DOSIMETRY & IONIZING RADIATION METROLOGY
The “Medical and Industrial Applications” group develops, for its needs and those of its employees, various instruments for measuring dose or characteristics of ionizing radiation beams
Dosimeters are more specifically dedicated to dose measurement at a point (absolute dose, Hp(10), Hp(0.07)…) or to the measurement of the dose-surface product in the case of beams.
Beam monitors are generally developed for fine measurements of beam characteristics (position, shape, intensity), allowing to stop a treatment machine when these parameters go out of the planned operating envelopes, or to control the treatment on a predefined setpoint.
The instruments are built ex nihilo according to the needs and the electronics adapted to the envisaged dose rate.
- Monitor chambers for IBA C230 proton therapy cyclotrons
- Beam monitor for CERAP/Atron
- Beta/EDF contaminameter
- Neutron dosimeter with EAMEA
- Beam monitor for Flash dosimetry at CPO
Flash dosimetry beam monitor at CPO
FLASH radiotherapy has become a key research area in the medical field. The interest of this treatment is to significantly reduce the impact of radiation on the healthy cells surrounding the tumor while maintaining tumor control. The term “FLASH” refers to ultra high dose rate (UHDR) (~ 10 Gy/µs versus 2 Gy/min in conventional radiotherapy) which consists in delivering a dose close to the conventional dose in a very short time, in the order of microseconds and in a single session. To date, electron FLASH has shown interesting results. Preclinical research is undertaken by the CPO under the supervision of V. Favaudon, the precursor of FLASH in France. A first patient was treated by FLASH – RT at the University Hospital of Lausanne.
The group is developing a beam monitor dedicated to electron FLASH-RT for the CPO. Currently the beam monitors used on conventional LINACs are ionization chambers. At low dose rate, ionization chambers allow to realize in real time a current measurement directly proportional to the dose rate at the beam axis. On the other hand, at high dose rates, phenomena such as recombination of charges in the chamber, or space charge, lead to a loss of proportionality. Our monitor couples the measurement of the ionization chamber with that of a current transformer. It is currently in the testing stage and tests under beam conditions will be performed shortly.
Characterization in terms of radiation protection of gloves produced by the company PIERCAN