Simultaneous irradiation with mixed helium and carbon ions is being proposed for online range verification in carbon radiotherapy. In 2024, a mixed $^4$He$^{2+}$ and $^{12}$C$^{6+}$ beam, generated by sequential injection of helium and carbon ions into the synchrotron, was extracted successfully for the first time at the MedAustron ion beam therapy and research center. This double injection scheme comes with challenges concerning the capture, acceleration, and slow extraction, as injection energy offsets and differences in horizontal phase distributions have to be considered in addition to the small offset in charge-to-mass ratio between $^4$He$^{2+}$ and $^{12}$C$^{6+}$. This proceeding reports on recent developments in the delivery of this mixed ion beam at MedAustron using a double injection scheme, which includes an additional deceleration ramp for helium ions between the injections of helium and carbon, as well as progress towards a measurement setup for the time-resolved quantification of the ion mixing ratio at delivery.

Irradiation with mixed helium and carbon ion beams is emerging as a promising approach to treatment monitoring in ion radiotherapy. In contrast to mono-isotopic beams, the full characterization of the mixed beam requires distinguishing ion species of almost identical charge-to-mass ratio, which is not feasible with most conventional beam diagnostic devices. This proceeding proposes a measurement concept that could allow for determining the ion mixing ratio after extraction from the ion source at energies around 10 keV/u. The concept relies on a gas-filled charge exchange cell, where the traversing ions experience electron capture events, followed by an electrostatic or magnetic analyzer and beam intensity measurement. The proposal is accompanied by proof-of-concept measurements performed at the *Helmholtz Zentrum Dresden-Rossendorf (HZDR)*, which showcase the potential but also several challenges associated with the measurement concept.

The low relative charge-to-mass ratio offset of 0.065

The low relative charge-to-mass ratio offset of 0.065% between fully ionized helium-4 and carbon-12 ions enables simultaneous acceleration in hadron therapy synchrotrons. At the same energy per mass, helium ions exhibit a stopping range approximately 3 times greater than carbon ions. They can therefore be exploited for online range verification downstream of the patient during carbon ion beam irradiation. One possibility for creating this mixed beam is accelerating the two ion species sequentially through the LINAC and subsequently “mixing” them at injection energy in the synchrotron with a double multiturn injection scheme. This work reports the first successful generation, acceleration, and extraction of a mixed helium and carbon ion beam using this double multiturn injection scheme, which was achieved at the MedAustron therapy accelerator in Austria. A description of the double multiturn injection scheme, particle tracking simulations, and details on the implementation at the MedAustron accelerator facility are presented and discussed. Finally, measurements of the mixed beam at delivery in the irradiation room using a radiochromic film and a low-gain avalanche diode detector are presented.

One challenge on the path to delivering FLASH-compatible beams with a synchrotron is facilitating an accurate dose-control for the required ultra-high dose rates. We propose the use of pulsed RFKO extraction instead of continuous beam delivery as a way to control the dose delivered per Voxel. In a first feasibility test dose rates in pulses of up to 600 Gy/s were observed, while the granularity at which the dose was delivered is expected to be well below 0.5 Gy.

MedAustron is a synchrotron-based Particle Therapy Accelerator located in lower Austria which delivers clinical proton and carbon beams in the range of 62-252.7 MeV/u and 120-400 MeV/u respectively in two clinical treatment rooms. A proton Gantry was recently commissioned in a third clinical treatment room and a fourth experimental beamline is dedicated to non-clinical research activities. Within the latter, the injector commissioning has recently started for He 2 + beam generation. The long-term goal is to use helium for cancer treatment due to its favourable physical and biological properties. The helium beam properties from the source up to injection further downstream into the accelerator, i.e. from the Low Energy Beam Transfer line to the Linear Accelerator are discussed in terms of beam emittance, intensity and transmission efficiency. Furthermore, a comparison with simulated data is presented.

Particle therapy relies on the advantageous dose deposition which permits to highly conform the dose to the target and better spare the surrounding healthy tissues and organs at risk with respect to conventional radiotherapy. In the case of treatments with heavier ions (like carbon ions already clinically used), another advantage is the enhanced radiobiological effectiveness due to high linear energy transfer radiation. These particle therapy advantages are unfortunately not thoroughly exploited due to particle range uncertainties. The possibility to monitor the compliance between the ongoing and prescribed dose distribution is a crucial step toward new optimizations in treatment planning and adaptive therapy. The Positron Emission Tomography (PET) is an established quantitative 3D imaging technique for particle treatment verification and, among the isotopes used for PET imaging, the 11C has gained more attention from the scientific and clinical communities for its application as new radioactive projectile for particle therapy. This is an interesting option clinically because of an enhanced imaging potential, without dosimetry drawbacks; technically, because the stable isotope 12C is successfully already in use in clinics. The MEDICIS-Promed network led an initiative to study the possible technical solutions for the implementation of 11C radioisotopes in an accelerator-based particle therapy center. We present here the result of this study, consisting in a Technical Design Report for a 11C Treatment Facility. The clinical usefulness is reviewed based on existing experimental data, complemented by Monte Carlo simulations using the FLUKA code. The technical analysis starts from reviewing the layout and results of the facilities which produced 11C beams in the past, for testing purposes. It then focuses on the elaboration of the feasible upgrades of an existing 12C particle therapy center, to accommodate the production of 11C beams for therapy. The analysis covers the options to produce the 11C atoms in sufficient amounts (as required for therapy), to ionize them as required by the existing accelerator layouts, to accelerate and transport them to the irradiation rooms. The results of the analysis and the identified challenges define the possible implementation scenario and timeline.

