Elekta Instrument Ab

Elekta Instruments Ab

Borje Nilsson

Dan Leksell

A radiotherapy appliance having a plurality of controllable radiation beams which converge on a focus volume wherein an object being irradiated can be movably positioned relative to the focus volume for varying time periods and with varying radiation exposure rates, optimally under control of a computer. The computer controls the focus volume radiation beam size, intensity, and exposure time for subareas of the treatment target in response to a radiation dose distribution determined for the treatment target. A determination of the radiation beam size, intensity, and dwell time of the focus volume in the target area, is made by initially dividing up the specified treatment area into volume elements or voxels and having biological characteristics of the treatment area assigned to each voxel. The energy deposition incident to each voxel to provide this biological characteristic is then calculated. Finally, from the energy deposition incident on each voxel, the dwell time of the focus volume at particular voxels can be determined. Once the dwell time has been determined, the computer generates a sequence of motor control movements to move the patient with respect to the focus volume such that the focus volume is at a position sufficiently long within the treatment target to deliver the necessary radiation for each voxel.

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Uppsala, Sweden

Borje Nilsson