Discription des technischen Sachverhalts

Radiotherapy treatment devices generate homogeneous fluence profiles on the surface of the gantry. Spatial fluence modulations can be obtained using compensator techniques or superposition of different fluence shapes. A modern device for shape generation is the multi-leaf collimator (MLC). The shapes are generated by different leaf motions and arrangements.

There are basically two techniques for shape generation using MLCs:

• Step-and-shoot-method

A series of static fluence profiles is sequentially realised. During the setup time (step) in between the irradiations (shoots) with different shapes, radiation source is off. Intensity modulation is obtained by superposition of different shapes with optimized beam-on times (monitor times).
 

• Dynamic method

The leafs move independently while radiation is continuously emitted. Intensity modulation is obtained by realisation of different beam-on times.

Project contents

The department of optimization at Fraunhofer ITWM works on modelling and realisation of step-and-shoot techniques using methods of discrete optimization. Planning goals like minimization of beam-on time or total treatment time can be modelled and solved as network-flow problems. This work strategically aims for an integration of physical requirements on the shape of the fluence profile to simplify the plan application. An extension to dynamic methods is planned for the future.

Stand: 01.08.03

Contact:

	Dr. habil. Karl-Heinz Küfer Tel.: +49 (0)631/36681-13