European Radiology

, Volume 29, Issue 8, pp 4315–4323 | Cite as

Dose estimation of ultra-low-dose chest CT to different sized adult patients

  • Tony M. SvahnEmail author
  • Tommy Sjöberg
  • Jennifer C. Ast



To evaluate the effect of patient size on radiation dose for standard CT (SD-CT), ultra-low-dose CT (ULD-CT) and two-view digital radiography (DR).


Dosimeters were distributed within the lungs of chest phantoms representing males of 65 kg and 82 kg (body mass indices 23 and 29). In contrast to SD-CT and DR which include automatic exposure control (AEC), the ULD scan employs a fixed mAs value. The phantoms were exposed to SD, ULD and DR while recording lung doses. Projected dose data were calculated from the phantoms. The resulting exposure settings were used in Monte Carlo programs to determine the effective dose for a standard-sized (BMI 24.2) adult male (170 cm/70 kg) and female (160 cm/59 kg). Patients previously examined by both ULD- and SD-CT were identified to determine post hoc size-specific dose estimates (SSDEs).


ULD-CT dose was inversely related to patient size; average lung doses summarised in terms of patient size BMI23/29 are 5.2/8.1 (SD-CT), 0.56/0.35 (ULD-CT) and 0.05/0.13 mGy (DR), while the effective doses for these techniques on a standard-sized male were 2.9, 0.16 and 0.03 mSv and 2.3, 0.247 and 0.024 mSv for a standard-sized female respectively. SSDEs for 15 patients (averages: BMI 26, range 18–37) averaged 5.5 mGy (3.6–10) for SD-CT and 0.35 mGy (0.42–0.27) for ULD-CT.


The effective doses for a standard-sized male and female examined by ULD-CT are (respectively) ~ 6%/~ 11% of SD-CT and ~ 5/~ 10 times higher than DR. ULD-CT gave a lower radiation dosage to larger patients than DR. AEC is warranted in ULD-CT for improved dose consistency.

Key Points

• For standard-sized patients, ULD-CT dose level is ~ 6%/~ 11% of SD-CT, and ~ 5/~ 10 times higher than DR. For larger patients, ULD-CT is currently being used clinically at lower dose levels than DR.

• Using ULD-CT should greatly reduce the risk of late effects from ionising radiation.

• AEC in ULD-CT is desirable for increased consistency in patient dose.


Tomography Thoracic radiography Digital radiography Radiation dosage 



Automatic exposure control


As low as reasonably achievable




Body mass index


Volume CT dose index


Dose length product


Digital radiography






Low dose






Standard dose


Size-specific dose estimate


Thermoluminescence dosimeter


Ultra-low dose



The authors would like to thank Prof. Hans Dieter Nagel at the Science & Technology for Radiology, Germany; Dr. Teemu Siiskonen, at the Finnish Radiation Authority (STUK); and Dr. Yoko Kagaku, Kyoto Kagaku Co., Ltd., for their support and assistance with this project.


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

Compliance with ethical standards


The scientific guarantor of this publication is Tony Martin Svahn.

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

One of the authors has significant statistical expertise.

No complex statistical methods were necessary for this paper.

Informed consent

Written informed consent was not required for this study because only exposure data and parameter settings were extracted from examinations in retrospect, in addition to phantom data.

Ethical approval

Institutional Review Board approval was not required because for this study because only exposure data and parameter settings were extracted from examinations in retrospect, in addition to phantom data.


