In-room performance evaluation of a novel online charged secondary particles monitor of light ions PT treatments

The advantages of using C, He and O ions as therapeutical beam particles in Particle Therapy is related to their enhanced Relative Biological Effectiveness and Oxygen Enhancement Ratio, resulting in an improved efficacy in damaging the cancerous cells. However, an accurate on-line control of the dose release spatial distribution is required to spare the healthy tissues surrounding the tumor area, preventing undesired damages caused by, for example, morphological changes occurred in the patient during the treatment with respect to the initial CT scan. This monitor technology is currently missing in clinical practice, and several studies are being performed to develop beam range verification systems exploiting the detection of the emitted secondary radiation. Charged secondary particles, produced by the projectile fragmentation in the collisions with the patient tissues, represent an interesting chance for C, He and O treatments since they are also emitted at large angles with respect to the beam direction and can be detected with high efficiency in a nearly background free environment. The Dose Profiler detector is a scintillating fibre tracker that allows an online charged fragments reconstruction and backtracking. The construction and preliminary tests performed on the DP, carried out using the Carbon ions beam of the CNAO treatment centre using an anthropomorphic phantom as a target, will be reviewed in this contribution.