The Belgian Nuclear Research Centre (SCK CEN)

The experts

Prof. Sarah Baatout

Dr. Bjorn Baselet

Ms Mieke Neefs

Mr Randy Vermeesen

Expertise in ionizing radiation and microgravity


Ionizing radiation


In physics, radiation can roughly be defined as the transport of energy without the necessary intervention of a transport medium, either by means of electromagnetic waves or by particles like electrons, neutrons or ions. Ionizing radiation is a form of radiation that has enough energy to remove an electron from an atom (a.k.a. ionize) which can alter the chemical composition of that material.

Ionizing radiation can be derived from either natural or artificial sources. It is omnipresent in our day-to-day environment as naturally occurring radioactive materials (e.g. uranium, radon and potassium-40) exist in the material that makes up our planet Earth. Natural radioactivity is present in the air we breathe, food we eat, water we drink and even in our bodies. On earth we are even exposed to natural ionizing radiation that comes from outer space and passes through our atmosphere. The artificial sources of ionizing radiation can roughly be classified in three main categories: (1) medical use including diagnosis of many diseases and treatment of cancer, (2) industrial use including measurement and scientific research and (3) fallout from nuclear weapons testing and accidents around the world.

There are three different kinds of measures that can be used to give an indication of quantity or dose of ionizing radiation you are exposed to. Radiation exposure is measured in an international (SI) unit called the Gray (Gy). The radiation exposure is equivalent to the energy “deposited” in a kilogram of a substance by the radiation. Exposure is also referred to as absorbed dose. However, we are often interested in the effect of ionizing radiation exposure on living systems. The equivalent dose takes this fact into consideration as it relates the absorbed dose in human tissue to the effective biological damage of the radiation. In other words, not all ionizing radiation has the same biological effect, even for the same amount of absorbed dose. Equivalent dose is measured in an international (SI) unit called the sievert (Sv).

The last one, called the effective dose, takes into account the fact that the probability of a harmful effect from ionizing radiation exposure depends on what part (or parts) of the body are exposed. In other words, some organs are more sensitive to ionizing radiation than others. The unit of effective dose is also sievert (Sv).

In the interdisciplinary field of radiation biology, we try to examine the biological effects of radiation on living systems. To be able to fully understand the relationship between radiation and biology, radiobiologists incorporate fundamentals of many fields such as biology, physics and engineering. The major goal of radiation biology in space is to enable safe human space exploration without exceeding an acceptable level of risk from exposure to space radiation.

Read more about the complementary UNamur LARN LAB expertise



Gravity is a naturally occurring phenomenon by which all things that have a mass or energy are brought towards one another.”Micro-” means “very small”, so the word microgravity refers to the condition where gravity seems to be very small.  During this phenomenon people or objects appear to be weightless, seen as astronauts and objects floating in space. However, microgravity negatively affects the human body in many different ways.

For example, due to the microgravity environment and the lack of induced strain, muscles and bones become weaker in space. Not a big problem in space, as everything is lightweight and you can float, but problematic when returning to Earth. As astronauts living on the space station (or even travelling towards Mars) spend months in microgravity, we must study the effects of microgravity on living systems to keep astronauts safe and healthy.

Comparison of rotifer & human resistance to irradiation


The term radioresistance gives an indication of the amount of ionizing radiation that a particular kind of organism is able to withstand. There are generally big differences in radioresistance for one species to another due to the way ionizing radiation affects different kinds of living tissues and their protection mechanisms. To be able to compare the radioresistance between different species we use the median lethal dose (LD50), in Gray (Gy), which measures the dose that is required to kill half the members of a tested population after a specified test duration. The LD50  for humans is 4.5 Gy X-rays, meaning that if were to give a human population 4.5 Gy that 50% would die (in this case after 30 days). The LD50 for adineta vaga is more than 1,000 Gy, underlying the fact that they demonstrate a remarkable capacity to survive human high doses of ionizing radiation. But what is the underlying cause?

Astronauts: guinea pigs for medicine


Space is a hostile environment for the human body: factors such as cosmic radiation and weightlessness undermine and, or the immune system, brains and skin. The processes taking place in astronauts are similar to disease processes on earth. What is the difference with patients? Astronauts take off in an excellent condition. This enables scientists to perform examinations before and after. What is the effect of radiation? How does our body react to it? How does radiation affect our healthy tissue? How can we protect healthy tissue?

With these insights, SCK CEN can set to work. The research center develops effective cancer therapies, whereby healthy tissue receives as little irradiation as possible, as well as techniques that strengthen the different systems of the human body.  In other words, space research gives medicine a boost and supports cancer patients and patients with dementia, skin problems or an immune disorder such as AIDS.

