1 Introduction

The MedAustron accelerator delivers proton and carbon ion beams for cancer treatment to three irradiation rooms with the goal of treating 800 patients per year. The center also offers a dedicated beam line and infrastructures to national and international research institutes.

Following the commissioning of the gantry beamline, all rooms at MedAustron are now operational. Since the first patient in 2016, more than 2,000 patients have been treated with protons and carbon ions using over 50,000 single fractions with an average weekly machine uptime during clinical operation > 96%. Accelerator parameters are defined by requirements for clinical treatment and research and an example for the fixed and gantry beam lines is shown in Table 1.

Table 1 MedAustron Accelerator and Beam Parameters for fixed and gantry beam lines
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2 Facility overview

MedAustron is located in Wiener Neustadt, Lower Austria region, approximately 50 km south of the Austrian capital city Vienna, as shown in Fig. 1. It is one of the only six proton and carbon ion therapy centers in the world.

Fig. 1
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MedAustron is located in Wiener Neustadt, Austria

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At today, the facility totals ca. 300 employees from 20 different countries with expertise in designing, building, commissioning, certifying and operating a particle therapy facility.

3 Facility History

In the early years of feasibility study, the facility was conceived as a neutron spallation source. It was only in the mid-90’ that it was reoriented to a clinical therapy facility for cancer treatment and research, then renamed MedAustron to emphasize the medical nature and the country of origin. In the same decade, an important milestone was the research study effort culminated with the Proton-Ion Medical Machine Study PIMMS document [1,2,3] that was the basis for the CNAO and MedAustron facilities. After a period of feasibility and design studies the company was founded in 2007 when the manufacturing of accelerator components started, followed by the construction of the buildings that terminated in 2012. In the following year, the installation and commissioning of the accelerator was begun and then completed in 2016 leading to the first successful patient treatment in December of the same year. At the same time, the research program also started in the dedicated irradiation room (IRs). The timeline of the facility history is shown in Fig. 2 layout.

Fig. 2
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Facility history

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As the clinical treatments were progressively extended for longer times during the week days, the beam commissioning of the remaining particle types and irradiation rooms including the gantry had to be performed during the available night and weekend hours.

Thus, the accelerator components and beam commissioning of all beam lines and particle types was completed in 2023, when the facility successfully reached its full functionality. Milestones of the facility over the years are shown in the Fig. 3 schematic.

Fig. 3
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Milestones of the MedAustron facility over the years of beam commissioning. During these years the clinical treatment was ongoing, occupying most of the beam time during the week days

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4 The technology behind

A bird’s eye view of a MedAustron facility model is shown in Fig. 4.

Fig. 4
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Bird view of the MedAustron facility representation including the ion sources, the LINAC first stage of acceleration, the synchrotron, the extraction to the HEBT and the rotator and the four irradiation rooms including the gantry

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Two sources are used to generate proton and carbon ion beams. A third source generates helium for research purposes and is also used as spare for the other particle types used for clinical operation.

Three Supernanogan Electron Cyclotron Resonance Ion Sources (ECRIS) are designed to provide \({H}_{3}^{+}\), 12C4+ and \({He}^{2+}\) beams to a low energy transfer line (LEBT) and subsequently to a Linac, shown in Fig. 5, consisting of a 400 keV/n RFQ and an interdigital H-mode (IH) DTL that accelerates the beam to 7 MeV/n. A multi-turn injection from the Medium Energy Transfer Line (MEBT) accumulates particles into the synchrotron, Fig. 6. Following RF capture and acceleration, the beam is extracted from the synchrotron by a third-order resonant slow extraction mechanism, driven by a so-called resonant sextupole and a betatron core magnet.

Fig. 5
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The solenoid magnet (purple device on the left side), the RF quadrupole RFQ and the linear accelerator LINAC system for acceleration up to 7 MeV/n. This first stage acceleration complex is placed in a “bunker” for enhanced radiation protection shielding

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Fig. 6
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MedAustron synchrotron hall

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The high energy transfer beam line (HEBT) shown in Fig. 7, transports the beam from the synchrotron and deflects it either to the research room or to one of three treatment rooms with the assistance of achromatic beam-deflection modules. Deflection branches are parallel to each other. Each deflection module contains switching dipole magnets. With all switching dipole magnets off, the beam is sent straight to the beam dump at the end of the extraction beam line.

