Speaker
Description
Rapidly producing accurate 3D spatial maps of the radiation dose distribution delivered to patients during proton therapy treatment would reduce existing beam delivery uncertainties and improve patient outcomes. Current dosimetry methods that use ionisation chambers have low spatial resolution and long acquisition times. An alternative to this would be the use of ionacoustic imaging to produce the required dose maps. This methodology utilises the back propagation of acoustic waves generated by the thermoelastic expansion of material where the proton energy is deposited. Ionacoustic imaging would be able to provide fast and accurate 3D dose maps non-invasively. In the short term, ionacoustic imaging could provide essential beam quality assurance prior to treatment and it is hoped that in the future it could be used for online dose monitoring during patient irradiations. The latter would help to mitigate against uncertainties arising from anatomical changes and internal organ movement. Some ionacoustic measurements have been documented in the literature. However, accurately predicting these signals to the degree necessary for optimising detection systems and enabling precise 3D map reconstruction remains challenging. As a first step towards experimentally measuring a 3D spatial map of radiation dose using ionacoustic imaging, we will present recent work into a modelling framework. The model demonstrates the ionacoustic signals expected from clinically relevant beam energies and geometries. These modelling results will serve as the foundation for designing future experimental setups and determining equipment requirements, including identifying the transducer frequency band response and minimum signal to noise ratios for ionacoustic signal detection.