Radiation Safety: Investigating Incidents & Implementing Changes
Home » Radiation Safety & Health Physics Blog » Dosimetry » Radiation Safety: Investigating Incidents & Implementing Changes

Radiation Safety: Investigating Incidents & Implementing Changes

By Dr. Zoomie

Hi, Doc! We had a bit of a faux pas and my regulators are asking me about my investigation. I’m not quite sure what they’re looking for – any tips?

Boy, have I been through a couple of these! And not to worry – nobody’s expecting an FBI-style investigation. What they are looking for is to see if you’ve made a good-faith effort to figure out what happened, why it happened, and to see if there are any lessons you learned that you can use to try to keep it from happening again. And, of course, I’ve got some examples that might help out!

The big thing is that you need to try to figure out what sequence of events led to your unfortunate faux pas – we’re going to call it an “incident” from here on out to stick with more standard terminology. Sometimes you can “investigate” via email. There was one time when I had a physician who got over 1 rem of exposure in just one month and I started my investigation by sending him some questions – how many procedures had he performed in the last month, did he perform more procedures than in previous months, how many of the procedures involved fluoroscopy versus simple x-rays, and so forth. But an emailed list of questions sometimes doesn’t give you the information you need. When that happens, you’ll need to talk with people to probe a little deeper.

In the case of the physician, he was so new that I had no earlier dosimetry information, so there very little that could be used for this sort of comparison. So I asked him to come to my office so we could have a chat. I asked him to tell me how he used radiation – in his case, fluoroscopy and x-ray machines – in his normal work. It turned out that he was doing some minor back surgeries that required fluoroscopy (a type of x-ray that can involve higher-than-normal doses to the physician). But, even here, he wasn’t doing so many procedures that I’d expect so high a dose in so short a period of time. So after our chat I decided that I really needed to see him in action – to see exactly how he used fluoroscopy; I needed to see how long each use of fluoroscopy took, where he stood, where other people stood, and so forth.

So I scheduled myself to spend an afternoon watching him work. And, at the appointed hour, I showed up at his office, notepad and pen in hand, to see if I could figure out why he was getting so much more dose than anybody else in the Orthopedics Department.

One of the things I noticed was that the doctor was using relatively long exposure times with the fluoroscope. Considering that most fluoro units have a dose rate of 5-10 R/hr in the beam and that the dose rate from radiation scattering from the patient’s body is about 1% of the dose to the patient, every extra minute of “beam time” meant that the doctor was getting an extra 50-100 mrem of exposure. Using a shorter exposure time would mean that everyone – the patient, the doctor, the nurse, and everyone else – would get less dose.

Something else I noticed was that, when the fluoro unit was turned on, the doctor was standing right at the side of the table and directly across from the fluoro head – where the x-rays were emitted. Not only that, but the nurse and the assistants were also clustered close to the table as well. Standing even another one or two feet back from the table – at arms’ length instead of at half-arms’-length would reduce exposure by a factor of four or more.

So my first two recommendations to the doctor were to use a shorter exposure time – maybe one or two seconds instead of 10-15 – and to have everyone stand further back from the table whenever the fluoroscopy machine was operating. These two simple steps were enough to reduce the physician’s exposure by a factor of almost 10 – and to reduce exposure to his other staff by a factor of 5 or more.

That was my investigation – asking the physician some simple questions via email, spending a half-hour talking with him in my office, and then spending a few hours watching him work. And what I learned from this was enough to let me come up with a few simple suggestions that reduced radiation exposure to one doctor, three or four of his staff, and the patient substantially. Not only that, but I was able to roll these lessons-learned into training and recommendations for other physicians using fluoroscopy to help keep them from receiving too much radiation.

This was all well and good – but I needed to go a little further in order to convince my regulators that we had the situation under control. So I also wrote a note for my files explaining what had happened (a high dose rate to this physician), what I’d done to investigate the incident (questions, interview, and observing work practices), what I’d observed (excessive beam time, standing too close to the emitter), and the corrective actions taken (described above). That way, when my regulators reviewed our dosimetry records and asked about this high dose, I could talk them through the incident, show them the incident report, and explain exactly what we did. And the regulators were happy with the actions we took – especially when they saw how much the exposures had dropped for everyone working in that office.

As to whether or not the “lesson” was learned…over a decade later I was on a plane flying back to visit some friends. This tall guy stopped next to my seat and asked if I’d ever worked at the university in question. I acknowledged that I had, at which point the man told me that he was that doctor and that my few easy suggestions had reduced his exposure by more than a factor of 10. He was happy about his own exposure – and even happier about the impact on radiation exposure to his workers and to his patients. That’s one of the nicest outcomes I’ve had from an investigation.