Patent Number: 
Section: claims

1. A radiation therapy apparatus configured to align a radiation beam with a target receiving therapy, the radiation therapy apparatus comprising:a target support configured to immobilize the target;a fixation device connected to the target support;a radiation detector connected to the fixation device so as to be positioned in front of the target, the radiation detector configured to determine an intersection position of the radiation beam with the radiation detector in front of the target; anda correcting device configured to correct a relative position of the radiation beam and the target support, based on the intersection positiion determined by the radiation detector. 2. The apparatus of claim 1 wherein the radiation detector has a longitudinal axis and the fixation device holds the longitudinal axis of radiation detector parallel to the target support. 3. A radiation therapy apparatus configured to align a radiation beam with a target receiving therapy, the radiation therapy apparatus comprising:a target support configured to immobilize the target;a fixation device connected to the target support;a radiation detector connected to the fixation device so as to be positioned in front of the target, the radiation detector having a planar detection surface which is configured to determine in front of the target an intersection position of the radiation beam along X, Y axes of the planar detection surface of the radiation detector; anda correcting device configured to correct a relative position of the radiation beam and the target support, based on the intersection position determined on the X, Y axes of the planar detection surface of the radiation detector. 4. The apparatus of claim 3 wherein the planar surface of the radiation detector has a longitudinal axis and the fixation device holds the longitudinal axis of radiation detector parallel to the target support. 5. The apparatus of claim 4 wherein the fixation device is configured to hold the planar detection surface perpendicular to the radiation beam. 6. A radiation therapy apparatus configured to align a radiation beam with a target receiving therapy, the radiation therapy apparatus comprising:a target support configured to immobilize the target;a radiation detector comprising a radiation detector plane which intersects the radiation beam on the radiation detector plane in front of the target, the radiation detector configured to determine an intersection position of the radiation beam on the radiation detector plane in front of the target;a fixation device configured to hold the radiation detector in proximity to the target support and in front of the target and hold the radiation detector plane perpendicular to the radiation beam; anda correcting device configured to correct a relative position of the radiation beam and the target support, based on the determined intersection position on the radiation detector plane. 7. The apparatus of claim 6 wherein the radiation detector plane has a longitudinal axis and the fixation device holds the longitudinal axis of the radiation detector plane parallel to the target support. 8. A radiation therapy apparatus configured to align a radiation beam with a target receiving therapy, the radiation therapy apparatus comprising:a target support configured to immobilize the target;a radiation detector comprising a radiation detector plane in front of the target, the radiation detector plane comprising an X axis corresponding to a first dimension, and a Y axis corresponding to a second dimension, wherein the radiation detector is configured to detect an intersection position of the radiation beam along the X axis and along the Y axis of the radiation detector plane in front of the target; anda correcting device configured to correct a relative position of the radiation beam and the target support, based on the intersection position determined on the two-dimensional radiation detector plane. 9. The apparatus of claim 8 wherein the planar surface of the radiation detector has a longitudinal axis and the fixation device holds the longitudinal axis of radiation detector parallel to the target support. 10. The apparatus of claim 9 wherein the fixation device is configured to hold the planar detection surface perpendicular to the radiation beam. 11. A method for positioning a target receiving therapy relative to a radiation beam, the method comprising:directing a radiation beam towards a radiation detector having a planar detection surface in front of the target, wherein the radiation detector is fixed to a target support configured to immobilize the target receiving therapy;determining an intended intersection point of a radiation beam on the radiation detector plane of the radiation detector, wherein the intended intersection point is defined by a two-dimensional coordinate system of the radiation detector;determining an actual intersection point of the radiation beam with the radiation detector plane of the radiation detector, wherein the actual intersection point is defined by the two-dimensional coordinate system of the radiation detector; andapplying a correction to a relative position between the radiation beam and the radiation detector plane of the radiation detector so the actual intersection point coincides with the intended intersection point. 12. The method of claim 11 wherein the method further comprises moving the radiation beam so that the beam hits the planar radiation detector at the intended intersection point.