What in the World Does a Medical Health Physicist Do?
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What in the World Does a Medical Health Physicist Do?

By Dr. Zoomie

Dr. Zoomie – I’ve been working as a rad tech with a “rent-a-tech” firm for several years and I’m ready to stop traveling from outage to outage. I saw a medical health physics position posted that looks interesting, but I’ve got to admit I’m not quite sure what a medical HP does and if it’s something a power plant tech can apply for. Appreciate any insights you can provide – thanks!

Let’s start off with good luck to you! When I got out of the Navy, I was tempted to go the rent-a-tech route, but I was intent on pursuing undergrad and grad school and didn’t see how to tackle my education while bouncing around the country from project to project; my first civilian radiation safety gig was as a student/tech at a big university with a hospital.

So…before getting into some of the details of medical health physics there are a few things that bear mentioning. One is that university and medical radiation safety programs, to someone from the commercial reactor and military radiation safety side of things, can be hard to adjust to – primarily because they can seem sort of lax. I ran into this – we had a researcher who was working with tritium and we kept finding contamination in his lab. I was ready to shut them down when our RSO reminded me that a university lab is a far cry from a nuclear reactor, and a university has a different mission than a submarine. He suggested that in a case like this – less than a millicurie of a very low-energy beta emitter – it usually works better to take a calmer and less adversarial approach. And when I thought about it, I realized he was right – nobody’s health was at risk, we weren’t in danger of losing our license or being fined, and there was no reason to shut a lab down, putting on-going research at risk. And in a medical setting it can be much the same, with the added factor that the patients’ health and lives are part of the equation.

This doesn’t mean that you ignore bad radiation safety practices or regulatory violations – you still need to have a good radiation safety program. But what it does mean is that you need to be willing to work with people to help them understand why they need to do things properly, you need to take a more gradual approach towards fixing problems and/or penalizing poor performers, and you need to have a number of tools at your disposal to try to persuade (or, if it comes down to it, to compel) compliance with good radiation safety practices. And, again, I’m not saying to let things slide – just pointing out that nobody will be injured or killed by a little contamination or minor paperwork problems.

The other thing to keep in mind is that, unlike a power reactor, radiation safety is a relatively minor player in a medical facility’s daily operations. At a reactor plant there are a lot of situations in which Radiation Safety pretty much calls the shots while, at most universities and hospitals Radiation Safety is a service organization. Our license was an important asset to our organization and it was our job to make sure we kept our license – it was also our job to deliver radioactive packages, to pick up and dispose of radioactive waste, to train radiation workers, to run the dosimetry program, to support the medical departments that used radiation and radioactivity, and to train our rad workers. Our job was not to be the center of attention – it was to support the folks who did the research, who treated the patients, and who brought in the money and grants that kept the school’s and the hospital’s doors open. All of this can be quite an adjustment from the military and commercial power reactor world, and not everyone can make the transition easily or successfully.

So – with all of that out of the way, here’s some of what medical health physicists do!

A lot of the work, especially for technicians, is pretty much the same as at a power plant; let’s face it, radiation and contamination surveys are done the same way, using the same equipment, whether you’re at a power reactor, a hospital, or any other radiological facility. The biggest difference is why you’re performing the surveys; in a medical setting, radiation surveys might be performed to measure the effectiveness of radiation shielding surrounding a linear accelerator used for cancer therapy (or shielding around a proton beam, around a Co-60 gamma knife, or a radiation oncology patient who’s had sources implanted inside a tumor), to determine how much time nurses can spend caring for a patient, the amount of time a physician can use a fluoroscope on a patient, and more. Same thing with contamination surveys – if you’re frisking a floor for contamination, you’ll be wielding your radiation detector the same way (and probably the same make and model of instrument) whether you’re looking for mixed fission products or radiopharmaceuticals. Here, too, the biggest difference is that you’re surveying in a medical setting rather than what you’re accustomed to.

This last point bears a little more explanation. At a reactor plant you can pretty much assume that everyone you run into is going to have some degree of familiarity with radiation and radioactivity, that they’re used to seeing people performing radiological surveys, and that they can take all of this (radiation, contamination, surveys) with a degree of equanimity. You can’t assume any of that in a hospital – not from patients, not from most medical staff, not from janitorial or maintenance staff, and certainly not from visitors. Which means that it’s not a bad idea to turn your instrument’s audio off to keep from alarming people – and let’s face it, the patients and their families have enough to worry about without wondering why your radiation instrument keeps beeping (or clicking).

