Dose reduction in medical radiation – regulators, industry and healthcare professionals seek common front

Ionizing radiation, from the sun and even the earth, is a daily fact of life. There is little that can be done about this, except to stay away from too much sunlight and protect the skin with sunscreens. On the other hand, people are also sometimes exposed to radiation for medical reasons – such as diagnostic X-Rays or CT scans, or a range of interventional radiology procedures. These procedures offer tremendous benefits for patients and for healthcare providers. The evidence for such benefits has become indisputable in recent years, and covers a wide range of diseases and conditions.

Medical imaging has profound impact on patient management
The American Journal of Roentgenology’ reported in 2011 that abdominal surgeries reduced significantly after CT scans. Physicians planned to admit 75percent of patients to hospital before CT. This level was changed to hospital discharge with follow-up in 24percent of patients after CT. The conclusions of the researchers, from Massachusetts General Hospital, were conclusive: CT ‘changes the leading diagnosis, increases diagnostic certainty, and changes potential patient management decisions.’
Massachusetts General Hospital was indeed one of the first institutions to study the impact of medical imaging. In 1998, a team from the hospital reported that CT was 93-98percent accurate in confirming or ruling out appendicitis. The condition accounted for 1 million patient-days per year in the US, with a similar level eventually found to have other conditions.

From emergency rooms to lung cancer
More recently, the New England Journal of Medicine’ published a study on non-invasive coronary CT imaging in the emergency room. The study found that out of the 8 million visits per year to emergency rooms by patients with chest pain, only 5-15percent were eventually found to be suffering from heart attacks or other serious cardiac diseases. As many as 60percent of patients faced unnecessary admission and testing to exclude acute coronary syndrome.
Meanwhile, it has also been reported that low-dose CT screening reduced lung cancer deaths by at least 20percent in a high risk population of current and former smokers aged 55 to 74. These findings were reported by the National Lung Cancer Trial in the US.

Fight against Alzheimer’s, speeding up clinical trials
In the future, medical imaging holds forth significant promise as a tool in the fight against diseases ranging from osteoporosis to Alzheimer’s, whose incidence is likely to grow sharply as the population ages.
Medical imaging also offers increasing promise as a surrogate endpoint in clinical trials, allowing measurement of the effect of a new drug far earlier than traditional endpoints, such as survival times or clinical benefit.

Concerns about over-use, some alarmist
Nevertheless, there are several concerns about over-use’ – especially for imaging accompanied by radiation such as CT. In the US, according to a June 2012 review in the Journal of the American Medical Association’, CT scans tripled in the period 1996-2010, corresponding to a 7.8percent annual increase. Although this was less than a near four-fold increase in MRI and a 30percent fall in nuclear medicine use, CT has been the target of sometimes emotive campaigns.
One good illustration of this was an Op-Ed in the New York Times’ on January 31, 2014. The article was titled ‘We Are Giving Ourselves Cancer.’ It opened with the observation that we are ‘silently irradiating ourselves to death,’ while its closing sentence urged finding ways to use CTs ‘without killing people in the process.’

The Times’ Op-Ed cited a British study which ‘directly demonstrated’ evidence of the ‘harms’ of CT, and it is here that its authors over-stretched their credibility. The study they referred to was published in Lancet’ in August 2012 and titled Radiation exposure from CT scans in childhood and subsequent risk of leukemia and brain tumours: a retrospective cohort study’. Its authors used data on 175,000 children and young adults and found that the cumulative 10-year risk was higher in relative terms, but translated into one extra case of leukemia and one extra case of brain tumour per 10,000 head CT scans.

ALARA and the principle of necessity and justification
In other words, while few would argue that there is no risk from radiation, it is clear that such risks are small and that even these small potential risks could be controlled further by reducing exposure to radiation.
Both industry and healthcare professionals are endeavouring to ensure that such a goal is achieved.
Manufacturers of CT and other radiation imaging equipment seek to keep exposure to radiation for both patients and medical staff to a minimum – and below their regulatory limits – by using the ALARA (As Low As Reasonably Achievable) principle to design their products. Key methods include use of the most dose-efficient technologies available and seeking to ensure that optimum scan parameters are used for a patient and examination type.
Meanwhile, in the clinical setting, doctors seek to ensure that radiation imaging examination is ordered only when absolutely necessary and justified, while radiographers optimize the radiation dose used during each procedure.