A faster treatment reduces the risk of intra-fraction movement of organs, offers a more comfortable treatment to the patient, allows to treat lesion of larger volumes in a reasonable time and most of all expands the capacity of the facility. This work presents possible machine upgrades for synchrotron based ion beam therapy centers to shorten the irradiation time. The expected delivery times for each scenario are simulated for the study case of proton beams of MedAustron. The second part of the work focuses on the MedAustron development roadmap, where recently increase of ring fillings and delivered intensities were implemented for proton treatments achieving an average irradiation time of ~50% since start of operation.

In this paper we discuss the possibility to generate and accelerate proton nanobeams in fully dielectric laser-driven accelerators (p-DLAs). High gradient on-chip optical-power dielectric laser accelerators (DLAs) could represent one of the most promising way towards future miniaturized particle accelerator. A primary challenge for DLAs are small beam apertures having a size of the order of the driving laser wavelength where low charge high-repetition (or also CW) ultralow emittance nanobeams have to be transported. For electrons beams generation and acceleration, intense research activities are ongoing, and several demonstrations have been already obtained by using electrons nanotip (or flat photocathode) sources feeding dielectric microstructures. In this article we aim at the possibility to integrate a nanosource for the generation of a light ion or proton nano-beams suitable for the subsequent acceleration into sub-relativistic (low-beta) p-DLA stages. Such integration includes the idea to use a proton dielectric radiofrequency quadrupole (p-DRFQ) for bridging the gap between the accelerator front-end and the drift-tube and high-beta sections. The paper has been prepared as a white book including state-of-art technologies and new solutions that now put the ambitious frontier of a fully nanostructured proton accelerator into reach. Conceptual studies of p-DLAs here presented could enable table-top proton nano-beams for several applications: proton beam writing, nuclear reaction analysis at sub-micrometer scales, the construction of miniaturized Proton-Boron Nuclear Fusion based Reactors, biological analysis at the micrometer scale, ion beam analysis at the sub-cellular level, mini-beams ion therapy to spare the shallow tissues, proton irradiation of transistors, compact proton linac for neutron generation.

MedAustron is a synchrotron-based particle therapy centre located in Wiener Neustadt, Austria. It features three irradiation rooms for particle therapy, where proton beams with energies up to 252.7 MeV and carbon ions of up to 402.8 MeV/u are available for cancer treatment. In addition to the treatment rooms, MedAustron features a unique beamline exclusively for non-clinical research (NCR). This research beamline is also commissioned for proton energies up to 800 MeV, while available carbon ion energies correspond to the ones available in the clinical treatment rooms. Based on the requirements for particle therapy, all irradiation rooms offer particle rates of up to 10^9 particles/s for protons and 10^7 particles/s for carbon ions. However, for research purposes, lower particle fluxes are required and were therefore commissioned for the NCR beamline. Three particle flux settings with particle rates ranging from ~2.4x10^3 particles/s to ~5.2x10^6 particles/s were established for seven proton energies below 252.7 MeV. In addition to the particle rate, the spot sizes and beam energies were measured for these settings. Furthermore, three low flux settings for 800 MeV protons with particle rates ranging from ~2x10^3 particles/s to ~1.3x10^6 particles/s were commissioned. Since the commissioned low flux settings are in a regime well below the limits of the available standard beam diagnostics, setting up the beam under these new operational conditions entirely relied on the use of external detectors. Furthermore, a beam position measurement based alignment without using the standard beam profile monitors was performed for 800 MeV protons.

