Radiosurgery

Surgery in certain regions of the brain may involve particular risks due to the location of the diseased tissue. For selected patients, radiosurgery may therefore be a non-invasive alternative to surgery or a supplement to other treatment methods.

Radiosurgery is used for:

• Various benign or malignant brain tumors
• Vascular malformations
• Functional disorders (such as trigeminal neuralgia, focal epilepsy, or tremor)

Radiosurgery can be used alone or in combination with microsurgical or endovascular techniques.

To ensure the best possible care, every case at Inselspital is carefully evaluated and discussed by an interdisciplinary team of physicians. Based on this, apersonalized treatment recommendation is developed collaboratively.

Specialists in radiation oncology, medical physics, and radiation nursing work closely together to prepare for and administer radiation therapy. Careful planning using imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) is essential for the precise delivery of radiosurgery.

During your first outpatient consultation, you will receive detailed information about the procedure, the chances of success, the risks, and possible side effects of the treatment, such as headaches, fatigue, or dizziness. If radiosurgery is an option for you, you will then be informed about your upcoming appointments.

Before treatment, a custom-fitted radiation mask is created. It consists of several layers of a special plastic material that are heated in warm water, making them malleable. This allows the mask to be precisely molded to the shape of your head and face.

A Plexiglas box is attached to the mask, which serves as a three-dimensional coordinate system during CT imaging. This system allows for the precise determination of the volume of the lesion to be treated as well as the boundaries of the radiation field.

An outpatient appointment is required for the fabrication of the mask.

In addition to your radiation therapy appointment, you will be given appointments for an MRI and/or CT scan.

For certain vascular malformations, particularly arteriovenous malformations (AVMs), an angiogram may also be necessary.

Based on the CT and MRI scans, as well as other test results, specialists in radiation oncology and medical physics develop a personalized radiation treatment plan.

The medical team defines the target area, the sensitive structures to be spared, and the required radiation dose. The technical implementation is then planned and optimized so that the intended dose is concentrated as precisely as possible on the target area and the surrounding healthy tissue is spared as much as possible. To this end, the number, shape, arrangement, and direction of the radiation fields are determined, among other factors.

This complex planning process takes several hours. Before the first radiation treatment, the complete treatment plan is carefully reviewed and approved by both the medical and medical physics teams.

Our clinic uses the CyberKnife®, a state-of-the-art device for radiosurgical treatments. The exact position of the target area is determined using CT and MRI scans and stored in the system. During radiation therapy, an integrated X-ray system continuously compares this data with real-time images. Any deviations from the planned position can thus be immediately detected and corrected.

The treatment is carefully monitored by our medical and technical staff. You will remain in contact with the care team throughout the entire treatment via a video and audio connection. You will not feel anything during the radiation treatment itself. The duration of the treatment depends on the complexity of the treatment plan and ranges from 20 minutes to 1.5 hours.

After the radiation treatment, the mask will be removed. You can usually go home afterward. Since you may experience temporary side effects, you should not drive yourself. Please arrange for someone to accompany you home. In certain cases, a one-day stay for observation at Inselspital is required.

Sensitivity to ionizing radiation varies depending on the type of cell and tissue. It is influenced by various factors, including the cells’ division rate, their respective phase in the cell cycle, and their ability to repair damage to their genetic material.

Ionizing radiation can damage the DNA of cells. Cells in certain phases of cell division are particularly sensitive. Cells in a resting phase or in other stages of the cell cycle may be less sensitive. This is one reason why different tissues—and even individual areas of a tumor—respond differently to radiation therapy.

In conventional fractionated radiation therapy, the planned total dose is divided into many smaller individual doses, known as fractions. A single dose is usually about 1.8 to 2 Gray. Radiation treatment is typically administered five days a week over a period of several weeks.

This fractionation allows healthy tissue to repair some of the radiation damage incurred between treatments. At the same time, the tumor cells are further damaged by the repeated radiation. The number and size of the individual doses are tailored to the specific disease and treatment goal.

In radiosurgery, numerous radiation beams from different directions are precisely directed at a clearly defined target area. This allows a high radiation dose to be delivered to that area. Outside the target area, the dose decreases rapidly, thereby sparing the surrounding healthy tissue as much as possible.

Radiosurgical treatment is often performed in a single session. However, depending on the size and location of the target area, as well as on adjacent sensitive structures, the total dose may be divided over several sessions—usually three to five. In this case, the treatment is referred to as fractionated stereotactic radiotherapy.