Safety, information and awareness
Since the mid-2000s, radiologists and medical physicists have taken steps to increase controls on radiation risks to patients. These have essentially focused on promoting the safe use of medical imaging devices, supporting informed clinical decision making and increasing patient awareness.
One of these initiatives is known as Image Gently, a collaborative initiative by radiology professional organizations and other concerned groups. Its target is to specifically lower radiation dose during the imaging of children.
A related initiative, led by the American College of Radiology (ACR) and the Radiology Society of North America (RSNA), is Image Wisely. This is essentially an awareness campaign whose goals are to eliminate unnecessary’ procedures and lower doses to minimal levels required for clinical effectiveness when necessary. One aspect of Image Wisely is collaboration between medical radiologists and manufacturers to improve performance of radiology equipment and allow physicians to make real-time assessments of whether radiation levels are acceptable.

Initiatives by professional societies
Such initiatives are closely supported by professional radiology societies. The ACR has developed Appropriateness Criteria (corresponding to the federal requirements on appropriate use) to assist referring physicians and radiologists in prescribing the best imaging examination for patients – based on symptoms and circumstances. One tool consists of the display of imaging options and associated radiation levels for a specific procedure. The aim is to reduce imaging examinations by assuring that the most suitable exam is done first.
In Europe, the European Society of Radiology’s flagship EuroSafe Imaging’ has the same objective, to maximize radiation protection and quality/safety in medical imaging. The initiative was launched at the European Congress of Radiology in 2014 and has so far attracted over 50,000 individual supporters (known as Friends of EuroSafe Imaging’). Over 200 institutions (industry and healthcare providers) have also endorsed the initiative.

Accreditation programmes
Accreditation programmes are also being targeted by the ACR and ECR, in order to assess facilities based on imaging competence, adherence to latest dose guidelines, and personnel training. Given the pace of technology development in imaging, certified radiology and nuclear medicine professionals are increasingly recommended or (in some cases) required to earn continuing education credits on radiation safety.
In Europe, the ECR has joined forces with the European Federation of Organizations for Medical Physics (EFOMP), the European Federation of Radiographer Societies (EFRS), the European Society for Therapeutic Radiology and Oncology (ESTRO), the European Association of Nuclear Medicine (EANM), as well as the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) on an EU-promoted radiation education project called MEDRAPET. The findings, published in 2014, revise the previous Radiation Protection 116 Guidelines on Education and Training.

The Bonn Call for Action sets roadmap for the future
Many of these initiatives have been inspired by a conference held in Bonn, Germany, at the end of 2012, which was sponsored jointly by two United Nations bodies – the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO). The outcome of the conference, which was attended by participants from 77 countries, is known as the Bonn Call for Action, and aims to strengthen medical radiation practices into the 2020s.

The Bonn Call consists of ten major actions. These are described below:

• To enhance implementation of the principle of justification. There is explicit emphasis on the use of clinical decision support (CDS) technology towards such a goal.
• To enhance implementation of the principle of optimization of protection and safety. There is a specific call to ensure the establishment, use and regular updating of diagnostic reference levels for radiological procedures, including interventional procedures, and to develop and apply technological solutions for patient exposure records, harmonize dose data formats provided by imaging equipment and increase utilization of electronic health records.
• Strengthen manufacturers’ role in contributing to the overall safety regime. This seeks to enhance radiation protection features in the design of both physical equipment and software, and to make these available as default features rather than optional extras.
• Strengthen radiation protection education and training of health professionals.
• Increase availability of improved global information on medical exposures and occupational exposures in medicine, with specific attention to developing countries.
• Improve prevention of medical radiation incidents and accidents. One interesting facet here is a call to work towards including all modalities of medical ionizing radiation as part of a voluntary safety reporting process, with specific emphasis on brachytherapy, interventional radiology, and therapeutic nuclear medicine, in addition to external beam radiotherapy.
• Strengthen radiation safety culture in healthcare.
• Foster an improved radiation benefit-risk-dialogue.
• Strengthen the implementation of safety requirements globally.
• Develop practical guidance to provide for the implementation of the International Basic Safety Standards in healthcare globally.

Although some of the Bonn Call points are repetitive, the document is noteworthy in terms of setting a minimal set of common rules for a very wide range of stakeholders – manufacturers, health professionals and professional societies.

Point 6 seeks new work on effective’ dose
Point 6 of the Bonn Call is both ambitious and timely. Although the concept of effective dose’ (or effective dose equivalent) was introduced in the mid-1970s to provide a common framework for evaluating the impact of exposure to ionizing radiation via any means, technology’s uneven leaps have not made it easy to follow through. Data for doses by different radiographic imaging modalities used in radiation therapy are scattered widely through literature, making it difficult to estimate the total dose that a patient receives during a particular treatment scenario. In addition, interventional systems are often configured differently from diagnostic set-ups and imaging systems do not distribute radiation in similar ways. For example, planar kV imaging attenuates rapidly along the line of sight, while CT dose is uniformly distributed through a patient. This makes it difficult to sum dose in a radiobiologically consistent manner.