Proton therapy

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Synchrotron for proton therapy

In the proton therapy is a therapy for the treatment of cancer tumors , that malignant tumors . In a synchrotron or cyclotron , a beam of protons is generated, accelerated and aimed at the tumor. The method is used in particular in patients for whom conventional radiation with hard X-rays (gamma rays) or electron beams from linear accelerators cannot be used adequately because the tumor is either too deep in the body or is surrounded by sensitive organs. Proton therapy enables an optimized dose distribution within the region to be irradiated.

Proton therapy is the most frequently used form of so-called particle therapy , which also includes, for example, radiation with the heavier carbon ions.

Mode of action

Penetration depth of protons in tissue compared to other types of radiation

Due to its accuracy, proton therapy enables tumors to be treated even in sensitive areas of the body. The accelerator delivers high-energy protons (up to 60% of the speed of light ) as a well-focused beam that can be precisely directed to the previously calculated location in the tumor tissue. When penetrating the human body, the beam is slowed down so that the protons discharge most of their energy directly in the tumor focus ( Bragg peak ). The ionizing effect of the protons then leads to damage to the tumor cells, especially their DNA .

Thanks to the three-dimensional precise proton deposition, the radiation dose that can be achieved in the target is higher than when using gamma radiation or electron beams . Compared to other forms of radiation, the risk of side effects is lower with proton therapy, since surrounding healthy tissue is better protected.

Medical evaluation

In around 60 years (end of 2019) more than 200,000 patients worldwide have received proton therapy with a wide variety of indications . The assumption of costs in statutory health insurance differs from health insurance to health insurance. A case-by-case check is carried out at some health insurers. Some radiation centers have separate regulations with certain health insurance companies that cover the costs for agreed indications without a separate application. Breast cancer and brain metastases , for example, are excluded from assumption of costs . In contrast, the costs for various primary brain tumors , ENT tumors , unresectable liver cell carcinoma , cerebral arteriovenous malformation and sarcomas - in particular chondrosarcomas and chordomas of the base of the skull - are covered . The treatment of prostate carcinoma is also paid for by the statutory health insurance in certain stages.

The list of treatments performed worldwide to date is continuously updated by the Particle Therapy Co-Operative Group .

Existing facilities

The first proton therapy center in Western Europe has been in operation at the Paul Scherrer Institute (PSI) in Villigen , Switzerland , since 1984 . By the end of 2012, around 6,000 patients with eye tumors had been treated with protons there. For the first time at PSI, a so-called gantry , which is a movable beam guidance that allows irradiation of a resting patient from different directions, was equipped for the so-called spot-scanning proton technology. The tumors are scanned three-dimensionally with a proton beam approx. 7 mm wide. More than 850 patients had been irradiated with it by the end of 2012, and since February 2007 with a new type of superconducting compact cyclotron. The PSI was also able to establish intensity-modulated proton therapy. The first patient with a chordoma in the spinal area was treated with this method at PSI back in 1999.

There are five proton therapy facilities in Germany: the Heidelberg Ion Beam Therapy Center (HIT) with a total of three irradiation stations, including a gantry for protons and heavy ions, the Rinecker Proton Therapy Center (RPTC) in Munich with four gantries, which will be closed at the end of 2019, the West German Proton Therapy Center Essen (WPE) in Essen with four treatment rooms, three of them with so-called gantries that can be rotated by 360 degrees and one treatment room with a horizontal beam line (fixed-beam line) and an eye therapy area that has yet to be opened, the University of Proton Therapy Dresden at the Dresden University Hospital , the Marburg Ion Beam Therapy Center (MIT) with 3 treatment places and the eye tumor therapy of the Helmholtz Center Berlin ( Hahn-Meitner Institute until 2008 ) in Berlin. Since 1998, more than 2000 (as of the end of 2012) eye tumor patients have been treated there. The RPTC in Munich was the first purely clinically operated proton therapy center in Europe; patient treatment began there in March 2009.

Furthermore, from 1997 to 2008 patients were treated with carbon ions as part of a pilot project at the GSI in Darmstadt. The follow-up project at Heidelberg University Hospital is the Heidelberg Ion Beam Therapy Center, which opened in November 2009. Since then, more than 2500 (as of 2014) patients have been treated with protons and carbon ions at HIT, mainly in the context of clinical studies. HIT is the first system in the world that can apply both protons and carbon ions using scanning technology. Other ions such as helium and oxygen ions are also available for research purposes.

The West German Proton Therapy Center in Essen started operations in spring 2013. All four treatment rooms have been in operation since spring 2016 and have treated over 1,500 patients so far (as of December 2017). In addition to Uniform Scanning and Double Scattering, the WPE routinely uses the Pencil Beam Scanning Method (PBS), with which the intensity-modulated proton therapy (IMPT) is also part of the standard program of this center. Using PBS and IMPT, the entire craniospinal axis (CSA, including the brain and spinal canal) can be routinely irradiated in tumors of the central nervous system (CNS). The availability of the IMPT also enables a Simultaneous Integrated Boost (SIB) - i.e. simultaneous boost irradiation - for tumors of the skull base, in the ENT area and the prostate. A special focus is on the treatment of children, which can be offered here for all age groups.

The Marburg Ion Beam Therapy Center (MIT) began operating patients in October 2015 . The MIT is a GmbH, the sole owner is the Rhön-Klinikum AG. At MIT, proton beams and carbon ion beams are available for therapy at four treatment stations. 142 patients have been treated since commissioning (as of October 2016). The facility is built similarly to the Heidelberg Ion Beam Therapy Center (HIT).

Patient care has been provided at the proton therapy facility in Dresden since September 2014 . It was set up by the Carl Gustav Carus University Hospital Dresden and the Medical Faculty of the Technical University of Dresden together with the Helmholtz Center Dresden-Rossendorf . In addition to health care, the facility is available to researchers at the “Center for Innovation Competence for Medical Radiation Research in Oncology - OncoRay”.

The world's first hospital-based proton therapy center opened in 1990 at Loma Linda University Medical Center (LLUMC) in California. In routine clinical operations, over 16,000 patients with over 50 different types of tumors and other clinical pictures have been treated there. With 1000 to 1500 patients annually , more treatments are carried out here with a powerful synchrotron (250 MeV , Optivus ) than in any other proton therapy center worldwide. The world's largest follow-up program for prostate cancer patients treated by the LLUMC is based on the patient self-organization Brotherhood Of The Balloon , which has over 4000 members (as of May 2009).

In Austria , in Wiener Neustadt am MedAustron, a ring accelerator started technical trial operation in 2014. Patients have been treated there with protons since autumn 2016 and with carbon ions as part of heavy ion therapy since 2019 .

Further centers around the world are planned or under construction. The Particle Therapy Co-Operative Group (PTCOG) regularly updates a current list of opened and planned centers.

Recent developments

The development of smaller and cheaper particle accelerators promises to make this therapeutic option available to an increasing number of cancer patients. For example, work is being done on the development of a table-sized superconducting cyclotron and the laser acceleration of ions. Companies that are leaders in the research, development and sales of such equipment as medical therapy facilities include Hitachi , Mitsubishi and Varian Medical Systems .

Web links

Wiktionary: Proton therapy  - explanations of meanings, word origins, synonyms, translations


  • Hans Rinecker: Proton Therapy - New Opportunities for Cancer. Herbig, Munich 2005, ISBN 3-7766-2422-1 .


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