Degrader comprising boron carbide

It is the objective of the present invention to provide a degrader that has excellent degrading capabilities with, for the same energy loss in the degrader, a lower emittance increase as currently used materials, without generating a strong neutron flux and without having severe toxic characteristics. This objective is achieved according to the present invention by a degrader (2) for use in the field of the application of a particle beam (6), comprising degrading active material wherein the degrading active material comprises Boron Carbide B4C. This degrader has an amount of multiple scattering that is lower than in graphite for the same energy loss. The use of B4C increases the transmission by at typically 35% for the beam degradation to low energies, which is a significant and useful amount of beam intensity increase in particle therapy. The B4C-material does not become more radio-active than graphite, so that there will be no additional problems at service activities. Further, B4C as degrading active material does not have severe toxic properties

A gantry for particle therapy as an arm rotating in the longitudinal plane

The present invention discloses a system (2, 2') for particle beam therapy, comprising as seen in the flow direction of the particle beam (4): a) an adjustable gantry (10, 10') for the beam delivery to a target volume, said gantry comprising: a1) a beam coupling section (6) for the incoming particle beam (4); said incoming particle beam (4) being oriented substantially horizontally thereby defining a horizontal plane; a2) a first beam bending section (8, 8') comprising a number of beam deflection and/or focusing magnets (12, 14) wherein the first bending section (8, 8') either bends the particle beam (4) with an adjustable angle into the vertical plane, or with 90 degrees in the horizontal plane, but with the mechanical possibility to rotate with an adjustable angle along the axis of the incoming particle beam (4); a3) a beam transport section (16) receiving the particle beam (4) leaving the first beam bending section (8, 8') and guiding the particle beam (4) to a second beam bending section (18); a4) the second beam bending section (18) comprising a number of beam deflection magnets and/or beam focusing magnets; a5) a beam nozzle (20) comprising a window for the exit of the particle beam (4); and b) a patient table/chair (22) being rotatable in the horizontal plane or in a plane being parallel to the horizontal plane and optionally being adjustable vertically, wherein: c) the gantry (10, 10') is supported by a tilting mechanism(24) allowing the gantry (10, 10') to be tilted vertically by an angle Φ1, Φ1 ԑ [-90°; +90°], wherein the gantry (10, 10') comprises a pivot (7, 7') being disposed in the region of the first bending section (8, 8'); and d) a rotation mechanism (26) beingdisposed in a way that the second beam bending section (18) and the beam nozzle (20) being rotatable by an angle Φ2, Φ2 ԑ [-180°; +180°] around a direction given by the angle Φ

Evolution of a beam dynamics model for the transport lines in a proton therapy facility

Despite the fact that the first-order beam dynamics models allow an approximated evaluation of the beam properties, their contribution is essential during the conceptual design of an accelerator or beamline. However, during the commissioning some of their limitations appear in the comparison against measurements. The extension of the linear model to higher order effects is, therefore, demanded. In this paper, the effects of particle-matter interaction have been included in the model of the transport lines in the proton therapy facility at the Paul Scherrer Institut (PSI) in Switzerland. To improve the performance of the facility, a more precise model was required and has been developed with the multi-particle open source beam dynamics code called OPAL (Object oriented Particle Accelerator Library). In OPAL, the Monte Carlo simulations of Coulomb scattering and energy loss are performed seamless with the particle tracking. Beside the linear optics, the influence of the passive elements (e.g. degrader, collimators, scattering foils and air gaps) on the beam emittance and energy spread can be analysed in the new model. This allows for a significantly improved precision in the prediction of beam transmission and beam properties. The accuracy of the OPAL model has been confirmed by numerous measurements.Comment: 17 pages, 19 figure