Glow-in-the-Dark Doc: Radiation Exposure

There are a few orthopedists who might like to enter the OR—or exam room—with a bullhorn. Their colleagues, naturally focused on the patient’s damaged anatomy, might not be paying much attention to the invisible danger lurking nearby…radiation.

The Sobering News on Radiation

Dr. Brian D. Giordano, an orthopedic resident at the University of Rochester Medical Center, has researched the effects of radiation on both patients and surgeons. And he’s concerned. “Orthopedists are increasingly reliant on radiographic imaging for our diagnostic and therapeutic work, thus putting our patients and ourselves in a vulnerable position. While patients are only occasionally exposed to radiation, surgeons may be exposed on a daily basis. In the last 20 years there has been a focus on making interventional procedures less invasive. While that has its upsides, of course, the downside is that we are now even more heavily reliant on indirect visualization, such as intraoperative fluoroscopy, which can be used to help guide the placement of various implants and facilitate reductions.”

Dr. Glenn Rechtine, also an orthopedist at the University of Rochester, is most alarmed about what is emanating from that beloved piece of diagnostic equipment—the CT scanner. “The statistics are sobering—patients are being subjected to 30 times more radiation now than they were 20 years ago. The greatest risk for patients is not from the OR or the C-arm but from a CT scanner. CT scans comprise only 5% of X-ray imaging but almost 50% of total radiation exposure to patients. Most doctors just don’t know what they’re subjecting their patients to. In fact, 95% of physicians grossly underestimate how much radiation exposure both they and their patients are getting. Only 14% of doctors have undergone any training on radiation.”

Exposure 101

Exposure usually begins in medical school. Dr. Rechtine: “Basic training can make a big difference in the level of exposure. For example, setting up a C-arm in a different way can change the amount of radiation exposure 50 fold. If patients are getting 50 times more radiation, then the doctor is too.”

Left agog by the nonchalance of some of his colleagues, Dr. Rechtine says,

About four years ago when I started this work, the radiation physicist did a presentation at Rochester on the dangers of radiation. It was disheartening to see a surgeon doing a crossword puzzle during the talk.

Pounding the drum louder, Dr. Rechtine has taken his message to wider audiences. “I have done presentations for the Cervical Spine Research Society, the North American Spine Society, and other entities. One powerful example I give is of a front to back X-ray of a trauma patient in the ER. The technician taped a hemostat to a film cassette and held this seven feet away while he was taking the X-ray, the point at which we traditionally think we’re safe from radiation. When the film was developed you could see the hemostat—there was scatter radiation. Yes, it was a small amount but the point is that it’s not 0. All you have to do is use the tools available to us—lead aprons, for example—and you can decrease your exposure.”

On one occasion Dr. Rechtine got a creative suggestion for combating the cavalier attitude of some of his colleagues. “A couple of years ago I was invited to speak at the University of Kentucky department of orthopedic surgery. When the program director told me that I was on the schedule to talk about radiation safety Friday night, I said, ‘No that’s the banquet. Families are there.’ The program director said, ‘Glenn, I have heard your talk and have been pounding on the surgeons to change, but to no avail. It’s time to talk to the spouses.’”

The Need for Research

Giving a bit of background on his research, Dr. Giordano notes, “We used a highly sensitive radiation monitor and found a chink in the six foot rule. We stood 20 feet away from a mini C-arm and were still getting 40 times the background radiation dose. Unfortunately, the dogma with regard to a mini C-arm is that because we use radiation reduction tools you don’t have to be as careful.”

Dr. Rechtine: “Someone I know actually stands inside the C-arm with his foot on the pedal…and with no apron. I evaluated the radiation exposure report of 24 attendings at a major university over a period of six months. ‘Miraculously, ’ the total exposure was 0. That was because of the 24 surgeons using the C-arms, only four of them picked up their radiation badges. Even these four didn’t wear them in surgery.”

“Such complacency carries forth in a lack of awareness of how radiation impacts patients, ” says Dr. Rechtine. “In general we are too casual about writing prescriptions that exposure our patients to radiation. And most times the patients don’t know enough to object. Estimates are that there are 30 times more CT scans being done now as opposed to 20 years ago. It has also been estimated that 2% of all cancers are from the excessive use of CT scans. If, for example, someone is in the hospital, he or she may have an abdominal CT four days in a row to see if something has changed. Or, if a trauma patient gets a CT of the abdomen, something might be picked up that leads to a CT of the spine. So they get a spine CT, which has more radiation than an abdominal CT. It is a tough call to make in some cases.”

