Innovative device for measuring the energy of therapeutic proton beams

In proton radiotherapy, the dose distribution in the tissue depends on the energy of the delivered beams. An innovative device for direct, fast and accurate measurement of proton beam energy has been developed, using state-of-the-art silicon detectors and a dedicated calibration method. The device facilitates the measures necessary to ensure the accuracy of the treatment. In proton radiotherapy, the dose distribution in the tissue depends on the energy of the delivered beams. An innovative device for direct, fast and accurate measurement of proton beam energy has been developed, using state-of-the-art silicon detectors and a dedicated calibration method. The device facilitates the measures necessary to ensure the accuracy of the treatment.

How does it work?

The energy measurement is based on the average time of flight taken by individual protons of the beam to cross the distance separating two detectors. The prototype uses thin silicon detectors optimized for high time resolutions, mounted on a mechanism that allows the detectors to be moved in order to align them along the beam direction and vary their relative distance. A self-calibration procedure uses time-of-flight measurements at different distances and energies, and a micrometrically accurate measurement of the displacements, to determine unknown parameters. Compared to the existing technologies based on the verification of beam penetration depth and requiring calibrations with reference instruments, the proposed device provides direct and absolute energy measurements with similar or better speeds and accuracies. Moreover, as it does not disrupt the beam, it can be used for real-time measurements without precluding the use of the beam.

Applications

• Beam quality controls for proton therapy centres;
• Characterisation of beam lines for proton therapy (clinical centres and companies);
• Research and development of linear proton accelerators for therapy;
• Research and development of new adaptive dose delivery techniques.

Advantages

• Direct and absolute measurement of the beam energy independent of calibration with reference instruments;
• Energy non-destructive, beam non-intercepting measurement;
• Possibility of real-time measurement during treatment.