Related publications

Combination Therapy With Charged Particles and Molecular Targeting: A Promising Avenue to Overcome Radioresistance. Konings K, Vandevoorde C, Baselet B, Baatout S, Moreels M. Front Oncol. 2020 Feb 14;10:128. doi: 10.3389/fonc.2020.00128. eCollection 2020.

Differential Impact of Single-Dose Fe Ion and X-Ray Irradiation on Endothelial Cell Transcriptomic and Proteomic Responses. Baselet B, Azimzadeh O, Erbeldinger N, Bakshi MV, Dettmering T, Janssen A, Ktitareva S, Lowe DJ, Michaux A, Quintens R, Raj K, Durante M, Fournier C, Benotmane MA, Baatout S, Sonveaux P, Tapio S, Aerts A. Front Pharmacol. 2017 Sep 22;8:570. doi: 10.3389/fphar.2017.00570. eCollection 2017.

Ionizing radiation biomarkers in epidemiological studies – An update. Hall J, Jeggo PA, West C, Gomolka M, Quintens R, Badie C, Laurent O, Aerts A, Anastasov N, Azimzadeh O, Azizova T, Baatout S, Baselet B, et al. Mutat Res. 2017 Jan-Mar;771:59-84. doi: 0.1016/j.mrrev.2017.01.001. Epub 2017 Jan 16.

Impact of Particle Irradiation on the Immune System: From the Clinic to Mars. Fernandez-Gonzalo R, Baatout S, Moreels M. Front Immunol. 2017 Feb 22;8:177. doi: 10.3389/fimmu.2017.00177.

How and why does the proteome respond to microgravity? Grimm D, Wise P, Lebert M, Richter P, Baatout S. Expert Rev Proteomics. 2011 Feb;8(1):13-27. doi: 10.1586/epr.10.105.

Vive la radiorésistance!: converging research in radiobiology and biogerontology to enhance human radioresistance for deep space exploration and colonization. Cortese F, Klokov D, Osipov A, Stefaniak J, Moskalev A, Schastnaya J, Cantor C, Aliper A, Mamoshina P, Ushakov I, Sapetsky A, Vanhaelen Q, Alchinova I, Karganov M, Kovalchuk O, Wilkins R, Shtemberg A, Moreels M, Baatout S, et al. Oncotarget. 2018 Feb 12;9(18):14692-14722. doi: 10.18632/oncotarget.24461. eCollection 2018 Mar 6.

Immune sensitization during 1 year in the Antarctic high-altitude Concordia Environment. Feuerecker M, Crucian BE, Quintens R, Buchheim JI, Salam AP, Rybka A, Moreels M, Strewe C, Stowe R, Mehta S, Schelling G, Thiel M, Baatout S, Sams C, Choukèr A. Allergy. 2019 Jan;74(1):64-77. doi: 10.1111/all.13545.

Modulations of Neuroendocrine Stress Responses During Confinement in Antarctica and the Role of Hypobaric Hypoxia. Strewe C, Thieme D, Dangoisse C, Fiedel B, van den Berg F, Bauer H, Salam AP, Gössmann-Lang P, Campolongo P, Moser D, Quintens R, Moreels M, Baatout S et al. Front Physiol. 2018 Nov 26;9:1647. doi: 10.3389/fphys.2018.01647.

Gene expression-based biodosimetry for radiological incidents: assessment of dose and time after radiation exposure. Macaeva E, Mysara M, De Vos WH, Baatout S, Quintens R. Int J Radiat Biol. 2019 Jan;95(1):64-75. doi: 10.1080/09553002.2018.1511926. Epub 2018 Sep 24.

Gravity-Related Immunological Changes in Human Whole Blood Cultured Under Simulated Microgravity Using an In Vitro Cytokine Release Assay. Van Walleghem M, Tabury K, Fernandez-Gonzalo R, Janssen A, Buchheim JI, Choukèr A, Baatout S, Moreels M. J Interferon Cytokine Res. 2017 Dec;37(12):531-540. doi: 10.1089/jir.2017.0065

Targeting the Hedgehog pathway in combination with X‑ray or carbon ion radiation decreases migration of MCF‑7 breast cancer cells. Konings K, Belmans N, Vermeesen R, Baselet B, Lamers G, Janssen A, Isebaert S, Baatout S, Haustermans K, Moreels M. Int J Oncol. 2019 Dec;55(6):1339-1348. doi: 10.3892/ijo.2019.4901. Epub 2019 Oct 18.

The Combination of Particle Irradiation With the Hedgehog Inhibitor GANT61 Differently Modulates the Radiosensitivity and Migration of Cancer Cells Compared to X-Ray Irradiation.  Konings K, Vandevoorde C, Belmans N, Vermeesen R, Baselet B, Walleghem MV, Janssen A, Isebaert S, Baatout S, Haustermans K, Moreels M. Front Oncol. 2019 May 14;9:391. doi: 10.3389/fonc.2019.00391. eCollection 2019.