Dynamic treatment using a Philips Linac SL 75/20

Dynamic treatment techniques make radiation therapy more efficient with respect to the dose distribution in the target volume and to the protection of the surrounding healthy tissue. The developments towards the introduction of dynamic treatment in the clinic are described. Some modifications of the Linac hardware were necessary and a computer with special interfaces was chosen. This control computer is responsible for system diagnosis, patient management and movement control. A separate planning computer will produce sequences of fixed field data, upon which the movement control is based. Control software is structured modularly and hierarchically. The main parts of this software system are independent motor control tasks, each controlling just one motor. Their control algorithms and the handling of deviations from the planned course are of special interest. Examples of two simultaneously controlled motors show that it is possible to keep deviations within a tolerable range. Finally, error detection is briefly described. (author). 5 refs, 7 figs