In addition to the surveys there’s other work that’s along the same lines – some of this is discussed in my recent post about what it means to provide radiological “coverage,” in which I gave some medical examples. This sort of work might be performed by either technicians or by health physicists, depending on the size of the radiation safety program. I know one medical program in which the RSO does everything from designing shielding for nuclear medicine suites to picking up and packaging radioactive waste. Most of this work will be similar to the work you’re already familiar with – just in a medical setting. But there’s more to medical health physics than this.

Say, for example, your Radiation Oncology Chief wants to put in a new gamma knife. Somewhere along the line a health physicist will need to write the license amendment request to your regulators to get permission to add this new treatment modality and buy the sources. This means explaining to the regulators how the sources will be shielded, how they’ll be secured against theft or use by unqualified workers, how you’ll make sure that users (radiation oncologists and medical physicists primarily) are qualified to plan and conduct treatments, and possibly explaining how you’ll deal with potential physical threats (e.g. fire or flooding). You’ll also need to show where the new device will be located and how that room will be shielded to ensure that nobody – workers, patients, or members of the public – will exceed a dose limit. An experienced health physicist might be tasked with designing the radiation shielding; a less-experienced HP might, instead, hire a consultant for the shielding design, discussing the details with the consultant and reviewing the work as it progresses. And, through all of this, the HP and/or RSO will be discussing the license amendment request with their regulators, answering their questions and discussing details of interest. Eventually the license amendment request will be granted and you’ll be able to tell the Chief of Radiation Oncology to buy their gamma knife.

The work doesn’t end there of course. A health physicist will also be involved when the sources are brought onsite and loaded into the device, performing surveys after the sources are loaded, and performing still more surveys with different numbers of sources exposed to ensure the adequacy of the shielding design. And, through all of this, there will be the need to document the work done.

Medical health physicists are also responsible for performing periodic audits of Nuclear Medicine and Radiation Oncology records to make sure each patient received the appropriate dose, investigating instances in which the dose delivered varied from the planned dose and, if necessary, reporting a misadministration. Depending on the hospital, a medical HP might also perform routine quality assurance/quality control checks on radiation-generating devices (x-ray machines, fluoroscopes, CT machines, and the like. And then there are the committee meetings – the Radiation Safety Committee at the least; if you’re at a research hospital then there might also be meetings of committees that review proposed research that involves using radioactivity or radiation exposure during research involving humans or animals, perhaps a Quality Assurance committee or a Safety Committee, and any other committees to which Radiation Safety reports or that might need information or advice from Radiation Safety. In general, the larger and more complex an organization is, the broader and more complex will be the responsibilities of the medical health physicists it employs.

Some of these responsibilities are fairly straight-forward; a medical HP for, say, a nuclear medicine clinic or nuclear pharmacy might spend most of their time performing surveys, tracking radioactive materials inventory, checking dosimetry records, and other fairly routine tasks – this sort of work is probably going to be well within the experience and skills developed while working as a reactor plant radiation safety tech. But working at a reactor isn’t always the best preparation for working as a health physicist for a large hospital with an active research program.

If you’re considering making a transition from a technician working at power reactors to medical health physics my recommendation would be to first read up on the medical use of radioactivity (e.g. https://hps.org/documents/summerschoolorderform.pdf). Start with a small licensee – a nuclear medicine clinic or a small hospital with a fairly simple radiation safety program – to get used to the difference between power reactors and medical licensees. And then, as you gain more experience, work your way up to larger and more complex radiation safety programs.

And, in the “for what it’s worth” category – I really enjoyed working in medical health physics. I got to spend time in the OR when physicians were implanting radioactive sources into prostate tumors, measuring radiation dose while cardiologists were taking biopsy samples from a transplanted heart, looking at camera images while a gastroenterologist cleared a blocked bile duct, watching an orthopedist perform procedures to help patients with back problems, and more. It was a great chance to learn and to do health physics in a completely different setting than the military reactors where I started my career.