Fig. 7
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The high energy transfer line HEBT delivers the beam to four irradiation rooms. Quadrupole magnets are noticeable (orange color) and the scintillating fiber hodoscopes (SFX) beam monitors are also visible (red and blue)

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Towards the end of the HEBT, there is an integral part of the gantry beamline: the rotator, a 9.9 m long straight section containing seven identical quadrupoles and independently powered. This configuration has been chosen by MedAustron to match the slowly extracted asymmetric beams to the rotating gantry. The rotator is connected to the gantry via an achromatic deflection module. Thus effectively, the gantry beam line is located 20 m downstream of the rotator. Such a beam-transport line has been commissioned for the first time world-wide.

Most importantly, by using the rotator system, all beam parameters at the gantry isocenter become independent from the gantry rotation angle. The beam commissioning covered several performance related tests of the rotator, the gantry, and finally of the whole beamline. The first proof-of-concept of a rotator system has been accomplished. The gantry beamline commissioning has been successfully completed and the line is now in clinical operation since the year 2022.

A picture of the rotator and the gantry structures are shown respectively in Fig. 8 and Fig. 9.

Fig. 8
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The world-wide first rotator system (white structure) in the HEBT. Seven quadrupoles (orange) are mounted on this mechanical supporting structure that is rotated by half of the gantry angle. The gantry beam line is located downstream of the rotator. With a rotator, the beam parameters at the room isocenter are independent from the gantry rotation angle

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Fig. 9
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Bird view of the MedAustron proton gantry laying in the horizontal position (gantry rotation angle 90°). The beam entrance into the gantry beam line is on the lower-right corner while the patient irradiation room is located behind the wall on the upper side of the picture

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One of the irradiation rooms of a fixed beam line and the patient positioning system are shown in Fig. 10. The automatic-controlled couch fulfils the requirements to placing the patient in the correct position and to monitoring the position continuously. An “imaging ring” on the couch provides X-ray and computerized tomography CT images to ensure sub-millimiter patient positioning.

Fig. 10
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Irradiation room and patient positioning system. The imaging ring mounted on the couch is used for the precise in room evaluation of the patient positioning

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The particle accelerator and all systems connected are subject to strict quality assurance on a daily basis and are constantly being further developed.

The facility includes four irradiation rooms (IR) as summarized also in Table 2: room 1 dedicated to research; room 2 with two beamlines, horizontal and vertical; room 3 with a horizontal beamline and room 4 hosting a proton gantry based on a PSI design [4, 5]. The fixed beamlines of IR1, IR2 and IR3 provide protons, carbon ions [6, 7], while the helium ion beam is currently under commissioning in IR1.

Table 2 Summary of the irradiation room, beam lines and particle species
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5 Indications treated at MedAustron

Particle beam therapy makes use of the physical effect where a beam of charged particles deposits most of its kinetic energy at a defined distance within the body. The penetration depth depends on the beam energy in a well-defined and reproducible correlation. This physical effect allows for a lower exposure of healthy tissues to radiation with a reduction of side effects and long-term damages with respect to conventional photon radiotherapy. In addition, irradiating the tumor from different directions also contributes to reduce the exposure of healthy tissue to radiation.

Thus, tumors in close proximity to radiosensitive organs are the main field of application of particle therapy. Paediatric tumors and local recurrences are also important patient groups in the treatment with charged particles. More information is also available at [8].

An overview of the indications by category and related fractional percent of the tumors treated at the MedAustron is shown in Fig. 11.

