Charged particle’s flux measurement from PMMA irradiated by 80 MeV/u carbon ion beam

Abstract

Hadrontherapy is an emerging technique in cancer therapy that uses beams of charged particles. To meet the improved capability of hadrontherapy in matching the dose release with the cancer position, new dose-monitoring techniques need to be developed and introduced into clinical use. The measurement of the fluxes of the secondary particles produced by the hadron beam is of fundamental importance in the design of any dose-monitoring device and is eagerly needed to tune Monte Carlo simulations. We report the measurements carried out with charged secondary particles produced from the interaction of a 80 MeV/u fully stripped carbon ion beam at the INFN Laboratori Nazionali del Sud, Catania, with a poly-methyl methacrylate target. Charged secondary particles, produced at 90° with respect to the beam axis, have been tracked with a drift chamber, while their energy and time of flight have been measured by means of a LYSO scintillator. Secondary protons have been identified exploiting the energy and time-of-flight information, and their emission region has been reconstructed backtracking from the drift chamber to the target. Moreover, a position scan of the target indicates that the reconstructed emission region follows the movement of the expected Bragg peak position. Exploiting the reconstruction of the emission region, an accuracy on the Bragg peak determination in the submillimeter range has been obtained. The measured differential production rate for protons produced with E(Prod)(kin) > 83 MeV and emitted at 90° with respect to the beam line is dN(P)/(dN(C)dΩ) (E(Prod)(kin) > 83 MeV, θ = 90°) = (2.69 ± 0.08(stat) ± 0.12(sys)) × 10⁻⁴ sr⁻¹.

Nuclear physics and particle therapy

“…The energy spectra are dominated by the carbon line (4.44 MeV) due to its presence both in the beam and in the target [74,75].…”

“…As far as the photon rate is concerned, one of the most accurate measurements [74] reports an observed rate in the case of a carbon ion beam with E = 80 MeV/u of (3.04 ± 0.20) × 10 −6 gammas per impinging carbon ion with energy E γ > 2 MeV at 90 • with respect to the beam incoming direction. Correcting for efficiency and acceptance, the production rate was estimated to…”

A novel dual-mode tracking device for online dose monitoring in hadron therapy

“…Currently the dose release is measured using beam monitor information or with PET (Positron Emission Tomography) scans just after the treatment. Promising new monitor techniques exploit the flux of secondary particles created by the beam interaction in the patient, namely: photons from β + emitters [1], prompt photons within the 1-10 MeV range [2] and charged particles [3], [4]. The detector should provide the dose measurement on-line, respecting the stringent space constraints in the treatment rooms.…”

“…Recent measurement of fluxes at different energies and angle are available in [3,4] and it has been shown that the Bragg peak position can be linked to the charged particles emission as shown in Fig. 1 b).…”

Charged and Neutral Particles Production from 80 MeV/u ¹²C ion beam on a PMMA target

“…The obtained accuracy on the position of the released dose should be regarded as an indication of the achievable accuracy for possible applications of this technique We measured the differential production rate for protons with E Prod kin > 83 MeV and emitted at 90 • with respect to the beam line: dN P /(dN C dΩ)(E Prod kin > 83 MeV, θ = 90 • ) = (2.69 ± 0.08 stat ± 0.12 sys ) × 10 −4 sr −1 [9].…”