Radiation therapy can only be successful if the therapeutic beam reaches the tumor accurately. Therefore, two very important condition must be met for all treatment plans:
Three-dimensional computer simulation of the tumor area
Radiaion Oncology starts with imaging: Using slice images from computer or magnetic resonance tomography, a three-dimensional computer simulation of the tumor and its surrounding normal tissue is displayed on the monitor within fractions of a second. The physicians then enter certain parameters such as the contours of the tumor and its spatial coordinates, the target dose in the tumor, and the tolerance doses for healthy adjacent tissue. The computer calculates the optimal radiation dose for every single point in the tumor and determines the optimal irradiation direction for the therapy beam. This is known as “three-dimensional computer-based radiation therapy planning”.
Patients are immobilized on a treatment couch
In order to prevent body movement which may cause inaccurate radiation delivery, patients must be immobilized for treatment planning and during radiation treatment. In case of an Irradiation of the head or the neck, an individual mask is made for each patient. In addition, indicator points on the mask mark the position of the tumor so that the beam can be directed to the right place – also for several subsequent radiation sessions. If the tumor is in a different location, positioning aids are used that enclose the patient’s chest and pelvic area to immobilize them.
Robot-controlled treatment tables
The technical equipment at HIT guarantees state-of-the-art radiation therapy. Two treatment rooms are equipped with a fixed horizontal beamline that enters through the wall. The third treatment room hosts the world´s first heavy ion gantry, a movable radiation source. It can rotate 360° around the tumor and the particle beam can target the tumor from different directions.
In addition, the treatment tables are robot-controlled and can be moved in six directions. The patient position can be optimized by combining these two movements. Thus, numerous angles of irradiation can be selected. Digital x-ray equipment and position-sensitive particle detectors monitor the accuracy of the patient position and the dose delivery radiation during treatment. The ion beam enters the patient at a very high speed. The patient does not feel anything. All treatment rooms are enclosed by thick walls with a width of 2.5m to protect the adjacent areas from the high-energy beams.
Up to 38 individual sessions
The decisive event that leads to the death of a cell is the destruction of its genetic material (DNA). Then, the cell can no longer multiply and dies. The tumor cannot continue to grow. The ion beam must irreparably destroy the genetic string of every single cancer cell. This cannot be done in one session, making several more treatments necessary. This is called fractionation. The breaks between treatments are selected so that healthy tissue affected by the radiation can recover and repair the damage caused by radiation. Cancer cells cannot recover as quickly. The radiation damage thus accumulates in the tumor cells which are destroyed by the radiation treatment.
For most patients, one session lasts only a few minutes. In rare cases, it can last up to 30 minutes. The entire treatment consists of an average of 38 sessions. Several weeks after the radiation, the physicians make a CT or MRI to check whether the tumor has shrunk or even disappeared entirely.
More detailed information on the radiation procedure you´ll find on the Homepage of the Klinik für Radioonkologie und Strahlentherapie.