Polyvinyltoluene scintillators for relative ion dosimetry: An investigation with Helium, Carbon and Neon beams

Abstract

We present a dosimeter prototype, devoted to ion beam dosimetry, tested with Helium, Carbon and Neon ions having an equivalent range in water of 150 mm. A polyvinyltoluene based plastic scintillator is used to convert the deposited energy into scintillation, a measurement probe and a long optical fibre guide the light to a photon counting unit. Using 10-40 µm thick scintillators we show that the dosimeter gain is enough to provide useful measurements, the ion-induced scintillation can be interpreted using a model taking into account the energy deposited by secondary electrons. For a practical purpose it is shown that a linear relationship can be established between the scintillation signal and the relative dose.

A prototype scintillating fibre beam profile monitor for Ion Therapy beams

“…3.2 produces a single value of B S = 5.4 ± 0.2 mg • MeV −1 cm −2 . This is consistent with the result from Broggio et al [21] where fixed energy helium (150 MeV/u), carbon (290 MeV/u) and neon (400 MeV/u) ions were incident on a vinyltoluene plastic scintillator, and PMMA blocks were used to reduce the ion energy before the scintillator. The combined fit to our data was also constrained to a single value of C BVT and produces a reasonable χ 2 /ndf = 142/93, which is slightly smaller than that of the Birks Model fit.…”

“…As such, T 0 was left as a free parameter for each data set. It can be seen that the value for oxygen agrees well with the other large Z measurements in [19] and [21]. However, the value for protons appears unphysical, as the kinematic limit for delta ray production by heavy charged particles is T max = 2m e c 2 β 2 γ 2 < 600 keV for protons with β < 0.6.…”

Toward a novel dosimetry system using acrylic disk radiation sensor for proton pencil beam scanning

“…This problem can be solved by correcting for quenching dose, unlike the double‐scattering beam, as the PBS irradiates one energy level per layer. In fact, the scintillation light yield due to the quenching effect was corrected using the Birk's formula given bywhere S is the scintillation efficiency, kB is the scintillator quenching factor (known as Birk's constant), dL/dx is the scintillation yield per unit thickness, and dE/dx is the energy loss per unit thickness.…”