Progress of quality control in radiotherapy daily control thanks to on-line dynamic visualization

Progress in assurance and quality control in radiotherapy, up to 25 MeV energy, come from daily verification of the quality of irradiations in terms of reproduction of positioning of the patient, of irradiation beams and of focused blocs interposed between the source of the beam and the patient. These improvements are now possible thanks to a new imager such as IRIS (Interactive Radiotherapy Imaging System), with improved image quality. IRIS is used in daily verification at the Centre Hospitalier Universitaire Vaudois, Lausanne, to control on-line the patient position and organs motion during the post-operative radiotherapy of a pancreatic cancer. IRIS is capable of producing up to 10 images/sec, and is based on a large area pixel matrix manufactured in thin film amorphous silicon technology, with wide dynamic range. The results are: the beam positioning adjustments and comparison to reference image in daily use for the different field of irradiation. The visualization and identification of several inner structures and organs (measuring amplitudes of movements of organs). The review of the treatment on a session to session basis. IRIS, on-line dynamic imager has the potential to quality treatment, especially in conformal radiotherapy and in irradiations where the amplitude of organ motion is are important.