The Medipix3, a hybrid pixel detector with a silicon sensor, has been evaluated as a beam instrumentation device with proton and carbon ion measurements in the non-clinical research room (IR1) of MedAustron Ion Therapy Center. Protons energies are varied from 62.4 to 800 MeV with 10 4 to 10 8 protons per second impinging on the detector surface. For carbon ions, energies are varied from 120 to 400 MeV/amu with 10 7 to 10 8 carbon ions per second. Measurements include simultaneous high resolution, beam profile and beam intensity with various beam parameters at up to 1000 FPS (frames per second), count rate linearity and an assessment of radiation damage after the measurement day using an x-ray tube to provide a homogeneous radiation measurement. The count rate linearity is found to be linear within the uncertainties (dominated by accelerator related sources due to special setup) for the measurements without degraders. Various frequency components are identified within the beam intensity over time firstly including 49.98 Hz with standard deviation, σ = 0.29, secondly 30.55 Hz σ = 0.55 and thirdly 252.51 Hz σ = 0.83. A direct correlation between the number of zero counting and noisy pixels is observed in the measurements with the highest flux. No conclusive evidence of long term radiation damage was found as a result of these measurements over one day.

MedAustron is a synchrotron-based hadron therapy center located in Lower Austria. Accelerated proton beams with energies of 62-252 MeV/u are used to treat patients since 2016. The carbon ion beam is currently under commissioning and will provide treatment in 2019 with energies of 120-400MeV/u. Two of the four irradiation rooms are used for clinical treatment while the preparation of the Gantry beam line is ongoing. Proton beams of up to 800 MeV will be provided for non-clinical research. The Injector features three identical ECRIS from Pantechnik, two of which are used to generate the proton and the carbon beam respectively. The medical environment of the accelerator puts strict requirements on the ion source long-term stability operation. The extracted beam current from the source allow for maximum current fluctuations on the order of ±2.5% on continuous run. In this work we discuss the impact of the ion source performances on the characteristics and stability of the entire accelerator. Further, we discuss the latest progress on carbon commissioning and the future perspectives with particular emphasis on the source requirements. INTRODUCTION The MedAustron is a synchrotron-based therapy center for cancer treatment. The design of the accelerator is based on PIMMS and CNAO [1,2]. Currently 26 patients (fractions) per day are treated with proton ion beams since 2016. Medical treatment with carbon ions is planned to start in 2019 [3]. A proton beam up to 800 MeV/u will be provided for non-clinical research. The Injector shown in Fig. 1 features three identical Supernanogan ECRIS from Pantechnik. One is reserved for proton beams production and one for carbon beams production. The third is foreseen as future use for clinical and non-clinical research. The extracted beam from the source at 8 keV/u is transported through the LEBT line to the linear accelerator. The LINAC contains a Radio Frequency Quadrupole (RFQ) module which accelerates the beam to 400 keV/u followed by a Buncher and an IH-Tank cavity where the energy reaches 7 MeV/u and finally by a Debuncher cavity. Through the Mid Energy Beam. Transport (MEBT) line the beam is then injected in the synchrotron where it reaches the clinical e non-clinical energies mentioned before. A slow extraction 3rd order resonance method via Betratron Core is used to extract the particles from the synchrotron. Through the High Energy Beam Line (HEBT) the beam is sent to four available irradiation rooms: IR1 with horizontal beamline for non-clinical research, IR2 with a horizontal and a vertical beamline, IR3 with a horizontal beamline and IR4 with a proton Gantry. The weekly machine uptime during clinical operation between 90% and 97% [4]. THE IONS SOURCE The identical design and the availability of three independent source lines allows for parallel running of the sources and for source switching in case of emergency. The ion beam in the source is produced through the Electron Cyclotron Resonance (ECR) heating mechanism [5]. The neutral gas is brought into a state of plasma magnetically confined in the vacuum vessel and the ions are extracted from the chamber with a dedicated extraction system. The Supernanogan of Pantechnik has been described in detail in [6]. It operates at 14.5 GHz heating frequency and is it entirely equipped with permanent magnets both for the radial magnetic field than for the longitudinal magnetic field with a BECR of 0.5 T. An axial mirror ratio Bmax/Bmin about two times higher than the ECR resonance magnetic field is obtained [5]. The plasma has limited contact to the chamber walls and the high charge state ions concentrate in the center of the extracted beam with a triangular intensity distribution. The longitudinal beam profile depends mainly on extraction parameters with respect to the plasma potential. The source body is placed at 24 kV, while a puller electrode is placed at negative potentials of about 2 kV to accelerate the beam towards the focus. The focus electrode on the order of 1.5 kV is fine tuned to adapt the beam size to the focal point of the dipole magnet for a good transmission into the beam line and further matching into the RFQ. The DC Bias tip, introduced from the backside of the vacuum chamber into the plasma, reduces the ion losses towards the injection. The RF tuner position is used to reduce the reflected power. The typical source parameters used for the proton and the carbon source are indicated in table 1: ___________________________________________ † nadia.gambino@medaustron.at 23th Int. Workshop on ECR Ion Sources ECRIS2018, Catania, Italy JACoW Publishing ISBN: 978-3-95450-196-0 doi:10.18429/JACoW-ECRIS2018-MOB2 Applications MOB2 5 Co nt en tf ro m th is w or k m ay be us ed un de rt he te rm so ft he CC BY 3. 0 lic en ce (© 20 18 ). A ny di str ib ut io n of th is w or k m us tm ai nt ai n at tri bu tio n to th e au th or (s ), tit le of th e w or k, pu bl ish er ,a nd D O I.

