Patents, industry research

A completely new on-line, non-invasive, bias-free detector for relative and absolute in-vivo dose monitoring, has been realized to be employed for patients undergoing charged particles radiotherapy. The basic idea is to use the patient as a Faraday cup, collecting the current injected from the beam directly from a section of its skin, far from the beam entering point and using a conductive electrode. Such new dosimeter has been tested in-vitro, in an electrically-isolated phantom irradiated with 62 MeV clinical proton beams at CATANA facility of INFN-LNS (Catania, Italy). The proton beam current has been collected from an electrode immersed in a water phantom and positioned outside the irradiation field. The charge measurements resulted in accordance with the theoretical prevision. The detector response has been studied as a function of the dose released in water, dose rate and irradiation field. In all cases, the experimental data have been compared with the theoretical results.

The acquired data demonstrate the usefulness of the proposed approach as in-vivo beam monitoring during a charged particles irradiation. Preliminary tests have been also carried out by using electron and carbon beams. In-vivo tests, carried out on protontherapy patients demonstrated the clinical applicability of the developed as on-line dose monitoring. The system has been protected by a National Italian patent, N 102017000087851 while submission for international patent is ongoing.

A fast and reliable method to measure transversal charged particles transversal dose profiles, is desirable in an hadrontherapy facilities, being the basis for an accurate treatment quality system. For this purpose, a quality control system was developed at the “Laboratori Nazionali del Sud” of Italian Institute for Nuclear Physics (INFN-LNS, Catania, I). It consists of a plastic scintillator screens (50 × 50 mm², variable in thickness from 0.5 mm to 1.0 mm), mounted perpendicularly to the beam axis and coupled with a highly sensitive cooled CCD detector (resolution 1928×1452 pixels) in a light-tight box. An in-house custom software for real-time data acquisition and processing was also developed in the LavView 2016 environment.

In this work a characterisation of the system is reported: transversal dose profile parameters (FWHM, field lateral penumbra, flatness, symmetry, reproducibility and linearity with beam current, etc.) have been investigated.

A comparison with other popular devices, able to transversal beam profiles reconstruction (Gafchromic films, silicon diodes, Lynx detector and Timepix detector) has been also carried out in small-field proton beams at the INFN-LNS (beam spot size of 35 mm in diameter, maximum) and at the Trento Institute for Fundamental Physics and Applications (TIFPA, Trento, I). Results will be reported and discussed.