And it’s especially hard if people are muddying the waters. Dr. Giordano: “I recently wrote a letter to the editor at the Journal of Neurosurgery: Spine about an article they published on the ‘safety’ of minimally invasive spine surgery. I pointed out that surgeons doing this procedure get a fair amount of radiation and patients gets huge doses…and yet the title included the word ‘safety.’ The high doses were essentially passed off as meaningless.”

But Dr. Giordano has hopes of making an educational impact with the younger generation. “Residents in particular are at a heightened risk for exposure because of all the minimally invasive techniques and use of the C-arm fluoroscopy in the OR. Because they are still learning, their skill levels are not as adept, so they repeat the tests. And when they are first learning to work with pedicle screws, they are checking every step of the way with an X-ray.”

Europe is often ahead of the U.S., not just on the clock, but in thinking. Dr. Rechtine: “I went to a meeting in Vienna with the International Atomic Energy Agency where we worked on a serious plan to educate doctors on the dangers of radiation exposure. Actually, the EU is on the brink of mandating that every doctor using a C-arm undergo a two day training course. While I would like to see that happen here, I think we’re a long way away.”

Uncovering the Facts

But Dr. Giordano’s research goes a long way toward making a case for prevention. “We conducted a series of studies, in the first one using mini C-arms to image anthropomorphic hand specimens (synthetic specimens with the tissue equivalent of human tissue). We positioned 13 radiation dosimeters at different angles and distances relative to our specimen, which we then imaged for a total of 300 seconds. After 155 sequential fluoroscopy images, we found minimum levels of radiation outside the direct path of the radiation. The point of greatest exposure was at the sensor positioned directly in the palm of the phantom limb. Based on our findings, we determined that a surgeon would exceed the annual radiation dose limit after approximately ninety-two minutes of direct beam exposure. If, however, the patient and the OR team remain beyond 15 centimeters from the point of focus on the image intensifier, they should only be exposed to minimal radiation.”

He continues, “Our initial imaging scenario offered some reassurance that beyond the direct path of the X-ray beam the surgical team was being subjected to minimal radiation. However, this did not take into consideration the effect to the patient, or how the radiation dose is effected by suboptimal imaging conditions such as varying the size of the specimen or the distance within the arc of the C-arm. We realized that there was much more we needed to understand about the relationship between radiation exposure and specimen size, position, and tissue density. Namely, we became curious about how much exposure the patient and surgical team were being subject to during in a ’worst case scenario’.”

Taking a step-by-step approach, the team then asked, “What would happen if we used a larger specimen?” Dr. Giordano: “Using large and mini C-arms, we imaged a cadaver ankle and foot under three scenarios. The best case scenario meant that the specimen was nearly touching the image intensifier. The worst case scenario involved placing the ankle/foot within two inches of the radiation source, while in the ‘middle’ scenario the specimen was ten inches from the radiation source and the image intensifier.”

Overall, ” says Dr. Giordano, “Our findings indicate that while there was higher exposure for the large, as opposed to the mini, C-arm, the latter can indeed produce substantial radiation. Additionally, we learned that as the ankle/foot increased in cross-sectional area and tissue density, or was brought nearer to the radiation source, there is a substantial amplification in the patient’s level of radiation exposure. In fact, when the large C-arm was used and the ankle specimen was brought from a best-case to a worst-case configuration, there was a tenfold increase in the patient’s direct radiation exposure. Repeating this with the mini C-arm, we found that yet again the patient’s exposure increased more than tenfold from the best-case to the worst-case scenario.

Dr. Giordano and the team then focused their attentions on quantifying the radiation involved in imaging the cervical spine with a mini C-arm. “Looking at the cervical spine and skull, we found that the scatter radiation to the patient was up to 10 times greater going from a best to worst case scenario. The scatter radiation to the surgeon was more than doubled going from the best to worst case position.

“Then we posed the question of whether imaging a larger specimen or altering the position of the extremity in the arc of the C-arm beam would have an effect on the level of radiation. Theoretically, larger specimens require more radiation to create a higher quality image, but you have more scatter radiation. We added a control—a large C-arm—and found that when the cervical specimen was brought closer to the radiation source, exposure to the patient was markedly amplified. This wasn’t the case with surgeon exposure, however, as it did not increase as dramatically. Exposure doses recorded by the peripheral dosimeters varied significantly, something that underscores the influence of the shape of the imaged specimen on reflected scatter.”

