Patients and relatives can contact short at this point of contact for questions, suggestions and criticism.

+49 (0) 800/ 660 68 00

We are there for you at the following times

Monday to Friday from 8.00 am to 6.00 pm


Franz-von-Rinecker Straße (main entrance)

Schäftlarnstraße 133 (postal address)

81371 München

Do you have any questions?
+49 (0) 89/ 660 680

About us


The RPTC, located in Munich, is the first fully certified European proton radiation center which provides a complete hospital setting for the treatment of cancer tumors.

Our innovative therapeutic procedure involves the use of high-energy proton beams for the treatment of cancer. A key characteristic of these proton beams is that protons facilitate the three-dimensional targeting of tumours; this capability is not available with the x-rays used in conventional radiation therapy. Therefore, highly effective dosages can be delivered to the tumour while the side effects of radiation are reduced by minimizing any trauma to the surrounding healthy tissue.

Questions? +49 (0)89 660 680

Properties of proton beams

Properties of proton beams

Figure 1

Protons accelerated to 60% of the speed of light (180,000 km/s, 250 MeV of kinetic energy) by cyclotrons and synchrotrons penetrate approximately 38 cm into the body. Initially, they transfer relatively small amounts of energy to the molecular electron clouds they pass through (low degree of ionization). However, this process slows them down
(see Figure 1).

Figure 2

The slower the particles, the greater the linear energy transfer and the braking effect become. This leads to an "energy explosion" known as the Bragg peak at the end of the particle's path, i.e., a characteristic tissue depth of 1-4 mm for monoenergetic particles. Unlike X-rays, proton radiation deposits a lower dose in front of the tumor. The tissue behind the tumor is not exposed to any radiation at all. This physical phenomenon makes it possible to determine the depth of the Bragg peak through modulation of the particle velocity and focus the radiation "three-dimensionally" onto the tumor with absolute precision, greatly improving the ratio of “good radiation” to “bad radiation.” The Bragg peak is so sharply defined that it must be “spread out” across the tumor by varying the particle speed. Figure 2 shows the resulting dose distribution for a large tumor. The reduced upstream dose is maintained while no radiation is deposited downstream of the tumor.

Figure 3 provides a direct comparison of the local dose distribution for photon beams versus X-rays as shown in Figure 4.

Figure 3
Figure 4
Figure 5


At the end of their penetration depth at the Bragg peak, protons penetrating the tissue release similar amounts of energy to molecules as photons (X-rays) do, at least with respect to the hydrogen present in cellular water. In both cases, this causes molecules to lose electrons. The tissue subsequently "forgets" the cause of the electron loss (whether protons or photons) and the resulting ionization. Ionization, which is identical for both types of radiation but is more effectively targeted in the case of protons, acts as a cellular toxin as illustrated in Figure 5. Thanks to the identical biological effects of these two radiation types, we can draw on the entire body more than 100 years of empirical clinical knowledge on X-rays and thus apply clinical experience in X-ray dosing to the use of protons.

Using proton beams instead of X-rays allows medical personnel to increase the therapeutic dose, which is limited due to side effects, while simultaneously reducing the dose deposited in healthy tissue. In clinical practice, this proton beam control, which is three-dimensional rather than two-dimensional thanks to lateral bundling, has reduced the radiation deposited in healthy tissue by roughly 43% to 78%, depending on the tumor geometry.

Figures 6 and 7
present comparisons of dose distributions in the same patients. The left-hand image in each figure shows the conventional photon radiation actually received by the patients. The right-hand image shows the exposure that would have been possible with proton therapy. The fine inner line within each image indicates the boundary of the target area (the tumor), while the other colors correspond to the local dose delivered.

For a better view, please click on each picture.



Left column (X-rays):

Two different perspectives of an X-ray treatment plan for a relapsing nasopharyngeal tumor with radiation from several directions are shown. Conventional radiotherapy with X-rays results in an unacceptable exposure of surrounding healthy tissue. In this case, the saliva glands are severely damaged.

Right column (Protons):

Compared with the X-ray plan, the illustrated proton therapy plan shows the superiority of the three-dimensional targetability of our method. Exposure of the tissue surrounding the tumor is minimized so that the tumor can be treated with higher doses, increasing the chance of recovery of the patient.



Left column (X-rays):

Three different perspectives of an X-ray treatment plan for a patient with a lung tumor are shown. Irradiation takes place from several directions. Both lungs are exposed to high levels of radiation.

Right column (Protons):

Compared with the X-ray plan, the proton therapy plan shows the superiority of the three-dimensional targetability of our method. Adjusting the penetration depth of the proton beams allows the heart and the healthy lung to be spared to a large extent.

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