WO2003041586A1

WO2003041586A1 - Compression device and mammography apparatus

Info

Publication number: WO2003041586A1
Application number: PCT/FR2002/003885
Authority: WO
Inventors: Yannick Demay; Rémy Klausz; Claude Meriau; Bruno Ferard
Original assignee: Ge Medical Systems Global Technology Company, Llc
Priority date: 2001-11-13
Filing date: 2002-11-13
Publication date: 2003-05-22
Also published as: FR2832050A1; EP1446052A1

Abstract

The invention concerns a compression device of a mammography apparatus comprising a compression paddle (12) including a plate (14) and a rim (16) projecting on the periphery of the plate (14), a support frame (54) adapted to link the paddle (12) to the mammography apparatus, the paddle (12) or the support frame (54) being deformable under the action of a force applied along a direction perpendicular to the plate. The invention provides the advantage of uniform compression of a patient's breast from the thoracic cage to the nipple as well as transverse compression.

Description

COMPRESSION DEVICE AND MAMMOGRAPHY APPARATUS

FIELD OF THE INVENTION The invention relates to a compression device for a mammography apparatus, as well as a mammography apparatus with such a ball.

BACKGROUND OF THE INVENTION

In the field of medical imaging, breast radiography or mammography is known for its effectiveness in the early detection of breast pathologies, and in particular in that of tumors. Given that the effectiveness of the treatments for these pathologies is directly related to the earliness of their discovery, it is particularly critical to perform mammograms under the conditions that provide the greatest possible sensitivity for interpretation. On the other hand, to apply the mammography technique to the largest possible population, including by means of systematic screening campaigns organized by age groups, it is necessary to take into account not only the benefit in terms of pathologies detected, but also the risk associated with radiation from the breast. To reduce the risk of radiation, the radiation dose should be minimized.

There exists in radiological imaging techniques, and in particular for breast imaging, a method making it possible to improve the quality of the images and reduce the doses of radiation absorbed by the patient; this method is compression of the breast examined, in particular, the breast of a patient.

The company GE Médical Systems offers for example under the references Sénographe 2000D, Sénographe DMR +, Sénographe 700T, Sénographe 800T, mammography devices. These devices include a compression pad that compresses the patient's breast against an image receptor so as to reduce the thickness of the breast under patient-tolerable conditions.

During breast compression, the compression pad meets contradictory requirements: ensuring uniform compression from one end of the breast to the other (from the rib grill to the nipple and transversely), despite the thickness variable breast, while being substantially parallel to the image receptor. According to the requirements of the Quality Control Protocol for Mammography Installations, General Directorate of Health of the French Ministry of Health, Revised Edition, July 1998: "the difference in height (...) should not exceed 5 mm. We accept a variation of 10 mm ”. According to the law of the United States on the quality of mammographic examinations ((MQSA): DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration, 21 CFR Part 900, Quality Mammography Standards) the difference in height should not exceed 1.0 cm . Solutions have been proposed in an attempt to resolve these requirements. Patent EP-B-406,455 describes a mammography apparatus with an image receptor and a compression pad for compressing the breast against the image receptor. The ball is rotatably mounted about an axis of rotation and forms with the surface of the image receptor facing the compression plate, an acute angle. Thus, the space between the compression pad and the image receptor narrows in the direction of the patient. During breast compression by the ball, the ball turns around the axis of rotation and the angle between the ball and the receiver decreases until the facing surfaces of the ball and the receiver are parallel to each other . US-A-5,506,877 describes a mammography apparatus comprising a compression pad. The compression ball is rotatably mounted about an axis parallel to the image receptor and to the patient's rib grill, the axis being at the end of the ball in contact with the patient's rib grill. The compression pad can be flat-bottomed or curved to match the shape of the breast. US-A-5,706,327 describes a mammography apparatus comprising a compression pad. The compression pad is rotatably mounted about an axis parallel to the image receptor and the patient's rib grill. The axis of rotation is located between the end of the ball located near the rib grill and the end located opposite. The ball can oscillate between two extreme angular positions ensuring respectively the position with low or zero compression (free spring) and maximum compression (loaded spring).

The document US 2002/0061090 describes a compression ball, with longitudinal and transverse directions, which is oriented in two directions depending on the position of the breast under the ball and the anatomy of the patient. For this, the compression device comprises a support supporting the ball by means of elastic elements placed between the ball and the support, for example elastomeric stops. The elements allow the pelota to rotate relative to the mammography apparatus around the longitudinal and transverse directions.

