Case study: From astronauts to cancer patients

A career in radiation physics offers plenty of variety and the chance to solve problems that directly affect patient care, as Lindsay Beaton-Green explains

Exposure to ionizing radiation can happen in several different contexts. People undergoing radiotherapy treatments for cancer are exposed to such radiation, as are astronauts on lengthy spaceflights and, of course, there is always the possibility of people receiving a dose as a result of radiological or nuclear events such as the reactor meltdowns at Chernobyl and Fukushima. As a radiobiologist in Health Canada's Consumer and Clinical Radiation Protection Bureau, I have worked on projects related to all three of these contexts, building on work that I did during my PhD at Carleton University in Ottawa, Canada.

Early on, I could not have predicted that I would end up working in radiation physics. I enjoyed many different subjects at school and had an affinity for both calculus and physics, but when I was an undergraduate at Carleton, I thought that I would likely go into optical engineering. Then, as I was completing my undergraduate degree in engineering physics, I was introduced to the world of medical physics. The idea that I could work in an area of physics with strong ties to the medical field fascinated me. I loved the idea that projects could be so closely related to patient care, and when I spoke with my professors at Carleton about applying to the university's graduate programme in medical physics, they were very encouraging.

When it was time to choose what to specialize in for my graduate thesis, I was quickly persuaded to focus on radiobiology thanks to the passion and excitement of Ruth Wilkins, who became my adviser. An adjunct professor at Carleton, Wilkins is also affiliated with Health Canada, the government department responsible for public health, and for my PhD thesis project, she guided me towards a Health Canada project on radiosensitivity among men being treated for prostate cancer. Patients who are radiosensitive exhibit severe side effects long after their radiation treatments are complete and, ideally, we would like to be able to predict someone's sensitivity before they receive treatment. Tests for radiosensitivity would need to be simple enough to be completed within the pre-treatment planning time, typically 1–2 weeks, and using a blood sample instead of a biopsy would be less invasive for the patient. By using a "case-control" study, in which patients had already been identified as sensitive or not, we found measurable "endpoints" – for example, the speed of the cell cycle or the amount of stable damage – that showed new and promising results, and also helped to further validate existing results that measured similar endpoints.

A range of projects
While working on my PhD, I also became involved with other radiobiology projects at Health Canada. One such project was to analyse the blood samples of astronauts to see if they had experienced long-lasting radiation damage following long-term space flights. Exposure to cosmic radiation is a concern for astronauts because the DNA alterations caused by such radiation can produce stable, long-lasting chromosome damage, which may pose a risk to the astronaut's health. By using fluorescence microscopy and image analysis, it is possible to compare damage in the cells of astronauts before and after their flights, and use that information to make an estimate of the dose received while in flight. Another project I worked on was related to the development and validation of rapid biodosimetry methods. In the event of a radiological emergency, rapid biodosimetry is needed to help determine who was exposed to high enough levels of radiation to require medical intervention. In order to be prepared for such an emergency, Health Canada conducts annual exercises and continues to improve on current methods, while also developing and validating faster methods that employ new technologies.

After I finished my PhD, I was lucky enough to be offered a job with Health Canada as a full-time employee. This meant that, in addition to working on other interesting projects, I have been able to continue the research I did for my PhD. At the moment, I am working to validate the results I found in different patient cohorts to find out if they are general biomarkers of patient sensitivity. To do this, we are revisiting the prostate cancer patients, as well as new patient cohorts (such as breast cancer patients) to see if the same measurable differences between the sensitive and non-sensitive patients can be found. In addition, these results still need to be tested in a predictive study, which is a long-term project that we hope to get started, and will likely involve collaborations with other radio-biology laboratories.

The need for curiosity
The aspect of medical physics I like best is that it requires you to apply many different skills. For example, my work involves a variety of sophisticated equipment, from using high-powered microscopes and flow cytometers (instruments that use laser optics, fluidics and electronics to make multiple measurements of single cells as they pass a point of interrogation), to modelling and calibrating different irradiation exposure systems such as X-ray machines and alpha-radiation exposure systems. Working with these advanced specialized technologies requires a certain amount of technical aptitude and in a field that touches on physics, engineering, biology and medicine, being able to learn new things quickly is also an asset. An understanding of programming is important, and image-analysis skills are increasingly crucial.

There are also some key general skills needed for a career in research, such as a sense of curiosity. It is important to keep asking questions, such as "What does this result imply?" or "How does it fit in with what we already know?" as well as "What's next?" and "How can I take this experimental result and use it to make a difference?" These are questions my colleagues and I ask ourselves often, and puzzling through them makes for rewarding days at the lab.

Research projects and method development can require long and painstaking effort, and working with patient samples also means it can be very unpredictable. Hence, patience and an ability to see the bigger picture are helpful skills, too. However, there are always new and interesting problems to solve, and with a background in physics, I feel I am able to apply my analytical skills to fun, challenging puzzles. I really enjoy the variety of projects, and there is a level of satisfaction that comes when you can combine the experimental work with the analysis and presentation of the results.

Some of my favourite moments have come from attending and presenting my work at regional and international conferences. It is exciting to find yourself surrounded by a network of scientists who are passionate and inspiring, and sometimes you encounter opportunities for interesting collaborations with other research groups. I can't emphasize enough how important it is to surround yourself with interesting people. Asking questions and getting involved with groups that have common interests has led me to many exciting opportunities and projects, and I look forward to where it will take me next.

About the author
Lindsay Beaton-Green is a radiobiologist in the Consumer and Clinical Radiation Protection Bureau at Health Canada