MedAustron is a synchrotron-based ion beam therapy center allowing the treatment of tumours with protons and other light ion species, in particular C6+. Commissioning of the first irradiation room for clinical therapy with proton beams has been completed [1] and in parallel to the commissioning of the remaining two irradiation rooms [2], a facility upgrade study has started. Our analysis includes considerations for the possibility to introduce different extraction mechanisms, new diagnostic tools, optimization of the accelerator cycle time, ripples mitigation for more accurate active beam stabilization and other improvements for hardware reliability. We present the concept, the main benefits, also in terms of treatment time reduction, and the challenges for implementation. Each option will be investigated including a detailed assessment on resources demand, impact and risk analysis. PERFORMANCE IMPROVEMENT PROJECT The MedAustron accelerator is operated in cycles of roughly 10s during which a spill of particles at one energy is delivered in 5s via betatron core driven slow resonant extraction. The machine is able to accelerate an average of 1.8 × 1010 particles in a spill, but this is artificially degraded to roughly 20% to mitigate the effect of spill ripples. The developments presented in this work are summarized in Table 1 and detailed in the paragraphs below: Table 1: Developments considered in this work and main motivation for their implementation. Spill smoothening also enables to run at higher intensities.

The synchrotron-based MedAustron accelerator in Wiener Neustadt, Austria, has seen the first clinical beam and has been certified as a medical accelerator in December 2016. This represented a major milestone for the facility whose original design originated more than a decade ago and construction started four years ago. The accelerator is designed to deliver clinical proton beams 60-253 MeV and carbon ions 120-400 MeV/u to three ion therapy irradiation rooms (IRs), including a room with a proton Gantry. Beams up to 800 MeV will be provided to a fourth room dedicated to non-clinical research. Presently, proton beams are delivered to the horizontal beam lines of three irradiation rooms. In parallel, commissioning of the accelerator with Carbon ions and the installation of the Gantry beam line are ongoing. At MedAustron, a third-order resonance extraction method is used to extract particles from the synchrotron in a slow controlled process over a spill time of 0.1-10 seconds to facilitate the measurement and control of the delivered radiation dose during clinical treatments. The main characteristics of the accelerator and the results obtained during the commissioning are presented.

MedAustron is a synchrotron based ion beam therapy center for proton (62-250MeV) and carbon ion(120-400MeV/n) treatments. The MedAustron synchrotron uses a betatron core driven slow extraction scheme based on a third order resonance. The commissioning of the extraction from the synchrotron involved the setup of the correct orbit and optics at flattop. In order to maximize the momentum spread before extraction and optimize spill structure the RF system enforces a so called RF-phase jump to the unstable phase. Different scenarios were simulated using MADX-PTC [1] in combination with Python to overcome the static nature of PTC. Simulations have shown that the initial phase of the beam and a finite time to jump to the unstable fix point have a strong impact on the performance. Using a high frequency intensity monitor in the extraction channel (QIM), the spill structure was analysed and used for optimization. Simulation and measurements of the procedure are presented.

MedAustron is a medical accelerator facility for hadron therapy cancer treatment using protons and carbon ions. The Synchrotron is driven by a 0.47-3.26 MHz Finemet® loaded wideband cavity powered by 12x 1kW solid state amplifiers connected to a digital Low Level RF system. It was developed in collaboration with CERN and put to operation at MedAustron in early 2014. The main Synchrotron RF (sRF )commissioning steps for proton beams involved the setup of the adiabatic capture process, the setup of the frequency and voltage ramps and feedback loops for fast acceleration and the RF jump for extraction. The adiabatic capture process was optimized in terms of energy and voltage mismatch by analyzing longitudinal empty bucket scans after beam injection into the synchrotron. The acceleration ramp optimization was based on calculations using a software tool developed in-house and adapted experimentally to minimize losses at injection and during acceleration. This paper provides an overview of the acceleration system and describes the commissioning process of the sRF system and the related beam commissioning efforts at MedAustron.

The Italian Centre for Hadrontherapy (CNAO) and the Austrian MedAustron Hadrontherapy Center are synchrotron-based medical accelerator therapy centers. The CNAO machine has five years of experience in patient treatments, whereas MedAustron will soon start patient treatments with protons. Their accelerator systems have common characteristics, in particular in regards to the extraction system: at acceleration flattop, particles are slowly driven through the 3 integer resonance longitudinally by a betatron core. This setup enables smooth extracted beam intensities. The rationale behind the use of a betatron core, its impact on the extracted beam quality and the performance from operation and commissioning of the two centers will be here presented.