• Retrospective

• Observational and experimental

• Performed at one institution


  1. 1.
    Båth M, Håkansson M, Börjesson S et al (2005) Nodule detection in digital chest radiography: effect of anatomical noise. Radiat Prot Dosimetry 114(1–3):109–113CrossRefGoogle Scholar
  2. 2.
    Blanchon T, Bréchot JM, Grenier PA et al (2007) Baseline results of the Depiscan study: a French randomized pilot trial of lung cancer screening comparing low dose CT scan (LDCT) and chest X-ray (CXR). Lung Cancer 58(1):50–58CrossRefGoogle Scholar
  3. 3.
    Terra-Filho M, Bagatin E, Nery LE et al (2015) Screening of miners and millers at decreasing levels of asbestos exposure: comparison of chest radiography and thin-section computed tomography. PLoS One 10(3):e0118585CrossRefGoogle Scholar
  4. 4.
    National Research Council (2006) Health risks from exposure to low levels of ionizing radiation: BEIR VII phase 2. The National Academies Press, Washington, DC, p 245Google Scholar
  5. 5.
    International Commission on Radiological Protection (1975) Report of the Task Group on Reference Man. ICRP Publication 23. Pergamon Press, Oxford Adopted October 1974Google Scholar
  6. 6.
    Zhu X, Yu J, Huang Z (2004) Low-dose chest CT: optimizing radiation protection for patients. AJR Am J Roentgenol 183(3):809–816CrossRefGoogle Scholar
  7. 7.
    Ketelslegers E, Van Beers BE (2006) Urinary calculi: improved detection and characterization with thin-slice multidetector CT. Eur Radiol 16(1):161–165CrossRefGoogle Scholar
  8. 8.
    Kubo T, Ohno Y, Nishino M et al (2016) Low dose chest CT protocol (50 mAs) as a routine protocol for comprehensive assessment of intrathoracic abnormality. Eur J Radiol Open 3:86–94CrossRefGoogle Scholar
  9. 9.
    Rampinelli C, De Marco P, Origgi D et al (2017) Exposure to low dose computed tomography for lung cancer screening and risk of cancer: secondary analysis of trial data and risk-benefit analysis. BMJ 356:j347CrossRefGoogle Scholar
  10. 10.
    Larke FJ, Kruger RL, Cagnon CH et al (2011) Estimated radiation dose associated with low-dose chest CT of average-size participants in the National Lung Screening Trial. AJR Am J Roentgenol 197(5):1165–1169CrossRefGoogle Scholar
  11. 11.
    Mettler FA Jr, Huda W, Yoshizumi TT, Mahesh M (2008) Effective doses in radiology and diagnostic nuclear medicine: a catalog. Radiology 248(1):254–263CrossRefGoogle Scholar
  12. 12.
    Fujita M, Higaki T, Awaya Y et al (2017) Lung cancer screening with ultra-low dose CT using full iterative reconstruction. Jpn J Radiol 35(4):179–189CrossRefGoogle Scholar
  13. 13.
    Schaal M, Severac F, Labani A, Jeung MY, Roy C, Ohana M (2016) Diagnostic performance of ultra-low-dose computed tomography for detecting asbestos-related pleuropulmonary diseases: prospective study in a screening setting. PLoS One 11(12):e0168979CrossRefGoogle Scholar
  14. 14.
    Brady SL, Kaufman RA (2012) Investigation of American Association of Physicists in Medicine report 204 size-specific dose estimates for pediatric CT implementation. Radiology 265(3):832–840CrossRefGoogle Scholar
  15. 15.
    Kyoto Kagaku Ltd. Multipurpose chest phantom N1 “LUNGMAN”. Accessed 27 Oct 2018
  16. 16.
    Shrimpton PC, Jones DG, Hillier MC, Wall BF, Le Heron JC, Faulkner K (1991) Survey of CT Practise in the UK. Part 2: dosimetric aspects (NRPB-R249). National Radiological Protection Borard, ChiltonGoogle Scholar
  17. 17.
    Stamm G, Nagel HD (2002) CT-expo--a novel program for dose evaluation in CT. Rofo 174(12):1570–1576CrossRefGoogle Scholar
  18. 18.
    Tapiovaara M, Lakkisto M, Sermovaa A (1997) PCXMC: a PC-based Monte Carlo program for calculating patient doses in medical x-ray examinations. Finnish Centre for Radiation and Nuclear Safety, HelsinkiGoogle Scholar
  19. 19.
    Cristy M, Eckerman K (1987) Specific absorbed fractions of energy at various ages from internal photon sources. Parts I-VII (ORNL/TM-8381). Oak Ridge National Laboratory, Oak Ridge, pp 1–74Google Scholar
  20. 20.
    Zankl M, Panzer W, Drexler G (1991) The calculation of dose from external photon exposures using reference human phantoms and Monte Carlo methods. VI. Organ doses from computed tomographic examinations. GSF-Forschungszentrum für Umwelt und Gesundtheit, Institut für Strahlenschutz, NeuherbergGoogle Scholar
  21. 21.
