Harmful rays - fluoroscopically guided interventional procedures

3 November 2016



Technologists who perform fluoroscopically guided interventional procedures face increased risks of brain and breast cancers and melanoma, according to a new study. Dr Preetha Rajaraman, South Asia programme director at the US National Cancer Institute’s Center for Global Health, discusses the safety issues for patients and radiologists.


The clinical benefits of medically appropriate, fluoroscopically guided interventional procedures outweigh any radiation risk, large or small, to the patient. They are cheaper, less invasive and result in shorter hospital stays for patients than surgical procedures.

In 2008, the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) estimated that more than 3.60 billion diagnostic radiology examinations were performed, 37.0 million nuclear medicine procedures were carried out, and 7.5 million radiotherapy treatments were given worldwide annually.

The benefits for patients are clear; but what about the risks to radiation technologists who perform these procedures? The World Health Organization classifies ionising radiation as a carcinogen, and while its use enables earlier diagnosis and less invasive treatments for patients, it does represent an occupational hazard for technologists. Although protected by special clothing and lead shields, they are exposed to varying degrees of radiation almost every day.

According to a study published in the American Journal of Roentgenology in May 2016, technologists who performed or assisted in fluoroscopically guided interventional procedures faced a two-fold increase in the risk of brain cancer mortality, and modest elevations in incidences, but not mortality, of melanoma and breast cancer, compared with technologists who did not.

Dangerous work

The study examined the risk of cancer incidence and mortality among 90,957 radiation technologists in the US who had responded to a previous survey between 1994 and 1998 about whether they worked with fluoroscopically guided interventional procedures. “The use of fluoroscopically guided interventional procedures has been growing rapidly in the US,” says Dr Preetha Rajaraman, South Asia programme director at the US National Cancer Institute’s Center for Global Health. “Although these procedures provide substantial benefits to patients, they also carry risks to patients and to the healthcare workers who perform them since the technology uses ionising radiation, a known carcinogen, to create images of internal organs.

“Very little is known about risks of cancer or other health outcomes associated with exposure to very low levels of ionising radiation received periodically over long periods of time, such as those experienced by radiologic technologists,” she continues.

Exposure to radiation in the workplace is one possible explanation for these findings, but the role of chance or confounding by other non-radiation risk factors cannot be ruled out.

“The US National Cancer Institute established a large study of radiologic technologists to examine these potential risks. Our findings will have relevance for the technicians who are regularly exposed through their work.”

Although the results suggested a small increase in the incidence of all cancers – excluding non-melanoma skin cancers – combined, there was no increase in mortality. The researchers observed no elevated risk of cancers of the thyroid, skin (other than melanoma), prostate, lung, or colon and rectum, or of leukaemia that was not chronic lymphocytic leukaemia in technologists who performed the procedures.

“Increased risks of breast cancer, brain cancer and melanoma were observed in technologists who reported working with fluoroscopically guided interventional procedures,” Rajaraman says. “Exposure to radiation in the workplace is one possible explanation for these findings, but the role of chance or confounding by other non-radiation risk factors cannot be ruled out until these results have been replicated in more studies, preferably with individual radiation dose data. In the meantime, medical personnel exposure to radiation to should be minimised whenever possible, as recommended by radiation protection organisations.”

The researchers believe more work is necessary to confirm their findings and they are already using the same data for further studies. “In this same cohort, detailed radiation doses are being characterised for the subset of workers who reported that they worked with fluoroscopically guided interventional procedures,” says Rajaraman. “Analyses of these data will shed further light on this issue. Additionally, studies of cancer risks in physicians who practice interventional procedures will soon be published.”

Quality before safety?

In the US, the focus is on obtaining the highest-quality image, meaning more radiation than necessary is often used. In Europe and Japan, safety is the focus and the radiation levels are kept lower: the ideal dose is the least amount of radiation possible to produce an acceptable result.

“Reduced patient dose means reduced technologist dose, since technologist dose is related to scattered radiation from the patient,” says Rajaraman.

Scatter radiation from a patient is the biggest source of exposure for healthcare workers, particularly in angiography procedures, where several personnel are needed around the patient while he or she is undergoing radioscopy for extended periods and with multiple radiographic exposures.

