Process and apparatus for determining the exact position of a target (C). The apparatus comprises a radiation source (22) emitting radiation forming an image of at least the target (C), capable of being received by a receiving device (30), said source (22) and said receiving device (30) being disposed on either side of the target (C), and the source (22) being in a known position in relation to a given point of reference (0) determined for example, by a device (12) for treating the target (C). The apparatus is characterized in that the receiving device (30) comprises a header (32) having a linear active part formed from a variety of discrete radiation-sensitive elements, whose positions in space are known, means (18) for displacing the radiation source between two different angular positions and means (40) for determining the position of the target (C) from at least two images obtained from two different angular positions of the radiation source. The invention provides a means for limiting irradiation of a patient.
展开▼
