Simon Sioen

CRIG member
Simon Sioen

PhD Student – Department of Human Structure and Repair – UGent – Faculty of Medicine and Health Sciences 
Principal investigator: prof. Barbara Vanderstraeten (PhD)


Research focus

Children are at a greater risk than adults of developing cancer after being exposed to ionizing radiation. The age at radiation exposure plays a major role in the type of side effects and second cancer formation after radiotherapy. The high risk is related to the high radiosensitivity of the bone marrow at young ages. Since the red bone marrow harbors hematopoietic stem and progenitor cells (HSPCs), a better understanding of the response to protons and photons of these HSPCs is warranted, particularly in the context of pediatric proton therapy (PT). The clinical application of PT is of great interest for pediatric patients due to the optimal dose distribution and the lower healthy tissue dose compared to conventional x-ray radiotherapy (i.e. photon therapy), resulting in a reduction of side effects. Despite some degree of normal tissue injury is still inevitable, radiotherapy for pediatric cancer is a life-saving procedure.
Currently, there is little information available on the response of HSPCs to proton therapy. In this project, radiobiological differences between proton and conventional x-ray (photons) exposure of HSPCs will be investigated together with the underlying mechanisms for the high radiosensitivity of HSPCs. The results will help estimate HSPC damage in radiotherapy-treated children, provide opportunities to improve treatment strategies in pediatric radiotherapy and enable better secondary cancer risk estimations for childhood cancer survivors.


In 2013 I started studying Biomedical Sciences at university Ghent as I always had a large fascination for science regarding the human body. During the 2 master years (2016-2018) I did choose a radiobiology thesis in the major ‘Medical Radiation Sciences’. The first master year consisted of education in both physical and biological principles in radiology, radiotherapy and nuclear medicine which really fascinated me. This way, at the end of the first master year I was eager to start my master dissertation that handled HSPCs exposed to X-ray irradiation. The exciting combination of reading literature, planning experiments, doing lab work, gathering and analyzing results during this 2nd master year led me to continue this thesis as a PhD Project.

Contact & links

  • Lab address: Ghent University Hospital (entrance 98, floor 1), Corneel Heymanslaan 10, 9000 Gent, Belgium
  • Simon Sioen is interested to receive invitations for presentations or talks