MedAustron is a synchrotron-based hadron therapy center located in Lower Austria. Accelerated proton beams with energies of 62–252 MeV/u are used to treat patients since 2016. The carbon ion beam is currently under commissioning and will provide treatment in 2019 with energies of 120–400MeV/u. Two of the four irradiation rooms are used for clinical treatment while the preparation of the Gantry beam line is ongoing. Proton beams of up to 800 MeV will be provided for non-clinical research. The Injector features three identical ECRIS from Pantechnik, two of which are used to generate the proton and the carbon beam respectively. The medical environment of the accelerator puts strict requirements on the ion source long-term stability operation. The extracted beam current from the source allow for maximum current fluctuations on the order of ±2.5% on continuous run. In this work we discuss the impact of the ion source performances on the characteristics and stability of the entire accelerator. Further, we discuss the latest progress on carbon commissioning and the future perspectives with particular emphasis on the source requirements.

MedAustron is a synchrotron-based Particle Therapy Accelerator located in Wiener Neustadt, Austria, which is delivering beams for medical treatment since end of 2016. The accelerator provides clinical proton beams in the energy range 62-252 MeV and is designed to provide carbon ions in the range 120-400 MeV/n to three ion therapy irradiation rooms IRs, including a room with a proton Gantry. Proton beams of up to 800 MeV will be provided to a fourth room dedicated to research. Presently, proton beams are delivered to the fixed horizontal beam lines of three rooms. Beam commissioning of the vertical beam line of the second IR is being completed and the beam line is in preparation for clinical treatment. Commissioning of the accelerator with carbon ions is advancing and first clinical beams have been sent to the IRs, while the preparation for the Gantry beam line is ongoing. A slow extraction 3rd order resonance method is used to extract particles from the synchrotron between 0.1-10 seconds to favor control of the delivered dose during clinical treatments. The main characteristics of the accelerator and results obtained during the latest commissioning activities are presented.

The MedAustron therapy accelerator[1,2] is intended to treat cancer patients with proton and carbon beams of 62252 MeV and 120-400MeV/u respectively. The accelerator features three Supernanogan ECR ion sources, a 400keV/u RFQ and a 7MeV/u interdigital H-mode Linac. A middle energy beam transfer line also serves as injector into a 77m synchrotron from which the beam may be transferred to 4 different irradiation rooms, 3 of which are dedicated to medical treatment. The therapy accelerator is in clinical operation since end 2016 [2] and is currently solely configured for the use of protons. After activation of a new vertical beam line the next clinical objective is to enable treatments using C6+ ions which triggered the carbon commissioning of the accelerator in 2017. This paper will discuss the ongoing carbon commissioning in the different sections of the accelerator, achieved efficiencies and outlook on future carbon activities. CARBON COMMISSIONING As the beam commissioning is tackled while parts of the machine are already in clinical use for proton therapy, the respective beam time is rather limited. Yet there is an important advantage to this situation which is that one profits from comfortable preparation and anylsis times in between dedicated beam commissioning shifts. Therefore a commissioning strategy was chosen as to preliminary test different parts of the machine as early as possible under different situations to identify and mitigate complications already at an early stage. The presented commissioning performance is preliminary results from the first tests of the MedAustron accelerator complex with carbons. Ion Source Three identical Supernanogan electron cyclotron resonance ion sources (ECRIS) are installed at MedAustron. Source 1 is driven with hydrogen gas for “proton” production (H+) whereas Source 2 is tuned for carbon ( C4+) and uses a CO2 and He gas mixture. Source 3 serves as a spare source and will be commissioned with multiple ion types for non-clinical research and to allow a swift substitution if need be. The commissioning of the second ion source for medical treatment with carbon beam is almost finalized. Stable source settings have been found which allow to reach the nominal carbon current for medical treatment (on the order of 150 μA). Long term stability tests of the extracted beam current showed only single deviations of the nominal current <5% within 45hours periods. The installation of an overpressure valve between gas bottle pressure reducer and injection mass flow controller mitigates a pressure build up in the CO2 line and improved plasma stability considerably. Commissioned source settings for optimal performance are summarized in Table 1. A more detailed description of the source commissioning can be found in [2]. Linac & MEBT As the ion sources deliver the same charge to mass ratio independent of the used particle type (H+ or C4+) the Linac is optimized for exactly this situation. Thus the electromagnetic field strengths and phase delays barely need adjusting in respect to proton operation as foreseen by design. The main commissioning effort concerning the Table 1: Detailed source settings of the Supernanogan ECRIS for carbon usage. RF Freq. [GHz] 14.464