A DEVICE FOR MAMMOGRAPHY

Abstract: The invention relates to a mammography device, having a frame pillar (3) comprising a slide (2) mounted vertically (Z) slidingly on bearings, at the horizontal axis (4) the photography head (1) is pivotally mounted on bearings. According to the in­ vention, the guide device (10), the photography head (1) being tilted, guides the hoisting mechanism (M1) of the slide (2) accor­ ding to a preset program and to the observed angle of inclina­ tion (Ω) in such a way that the centre point of the support plate (6) in the photography head is at essentially the same height abo­ ve the support (20) at the end of the tilting movement as prior to this.

Description: The invention relates to the type of device for mammography that is defined in the preamble of claim 1. In mammography devices, the breast to be photographed is X-rayed both vertically and with the photography head being inclined. In known devices (e.g. EP-A-0 145 893), the displacing of the photography head is done manually or under manual control by means of a motor. The object to be photographed is placed on the support plate of the photography head, the height position of which having been appropriately adjusted. When inclining the photography head, the centre point of the support plate moves on a circumference the centre point of which is the rotation axis of the photography head, whereby the centre point rises to a higher position. In order to provide the proper support for the photographed breast, the support plate has to be lowered. This is done by lowering the slide of the photography head, which is usually done by manual adjustment. The above tilting operation and the connected height adjustment of the slide are time-consuming measures that require great precision, which are simplified by the present invention. The present invention is characterized by the facts described in greater detail in the characterizing part of claim 1. The other features of the invention are described in a preferred embodiment according to the claims with the aid of the following description and the drawing, in which: figure 1 shows a mammography device according to the invention, the height of which is vertically adjustable Z: figure 2 shows the device of figure 1, which can be inclined (in the angle Ω) from the vertical direction (the tilting shown in the figure is done without automatic height compensation); figure 3 is a schematic partial section view of the hoisting mechanism of the slide of the device according to the invention; figure 4 is a schematic presentation of the tilting mechanism of the photography head of the device according to the invention; figure 5 illustrates an optional embodiment of the device according to the invention, in which the photography head is horizontally displaceable X (the horizontally displaced photography head is indicated by dotted lines); figure 6 is a schematic view of the control system of the device according to the invention. The mammography device stands on a support 20 at the base of a frame pillar 3. According to figure 1, the frame pillar 3 of the device supports the slide 2 of the photography head, which is slidingly mounted onto bearings on the pillar and the upper end of which comprises an X-ray source 7 and the lower end a support plate 6. The height of the slide is adjusted by the actuator M1 (figure 3). Figure 2 shows the inclination of the photography head about the axis 4 in the slide (cf. also figure 4), whereby the angle of inclination Ω with regard to the vertical plane can be as large as ± 100°. The inclination can be guided either manually or by means of the actuator M2. The breast object to photographing is placed on the support base 6, the slide having first been adjusted to the proper height. When needed, a height correcting adjustment can be carried out depending on the patient. Before the photographing, the breast is slightly compressed into position by means of a compression plate (not shown). The radiation source (X-ray source) 7 is disposed in the photographing head above the breast and the recording means, the film, is disposed in the support plate or underneath the support plate 6. If desired, the photography head can be tilted, e.g. 45°, the actual angle of inclination being detected by the detector 8 shown in figure 4, e.g. a potentiometre. When comparing the positions of the photography head in figures 1 and 2, it can be observed that without the height compensation of the photography head (figure 2) the support plate rises to a higher position, when the photography head is being tilted. By connecting the communication from the angle detector 8 to the control means 10 according to figure 6, a communication is obtained in the output of the control means 10 according to a preset program, which is proportional to the angle Ω, and by means of which the actuator M1 is controlled via the amplifier 11 in order to adjust the height Z of the photography head. In this manner, the centre point of the support plate 6 is maintained on the same height level with regard to the support 20, regardless of the angle Ω. Optionally, instead of direct proportionality, the control means 10 can be given a form factor/form function describing the shape of the photographed breast, according to which the height position of the support plate is corrected so that it conforms still better to the outline of the cross-section of the base of the breast. The control means can also comprise a connection, by means of which the tilting motor M2 is controlled according to a specific program or instruction. This is not shown in the figure. In the embodiment of figure 5 the device is further provided with an actuator M3 displacing the photography head horizontally X and with a support arm 5. On the basis of the inclination angle Ω the actuator M3 can be controlled via the amplifier 12 according to the program on the control means 10. The horizontal movement can be controlled so as to maintain the central point of the support plate 6 essentially on the same vertical line. Optionally, the photography head can be horizontally displaced so that the support plate conforms optimally to the outline of the cross-section of the base of the breast.

Claims: 1. A mammography device, having a slide (2) mounted slidingly onto bearings vertically in its frame pillar (3), in which the photography head (1) is mounted pivotally onto bearings in the horizontal axis, comprising a radiation source (7) and a support plate (6) facing each other, characterized in a control means (10) which, the photography head (1) being tilted, controls the hoisting mechanism (M1) of the slide according to a preset program and to the angle of inclination (Ω) in such a way that the centre point of the support plate (6) disposed in the photography head is at essentially the same height above the base of the frame pillar at the end of the tilting movement as prior to this. 2. A mammography device according to claim 1, characterized in that, the photography head (1) being tilted, the control means (10) controls the motor (M3) displacing the photography head horizontally (X) according to a preset program and to the observed angle of inclination (Ω) so that the centre point of the support plate in the photography head is essentially on the same vertical line at the end of the tilting movement as prior to this. 3. A mammography device according to claim 1 or 2, characterized in that the control means (10) is disposed to control also the motor (M2) tilting the photography head (1) according to a preset program or instruction. 4. A mammography device according to claim 2 or 3, characterized in that, the photography head (1) being tilted, the central point of the support plate (6) follows a trajectory according to a preset program, the trajectory following essentially the cross-section of the base of the breast to be photographed by the device.

Inventors: JAERVINEN, ERKKI,, KYLLOENEN, TUOMAS,, MIKKONEN, HANNU,, Järvinen, Erkki,, Kyllönen, Tuomas,
Applicants: ORION-YHTYMAE OY
Application year: 1989
Main classification: A61B6
IPC codes: A61B6