Proton therapy is an advanced form of radiation therapy that uses a high-energy proton beam for cancer treatment. In contrast to conventional therapy, proton beams deliver their maximum energy within a confined range, known as the Bragg peak, reducing adverse effects to adjacent healthy tissues.
In proton therapy, the control of the proton beam penetration depth is a key aspect. Although the energy of therapeutic proton beams is usually controlled with a high level of accuracy, the actual range of such beams in patients may be affected by uncertainties of up to 10-15 mm.
The aim of the project is the design and development of a gamma camera for real time range beam control, in collaboration with IBA - a leading company in this field - and XGLab.
The proposed method is based on the detection with a slit collimator of prompt gamma rays emitted by excited nuclei during proton irradiation and on their imaging with a pixelated scintillator to obtain a 1D projection of the proton beam path. Previous studies have indeed demonstrated the correlation of these gammas with the position of the Bragg peak.
There are different solutions under investigation to address the issue of range uncertainty in proton therapy (before, after and during treatment).
The focus of this project is on the real time monitoring of the beam range, wich would provide feedback during treatment, allowing correction before the entire fraction is delivered. Among several options, the project concentrates on prompt gammas imaging.
Classical gamma cameras used in nuclear medicine are not adapted for the detection of high energy gammas (1 MeV-10 MeV) with high rates (up to 50 MHz) in the presence of an important neutron background, so a dedicated camera is needed. In addition to specifications fulfillment, the gamma camera designed could be advantageous in terms of its simplicity, reduced cost and limited footprint. The dedicated gamma camera developed during the project process will be tested in a proton therapy center to monitor the beam range in a PMMA target. In case of success, the slit camera concept for prompt gamma imaging will be experimentally confirmed for the first time with the beam operated as in clinical conditions (previous measurements were performed with beam parameters which were far from those required to deliver a real treatment). The prototype validation would allow the realization of a new monitoring system that could be introduced and used during patients treatments. Safety margins in current treatments could be reduced and the overall therapy would be safer and more efficient.