Geometrical optimization of piezoelectric sensors for acoustical monitoring in proton therapy treatment.

The hadrontherapy has been in constant evolution by leaps and bounds since the fifties, when the use of heavy particles was proposed as an alternative treatment to radiotherapy with gamma rays or electrons. The main objective of this treatment is to maximize the dose applied to the tumour avoiding damage to the surrounding tissue. One of the keys to the success of the hadrontherapy is to achieve an instantaneous monitoring of this energy deposition in the environment. Since the energy deposition leads to the generation of a thermoacoustic pulse, acoustic technologies have been tested with successful results. However, for this purpose, it is essential to increase the sensitivity of the sensors for the acoustical signal and, therefore, to optimize their geometry as a function of the beam that would be used. We have studied a PTZ material in volumetric and surface volumes through experimental measures and FEM methods. In this text, we start with numerical studies which determine the dependence of the thermoacoustic signal frequency with the energy and duration of the hadron beam.