MONDO project – a collider for adrotherapy

The MONDO (MOnitor for Neutron Dose in hadrOntherapy) project’s goal is to develop a tracker for the neutrons produced from the beam of the patient undergoing oncologic therapy. The interest in this project stems from the fact these beams are “secondary” products, unintended, and as such their action is still little known and up for determination.

Secondary particles are generated by the interactions with the healthy tissue of the patients, and among these there are neutrons, considered quite dangerous because they carry the maximum amount of unwanted extra dose on the tissues themselves, and are possibly responsible for secondary neoplasia.

A better control on the beam’s quality is essential to increase the patients’ life expectancy: hence the need for a new detector which will guarantee the chance to individuate the neutrons’ path and to detect their energy. MONDO will be made up of a 10 x 10 x 20 cm3 matrix of brilliant fibers (250 micron) read by digital SPAD (Single Photon Avalanche Diode).

At the Beam Test Facility (BTF) also ORAnGE (Optically ReAdout GEm Detector) was tested, a technology for gas detection born alongside the MONDO project itself. It allows to “capture” the loaded particles’ trajectories crossing the detector’s zone, which is filled with a specific gas whose particles act as billions of “fireflies”.

This phenomenon happens thanks to the action of the secondary electrons ripped from the gas’ molecules of the BTF beam. These secondary particles are multiplied in number by a triple GEM ORAnGE (Optically ReAdout GEm Detector) structure, amplifying their signal. The light produced in the multiplication process is detected by the CMOS sensor of an incredibly fast camcorder with 4 billion pixel.

This last technology, eventually, allows to obtain high quality images of the path through the gas of single particles or whole groups (see pictures) with a resolution of a few tens micron.