Therapy: effective, well-tolerated and safe

To fully exploit the advantages of the carbon beam, the treatment planning as well as the therapeutic procedure itself are performed with the utmost precision. The pursuit of this objective led to the development of innovative new methods at GSI.

Biologically optimized treatment planning

To enhance the precision of treatment planning, GSI developed a model for calculating the biological effectiveness of carbon ions in different tissues. This, in combination with the physical dose distribution, allows the computation of the biologically effective radiation dose for each point in the tumor.

Precisely tumor-conformant irradiation

The raster-scan method developed at GSI allows the carbon beam to precisely and selectively scan the tumor volume. To this end, the speed of the ions—and consequently their penetration depth—is controlled by varying the energy level of the accelerator. In this manner the tumor is scanned layer by layer. Within each layer the scan is performed by deflecting the beam horizontally and vertically using magnets, much like the electron beam in a cathode ray tube. Even complex tumor shapes within the body can thus be uniformly irradiated to the nearest millimeter. Damage to healthy tissue is minimized.

Online therapy monitoring

As they travel through tissues, a small number of carbon ions are transformed into a different carbon isotope. Each such event liberates two quanta of gamma radiation, which can be measured by special detectors. This process can be used to monitor the ion beam location within the patient during the treatment. Such online monitoring substantially enhances patient safety.