Throughout our lives we are exposed to various amounts of radiation. Some of this we experience when we undergo medical exams in which x-rays or radioactive tracers are used. Martin Andersson at Lund University has written a thesis in a research area which tries to estimate the impact of radiation on the body.
Most of us undergo several x-ray exams in our lives. Some of us also get cancer or other diseases which are treated with ionising radiation. Patients and healthcare would both like the radiation dose not to be higher than necessary, and there to be rules concerning the calculation and control of the radiation.
Martin Andersson is a hospital physicist and doctor of medical science at the Department of Translational Medicine at Lund University. His research is about how to calculate the absorption, metabolism and secretion of radioactive tracers in the body’s various organs. Radioactive tracers are usually supplied via an intravenous injection (a shot in the arm), in some cases orally or through the lungs (inhalation). An example of such a tracer is radioactively (fluorine-18) labelled sugar (FDG) that provides valuable image information about cancer tumours. The subject area is called nuclear medicine.
“In healthcare, we subject patients to a planned exposure to radiation, in which case we must be able to describe and justify any associated risks. In 2018, a new EU directive will take effect, which will focus more on the responsibility of healthcare to properly inform patients of the benefits and risks associated with different types of exams and treatments offered to them”, says Martin Andersson and continues:
“You can’t ignore the risk that the radiation from the tracer given to patient could lead to cancer in the long term. But the risk is very low and, of course, it must be weighed against the benefit.”
Calculating the impact the tracer has on the body is more difficult than it might seem at first. To minimise the risk of damage to the body, the radioactive tracer usually breaks down very quickly, which means that any radioactivity has worn off already after a few hours. Should the exposure still lead to the development of cancer, it would occur much later in life, probably several decades later.
Studying the risk of cancer in real life, over a long period of time, in a large number of people, and at the same time tracing potential cases of cancer to a medical exam that was conducted several decades before – is associated with major difficulties. Estimates of health risks in nuclear medicine studies are therefore based entirely on patient data, supplemented with information from people exposed to higher radiation doses in connection with the nuclear bombs that were dropped on Hiroshima and Nagasaki in 1945.
In his thesis project, Martin Andersson has fine-tuned the calculation models for how some of the most common radioactive tracers are metabolised in the body and its various organs. His research results are an important part of the supporting documentation for a new ICRP (International Commission on Radiological Protection) handbook, which will provide a basis for future estimates concerning radiation risks in nuclear medicine exams in hospitals around the world.
Are the methods used today not sufficiently safe and effective?
“We will never know the whole truth, but the more precise estimates of the radiation doses we can make, the more realistic are the calculations of radiation risks. The current ICRP handbook has to be updated regularly as new radioactive drugs are developed constantly, and the imaging techniques and calculation models are improved”, says Martin Andersson.
The images used to illustrate this article depict part of Martin Andersson’s contribution to the development. The calculation models currently used are based on a very simplified image of the human body as composed of spheres, cones and other simple shapes according to the same principle as the English confectionary company Bassett’s well-known mascot Bertie. However, the new calculation model is based on a much more realistic image of a human being, in which both the body as a whole and the individual organs are very accurately depicted.
How does it feel to be contributing to something that is likely to be used all over the world?
“It is flattering, stimulating but also important. Healthcare is largely governed by the economy, and this type of research is at risk of being pushed to the sidelines”, says Martin Andersson.