Radiation therapy has been a mainstay of cancer treatment for more than a century. In recent years, a newer method – one that uses beams of protons instead of X-rays to target and destroy cancerous tissue – has emerged. This method is known as proton therapy, and it has some important advantages over conventional radiotherapy. In particular, proton beams can be tuned so that they deposit nearly all of their energy at the tumour, avoiding surrounding healthy tissue – thereby both minimizing complications and allowing for higher tumour dose. The downside is that the accelerators used to create proton beams are massive, expensive and require specialist knowledge to install and operate. For more than a decade, Thia Keppel has worked to overcome these barriers, using her expertise in nuclear physics and business to help start proton-therapy centres around the world.

How did you become interested in physics?

I went to a small liberal arts college where the focus is on philosophy (St John’s College in Annapolis, Maryland, US), and at some point I got a bit frustrated. We would discuss deep questions at length in class, and I would think, “There’s got to be a way to answer some of this, rather than just discourse, logic, opinion. Can’t we test something?” Physics seemed to be a place where people were striving to provide concrete answers to big questions, so I looked for summer internships in physics, and to my surprise – because of course they had actual physics students applying too – I got one.

My internship was with a group of plasma physicists who had created a model of the solar magnetic flux cycle, where motion of plasma within the Sun causes it to flip its north and south magnetic poles every 11 years or so. They wanted an “artsy” person to make a movie based on their model so that people could visualize the plasma motion that causes sunspots and makes the Sun flip its poles. Nowadays you could do this with Flash animation on a regular PC, but back then it required a specialized computer system. I had to open the box and get the system running, learn how to make movies with it, input observatory data and create a movie – and I loved it. I liked learning the physics, I liked being sent off on my own, and it turned out I even liked the programming.

I liked learning the physics, I liked being sent off on my own, and it turned out I even liked the programming

My other path into physics is that I worked a bit on cars for fun. That’s a legacy from my father, who built performance cars in a local garage and raced them. I like experimental hardware of nearly any kind. Nowadays this is mostly particle detection systems, but I do still take my car out on the track sometimes.

How did you get involved in proton therapy?

I did my PhD research in nuclear physics at the Stanford Linear Accelerator Center (SLAC), and afterwards came to what is now the Thomas Jefferson National Accelerator Facility (Jefferson Lab) in Virginia to continue my career in nuclear science. One night, I was working late on a scintillating fibre type particle detector, and I realized that a colleague in the lab across from me was building the same type of detector – but for a project in medical instrumentation, not nuclear or particle physics. We started working together, and a few years later I founded something called the Center for Advanced Medical Instrumentation at Hampton University, which is located about 10 miles from Jefferson Lab, and where I held a joint faculty appointment.

I directed the centre for a few years. Our idea was to bring nuclear physics detection techniques into medical applications, and we patented more than a dozen technologies. I’m particularly proud that around three-quarters of those patents were licensed to private industry. We made an effort to work with physicians from the get-go, so that we had reasonable confidence that what we were developing had a substantial chance to make it to medical device manufacturers and ultimately to the clinic.

A few years into that effort, our local medical school asked whether we’d be interested in working with them to start a graduate medical-physics programme. This initiative led us to shift our technology development focus away from diagnostic applications and towards treatment, because that’s where most of the medical-physics jobs are and we were training graduate students. Around that time, someone approached Hampton University’s president about proton therapy. He called me in and, to make a long story short, we realized that between the university and the lab and the local healthcare community, we had the resources and know-how to build our own centre. It ended up being a $200m project. We mutated; our little medical instrumentation centre turned into one of the two largest proton-therapy centres in the world.

What did you do next?

I directed the centre from ground- breaking up to a couple years into clinical operations, but directing it in the operations era for me wasn’t as much fun as building, instrumenting and commissioning it to prepare for that era. So, when Jefferson Lab had an opening for the leader of one of the four experimental halls, I decided to switch over. Around that same time, a colleague and I also set up a consulting company to help other institutions start their own proton-therapy centres. There are a lot of choices and calculations that need to be made during the start-up phase in terms of equipment, shielding and calibrations that a traditionally trained clinical medical physicist doesn’t necessarily know how to make. This is where we help out, coming alongside the construction and/or clinical teams to ease the transition from design to successful operations. So far, I’ve helped to start 16 proton-therapy centres.

You’ve been awarded a lecturership by the American Physical Society for promoting applications of physics. Can you tell me more about that work?

When I got interested in medical applications of nuclear physics, I found that language was a big barrier to understanding. If you talk to a physician, they may tell you that you have a subcutaneous haematoma, and you need to be able to hear, “Oh, I have a bruise.” There’s a wealth of compellingly interesting stuff going on in medicine, but it needs to be translated. Similarly, I won’t be terribly successful talking to a physician about quantum chromodynamics without explaining that it’s the fundamental theory of how nuclei hold together. Clear translation is requisite to foster a successful flow of communication.

I think that my discourse-based philosophy education has been a help in learning to express ideas clearly and succinctly to people, and I also was able to hone my communication skills when I was running the proton-therapy centre. If you’re going to irradiate people, you must explain carefully and well why that’s a beneficial thing – or at least, why it might be better than traditional radiotherapy or other options for treating their tumour. Once you’re used to explaining things in plain language to potential patients or the public, you can give the same talk in a boardroom.

Do you have any advice for physics students?

This is something that’s particularly near to my heart lately, because my daughter is studying physics. What I said to her that I think all students need to hear is, basically, “Physics is a difficult odyssey, so you really need to love it. Maybe you won’t love it every day, but it should generally be so compellingly fascinating that it feels worth your effort.” If you do love it, stick with it. Buckle down and get through your classes, because after you graduate, you’ll get to decide what to do. There’s a universe of amazing options out there for you.

Maybe you’re a theorist who wants to delve into multidimensional field theory. Or maybe you’re an experimentalist who wants to detect dark matter. Or maybe you want to build the first desktop quantum computer. Whatever it is that you enjoy, you’ll be able to pursue it. Don’t get too focused on the standard academic career path. A lot of people go into industry after they get their bachelor’s physics degree, and a lot of others go all the way through to a PhD but then take their knowledge into an industrial or clinical setting. There are fundamental laws yet to be discovered and applied, many interesting puzzles to solve, new instruments to devise, and a wide variety of career paths to take you to them.

• This article first appeared in APS Careers 2020, produced in conjunction with Physics World

• Cynthia (Thia) Keppel is experimental group leader for Halls A and C at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia, US, e-mail keppel@jlab.org.