Fig. 11
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Indications treated at MedAustron at the first quarter of 2024

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The biological effect of proton therapy is very similar to that of conventional photon therapy; thus, the chances of cure at the same dose are similar after proton therapy as after conventional irradiation. Though, due to a lower exposure of healthy tissues to radiation, in special situations the total dose can be increased during proton therapy and consequently an improvement in local control can be achieved [9]. For these reasons, proton therapy renders the use of high doses of radiation a viable option.

Additionally, the low dose bath which is present in the irradiation with photons can be minimized to a large extent with protons and carbon ions due to the absence of the exit dose (dose beyond the tumor in beam direction) and a smaller dose in the entrance of the beam. Consequently, large volumes of normal tissue get a significant amount of lower dose.

On the other hand, the therapy with carbon ions provides several unique physical and radiobiological advantages, high conformity along with high relative biologic effectiveness (RBE) and linear energy transfer (LET) with different damaging effects on the tumor DNA with respect to protons and photons.

Particle therapy depending on the tumor, can be combined with systemic therapy, as it is with conventional radiotherapy as well. Particle therapy can also be performed after surgery, or in situations where surgery is associated with high risks particle therapy can also be performed as an option.

6 Research at MedAustron

In addition to patient treatment in clinical studies, the MedAustron accelerator facility offers a wide range of research opportunities.

Different aspects of research are addressed at MedAustron: on one hand, translational research addresses topics close to medical applications, on the other hand, particle beams can also generally be used in radiation physics and applied particle physics. Medical University of Vienna and Vienna University of Technology are the priority partner institutes for research projects, whose implementation is decided by an independent advisory board. There is also close cooperation in scientific work with the Institute for High Energy Physics of the Austrian Academy of Sciences, University of Applied Sciences Wiener Neustadt and Medical University of Graz. An executive committee supports practical research work on site and accompanies research progress.

Recently, two professorships have been appointed at the Department of General and Translational Oncology and Haematology at the Karl Landsteiner University for Health Sciences, Austria. Prof. Markus Stock from MedAustron in the Division Medical Physics and Prof. Piero Fossati from MedAustron in the Division Radiation Oncology. Together, they form a Research Cluster on Cancer with Prof. Klaus Podar and the Division of Molecular Oncology and Hematology.

Three main field of research are undergoing at MedAustron.

Clinical research

Dedicated to registry study and clinical studies, creating more evidence in particle therapy. MedAustron is also involved in a collaborative study program on clinical research and studies PROSPER [10]. The PROSPER study is a tricontinental, nonrandomized, prospective, three-arm, pragmatic trial evaluating the same indication with treatments performed using different particle species, namely proton and carbon ions. The comparative studies are conducted in collaboration with the Mayo Clinic campuses in Arizona, Florida, and Minnesota, U.S.A.

Interdisciplinary oncology research

The teaching and research site of the Karl Landsteiner University support the interdisciplinary research in oncology that includes two main branches:

  • Medical Physics

  • Radiation Oncology

Medical Physics research focuses on the development and optimization of medical physics methods including dosimetry and micro-dosimetry, Monte-Carlo simulations, Big Data, radiation plan optimization, software development and process management.

Radiation Oncology research concentrates on the optimization of patient treatments with radiotherapy by applying the highest standards of care and by performing clinical research while fostering the translation of preclinical research in a clinical setting.

Translational and scientific research

It is based on four research pillars: Applied Particle and Medical Physics, Technological Innovations and Clinical implementations, Biophysics and Molecular Radiobiology and Accelerator Physics, as shown in Fig. 12. Each of them includes a subset of research topics that are worked on in cooperation with Medical Universities Vienna & Graz, Technical University Vienna, HEPHY and FH Wiener Neustadt.

Fig. 12
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Research pillars and work packages

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7 Development projects

Several development projects are ongoing or planned to improve the performances and enhance the treatment capabilities.

Currently, helium ions are being commissioned and will be available for research purposes in IR1 by the end of 2024.

This year will also be possible to treat a new indication with the dedicated project implementation for eye treatment and improve the treatment quality by the activation of respiratory gating. Furthermore, a new beam delivery system is now under commissioning to support the planned projects to reach 800 treated patients per-year goal.

