Speaker
Ms
Nathalie DUFOUR
(PhD Student - Centre Léon Bérard)
Description
Heavy charged particles like protons or light atom nuclei like carbon ions have
interesting ballistic properties in cancer therapy. When used as projectiles,
their electromagnetic interaction with matter is characterized with an energy loss
spectrum peaking at a localized penetration depth: the so called Bragg peak.
However, projectile particles used in hadrontherapy have sufficient kinetic
energies to undergo nuclear reactions with target nuclei. As a consequence,
depending on the nuclear process involved, multiple nuclear fragments can be
produced. Even though the cross section of these processes would hardly exceed 40%
of the total interaction cross section, they would contribute to a significant
spread of the deposited dose over the target volume of interest. Despite this
unwanted effect in hadrontherapy, among the produced radioactive isotopes a small
fraction of those would β+ emitters and offers the only way for an online dose
deposition control and even more the only way for the exploitation of inline and in-
situ PET (Positron Emission Tomography) techniques for real time imaging.
Here, we present our preliminary results concerning Monte Carlo GEANT 4 simulation
to study the physical dose induced by fragments in a patient during an irradiation
with carbon ions. The first step of this work concerns the improvement of the
experimental database of the fragmentation’s cross sections in the range of
energies used in therapy and their integration in GEANT4. After, we will present
the proper implementation within Monte Carlo simulation framework of the patient
data usually represented with a regular grid of heterogeneous voxels, obtained from
a CT image. The use of this type of geometry in Monte Carlo requires the
optimisation of the particle tracking to reduce the simulation time.
Author
Ms
Nathalie DUFOUR
(PhD Student - Centre Léon Bérard)