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When I was in secondary school, I had two great loves: physics and medicine, in that order. It seemed to me at the time, that these were polar opposites. When I chose to study physics, that meant leaving medicine behind, of course, they’re different fields! I had an idea of what a physicist was, some names came to mind: Marie Curie, Stephen Hawking, Lise Meitner, legendary investigators and pioneers.  I had an idea of what I’d be doing years down the line: looking at black holes, colliding hadrons (large ones, apparently), searching for a grand unified theory, you know, physics-y things. That’s what I thought a physicist did at the time, that and nothing else! That was 6 years ago, so it would surprise my younger self to learn that in 2020, I work in a hospital.

This February, I gave a talk to secondary students at Lord Williams’s school on radiotherapy, explaining the key physics and biological principles behind how to plan and perform radiation therapy to treat cancer. I got to share some of what I studied at work, as well as how a physicist might be useful in trying to treat cancer.

Ultimately, cancer treatment all comes down to one task, kill the cancerous cells while minimizing harm to healthy cells. This is the foundational principle behind radiation therapy as well, in which pencil-thin beams of x-ray radiation are aimed at tumors within patients. Radiation therapy has the advantage of being able to treat cancer anywhere in the body, even if it’s hard to reach surgically. The task is one of optimization: maximize the radiation that is hitting the tumor while minimizing the radiation hitting healthy cells. Students were introduced to some important concepts within radiation therapy, such as the behavior of a single photon as it related to the behavior of a radiation beam, as well as how we can take advantage of this behavior to achieve our clinical objectives. The talk featured interactive activities, such as identifying chocolate from their CT scans, a discussion of how radiation is (and isn’t) like a cannonball, and the importance of Monte Carlo simulations on ensuring optimal radiation dose delivery. Something I was keen to emphasize was that I was a physicist by training, and that ultimately these problems require someone with a background in physics in order to be able to solve.

The students were very bright and eager to engage, asking incredibly insightful questions on the subject. Something that particularly stood out to me was when a student asked me asked me how I got to be a medical physicist. This was perhaps the first time many of them were hearing that this job existed, and I was quite happy to be able to highlight that physicists work in a wide variety of contexts beyond what may immediately come to mind.  Modern day science is interdisciplinary, and as it turns out, physicists come in many different forms.

Spending an hour with this group of students was an incredibly positive experience; I really enjoyed it.