On a longer term, improvements for enhanced treatment quality consider the implementation of RF Knock-out driven extraction, multi-energy per single-spill treatments and dynamic intensity control.

MedAustron also actively contributes to international collaborations such as EuroSIG and HITRI + for the design study of a superconducting ion accelerator and gantry.

8 Knowledge transfer

Over the last fifteen years, MedAustron has acquired a solid and extensive experience in the field of particle therapy accelerator and certification of medical devices.

MedAustron technical expertise and its innovative technology are available for scientific and commercial purposes throughout a variety of technology transfer options: R&D collaborations, MedAustron technology in start-ups, service, consultancy and licensing in all aspects related to:

  • Concept and planning

  • Hardware and Software development

  • Maintenance and Services

  • Commissioning and Operation

  • Certification

  • Training of accelerator personnel and operators

  • Radiation Protection

MedAustron grants licences to commercial and academic partners for the exploitation of its technologies. MedAustron expertise and infrastructures represent an opportunity for companies and academics in need of a specific high-tech service. Experts in many areas of particle accelerator aspects are available to provide advice or specific studies to particle accelerator projects for medical applications.

9 Certification aspects of heavy ion therapy machines

Once a particle therapy accelerator has been developed, there are certain requirements to be fulfilled to be able to bring it to the market as a medical device. The safety of the patient, the operating and service personnel, the environment affected by electromagnetic field and radiation need to be testified for conformity with the standard directives.

The Conformité Européenne (CE) Mark is defined as the European Union’s (EU) mandatory conformity marking for regulating the goods traded within the European Economic Area (EEA) since 1985. The CE Marking serves as a declaration from the manufacturer that their product complies with the essential requirements of the relevant European health, safety and environmental legislation laid out in the different product directives. Once a product has been awarded the CE Marking, then it is able to move freely within the European Free Trade Association (EFTA) and the European Union (EU).

Manufacturers play a crucial role in ensuring that products placed on the extended single market of the European Economic Area (EEA) are safe. They are responsible for checking that their products meet EU safety, health, and environmental protection requirements. It is the manufacturer’s responsibility to carry out the conformity assessment, set up the technical files, issue the EU declaration of conformity, and affix the CE marking to a product. Only then can this product be traded on the EEA market.

MedAustron, having the expertise on the certification aspects of heavy ion therapy machines, can support with obtaining the CE marking according to the Medical Device Regulations (MDR) and obtaining the declaration of conformity. This process requires preparing the technical documentation, testifying the safety and environmental protection, dealing with regulatory affairs and the aspects related to the risk management to ultimately certify the technology as a medical product and be able to treat patients.

10 Summary and outlook

Since more than seven years, patient treatment is ongoing at the MedAustron facility in Austria, using proton and carbon ion beams, with a continued ramp up in the number of patients throughput towards the final goal of 800 patients per year.

Protons and carbon ions with high intensities and transmissions are available for patient treatment and research in all three rooms with fixed beam lines, while protons are available in the rotating gantry beam line. The machine is remarkably stable in terms of its beam parameters robustness and reproducibility.

The proton gantry beamline including the world-wide first rotator is clinically operational since already two years. The rotator, designed, built, installed, and tested at MedAustron, is the first and the only hardware implementation of its kind all over the world. The rotator concept has been successfully proven to work resulting in a beam spot at the gantry isocenter to be round and independent from the gantry rotation angle.

Recently, carbon commissioning has also been completed in a second irradiation room, which completed the commissioning of the facility and MedAustron is now operating at its full functionality.

In addition to clinical operations, one irradiation room is fully dedicated to research, available to national and international research groups. The research room is delivering carbon, recently helium ion beams and proton beams up to 800 MeV are also provided.

A number of performance improvement projects are ongoing including eye treatment that will be available on a short term and the activation of respiratory gating. A new beam delivery system is under commissioning to facilitate reaching the 800 patients per-year goal. On a longer term, multi-energy extraction in a single beam is part of the improvement projects for enhanced treatment quality.