He continues, “While a larger specimen like the spine produces 10 times more radiation to the patient, there is at least two times more radiation to the surgical team. The reason that both parties are subjected to more radiation is because the cross sectional area of the specimen is much larger. When the C-arm is set to the ‘normal’ mode, technique factors are automatically adjusted to produce an image of optimal clarity. Therefore, when a larger specimen is placed into the beam, technique factors automatically increase to accommodate the large size of the body area, thus increasing the X-ray dose emitted by the X-ray tube. The traditional argument is that standing on one side or another makes a difference. We found that no matter where you stand there are elevated levels of radiation.”

A former Medical Officer in the Navy, Dr. Rechtine gives details on measuring exposure: “The Rem (Roentgen Equivalent Man) is the unit of radiation exposure. By law, occupational exposures, such as working at a nuclear plant, are limited to five Rem per year. Interestingly, the international standard is two. In 1991 the international standard was changed after investigators revisited Hiroshima and found that the cancer risk from low dose radiation was higher than they had thought. The average level of exposure of those surveyed was three Rem. The policy at our institution is that if you get 1/10 of that you have to meet with the radiation safety expert and explain why the situation warrants that kind of exposure.”

Dr. Giordano also wants to lower the definition of a “normal” dose of radiation:

One of the most important things we found when examining the literature on this topic is that many authors look at the best case scenarios and extrapolate forward. The reasoning is, ‘Well, the patient and the surgical team are exposed to X, so in a given year a surgeon can do 200 of these procedures before he reaches his limit. This thinking is flawed because the maximum annual occupational radiation level should not be a desirable value we aspire to. Instead, the focus should be, ‘How can I change my practice so that I minimize the risk to my patients and myself?’

In a way, the more you know, the more you should be scared. Delineating how research brings about practical changes, Dr. Rechtine says, “In 1930 the Rem allowance was 500 per year, in 1940, 50 per year, etc.—the real question is what level is safe. We should continue to strive for the concept of ALARA (as low as reasonably achievable).”

The other major issue, says Dr. Jonathan Grauer, Co-Director of the Orthopaedic Spine Service at Yale School of Medicine, is what is clinically relevant. “My colleagues and I are trying to establish what specific X-rays make a clinical difference. Looking at this issue from an overall resource utilization standpoint, it is clear that certain routine imaging does not significantly impact clinical care. For example, potentially not every postoperative cervical spine series needs an AP image.”

But we do need more concrete research on the effects of imaging tests. Dr. Grauer notes, “I went to a radiologist colleague and asked him to produce a relative risk association with imaging and determine how much radiation was being imparted to patients with routine studies. Even though the radiologist said it would be easy, in the end he was unable to give us useful information.”

With “niche” practically written in neon, Dr. Grauer and his colleagues moved forward to fill a hole in the literature. “Our overarching aim was to examine the increasingly accepted concept of ‘effective dose, ’ something which takes into account the relative sensitivities of different organs. We began with plain X-rays of the spine, calculated the effective doses, and related them to the amount of radiation associated with a routine chest X-ray. Then our attention turned to CT scans, known to be the worst offenders. We looked not just at the spine, but throughout the musculoskeletal system to find the effective dose of radiation associated with clinical studies.”

“Working with a physicist and safety specialist, ” explains Dr. Grauer, “we found that as you move further from the torso there are dramatically less effective doses of radiation associated with CT scans. For example, in a scan of a distal radius fracture, we found the effective dose of radiation to be less than that of a chest X-ray. Incredibly, a CT scan of the lumbar spine is equivalent to several hundred chest X-rays because of the organs exposed in the process. This work has just been published in the August 2009 edition of the Journal of Bone and Joint Surgery.”

Final Words of Advice

And if Dr. Grauer had the bullhorn? “Our biggest message is that orthopedists have to understand this concept of effective dose and be aware of what is associated with more and less radiation. We should not be getting films without careful consideration. For example, during my training I noticed that all patients who came in for cervical or lumbar spine problems got a series of four films for the affected region. As we looked at our practice, my partners and I found that flexion and extension films were not routinely clinically mandatory at the time of the initial patient encounter. For the last three years, after we objectively demonstrated this point, we have stayed away from flexion and extension films unless there is a specific clinical question being asked, or for the preoperative patient.”

In the future, ” says Dr. Grauer, “we will see a more conservative attitude when it comes to ordering imaging studies. And with any luck—and a lot of hard work on the education front—some of this will emanate from the drive to minimize radiation.