Physics in Real Life, by Dr. Rebekah D’Arcy

In the second in our series of articles by NUI Galway researchers, School of Physics Lecturer Dr. Rebekah D’Arcy, writes about the ever evolving world of Medical Physics.

Physics in Real Life – Medical Physics

Hippocrates (460-377 BC), who is known as the “Father of Western Medicine”, may have been the first medical physicist. Over two thousand years ago, in order to locate where an infection was located, he would smear mud over a patient’s back, knowing that infected tissue is warmer and would therefore dry the mud faster. Technology has improved a lot since then and modern thermography, which looks at heat coming from the body using an infrared camera, is very different from Hippocrates’ methods.

In fact modern medical physics uses techniques which sound like they come straight from a science fiction movie.

Computer model of the Siemens Oncor linear accelerator used in the treatment of cancer patients, generated by simulation on a supercomputer (Image credit: Dr. Mark Foley)
Computer model of the Siemens Oncor linear accelerator (and selection of electron and photon tracks) used in the treatment of cancer patients, generated by simulation on a supercomputer (Image credit: Dr. Mark Foley)

Using Particle Accelerators to defeat Cancer

After the Large Hadron Collider built by CERN came online, particle accelerators have become familiar to almost everyone, and have gained notoriety as devices that could bring the universe to an end. However, in the last 50 years, medical physicists have spearheaded the development and application of particle accelerators for cancer treatment. Once confined only to physics laboratories, these accelerators are sophisticated high energy machines that can now deliver beams of energetic electrons or X-rays to malignant tumours, at doses capable of killing cancerous cells and stopping the tumour’s growth.

Diagnostics and Imaging

In the fictional world of Star Trek, Dr. McCoy relied on his hand-held tricorder and whole-body scanners for patient diagnosis. These produced a non-invasive diagnosis identical in concept to magnetic resonance and computerized tomography that physicians today use to ascertain a patient’s condition. These procedures use magnetic fields (MR) or X-rays (CT) to provide a virtual look inside the body, allowing physicians to investigate the physiology and anatomy of a patient. Devices that were once exclusive to the realm of science fiction are now widely used to better assess disease risk, and, in some cases, even find tumours or evidence of disease that might otherwise have gone undetected.

Annihilation Reaction (Image credit: Dr. Rebekah D'Arcy)
Annihilation Reaction (Image credit: Dr. Rebekah D’Arcy)


Nuclear Medicine

Another rapidly growing technique used to detect diseases in people of all ages is positron emission tomography (PET). At the core of this technique is antimatter. Antimatter is most famously associated with the faster than light “Starship Enterprise”, but in reality antimatter-matter reactions are science fact rather than science fiction. Short-lived radionuclides decay and emit particles known as positrons, the antimatter equivalent to electrons. These positrons rapidly encounter electrons, collide, annihilate, and produce a pair of photons which move in opposite directions. These photons are then captured and imaged in order to study and monitor a variety of physiological conditions.

Medical Physics in NUI Galway

The world of medical physics is constantly evolving and advancing. According to Enterprise Ireland, 8 of the world’s 10 largest medical device companies are located in Ireland, with Europe’s premier cluster based in the Galway region.

Here at NUI Galway we are involved in several aspects of Medical Physics research from Imaging through to Therapy. For example, we have used supercomputers around the globe to model particle accelerators used in the treatment of cancer and also virtually model the interactions of these particles within the patient so we can better understand how they interact and deposit their radiation dose during cancer treatments. We also have several medical imaging projects with the ultimate aim to improve future cancer treatments by, for example, tracking and accounting for organ motion within patients.

For details about our research go to and keep up to date with all types of Physics research through our Facebook page

To find out more about studying Physics, or Physics with Medical Physics at NUI Galway, check out these videos


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