When German physicist Wilhelm Roentgen discovered x-rays in 1895, it was clearly groundbreaking. Less than a year later, three doctors at the Hospital of the University of Pennsylvania (J. William White, chief of surgery; Charles Lester Leonard, HUP’s first radiologist; and physicist Arthur Goodspeed) published an article describing the many applications for this new technology. The Roentgen method, stated the authors, “is, of course in its infancy. It has, however, already reached a degree of usefulness that makes it obvious that the necessary apparatus will be an essential part of the surgical outfit of all hospitals and will be employed constantly in a variety of cases.”
But one thing these pioneers were not aware of: radiation’s potential dangers. After all, how could electromagnetic waves – which could not be seen or felt – be dangerous? “In the early days, there was no presumption of risk,” said physicist Andrew Maidment, PhD, an associate professor of Radiology at HUP. As a result, those in the field frequently suffered burns and reddening of their hands, the first sign of injury from radiation (similar to a sunburn). Some doctors eventually lost fingers; others were diagnosed with cancer years later. “Almost the entire first generation of radiologists died from their occupational exposure,” Maidment said.
It’s not that exposure to radiation is dangerous. In Philadelphia, we’re exposed to radiation levels equivalent to 30 chest x-rays a year. “We’re constantly bathed in it,” he said. Terrestrial radiation comes from the ground (think radon) and cosmic radiation pours down on us from the sun and the stars. And we ingest radiation! Bananas contain potassium 40, which is measurably radioactive. But, Maidment stressed, “the benefits of eating bananas –such as preventing muscle cramps – far outweigh the risks.”
By 1903, Leonard had noted in a paper that “I have been suffering from x-ray burns for some time…. I have found that relief has resulted, not from protecting either my person or my hands, but from covering the tube in such a way that the rays are not carried out into the room.”
This type of shielding – which, along with time and distance, control radiation exposure – became progressively better over the years. “Initially they put a lead glass bowl around the x-ray tube, with a small hole that pointed towards patients,” Maidment said. Over time, this expanded to wrapping the whole tube with lead. Modern tubes are large lead cylinders with the x-ray tube sitting inside. Only a small amount of radiation gets out.
All x-ray rooms at HUP have a shielded operator booth, and surrounding walls have lead sheets in them. “That’s one of my jobs, to make sure every room in the hospital is safe from radiation,” he said. And every person as well – not only employees who work with radiation but also those working in adjoining rooms or even walking past in hallways.
Radiation exposure for patients undergoing any type of imaging is also closely monitored. Every image is examined and data analyzed to make sure the radiation levels aren’t too high. And special software will automatically alert a clinician ordering exams if a patient has recently undergone imaging.
Maidment and other Radiology physicists are responsible for making sure “our images have the highest quality for the minimum exposure.” They cover 600 instruments throughout Penn Medicine, which produce over 1.3M radiographic studies a year. “We ensure consistency in quality throughout the Health System,” he said. “That’s what distinguishes Penn. Many hospitals have consultants that come in a few days a year. We provide constant quality assurance.”
All Radiology employees at HUP are monitored with film badges “to make sure we don’t get too much exposure,” he said. “No matter what precautions you take to keep it to a minimum, some radiation does get through.” These personal dosimeters record how much radiation a person had been exposed to over a period of time, usually one to three months. If any badge records show too much radiation exposure, “we investigate.” Typically, there’s a simple explanation. For example, the employee may have been wearing the film badge while having an x-ray.
Employees are also regularly and extensively educated on using best practices when working with radiation. For example, let’s say a patient is undergoing a stress test in Nuclear Medicine. “The radioactive material is injected and then the person goes on the treadmill,” Maidment said. “Employees have to stay near in case a patient falls, but if they can take one step back, they’ve cut their exposure in half.”
To ensure that this level of quality and safety continues into future generations, HUP’s Radiology residents are trained in the physics of x-rays. “You have to be an expert in the technology you’re using,” Maidment said. “A racetrack driver will know exactly what to adjust or change on the car to get him around the track one or two miles per hour faster. That’s the radiologist we want – someone who can look at the image and know exactly what to tweak to make it better.”
Photo caption: Charles Leonard, HUP's first radiologist, with Mrs. McNally, head nurse in the men's surgical ward, in one of the original roentgen-ray rooms at HUP.