Variants for a Riesenrad Ion Gantry

Hadrontherapy is widely believed to improve cancer treatment. The Bragg-peak effect of hadrons (protons and ions) makes them suitable for high precision and conformal scanning of tumours. To maximise the benefit it should be possible to deliver the particle beam from any direction in space towards the patient. A machine capable of performing such a task is called a medical gantry. So far only proton gantries have been built. The increased (magnetic) beam rigidity of say carbon ions yields considerable structural difficulties and has so far prevented realisation of an ion gantry. The structure would have to support large and very heavy bending magnets (50 t and more) and nevertheless deliver the beam with a sub-millimetre precision onto a patient in a supine position. The promising concept of a Riesenrad Gantry is suited to overcome this deadlock. The basic idea is to deflect the ion beam with a single 90° dipole, which rotates around the incoming beam axis, and direct it towards the eccentrically positioned patient cabin. Inside the (rotating) cabin similar conditions as in a classical isocentric treatment room prevail. The objective of this paper is to present and - to a certain degree - evaluate different versions of a Riesenrad gantry with clear focus on the mechanical performance. Two different ideas of how to achieve the specified accuracy are presented. Emphasis is also given to the decision making process leading to the designs

Program for a novel ion gantry

In conjunction with the CERN-based development of a specially designed cancer therapy synchrotron (Proton-Ion Medical Machine Study - PIMMS), the need for the development of a facility equipped with an ion gantry emerged. Such a medical machine shall be capable of delivering a carbon ion beam virtually from every position and direction best suited for the treatment of the patient. Therefore the gantry allows to conform the delivered dose very closely to the tumour volume, minimise the dose deposited in healthy tissue and spare any critical organs. The technical challenges for the design are the high beam rigidity of the ion beam, requiring large and very heavy bending magnets, as well as the specified high precision of the whole system

Design of a "Riesenrad" Ion Gantry for Hadrontherapy

The benefit of hadrontherapy can be maximized by offering the possibility to deliver the particle beam from any direction in space towards the patient with the help of a medical gantry. For carbon ions, their increased (magnetic) beam rigidity yields considerable structural difficulties and has so far prevented a practical realization of an ion gantry. The concept of a 'Riesenrad' ion gantry promises to provide an effective and efficient solution. The basic idea is to deflect the ion beam with a single 90° dipole, which rotates around the incoming beam axis, and direct it towards the eccentrically positioned patient cabin. Inside the cabin similar conditions as exist in a classical isocentric treatment room prevail. The practical design of such a Riesenrad gantry, its structural principles and its function are presented. The underlying beam optics and its integration into the mechanical structure are explained. Aspects of safety, and flexibility are discussed

Mechanical analysis and optimisation of large and highly-loaded bearing rollers For the "Riesenrad" Ion Gantry

A carbon ion gantry would allow the irradiation of cancer patients with carbon ions from any direction in space best suited for therapy. Till today, such a machine has not been built due to the expected size, mass and cost. A novel design, called "Riesenrad" ion gantry, promises to provide a competitive solution. The central part of the Riesenrad, which can rotate ± 90°, is supported (statically determinate) on pendular bearing units with two rollers each. High precision requirements for the structure rule out any plastic deformations in the area of contact. The present report describes the design of the highly-loaded rollers. In order to achieve a large contact area and a uniform distribution of contact stresses, a "barrel shape" for the rollers is proposed. An analysis using the finite element method (FEM) was performed to optimise the roller design, namely to establish the required crown roll (camber radius)

Development and Engineering Design of a Novel Exocentric Carbon-Ion Gantry for Cancer Therapy: The "Riesenrad" Gantry

Mechanical structures capable of delivering a therapy beam for cancer treatment from any direction to the patient are called medical gantries. Typically, a gantry rotates around the patient who is kept in the supine position (rotating gantries). In Europe several currently proposed clinic facilities for ion therapy want to install an ion gantry equipped with a pencil-beam scanning system. Such a treatment apparatus allows the optimisation of the dose-to-target conformity, but the active pencil-beam scanning increases the demands considerably on the beam transport accuracy. Usually, a sub-millimetre precision of the beam position at the patient (i.e. in the gantry isocentre) is required in order to treat tumours in the vicinity of critical organs, which is one of the main domains of ion therapy..

Genetic variability and differentiation in roe deer (Capreolus capreolus L) of Central Europe

International audienc

Proton-Ion Medical Machine Study (PIMMS), 2

The Proton-Ion Medical Machine Study (PIMMS) group was formed following an agreement between the Med-AUSTRON (Austria) and the TERA Foundation (Italy) to combine their efforts in the design of a cancer therapy synchrotron capable of accelerating either light ions or protons. CERN agreed to support and host this study in its PS Division. A close collaboration was also set up with GSI (Germany). The study group was later joined by Onkologie-2000 (Czech Republic). Effort was first focused on the theoretical understanding of slow extraction and the techniques required to produce a smooth beam spill for the conformal treatment of complex-shaped tumours with a sub-millimetre accuracy by active scanning with proton and carbon ion beams. Considerations for passive beam spreading were also included for protons. The study has been written in two parts. The more general and theoretical aspects are recorded in Part I and the specific technical design considerations are presented in the present volume, Part II. An accompanying CD-ROM contains supporting publications made by the team and data files for calculations. The PIMMS team started its work in January 1996 in the PS Division and continued for a period of four years

Large-Scale Model-Based Assessment of Deer-Vehicle Collision Risk

Ungulates, in particular the Central European roe deer Capreolus capreolus and the North American white-tailed deer Odocoileus virginianus, are economically and ecologically important. The two species are risk factors for deer–vehicle collisions and as browsers of palatable trees have implications for forest regeneration. However, no large-scale management systems for ungulates have been implemented, mainly because of the high efforts and costs associated with attempts to estimate population sizes of free-living ungulates living in a complex landscape. Attempts to directly estimate population sizes of deer are problematic owing to poor data quality and lack of spatial representation on larger scales. We used data on 74,000 deer–vehicle collisions observed in 2006 and 2009 in Bavaria, Germany, to model the local risk of deer–vehicle collisions and to investigate the relationship between deer–vehicle collisions and both environmental conditions and browsing intensities. An innovative modelling approach for the number of deer–vehicle collisions, which allows nonlinear environment–deer relationships and assessment of spatial heterogeneity, was the basis for estimating the local risk of collisions for specific road types on the scale of Bavarian municipalities. Based on this risk model, we propose a new “deer–vehicle collision index” for deer management. We show that the risk of deer–vehicle collisions is positively correlated to browsing intensity and to harvest numbers. Overall, our results demonstrate that the number of deer–vehicle collisions can be predicted with high precision on the scale of municipalities. In the densely populated and intensively used landscapes of Central Europe and North America, a model-based risk assessment for deer–vehicle collisions provides a cost-efficient instrument for deer management on the landscape scale. The measures derived from our model provide valuable information for planning road protection and defining hunting quota. Open-source software implementing the model can be used to transfer our modelling approach to wildlife–vehicle collisions elsewhere