Two recent studies on cumulative dose have raised concerns about whether patients undergoing multiple exams are receiving too much radiation dose, too often. During an ECR session dedicated to the issue, experts will discuss the steps that need to be taken and present the results of a survey launched by EuroSafe Imaging to assess the situation in Europe.

EuroSafe Imaging, the ESR’s flagship initiative for the promotion of quality and safety in medical imaging across Europe, has taken further steps to evaluate cumulative dose to patients, after two studies published in European Radiology showed that a significant number of patients undergoing multiple CT exams received cumulative effective dose (CED) of ≥ 100 mSv1, 2.

Prof. Guy Frija is chair of the EuroSafe Imaging Steering Committee. He is Professor Emeritus at Université Paris Descartes, France, Professor at McMaster University in Hamilton, Canada, and radiologist consultant at the Paris Georges Pompidou European Hospital.

The first study, carried out by a group led by Massachusetts General Hospital, gathered data on 2.5 million patients at three institutions in the United Sates and one in Slovakia, who underwent 4.8 million CT exams in a period of between one and five years. About 33,407 (1.33%) patients received a CED of ≥ 100 mSv, with an overall median CED of 130.3 mSv and maximum of 1,185 mSv, with nearly 20% of patients under 50 mSv.

The International Atomic Energy Agency (IAEA) communicated these results, and those of another study it carried out in 20 countries, covering 700,000 patients, during a meeting in March 2019, after which it raised a Call for Action.

In response to these events, EuroSafe Imaging has launched a Europe-wide survey to evaluate dose from recurrent CT examinations in adults and children, such as patients undergoing follow-up studies for cancer and chronic diseases.

EuroSafe Imaging will present the results of this study, in order to better reflect European practice, explained Prof. Guy Frija, Chair of the EuroSafe Imaging Steering Committee and of this session.

“Our goal is to add a European voice to this context and to help determine whether these repeated examinations are only reflecting the practice of the institutions where these data were collected, or if it is a more general phenomenon,” he said.

Based on these results, EuroSafe Imaging will publish new recommendations that will complete those already published on patients with cancer and chronic diseases.

With dose, the benefit/risk ratio must always prevail, but every patient’s case should be evaluated properly to decide on the appropriateness of imaging examinations.

“Cumulative examinations usually occur in the setting of a severe or chronic disease. Expensive treatments, often with significant side effects, are used in this context and need careful imaging follow-up. The benefit/risk balance also has to consider the radiation parameter through a structured approach between the radiologists and the physicians,” said Frija.

Jenia Vassileva is a radiation protection specialist at the International Atomic Energy Agency (IAEA) in Vienna.

The IAEA will also take part in the session, providing more details about the study it recently published, in which the agency found that every year around one million patients worldwide accumulate 100 mSv from repeated CT studies.

Although those results were obtained by extrapolation, one million is not an insignificant number, according to Jenia Vassileva, a radiation protection specialist at the IAEA in Vienna, Austria. “We do not want to frighten people, but a significant number of patients need imaging to be properly followed-up as part of their treatment, and increased cumulative exposure means the risk is higher than just undergoing one or two exams. The magnitude of this is larger than previously known or expected,” she said.

Vassileva added that 100mSv is not a threshold per se, but above that dose level, epidemiology provides sufficient evidence of increased risk. “While these doses are relatively small, we need to think about their long-term effects,” she said.

The IAEA issued a Call for Action to all stakeholders, which was published in European Radiology last December2. “Medical professionals including radiologists need more guidance to image patients with chronic diseases, be they oncologic, cardiac, renal, gastroenterological, etc.,” said Vassileva.

Initial research shows that most examinations are justified, but more investigation is needed into dose magnitude and examination appropriateness.

The industry must also be involved in the discussion about dose and must continue to offer imaging equipment that delivers lower dose to patients who need to be followed up. “The industry has a big role to play, but the end users also have a responsibility to use these low-dose features properly to customise clinical protocols to the individual patient’s needs,” Vassileva said.

The IAEA will hold a technical meeting straight after the ECR, in which it will invite international organisations, industry partners and professional medical societies who are involved in referring patients and performing exams to propose solutions for ensuring that the whole chain of imaging, from diagnosis to follow-up, is properly justified and optimised for those patients who need these studies more often than others.

Dr. Franz Kainberger is deputy chief of the Division of Neuroradiology & Musculoskeletal Radiology and Medical Director of the Computer Image Analysis (CIR) Lab at the Department of Biomedical Imaging and Image-Guided Therapy at the Medical University of Vienna, Austria.

EuroSafe Imaging also published a Call for Action in 2014, and repeated the initiative in 20183, to raise awareness of the issue of dose among the wider public. The campaign has just released an editorial on awareness of radiation protection4.

EuroSafe Imaging will continue its efforts in this area and promote the ESR iGuide, a clinical decision support system for imaging referral guidelines in Europe and low and middle-income countries. EuroSafe Imaging also plans to widen its educational offerings, through currently published material and the ESR’s Education on Demand platform. The ESR is developing a series of regular webinars that will help radiologists improve the appropriateness and justification of examinations.

Please note that for pre-recorded sessions published during the ECR Highlight Weeks, there will be no chairpersons. However, we still wanted to keep Professor Frija’s statements for the article as he initially gave them.

1 Rehani MM, Yang K, Melick ER et al. Patients undergoing recurrent CT scans: assessing the magnitude. Eur Radiol (2019).
3 Call for Action 2018;
4 Kainberger F, Frija G. Management of Cumulative Effective Dose – Awareness in Radiation Protection Needed. Eur Radiol (in press)

EuroSafe Imaging Session
EU 3 Cumulative dose: too often and too much

  • Cumulative doses: an awareness problem
    Jenia N. Vassileva; Vienna/AT
  • Defining scenarios with a risk for cumulative dose
    Franz Kainberger; Vienna/AT
  • EuroSafe Imaging: opportunities to reduce cumulative doses in children
    Raija Seuri; Helsinki/FI
  • This session is part of the EuroSafe Imaging campaign.


Das M, Jeukens CR, Schnerr RS, Niesen S, Wildberger JE (2015) Assessment of high cumulative patient doses of repetitive CT examinations. ECR 2015 / B-0782:

Ciacchini B, Formica M, Lisciandro F (2018) Cumulative radiation dose in pediatric patients with haematological diseases in the first 5 years after diagnosis. ECR 2018 / C-0979:

Caramella D, Falaschi F, Cioni R et al (2019) Setting up a dose team steering committee to supervise Dose Management Systems. EuroSafe Imaging 2019 / ESI-0012:

Sullivan CJ, Murphy KP, McLaughlin PD (2015) Radiation exposure from diagnostic imaging in young patients with testicular cancer. Eur Radiol. 25(4):1005-13: