The treatment of cancer by proton therapy has several advantages over photon radiotherapy. One advantage is the increased conformation of the dose to the target volume allowing therefore, on the one hand, an increase of the delivered dose to improve the therapeutic efficiency, and on the other hand, a decrease of the toxicity of the treatment.
However, the increased accuracy is a double-edged sword. Indeed, the treatment lasts for several weeks and for each fraction, the alignment between the tumour and the beam must be achieved. Any deviation can lead to an under-dose to the tumour and/or an over-dose to the surrounding organs at risk. Therefore, the advantages of proton therapy can be fully exploited only if the patient alignment devices, such as imaging before each fraction, are combined with means to predict and/or control whether the dose that was or will be delivered complies with the treatment plan. Eventually, this information will be used in order to modify the treatment parameters or the beam properties in order to adapt to the daily patient settings and the evolution of the disease.
The project aims to shift from Image Guided Proton Therapy (IGPT) to Dose Guided Proton Therapy (DGPT) so as to allow the visualisation and quantification of the delivered dose (simulation and measurements) in order to comply with the prescription with a precision of 5% in the CTV (Clinical Target Volume). The compliance will be evaluated from the deviation to the planned DVH (dose volume histogram) while including the dynamic motion of the tumour due to breathing and the morphological variations occurring during the course of the treatment.
This objective meets the needs in proton therapy to predict or measure for each daily fraction that the dose will be (or was) optimally delivered in order to adapt the treatment to the evolution of the disease. This will be the way to new strategies of adpatative treatments for tumour types that cannot currently be treated in proton therapy.
The project is a joint project between the UCL (ISP Group and the Molecular Imaging Radiotherapy and Oncology research group) and IBA. It is led by the iMagX research group.
Improving imaging for dose computation thanks to quantitative imaging techniques by using:
Design of dose mapping tools will allow merging into in situ images of the patient, the simulated and measured dose distribution by:
Assessment of new treatment strategies for proton therapy, e.g. by intra-fraction treatment adaptation (e.g. real time correction of beam position) or inter-fraction adaptive therapy. The impact of these strategies will be evaluated retrospectively by simulation and their sensitivity to breathing motions, positioning error and morphological changes will be assessed.
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Last updated January 07, 2020, at 11:08 AM