    International Committee on Radiological Protection (2007) The 2007 Recommendations of the International Commission on Radiological Protection. ICRP publication 103. Ann ICRP 37(2–4):1–332Google Scholar
  22. 22.
    International Committee on Radiological Protection (1991) 1990 Recommendations of the International Commission on Radiological Protection. ICRP publication No. 60. Pergamom, OxfordGoogle Scholar
  23. 23.
    Rubin DL (2011) Informatics in radiology: measuring and improving quality in radiology: meeting the challenge with informatics. Radiographics 31(6):1511–1527CrossRefGoogle Scholar
  24. 24.
    McCollough C, Bakalyar DM, Bostani M et al (2014) Use of water equivalent diameter for calculating patient size and size-specific dose estimates (SSDE) in CT: the report of AAPM task group 220. AAPM Rep 2014:6–23PubMedPubMedCentralGoogle Scholar
  25. 25.
    Weatherburn GC, Bryan S, Davies JG (2000) Comparison of doses for bedside examinations of the chest with conventional screen-film and computed radiography: results of a randomized controlled trial. Radiology 217(3):707–712CrossRefGoogle Scholar
  26. 26.
    Fasola G, Belvedere O, Aita M et al (2007) Low-dose computed tomography screening for lung cancer and pleural mesothelioma in an asbestos-exposed population: baseline results of a prospective, nonrandomized feasibility trial—an Alpe-Adria thoracic oncology multidisciplinary group study (ATOM 002). Oncologist 12(10):1215–1224CrossRefGoogle Scholar
  27. 27.
    Carrillo MC, Alturkistany S, Roberts H et al (2013) Low-dose computed tomography (LDCT) in workers previously exposed to asbestos: detection of parenchymal lung disease. J Comput Assist Tomogr 37(4):626–630CrossRefGoogle Scholar
  28. 28.
    Båth M, Svalkvist A, von Wrangel A, Rismyhr-Olsson H, Cederblad A (2010) Effective dose to patients from chest examinations with tomosynthesis. Radiat Prot Dosimetry 139(1–3):153–158CrossRefGoogle Scholar
  29. 29.
    Dobbins JT 3rd, McAdams HP, Sabol JM et al (2017) Multi-institutional evaluation of digital tomosynthesis, dual-energy radiography, and conventional chest radiography for the detection and management of pulmonary nodules. Radiology 282(1):236–250CrossRefGoogle Scholar
  30. 30.
    Lång K, Andersson I, Rosso A, Tingberg A, Timberg P, Zackrisson S (2016) Performance of one-view breast tomosynthesis as a stand-alone breast cancer screening modality: results from the Malmo Breast Tomosynthesis Screening Trial, a population-based study. Eur Radiol 26(1):184–190CrossRefGoogle Scholar
  31. 31.
    Han D, Heuvelmans MA, Oudkerk M (2017) Volume versus diameter assessment of small pulmonary nodules in CT lung cancer screening. Transl Lung Cancer Res 6(1):52–61CrossRefGoogle Scholar
  32. 32.
    Alvare G, Gordon R (2017) Foxels for high flux, high resolution computed tomography (foxelct) using broad x-ray focal spots: Theory and two-dimensional fan beam examples. Radiol Diagn Imaging 1(1):1–40CrossRefGoogle Scholar
  33. 33.
    Oyama A, Kumagai S, Arai N et al (2018) Image quality improvement in cone-beam CT using the super-resolution technique. J Radiat Res 59(4):501–510CrossRefGoogle Scholar
  34. 34.
    Naidu SG, Kriegshauser JS, Paden RG, He M, Wu Q, Hara AK (2014) Ultra-low-dose computed tomographic angiography with model-based iterative reconstruction compared with standard-dose imaging after endovascular aneurysm repair: a prospective pilot study. Abdom Imaging 39(6):1297–1303CrossRefGoogle Scholar
  35. 35.
    Rob S, Bryant T, Wilson I, Somani BK (2017) Ultra-low-dose, low-dose, and standard-dose CT of the kidney, ureters, and bladder: is there a difference? Results from a systematic review of the literature. Clin Radiol 72(1):11–15CrossRefGoogle Scholar
  36. 36.
    Thurley P, Crookdake J, Norwood M, Sturrock N, Fogarty AW (2018) Demand for CT scans increases during transition from paediatric to adult care: an observational study from 2009 to 2015. Br J Radiol 91(1083):20170467PubMedGoogle Scholar

Copyright information

© European Society of Radiology 2018

Authors and Affiliations

  1. 1.Centre for Research and DevelopmentUppsala University/Region GävleborgGävleSweden
  2. 2.Department of Surgical ScienceUppsala UniversityUppsalaSweden
  3. 3.Department of Organismal BiologyUppsala UniversityUppsalaSweden

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