The compression device of document US 2002/0061090 however has drawbacks. Indeed, the elastic elements between the ball and the support also allow the ball to move in a front / rear direction relative to the patient when the latter is pressed against the ball during the radiography. Consequently, the edge of the ball in contact with the patient's rib grill and the tissues of the patient's rib grill enter the field of view of the mammography device, which decreases the quality of the shot. . In addition, the manufacture of the elastic elements and the mounting of the ball on the support by means of the elastic elements are complex.

The solutions proposed in these documents have the disadvantage of being expensive because the implementation of axes of rotation on the ball complicates the construction of the ball and increases the number of construction parts. In addition, the maintenance of the ball provided with such an axis of rotation requires special care.

AR Custom Medical Products Ltd. offers a compression ball under the name "" Compassion "Flex", which flexes when a compression force is applied. The ball has the shape of an L, a compression surface forming the horizontal part of the L and a protruding rim in contact with the costal grill of the patient forming the vertical part of the L.

The disadvantage of this ball is that compression of the breast near the patient's rib grill is not sufficient and does not provide a reliable estimate of the thickness of the compressed breast. In addition, tissues from the patient's rib grill above the compression pad may penetrate the imaged field and be superimposed on the imaged breast tissue. This degrades the quality of the image.

There is therefore a need for a compression device which is of a simple and inexpensive construction, providing uniform compression of the breast while meeting the requirements of standards regulating the field of mammography.

BRIEF SUMMARY OF THE INVENTION

In summary, according to the invention, a compression device of a mammography device comprises a compression ball having a plate and a protruding rim around the periphery of the plate, a support adapted to connect the ball to the mammography, the ball or support being liable to deform under the action of a force applied in a direction perpendicular to the plate.

The device has the following advantages. The device ensures uniform compression from one end to the other of the breast (from the rib grill to the nipple and transversely), despite the variable thickness of the breast, while being substantially parallel to the image receptor.

The construction of the device is simpler and less expensive because the device fits within without the manufacture of an axis of rotation.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a compression device.

Figures 2 to 7 show a first embodiment of the compression device of Figure 1.

Figure 8 shows a second embodiment of the compression device. Figure 9 shows a third embodiment of the compression device. Figures 10 to 13 show a fourth embodiment of the compression device. Figures 14 to 16 show a fifth embodiment of the compression device.

Figures 17 to 20 show a method of fixing the ball to the support. Figure 21 shows a mammography machine.

DETAILED DESCRIPTION OF THE INVENTION

The compression device comprises a compression ball and a support adapted to connect the ball to the mammography device. Either ball or support may be deformed during a mammography shooting process. The ball or the support are deformed in the sense that their shape is altered. During the process, an organ such as the breast of a patient is compressed by the ball with a compressive force; the location and intensity of the deformation is determined by this compressive force as well as by the anatomy of the breast.

Figure 1 shows the compression device 10. The device 10 comprises the compression ball 12 having a plate 14 and a flange 16 projecting from the periphery of the plate 14. The device 10 also comprises a support 54 adapted to connect the ball 12 to the mammography apparatus. The ball 12 or the support 54 is liable to deform under the action of a force applied in a direction perpendicular to the plate. This force is that exerted by the ball on the patient's breast during the mammography process. The deformation of the ball or support makes it possible to adapt the compression within the X-ray. The deformation of the ball or support rather than of elements linking the ball to the support, makes it possible to prevent the rib rib tissues situated above the edge of the ball in contact with the rib grill and said edge of the ball in contact of the patient's rib grill to enter the field of view of the mammography unit. Furthermore, the deformation of the ball or of the support makes it possible to prevent the ball from pivoting around predefined axes obtained by construction of the device 10 to adapt to the anatomy of the breast. Also, mounting the ball on the support is simple.

