Real-Time Beam Monitor for Charged Particle Medical Accelerators

A novel real-time charged particle detector for medical accelerators is proposed in this paper. The system, by means of a passive resonant cavity, performs a non destructive measurement of the beam current and provides a real time monitoring of the absorbed dose delivered to the patient. The system complies with requirements of the relevant International Standards for being used as a Radiation Detector for Charged Particles. The formulated theory allows the system design versus the accelerator features by providing analytical formulas and a development strategy. A prototype has been realized and tested in order to check the compliance with the expected behavior in the operating conditions of the Medical Accelerator. The system has been proved to be equivalent to the standard ionization based monitor chambers, furthermore offering several advantages: the absence of bias high voltage, more compactness, small size and the fact that this system measures the physical observable quantity directly related with the dose, the beam current.