Hadrontherapy makes possible to deliver high doses of energy on cancerous tumours by using the large energy deposition in the Bragg-peak. However, uncertainties in the patient positioning and or in the anatomical parameters can cause distortions in the calculation of the dose distribution. In order to maximize the effectiveness of heavy particle treatments, an accurate monitoring system of the deposited dose dependent on the energy, the beam time and the spot size is necessary. The localized deposition of this energy leads to the generation of a thermoacoustic pulse that can be detected using acoustic technologies. This article presents different experimental and simulation studies of the acoustic localization of thermoacoustic pulses. With respect to the experimental measurements, the pulse is emulated by means of piezoelectric ceramic or thermoacoustically generated by an electrical source. Both sources are placed in water and within a "phantom" medium that recreates the mechanical properties of the human body.. The signals have been captured with a set of sensors around the samples with a data acquisition system. In addition, numerical simulations have been done where thermoacoustic pulses are emitted for the specific case of three proton beams of 20, 80 and 100 MeV, and the pressure signal is then determined at different positions in the space. Several methods for the localization of the source from the signals measured or simulated are used and compared. The results of the location of all these acoustic sources show that an accuracy of the order of a millimetre or less is possible, that is, the precision necessary for proton therapy monitoring is being reached.
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Acoustic location of Bragg peak for hadrontherapy monitoring
Published: 14 November 2018 by MDPI in 5th International Electronic Conference on Sensors and Applications session Applications
Keywords: Hadrontherapy; Acoustic Localization; Bragg peak; Thermoacoustics; Piezoelectric ceramics