The ball allows the compression of an organ of a patient, but also that of a patient. The ball comprises the plate 14 which is the surface of the ball coming into contact with a member to be compressed. It is made of a material transparent to X-rays such as Polycarbonate, marketed for example under the reference Lexan from the company GE Medical Systems. The plate 14 has for example a quadrilateral shape, for example square, rectangular or trapezoidal whose sides have a length of between 8 and 30 cm. The thickness of the plate 14 is between 2 and 4 mm. The rim 16 stiffens the plate 14 when the latter, cantilevered, is bent by a force perpendicular to the plate 14. The rim has the function of a rib whose largest dimension is in contact with the plate 14. The rim 16 has parts 16a, 16b, 16c, 16d along the periphery of the plate 14. The flange 16 forms an angle with the plate 14; the flange 16 is for example inclined towards the outside of the ball 12 and forms an angle between 0 and 5 ° with a plane perpendicular to the plate 14. Preferably, the flange is substantially perpendicular to the plate 14. Each of the parts 16a, 16b, 16c, 16d of the rim 16 can have its own height. A part of the rim 16 can for example reach a height of 3 to 5 cm. The rim 16 may have a thickness of

2 to 9 mm. It can be obtained by molding at the same time as the plate 14. The projecting angles of the ball 12 capable of coming into contact with the patient are rounded. The radius of curvature of the angles will be chosen so that the patient does not injure herself in contact with the ball and that the quality of compression of the breast is not affected.

The ball has the following advantages. The construction of the ball is simple and inexpensive. It offers the possibility of compressing the breast evenly from the rib grill to the nipple as well as transversely. Maintaining the ball is also made easier. Furthermore, the rim 16 on the periphery of the plate 14 makes it possible to prevent tissue from the patient's rib grill from spreading on the plate 14 and to prevent these tissues from being visible in the field of view.

The ball 12 can include a fold 20. This fold 20 projects from the rim 16 and extends along a plane substantially parallel to the plate 14. This fold extends towards the outside of the ball 12 and allows gripping by the ball support 54. Preferably, the fold allows the ball 12 to be held in overhang. In FIGS. 1 to 5, the fold 20 is projecting over a part of the periphery of the rim 16. The fold 20 is on the part 16b of the rim opposite the part 16a in contact with the costal grill of the patient and extends over the parts 16c and 16d perpendicular to the part 16b. The fold 20 has a thickness of between

3 and 6 mm. Figure 1 also shows the support 54. According to Figure 1, and without limitation, the support has a holding member 56 and a heel 55. The holding member can be an interface having the shape of a U , with vertical branches one in connection with the ball and the other with the heel 55. The holding member 56, such as a bar, can be provided with a groove 57 for receiving the fold 20 projecting from the rim 16. The bar can be made of a light alloy and the groove can be obtained by machining. The groove 57 constitutes a slide for gripping the fold 20. The ball 12 is slid into the groove 57 until the position of FIG. 2. The contact between the groove 57 and the fold 20 makes it possible to transmit to the plate 14 by the rim 16 the compression force to the ball 12 as a whole, and through the plate 14, the compression force within. This movement makes it possible to compress an organ placed under the ball 12. The part of the rim 16 carrying the fold 20 is preferably that opposite to the part of the rim 16 in contact with the costal grill of the patient. This allows the gripping of the ball 12 without interference between the support 54 and the patient. Advantageously, the holding member 56 is a fork. The inner periphery of the U-shaped fork 56 is provided with the groove 57 to receive the U-shaped fold 20 in top view. The advantage of a fork-shaped support and a U-shaped fold is to obtain better grip of the ball 12, and consequently, better compression of the breast. The fork 56 comprises for example arms 56c and 56d holding the ball 12 by the parts 16c and 16d.

The fold 20 and the support 54 may be provided with a hole 53 for the passage of a ball immobilization member 12 in the support 54. The immobilization member is inserted through the fold 20 and the support 54 through the passage hole passing through the support and the fold 20. The immobilization members also make it possible to avoid the front / rear displacement relative to the patient of the ball. Advantageously, the through hole made through the support 54 extends from the underside of the support 54, turned towards the breast to be compressed, as far as the groove 57. Several immobilization members can be inserted in holes 53 provided for this effect. The immobilization members are typically screws. The use of oblong holes 53 instead of simple holes makes it possible to achieve precise positioning of the ball 12 with respect to the support 54 while eliminating any manufacturing drifts.