Higher radiation levels, larger patients and higher fields of view all result in more scatter, and therefore present a higher potential radiation dose for the radiological technician. In 2012, the National Council on Radiation Protection and Measurement (NCRP) issued ‘Report No. 168: Radiation Dose Management for Fluoroscopically Guided Interventional Procedures’. Although aimed at preventing unexpected or avoidable tissue reactions in patients, it emphasises the need for a controlled radiation dose to ensure the safe performance of fluoroscopically guided interventional procedures. Controlling and reducing the radiation dose – as well as fluoroscopy time and the number of images required – is beneficial not only for patients and radiation technologists but also for other healthcare workers.

The NCPR also set 5,000 millirems a year, in addition to background radiation, as an acceptable level of radiation for technicians to be exposed to. This level can be monitored via a dosimeter – in the form of a ring or badge – that keeps a detailed record of the wearer’s cumulative lifetime dose and should be worn whenever they are working with radiation.

It is imperative that these are worn and that any high badge/ring value is investigated rather than ignored. Often, the reason for a high dosimetry is easily resolved; these devices allow for dosimetry to be tracked through any job changes.

Rajaraman says the results from her group’s studies underscore the need for consistent use of personal protective equipment while performing procedures involving exposure to ionising radiation. But how are radiation technicians currently protected?

Shielding benefits

There are three ways in which radiology technicians can safeguard themselves: shielding, time and distance. The first is an incredibly important safety mechanism: any object between the technologist and a source of radiation will provide some shielding. In general, the more dense an object or material, the better the shielding it provides.

Types of shielding include:

  • personal shields such as lead aprons, ranging from 0.25 to 0.50mm of lead depending on the peak X-ray voltage; glasses; gloves; and thyroid and groin shields
  • equipment-mounted, such as drapes
  • rolling and stationary shields
  • disposable patient drapes to prevent scatter radiation
  • architectural shielding – rooms in which radiation is used must have a predetermined thickness of lead in the walls, doors and windows.

The amount of exposure to radiation an individual receives is directly proportional to the time he or she spends in its presence, so minimising this is important. Fluoroscopy procedures should be completed as quickly as possible, and fluoroscopes have a five-minute reset timer to remind users of the elapsed period. Pulsed progressive fluoroscopy, in which the X-ray beams are pulsed, rather than continuous, can also reduce patient and caregiver doses by 90% or more.

Distance is important as well. Technologists should be outside the room (or, at the very least, behind shielding) when equipment is in use, and remain as far from the patient as possible. This is not always possible, particularly if the subject does not remain still. Moving can affect the quality of the image, so mechanical devices and restraints can be used, but sometimes it is necessary to hold the patient still.

Healthcare providers should keep radiation exposure as low as reasonably achievable without compromising essential imaging information or treatment.

The medical industry also monitors short and long-term exposure as our current understanding of how long-term low-level radiation exposure works helps to keep cancer risk low. Protective equipment should be designed to provide complete protection, checked regularly and changed when necessary.

Manufacturers are working on methods to reduce patient dose without sacrificing image quality, says Rajaraman. It might therefore be beneficial for technicians to undergo further training to learn how to make full use of the radiation-reduction features built into equipment, for example, or how to position X-ray tubes to obtain better images with less radiation.

It should be a requirement that everyone working with or around radiation – physicians, equipment operators, technologists, nurses and others – take a safety course. In California, for example, anyone working with fluoroscopy must take a class in order to obtain a permit.

Risk will always exist, of course, but the level can be manageable with appropriate working practices. Rajaraman offers this advice: “Patients should continue to undergo medically necessary imaging examinations and fluoroscopically guided interventional procedures, because the benefits greatly exceed the risks.

“Healthcare providers should keep radiation exposure as low as reasonably achievable without compromising essential imaging information or treatment. Personal protective equipment, when used properly, can reduce exposure for technicians.”

Dr Preetha Rajaraman is South Asia programme director at the at the US National Cancer Institute’s Center for Global Health. She obtained her doctoral degree in epidemiology from the Johns Hopkins University Bloomberg School of Public Health in 2004.
Radiation technicians are exposed to low levels of ionising radiation over long periods of time.
Potential risks associated with exposure to ionising radiation can be managed.


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