X-ray diagnostic apparatus for tomosynthesis

p0001a method is known from WO 93/22 893 A1, with which it is possible to reconstruct a picture of a subject without this the projection angle α and the geometric arrangement of the radiation emitter and radiation detector and the focal plane are known. According to this method, a reference from radiation-absorbing material is provided with a known size and known distance from the radiation receiver in the range of the radiation receiver, which is projected at every single projection on the beam receiver. Based on local mapping of the reference on the radiation receiver for each individual projection of the geometric arrangement and the two-dimensional projection angle α can be determined.

p0002A holder for positioning a beam emitter of X-ray diagnostic apparatus for tomosynthesis is known from DE 44 14 689 A1. At the holder arm is coupled to the - viewed in the radiation direction - before the examination subject a spherical reference object and behind the object under examination, a radiation receiver are arranged. About the holder is set to a distance of the radiation transmitter to the reference object and the radiation receiver and the angle α of the light emitted by radiation transmitter beam to a reference axis of the holder. It is further known to arrange the adjustable radiation source in a housing to which a positioning device for the reference object and the radiation detector is coupled.

p0003Object of the invention is further advantageous embodiment of the X-ray diagnostic device of the type mentioned.

p0004The object is achieved by the subject of claim 1.

p0005Advantage of the invention is that the reference object is no longer subject is close, so that it no longer interferes or interference with the positioning.

p0006It is particularly advantageous if the reference object consists of several objects that have form of a bar and the cross. By the projection of the reference object to the radiation receiver and evaluating the signals which are generated from the reference object, both the distance between the beam emitter to the beam receiver, the irradiation angle (projection angle), and the irradiation direction can be determined. It is thus possible to obtain data for calculating a Tomosyntheseaufnahme from the image signals during irradiation of the examination object obtained from different directions, and derived from the radiation receiver. Alternatively, the reference object may be formed of at least three subobjects this also, their mutual arrangement deviates from a straight line. It is particularly advantageous when the partial objects or different portions of the sub-objects in terms of radiation absorption, so that can be the distance, the angle of incidence and the radiation direction determining unequivocally is.

p0007Further advantages and details of the invention will become apparent from the following description of an embodiment with reference to the drawing in conjunction with the dependent claims.

p0008It shows: <dl id="dl0001" compact="compact"><dt>1 shows</dt><dd>an X-ray diagnostic apparatus for tomosynthesis in basic representation, wherein the reference object has a fixed relation to the radiation source,</dd><dt>FIG 2</dt><dd>a first and</dd><dt>FIG 3</dt><dd>a second embodiment of a reference object of X-ray diagnostic device according to FIG. 1</dd></dl>

p0009In FIG 1, reference numeral 1 designates a beam transmitter, in particular a radiation source in to the / of a reference object 2 has a fixed reference and the / of it is exclusively connected. The reference object 2 can this example be coupled via a holder 3 only with the radiation transmitter. 1 The preferably consisting of at least two partial objects 4.5 reference object 2 is in this case arranged such that it is in the beam 6 emanating from the radiation transmitter. 1 In the embodiment, the part objects 4.5 are form of a bar and intersect, which is apparent in particular from FIG. 2 The length 1 of the beam portions as partial areas of the partial objects can be equal to 4.5 or different. Preferably, the partial objects are 4.5, but designed differently with respect to the radiation absorption, so that the irradiation direction can be determined in an unambiguous way, while the distance from the radiation receiver 13 and the angle of incidence (in absolute value) can be determined already when the lengths or dimensions of the portions of the part objects 4.5 are known. The distinction in terms of radiation absorption may in this case be effected by that portions of the part objects 4.5 differ in the length and / or the form or in any other way. It is also possible to vary execute only a portion of a part object 4.5 in terms of radiation absorption to the other subregions.

p0010In an alternative reference object 7 at least three sub-objects and 8,9,10 in the embodiment, another portion of object 11 are provided, whose arrangement to one another deviating from a straight line. These sub-objects 8,9,10,11 form a geometric body, such as a polygon, the distances of the partial objects are predefined 8,9,10,11. In this embodiment, the sub-objects are 8,9,10,11 designed as disks, but they can also be spherical or assume a different shape. To determine the actual radiation direction at least part of the object 11 with respect to the shape and / or the radiation absorption may differ compared to other sub-objects 8,9,10.

p0011All described reference objects and / or partial objects can also be configured in an inverted form, ie. As recesses in full material Preferably, one will choose disc-shaped solid material with outer dimensions that are not much larger than the reference object itself, and the recesses are completely or almost completely go through the windshield.

p0012One evaluator 12, the signals of a radiation receiver 13 supplied, so that can be determined from the derivable by the projection of the reference object 2 on the radiation detector 13 signals the distance, the angle of incidence and the direction of irradiation. an examination subject is - from the direction of the radiation transmitter 1 seen - before the radiation receiver 13 and this irradiated from different directions, so can be created on the basis of the obtained from each direction of transmission signals of the object under examination and the signals of the reference object a Tomosyntheseaufnahme the examination subject.