • 1
  • Michiko Kobayashi
    • 1
  • Masami Fujii
    • 1
  • Yukunori Korogi
    • 1
  1. 1.Department of RadiologyUniversity of Occupational and Environmental HealthKitakyushuJapan
  2. 2.Department of Radiological TechnologyKyoto College of Medical ScienceKyotoJapan

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