Particle therapy is employed particularly for radiation treatment of tumor tissue in humans. For the radiation treatment, ions such as protons, helium ions, pions, carbon ions, or other types of ions can be employed. In comparison to conventional radiation treatment with photons or electrons, radiation treatment with ions is characterized by the fact that the penetration depth of the radiation into the human tissue can be controlled more precisely. This makes more-precise radiation treatment of the tumor possible, and, in the treatment, the surrounding tissue that is to be spared can be better protected from the radiation.
For radiation treatment, the ions are accelerated to high energies in an accelerator system which, for instance, includes a synchrotron or cyclotron, and are aimed in a beam at the body to be treated. The beam is deflected and controlled by a magnet system. Parameters of the beam that are essential and relevant for safety are dependent essentially on the settings at the system. The parameters determine the beam properties. These include, among others, the beam diameter, the beam position, and the energy of the beam.
The properties of the particle beam used for the therapy must be known and controlled. To ensure this, quality assurance (QA) procedures (also called QA procedures; quality control (QC), or similar terminology may also be used) are performed at regular intervals.
The monitoring of the beam properties is performed, for example, with so-called “phantoms”. Such phantoms are irradiated with the particle beam and have a sensitive unit with which the interaction of the particle beam with the phantom can be measured and monitored. The sensitive units are typically films, which are exposed to irradiation by the particle beam. However, depending on the type of phantom, detectors of other types may also be used, such as ionization chambers or thimble chambers.
Until now, for monitoring various beam parameters at different intervals, different phantoms have each been employed. For each QA procedure, the phantom used must be put in a defined position relative to the beam, so that for different phantoms, positioning must be done for each one, thus requiring repeated manual interventions. Hence in phantoms in which a film, such as an X-ray film, is used as the sensitive unit, a separate film is used, developed and evaluated for each QA procedure and for each phantom.