Introduction

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

Technical features

The energy measurement is based on the mean time of flight required by single beam protons to travel a distance between two detectors. In the prototype thin silicon sensors optimized for high resolution timing measurements are mounted on a mechanical system that allows the movement of one detector to change the relative distance and for the alignment along the beam direction. A calibration procedure, based on time of flight measurements at different distances and beam energies, and on the micrometric measure of the position offsets, allows to determine the unknown parameters of the system. With respect to existing technology for fast energy verification based on the beam penetration depth and requiring calibration with respect to reference systems, the proposed device provides a direct and absolute energy measurement, with similar or better speed and precision. In addition, the proposed device can be used for on-line beam measurements without perturbing the beam.

Possible Applications

• Routine quality controls in proton-therapy centers;
• Characterization of the beam lines for proton therapy;
• Research and development of linear accelerator for proton therapy;
• Research and development of new adaptive dose release techniques.

Advantages

• Direct and absolute energy measurement independent of calibration with reference devices;
• The energy measurement does not intercept the beam;
• Possibility to measure the energy in real time during the treatment.