Jury

  • Prof. Carine MICHIELS (UNamur), Chair
  • Prof. Anne-Catherine HEUSKIN (UNamur), Secretary
  • Prof. Stéphane LUCAS (UNamur)
  • Dr. Rudi LABARBE (IBA)
  • Prof. Joao SECO (German Cancer Research Center)
  • Prof. Simon GALAS (University of Montpellier)

Abstract

Radiotherapy is one of the most widely used treatments for cancer and plays a central role in modern oncology. While technological advances have greatly improved the precision of radiation delivery, damage to healthy tissues surrounding the tumor remains a major limitation. In recent years, an innovative approach known as FLASH radiotherapy has attracted considerable attention. Unlike conventional radiotherapy, FLASH delivers the therapeutic radiation dose within a fraction of a second using ultra-high dose rates. A growing body of evidence suggests that this approach may reduce radiation-induced side effects in healthy tissues while maintaining the ability to control tumours. However, the biological mechanisms responsible for this protective effect remain poorly understood.

This thesis addressed two key challenges in FLASH research. The first was the development and characterization of an experimental platform capable of generating ultra-high dose rate irradiations using the ALTAÏS accelerator at the University of Namur. This work involved designing irradiation systems, validating beam dosimetry, and establishing robust experimental protocols to ensure accurate and reproducible exposure conditions. The second objective was to introduce a new biological model for FLASH investigations: the microscopic nematode Caenorhabditis elegans (C. elegans). This organism offers several advantages, including a short life cycle, ease of handling, low cost, and the conservation of many fundamental biological processes shared with higher organisms. These characteristics make it an attractive complementary model for studying radiation responses and exploring the mechanisms underlying the FLASH effect.

This thesis demonstrated the suitability of C. elegans as a model for investigating biological responses to ultra-high dose rate irradiation. Studies of developmental and neurobiological endpoints across multiple irradiation conditions highlighted its potential for mechanistic FLASH research. Together, these findings provide valuable tools to advance our understanding of the FLASH effect. More broadly, they contribute to the development of safer radiotherapy strategies aimed at reducing treatment-related toxicity and improving patient quality of life.