MedAustron has completed its proton commissioning activities for clinical treatment in the horizontal Irradiation Room 3 (IR3). Work involved the preparation of 255 energies in clinical range (60 – 250 MeV) for one spill length, one spot size and 4 intensity levels. After resonant slow extraction, the beam crosses four different functional areas in the High Energy Beam Transfer Line (HEBT): the dispersion suppressor (DS), the phase shifter stepper (PSS), two straight extension modules and a deflection module to IR3. Quadrupole-variation methods were applied to center the beam in the beamline. The DS section was commissioned to provide high intensity beams with closed dispersion. The PSS section was commissioned to provide symmetric and minimal spot sizes at the iso-center in the room (after scattering in the nozzle and air). The definition of the 255 clinical energies was given by the Medical Physics team after measuring the beam ranges at the iso-center.

The commissioning process of the MedAustron Particle Therapy Accelerator (MAPTA) has delivered the configurations providing the requested beam parameters in the first irradiation room to be used for proton clinical treatments, and at the same time it identified the critical points where a performance drift can appear. The strategy for Beam Quality Assurance (QA) has therefore two components: testing the specific parameters of the beam delivered to the irradiation room, and testing for any drifts that might appear at the critical points. We present here the monitoring strategy, the observed limitations, the tools employed and the long-term statistics of the beam quality assurance for proton clinical beams.

The MedAustron accelerator (Wiener Neustadt, Austria) will deliver clinical beams of protons (60 250 MeV) and carbon ions (120 400 MeV/n) to three ion beam therapy irradiation rooms (IR). Clinical beams and proton beams up to 800 MeV will be provided in a fourth IR, dedicated to non-clinical research. A slow-extracted proton beam of maximum clinical energy reached for the first time the IR3 in October 2014, thus providing the technical proof-of-principle of the entire accelerator chain. The main characteristics of the MedAustron accelerator system are presented, along with the results obtained along the ongoing commissioning. INTRODUCTION MedAustron is a synchrotron-based ion beam therapy centre. The accelerator supports beam rigidities up to 6.4 Tm. The accelerator layout is shown in Fig. 1. Its design [1] originates from those of PIMMS [2] and CNAO [3]. The injector produces beams of H3 or C, which are chopped with a fast electrostatic deflector, then bunched and pre-accelerated to 7 MeV/n with a Radiofrequency Quadrupole (RFQ) and an IH-DTL linac. In the Medium Energy Beam Transfer line (MEBT), the beam is stripped to H or C before injection into the synchrotron. The synchrotron has a superperiod of 2 with non-dispersive regions for injection and the Radiofrequency (RF) cavity. After acceleration, the beam is extracted via the thirdinteger resonance in the High Energy Beam Transfer Line (HEBT). Since last year [4-5], the installation of accelerator components for proton treatments in the two horizontal beam lines of IR2 and IR3 has been completed and a first beam of protons at 62.5 MeV reached IR3 in October 2014. Beam commissioning is currently resuming and passing the torch to medical commissioning. INJECTOR AND MEBT The commissioning of the beam from the source to the end of the MEBT has been completed at the end of 2014 with very positive results, in terms of intensity, transmission and stability. The main contributors to this progress have been: the extensive work on the IH stability (cooling and setpoint adjustment), optimization of the IH quadrupole strengths, steering at the source exit and in the matching section between RFQ and linac and finally, the increase of the RFQ output energy. The appropriate choice of the operation point of the linac was critical in stabilizing the energy of the beam injected into the ring. A summary is shown in Table 1. Table 1: Results of Commissioning up to the MEBT Parameter Performance

