An avoidance method to minimize dose perturbation effects in proton pencil beam scanning treatment of patients with small high-Z implants.

To implement a multi-field-optimization (MFO) technique for treating patients with high-Z implants in pencil beam scanning proton-therapy and generate treatment plans that avoids small implants. Two main issues were addressed: (i) the assessment of the optimal CT acquisition and segmentation technique to define the dimension of the implant and (ii) the distance of pencil beams from the implant (avoidance margin) to assure that it does not affect dose distribution. Different CT reconstruction protocols (by O-MAR or standard reconstruction and by 12 bit or 16 bit dynamic range) followed by thresholding segmentation were tested on a phantom with lead spheres of different sizes.

On the lateral dose profile of He beams in water.

Purpose: We investigate the possibility to improve the accuracy of the lateral dose profile for He beams with a novel approach, by extending an already validated model for proton beams to heavier ions.

Methods: The full Molière theory for the Coulomb multiple scattering is applied to the case of He beams, with a complete separation of the electromagnetic and of the nuclear contributions in the calculation of the total dose. The latter is described with only three free parameters.

An accurate model for the computation of the dose of protons in water.

Purpose: The accurate and fast calculation of the dose in proton radiation therapy is an essential ingredient for successful treatments. We propose a novel approach with a minimal number of parameters.

Methods: The approach is based on the exact calculation of the electromagnetic part of the interaction, namely the Molière theory of the multiple Coulomb scattering for the transversal 1D projection and the Bethe-Bloch formula for the longitudinal stopping power profile, including a gaussian energy straggling.

On the parametrization of lateral dose profiles in proton radiation therapy.

Purpose: The accurate evaluation of the lateral dose profile is an important issue in the field of proton radiation therapy. The beam spread, due to Multiple Coulomb Scattering (MCS), is described by the Molière's theory. To take into account also the contribution of nuclear interactions, modern Treatment Planning Systems (TPSs) generally approximate the dose profiles by a sum of Gaussian functions.

Mechanisms of the induction of apoptosis mediated by radiation-induced cytokine release.

The aim of the present work was to investigate the mechanisms of radiation-induced bystander signalling leading to apoptosis in non-irradiated co-cultured cells. Cultured non-transformed cells were irradiated, and the effect on the apoptosis rate on co-cultured non-irradiated malignant cells was determined. For this, two different levels of the investigation are presented, i.