Contrast-enhanced Synchrotron Stereotactic Radiotherapy Clinical Trials from a Medical Physicist Point of View
Résumé
The first clinical study of therapeutic applications of Synchrotron Stereotactic Radiation Therapy (SSRT) is underway since June 2012 at the European Synchrotron Radiation Facility (ESRF) and at the University Hospital (CHU) in Grenoble (France). This phase I-II clinical trial is designed to test the feasibility and safety of SSRT through a series of steps of increasing complexity. The treatment is based on stereotactic irradiations using high-flux quasi-parallel monochromatic medium energy x-ray beams (80 keV), in presence of heavy atoms, previously introduced in the tumor. At these energies, a localized dose enhancement occurs in the target, due to increased photoelectric absorption. The moderate kinetic energy photoelectrons deposit their energy over a submillimetric distance, in the close vicinity to the heavy atoms; whereas Compton scattering predominates in the surrounding healthy tissues. Consequently, the radiation becomes more penetrating, and hence interesting, for treating deep-seated tumors. The medical physics developments required by this innovative technique will be discussed in this presentation.