Doctor Doctor


4th year medical physics PhD student Daniel O’Brien talks to Alison Lee about his postgraduate study of radiation and how he hopes to help the world of medicine

What is the official title of your PhD?

Optimisation of Small Field Dosimetry.

In layman’s terms, what does that mean?

My project is about improving the accuracy of radiotherapy, specifically when “small fields” are involved. Small fields are very narrow beams of radiation.

Briefly explain the background to your work.

Small fields have become more important in recent years as more advanced treatment techniques have become widespread. As the fields get smaller, their properties change for a variety of reasons and the uncertainty in the dose delivered by the beam becomes higher. There is an international effort to improve the accuracy of small field dosimetry and I’m contributing to this.

Describe your typical “day at work”.

I’m not sure there is such a thing. Every day can be very different depending on what I’m doing. Most of my research is conducted at St. Luke’s Hospital in Rathgar. A large chunk of my work has been focused around computer simulations, which means a lot of coding and computer work. However, some days I also use the radiotherapy machines themselves (which are medical linear accelerators, kind of like much smaller versions of the Large Hadron Collider at CERN) to perform experiments with actual radiation beams. Hospital life involves going to meetings, working on the computers, trying to get access to machines whenever they’re not in use, bouncing ideas and problems off of the other physicists there. The staff are really friendly. When I’m in UCD I demonstrate to third and fourth year physics students in the lab. Sometimes I get to use specialist equipment in UCD which I don’t have at the hospital.

What, for you, is the most fascinating thing about your field of study?

My field of study is Medical Physics and I think the most fascinating thing about it is the fact that it uses physics to actually improve people’s lives, even to help save them. It’s an extremely practical and hands-on field of physics and it’s also very rewarding.

How could your work make a difference to this particular scientific field, and to the world in general?

My work will hopefully help to refine international best practice protocols for dealing with small fields. This could enable a broader range of treatment options available to patients with cancer in any radiotherapy treatment centre around the world.

What undergraduate degree course did you do and where?

I did the omnibus science degree course in UCD, specialising in physics in third and fourth year and ending with a BSc (Hons).

What made you choose to do a PhD?

I came to college to do science and to be a scientist. A PhD meant brand new research! There really wasn’t a plan B.

In your opinion, what are the best and worst things about being a postgraduate?

The best thing is the freedom you have. You are very much independent and this allows you to take ownership of your project. This can be a little overwhelming at first but the experience you gain from that is invaluable. It does however become all-consuming, particularly towards the end. That can be frustrating but I feel it’s worth it.

How do you feel your PhD will affect your career prospects?

A PhD certainly opens doors. You really do obtain a broad range of skills from a PhD, from computer skills and teaching skills to problem solving skills, specialist knowledge and experience with wide range of equipment (simple and complex), all of which can be valuable in many other lines of work. You can also become acquainted with many distinguished people in your field. I feel my PhD has certainly opened many more doors than I realised when I first started.