What is proton therapy?
Proton therapy (also known as proton or proton radiotherapy) is a form of external radiotherapy in which malignant neoplasms ( cancer ) in the body using ionizing radiation fought. Radiotherapy forms together with surgery and chemotherapy, the three pillars for the treatment of patients with cancer . The effect of radiation therapy is based on the difference in sensitivity to radiation between healthy tissue and cancer tissue. Proton therapy and conventional forms of radiotherapy differences used in the kind of radiation to destroy cancer tissue. In conventional radiation therapy, patients are irradiated with high-energy X-ray radiation that is made up of packets of energy without mass, photons called. In proton therapy, use is made of a beam of protons . Protons are subatomic particles with an electric charge and a small mass. Because protons and photons have a fundamentally different interaction with tissue, proton therapy and irradiation have X-rays different effects. Although there are few large-scale comparative studies exist, there is a lot of experimental evidence that protons for ensuring better results in the treatment of certain types of cancer .
Besides protons other particles can also be used for radiotherapy, for example, such as carbon ions. Each type of particle has a different interaction with the cancer tissue. A collective term for all types of radiation using particles with a (tiny) mass and electric charge particle therapy or hadron therapy.
Benefits
The protons that are necessary for proton therapy are accelerated and focused by a particle accelerator (such as a synchrotron or cyclotron ), to a speed of 60% of the speed of light . The beam can be adjusted so that the protons to enter the body and only when reaching the tumor already release their energy. This phenomenon of energy output has been described by the British physicist William Henry Bragg who showed that photons distribute the energy delivered over the whole route by the body, while protons, and other particles of mass will not issue their energy in the achievement of their depth of penetration. This is referred to as Bragg peaks. The advantage of protons is based on this principle: while photons basically wreak havoc on healthy tissue around the tumor, protons can be adjusted so that they cause minimal damage outside the tumor and maximum damage to the tumor itself. As a result, can be more accurately irradiated and / or a higher dose be delivered to the tumor. These advantages are of importance in, for example, tumors that are close to a household radiation-sensitive parts of the body, or tumors that are relatively insensitive to radiation. In general, the side effects will as a result of proton irradiation are less than with conventional radiotherapy.
Disadvantages
One important disadvantage of proton therapy compared to conventional radiotherapy relates to the costs and size of the equipment necessary for the generation of the proton beam. This proton facility is a lot more expensive than facilities that use X-rays. This was in 2007, the reason for the Belgian government not to invest in a proton facility . Another disadvantage is related to the advantage of proton therapy: in that the beam very accurately may deliver a high radiation dose, it is the risk of damage to healthy tissue in cases where the beam is not focused properly in the tumor, for instance in that the patient moves too much during irradiation, increases proportionately.
Medical application
The first to suggest the use of protons for the treatment of tumors was the American Robert R. Wilson. This was in 1946, when Wilson was involved in the design of the Harvard Cyclotron Laboratory in the US The first patients were not treated in hospitals but in particle accelerators for scientific research, such as Berkeley Stralingslaboratium in the US (1954) and in Uppsala , Sweden (1957). In 1961, the treatment was introduced in a hospital environment in Massachusetts (US). Here are until 2002 some 10,000 patients treated and the treatment method developed The first European treatment facility founded in 1984 and is located in the Paul Scherrer Institute (PSI) in Villigen, Switzerland. There are now many countries treatment. Worldwide are now (March 2010) to treat about 67,000 patients with protons.
In the Netherlands
In the Netherlands there are no centers where cancer patients can be treated with protons. However, there are plans in that direction: four initiatives have announced their intention to realize a proton facility. These initiatives are UMC Groningen Proton Therapy Center ( University Medical Center Groningen ), HollandPTC , a collaboration between the Delft University of Technology , Daniel den Hoed Cancer Center, and Leiden University Medical Centre ) in Delft , Maastro Clinic in Maastricht and the APTC, a collaboration between VU University Medical Centre, Amsterdam, Academic Medical Center, Amsterdam, and Antonie van Leeuwenhoek / NKI in Amsterdam. Wanted to realize a proton facility around 2017 these initiatives. Whether this will happen depends on the contracting of this care by health insurers. In 2009, the Minister of Health, Welfare and Sport has already announced that he favors a gradual introduction of the therapy in the Netherlands, starting with those types of cancer will be treated with the advantage of protons is the largest and best-proven. In 2009, the Health Council of the Signalement Proton Irradiation published. Here are the indications described for proton therapy, an estimate is made of the number of patients that can qualify for proton therapy and recommendations are made for the introduction of proton therapy in the Netherlands. CVZ (Current Care Institute Netherlands) in two reports in 2010 and 2011 found that proton therapy for a number of indications complies with the state of knowledge and practice among the insured package of the Health Insurance Act. On July 29, 2013 a regulation was published in the Government Gazette, which made it possible to provide up to 4 licenses. In December 2013, the Minister of Health licenses granted to UMC Groningen Proton Therapy Centre and HollandPTC and in February 2014 to APTC and Maastricht.