Estimates of the number of patients with high cumulative doses through recurrent CT exams in 35 OECD countries


      • Estimates were made of number of patients likely receiving cumulative effective dose ≥100 mSv in 5-years from CT exams.
      • It results in about 2.5 million patients in 35 OECD countries.
      • Countries were classified into Low: 0 to <1, Medium: 1 to <2 and High: ≥2 patients with CED ≥ 100 mSv/1000 population.
      • There are 2 countries in Low, 24 in medium and 9 in high number group.
      • Stake holders in patient radiation safety should attend to the issue of high doses to such large number of patients.



      To estimate the number of patients in OECD (Organization for Economic Co-operation and Development) countries who receive a cumulative effective dose (CED) ≥ 100 mSv from recurrent computed tomography (CT) exams.


      Taking into account recently published data on the number of CTs per patient and the fraction of patients with CED ≥ 100 mSv as well as country-specific data for the number of CT exams/1,000 population from OECD publication, this paper makes estimations for 35 OECD countries.


      The estimated total number of patients with CED ≥ 100 mSv for all 35 OECD countries combined in a 5-year period is around 2.5 million (2,493,685) in a population of 1.2 billion (1,176,641,900), i.e., 0.21% of the population. Expressed per 1,000 population, the range is from 0.51 for Finland to 2.94 for the US, a nearly six-fold difference. Countries with more than 2 patients with CED ≥ 100 mSv in a 5-yr period per 1,000 population are: Belgium, France, Iceland, Japan, Korea, Luxembourg, Portugal, Turkey, and US.


      The first estimates of the number of patients likely receiving CED ≥ 100 mSv through recurrent CT exams in 35 OECD countries indicate that 2.5 million patients reach this level in a 5-year period. There is an urgent need for various stakeholders including medical physicists, referring physicians, health policy makers, manufacturers of CT equipment and epidemiologists to attend to the issue in the interest of patient radiation safety.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Physica Medica: European Journal of Medical Physics
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Mettler Jr., F.A.
        • Mahesh M.
        • Bhargavan-Chatfield M.
        • Chambers C.E.
        • Elee J.G.
        • Frush D.P.
        • et al.
        Patient exposure from radiologic and nuclear medicine procedures in the United States: procedure volume and effective dose for the period 2006–2016.
        Radiology. 2020; 17192256
      1. European Commission. Medical Radiation Exposure of the European Population. Radiation Protection N° 180. 2015.

        • Rehani M.M.
        • Szczykutowicz T.P.
        • Zaidi H.
        CT is still not a low-dose imaging modality.
        Med Phys. 2019;
        • Kachelrieß M.
        • Rehani M.M.
        Is it possible to kill the radiation risk issue in computed tomography?.
        Phys Med. 2020; 71: 176-177
        • Sakane H.
        • Ishida M.
        • Shi L.
        • Fukumoto W.
        • Sakai C.
        • Miyata Y.
        • et al.
        Biological effects of low-dose chest CT on chromosomal DNA.
        Radiology. 2020; 10190389
      2. Meulepas JM, Ronckers CM, Smets AMJB, et al. Radiation exposure from pediatric CT scans and subsequent cancer risk in the Netherlands [published correction appears in J Natl Cancer Inst. 2018 Oct 1;110(10):1154]. J Natl Cancer Inst. 2019;111(3):256–263. doi:10.1093/jnci/djy104.

        • Pearce M.S.
        • Salotti J.A.
        • Little M.P.
        • et al.
        Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study.
        Lancet. 2012; 380: 499-505
        • Bernier M.O.
        • Baysson H.
        • Pearce M.S.
        • et al.
        Cohort Profile: the EPI-CT study: a European pooled epidemiological study to quantify the risk of radiation-induced cancer from paediatric CT.
        Int J Epidemiol. 2019; 48: 379-381g
        • Rehani M.M.
        Challenges in radiation protection of patients for the 21st century.
        Am J Roentgenol. 2013; 200: 762-764
        • Rehani M.M.
        • Yang K.
        • Melick E.R.
        • Heil J.
        • Šalát D.
        • Sensakovic W.F.
        • Liu B.
        Patients undergoing recurrent CT scans: assessing the magnitude.
        Eur Radiol. 2020; 30: 1828-1836
      3. National Council of Radiation Protection and Measurements. Implications of Recent Epidemiologic Studies for the Linear-Non threshold Model and Radiation Protection. NCRP Commentary No. 27. 2018, Bethesda, Maryland: NCRP.

      4. UNSCEAR. United Nations Scientific Committee on the Effects of Atomic Radiation. Sources, Effects and Risks of Ionizing Radiation. Uncertainties in risk estimates for radiation-induced cancer. Annex B. 2015,

      5. International Commission on Radiological Protection. Low-dose Extrapolation of Radiation-related Cancer Risk. ICRP Publ 99. Ann ICRP Ann. ICRP 35(4); 2005.

        • Hauptmann M.
        • Daniels R.D.
        • Cardis E.
        • Cullings H.
        • Kendall G.M.
        • Laurier D.
        • et al.
        Epidemiological studies of low-dose ionizing radiation and cancer: summary bias assessment and meta-analysis.
        J Natl Cancer Inst Monogr. 2020; 2020: 188-200
      6. OECD Organization for Economic Co-operation and Development.

      7. OECD Organization for Economic Co-operation and Development (2019) Health at a glance 2019: OECD indicators. OECD Publishing, Paris.

        • Brambilla M.
        • Vassileva J.
        • Kuchcinska A.
        • Rehani M.M.
        Multinational data on cumulative radiation exposure of patients from recurrent radiological procedures: call for action.
        Eur Radiol. 2019;
        • Smith-Bindman R.
        • Wang Y.
        • Chu P.
        • et al.
        International variation in radiation dose for computed tomography examinations: prospective cohort study.
        BMJ. 2019; 364: k4931]
        • Rehani M.M.
        • Melick E.R.
        • Alvi R.M.
        • Khera R.D.
        • Batool-Anwar S.
        • Neilan T.G.
        • et al.
        Patients undergoing recurrent CT exams: assessment of patients with non-malignant diseases, reasons for imaging and imaging appropriateness.
        Eur Radiol. 2020; 30: 1839-1846
        • Klein L.
        • Dorn S.
        • Amato C.
        • Heinze S.
        • Uhrig M.
        • Schlemmer H.-P.
        • et al.
        Effects of detector sampling on noise reduction in a clinical photon counting whole-body CT.
        Invest Radiol. 2020; 55: 111-119
        • Rehani M.M.
        • Berris T.
        International Atomic Energy Agency study with referring physicians on patient radiation exposure and its tracking: a prospective survey using a web-based questionnaire.
        BMJ Open. 2012; 2: e001425
        • Seuri R.
        • Rehani M.M.
        • Kortesniemi M.
        How tracking radiologic procedures and dose helps: experience from Finland.
        AJR Am J Roentgenol. 2013; 200: 771-775