Abstract: A position detector arranged to be mounted at a radiation detector of a radiotherapy treatment apparatus, which includes a gantry rotatable about a gantry rotation axis, and a collimator rotatable about a collimator rotation axis. The radiation detector is mounted at the collimator. The position detector comprises: —an accelerometer device, which is arranged to detect at least gravitational acceleration in at least one dimension; —a gyro device arranged to detect at least angular velocity in at least one dimension; wherein the accelerometer device and the gyro device in common are arranged to be operative in three dimensions, and —a controller connected with the accelerometer and the gyro; wherein the controller is arranged to receive first input data from the accelerometer device and second input data from the gyro device, and to determine at least a collimator angle and a gantry angle by means of the first and second input data.

Abstract: A position detector arranged to be mounted at a radiation detector of a radiotherapy treatment apparatus, which includes a gantry rotatable about a gantry rotation axis, and a collimator rotatable about a collimator rotation axis. The radiation detector is mounted at the collimator. The position detector comprises: an accelerometer device, which is arranged to detect at least gravitational acceleration in at least one dimension; a gyro device arranged to detect at least angular velocity in at least one dimension; wherein the accelerometer device and the gyro device in common are arranged to be operative in three dimensions, and a controller connected with the accelerometer and the gyro; wherein the controller is arranged to receive first input data from the accelerometer device and second input data from the gyro device, and to determine at least a collimator angle and a gantry angle by means of the first and second input data.

Abstract: When controlling and/or determining the thicknesses of layers or surface coatings there is chosen a coating composition that incorporates a fluorescing indicator substance, the proportions of which in the coating composition can be measured by X-ray fluorescence. The coating composition is applied to a substrate surface in solution, slurry or molten form and the thickness of the coating, or layer, is controlled and/or monitored in accordance with the intensity of the light which fluoresces from the coating.