gms | German Medical Science

48th Meeting of the Particle Therapy Co-Operative Group

Particle Therapy Co-Operative Group (PTCOG)

28.09. - 03.10.2009, Heidelberg

Quality assurance of beam tracking

Meeting Abstract

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  • N. Saito - GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Deutschland

PTCOG 48. Meeting of the Particle Therapy Co-Operative Group. Heidelberg, 28.09.-03.10.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09ptcog170

DOI: 10.3205/09ptcog170, URN: urn:nbn:de:0183-09ptcog1703

Published: September 24, 2009

© 2009 Saito.
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Outline

Text

Quality assurance of beam delivery is very important for reliable external beam radiotherapy. Especially dynamical irradiation (e.g. intensity modulated radiotherapy, active scanning, beam tracking, etc.) which changes parameters of mechanical devices or electronics during the irradiation has to be assessed with a great caution. Although such a careful assessment is needed, time duration for the assessment has to be considered to be minimized for an efficient clinical routine. In this contribution a concept of quality assurance (QA) of beam tracking is presented.

Beam tracking is a dynamic beam delivery method to irradiate moving targets efficiently and effectively by adapting the beam continuously. At GSI a prototype ion beam tracking system was developed and integrated into the GSI therapy system which uses an active beam delivery technique, the so called rasterscan technique. The GSI beam tracking system can control the ion beams laterally with the scanning magnets of the rasterscan system and longitudinally with a range shifter according to the target position monitored in real-time based on a pre-calculated beam displacement from time resolved treatment planning. The beam tracking system was validated experimentally by irradiating moving phantoms, and the dose deliveries were assessed with various dose detectors, e.g. ionization chambers, radiographic films, or biological cell probes.

QA of beam tracking can be considered with different levels of components. At the lowest level, connections of individual devices are assured. At the second level simple device functionalities are tested e.g. by sending a test motion signal to the beam tracking unit and show the phantom motion on a display. At the highest level one can perform beam tracking as a QA irradiation with a moving phantom.

In this contribution a practical case of a patient treatment plan will be presented as an example of the QA method.