The MedAustron facility [1, 2] is a synchrotron-driven hadron therapy and research center presently under construction in Wiener Neustadt, Austria. In its final outline, the facility will provide H beams with kinetic energies ≤250MeV and C beams of ≤400MeV/u for clinical applications, and H of up to 800MeV for nonclinical applications. At a later stage of the project, beams of other species can be generated with similar optics. First patient treatment is foreseen for the end of 2015. This contribution presents the results of commissioning and operation of the injector of the MedAustron accelerator. A comparison with the baseline optics and with the design error studies is given alongside with an overview on the operational experience, with emphasis on the system reliability, stability and reproducibility. THE MEDAUSTRON INJECTOR The layout of the MedAustron injector, as commissioned, is presented in Figure 1. Figure 1: The MedAustron injector. The primary particle beams (H3, C) are generated in continuous mode at 8keV/u by two ECR ion sources (one for each particle type). A third ion source is used as backup and can be tuned for both ion species, and at a later stage for other light ions. All three ion sources are connected by individual transport lines to a common LEBT comprising a fast electrostatic deflector for beam pulse length adjustment. From there, they are transported to the RFQ for acceleration to 400keV/u. An inter-tank matching section (IMS), encompassing a Buncher (BU) RF cavity, two quadrupole doublets, and two steerers, matches the beam to the entrance plane of an IH-mode DTL (KONUS) that accelerates the particles to 7MeV/u before they are stripped to, respectively, H and C, debunched and transported to the injection plane of the synchrotron. The Linac RF system is operated with 10Hz repetition rate and a maximum pulse length of 500μs. A beam dump located after the stripping foil allows operating the source lines, LEBT and the Linac even when installation works are taking place inside the synchrotron hall, which increases availability for beam commissioning. The beam diagnostic (BD) devices available for beam characterisation in the Injector involve [3]: profile grids (PGX), wire scanners (WSX; only in the source lines and LEBT, where the beam is continuous) and slits (SLX) for transverse profile and emittance measurements, current transformers (CTAs) and Faraday Cups (FCs) to measure the beam current, Phase Probes (PHPs) for beam energy measurements, and a four-button probe to determine the beam position at the entrance plane of the IH-tank. The injector commissioning was started in 2012/12 using the H beam from ion source 1 (IS1). First H beam was seen on the injection plane of the synchrotron in 2014/03. INJECTOR COMMISSIONING STRATEGY The injector of the MedAustron accelerator has been commissioned in a stepwise process in order to fully characterize the beam for each section of the injector, by making use also of two temporary installations of beam diagnostics. Due to the tight time constraints, the commissioning strategy was optimized to allow the acquisition of sufficient data with only one ion beam species (H3), from one ion source (S1). Based on this commissioning data, the injector can be commissioned for any new beam, even though the temporary test benches are no longer available. The commissioning stages are described in the following. Ion Sources The MedAustron ion sources have several operational parameters that affect directly the emittance and the Twiss parameters of the generated beam. The commissioning goal was to find at least a set of source parameters providing a beam within the specified requirements [4] and to identify on which beam property each ion source parameter is acting on. A notable dependence, integrated into the strategy of the next commissioning stages, is the possibility to tune THPME001 Proceedings of IPAC2014, Dresden, Germany ISBN 978-3-95450-132-8 3202 C op yr ig ht © 20 14 C C -B Y3. 0 an d by th e re sp ec tiv e au th or s 04 Hadron Accelerators A08 Linear Accelerators the Twiss parameters of the beam after the spectrometer magnet via the electrical potential on the middle extraction electrode of the ion source (“Focus” electrode). The dependence of α and β in the horizontal plane is presented in Figure 2; in the vertical plane, the influence on α and β is considerably weaker. Figure 2: Dependence of the horizontal Twiss parameters after the spectrometer on the potential of the Focus electrode.

MedAustron is a synchrotron based accelerator complex, used for cancer treatment as well as for nonclinical research, and is situated in Wiener Neustadt,

The MedAustron facility [1, 2] is a synchrotron-driven hadron therapy and research center presently under construction in Wiener Neustadt, Austria. In its final outline, the facility will provide H + beams with kinetic energies ≤250MeV and C 6+ beams of ≤400MeV/u for clinical applications, and H + of up to 800MeV for nonclinical applications. At a later stage of the project, beams of other species can be generated with similar optics. First patient treatment is foreseen for the end of 2015. This contribution presents the results of commissioning and operation of the injector of the MedAustron accelerator. A comparison with the baseline optics and with the design error studies is given alongside with an overview on the operational experience, with emphasis on the system reliability, stability and reproducibility.

The MedAustron centre is a synchrotron based accelerator complex for cancer treatment and clinical and non-clinical research with protons and light ions, currently under construction in Wiener Neustadt, Austria. The accelerator complex is based on the CERN-PIMMS study [1] and its technical implementation by the Italian CNAO foundation in Pavia [2]. The MedAustron beam diagnostics system is based on sixteen different monitor types (153 devices in total) and will allow measuring all relevant beam parameters from the source to the irradiation rooms. The monitors will have to cope with large intensities and energy ranges. Currently, one ion source, the low energy beam transfer line and the RFQ are being commissioned in the Injector Test Stand (ITS) at CERN. This paper gives an overview of all beam monitors foreseen for the MedAustron accelerator, elaborates some of the design choices and reports the first beam commissioning results from the ITS.