Figures 17 and 18 show in more detail the preferred method of attachment of the ball 12 to the support 54. Figure 17 shows the attachment described above; it shows a sectional view of the fork 56 with the groove 57, and, after assembly of the assembly, the fold 20 in the groove 57. FIG. 18 shows the fixing between the fold 20 and the groove 57; the dimension of the groove 57 can be sufficiently wider than the fold 20 so as to allow the introduction of a seal 58 between the fold 20 and the groove 57. The seal 58 is made of a flexible material such as natural rubber or a synthetic elastomer. This last method of fixing has the advantage of reducing the resistance of the ball 12 in torsion around an axis perpendicular to the costal grill of the patient and in bending in a direction perpendicular to the plate 14.

Furthermore, as shown in Figures 19 and 20, the flexibility of the joint allows the deformation of the support 54 and the inclination of the ball 12 during compression of the breast.

Advantageously, the ball 12 is capable of being deformed by bending in a direction peφendicular to the plate 14 under the action of a force applied in this direction. Thus, when the patient's breast is placed on the mammography device, the ball deforms and adapts to the anatomy of the breast. For example, the ball is deformed by bending of the plate 14 in contact with the breast. The ball undergoes a controlled deformation in the sense that, by construction, we choose how the shape of the ball changes. Figures 2 to 7 shows a first embodiment by which the ball is deformed under the action of the compressive force. In this embodiment, the compression ball 12 has a conformation

18 which allows the compression ball to deform when a bending force is exerted perpendicular to the plate. The location and intensity of the ball deformation is determined by the conformation performed. Figure 2 shows the compression ball 12 with the conformation.

Preferably the conformation 18 is on the rim 16. The conformation 18 of the rim 16 makes it possible to reduce the flexural strength of the plate 14 when a force is applied perpendicular to the plate 14. The conformation 18 locally modifies the cross section of the rim 16; at this point, the flexural strength of the flange decreases, thereby causing a reduction in the flexural strength of the plate 14. The flexural strength of the plate 14 locally decreases in the sense that the strength of the plate is lower in the zone located near the conformation 18 than in a zone of the plate 14 situated near the rim 16 without conformation. The conformation 18 is for example obtained by machining the molded ball 12 or during the molding of the ball 12. Typically, the conformation 18 has one or more openings through the rim 16. The opening or openings can be made through any part of the rim 16. Preferably, the opening is through the parts of the rim 16 which are not in contact with the patient so that the patient's skin is not pinched. Figures 3 to 7 show different embodiments of the opening without limitation. In Figures 3 to 5 the opening has the form of a slot; in Figure 7, the opening is a notch. According to Figure 6, the opening can also be circular.

In Figures 3 to 7, the conformation 18 has an opening. The figures show different relative positions of the fold 20 relative to the opening. In these figures, the fold 20 extends over the part 16b of the rim opposite to the part 16a of the rim in contact with the costal grill of the patient; the fold extends over a portion of the parts 16c and 16d which extend peφendicululaire to the costal grill partially support the fold 20. In top view, the fold 20 has a U-shape.

FIG. 3 shows the ball 12 in which the opening 18 is a slit with a closed contour, the largest dimension being parallel to the plate 14. The opening is through the part 16b of the flange 16, between the plate 14 and withdrawal 20.

Figure 4 shows a preferred embodiment of the ball 12 in which the opening 18 is a slot. The slot is made over the entire length of the part 16b and opens into at least one part, preferably the two parts, 16c, 16d adjacent to the part 16b. Part of the contour formed by the edge of the ball is then split. In the figure, on the parts 16c and 16d of the rim 16, the fold 20 extends beyond the slot. According to this variant, the flexural strength of the part of the plate 14 located under the slot is lower than that of the part whose rim does not have a slot. The advantage is that during compression of the breast, the front portion of the ball 12, compressing a thick part of the breast on the rib side, has greater resistance to flexion than the posterior part of the ball 12, compressing a part of the breast on the nipple side a priori less thick. The front part of the ball 12 lifts, which causes this part to rotate relative to the rear part of the ball, around an axis marking the border between the two parts. This allows an increase in the pressure of the rear part of the ball 12 on the part of the breast on the nipple side.

The slot may have edges along the largest dimension which are not parallel. For example, the lower edge of the slot can be curved, the curvature being able to be turned in the direction of the plate 14 or in the direction of the top of the slot. The lower edge of the slot can also have inclined planes so as to constitute a V turned in the direction of the plate 14 or in the direction of the top of the slot. The advantage of this form of slot is to provide a bending of the plate 14 when it compresses the breast; the part of the breast located near the nipple is thus better compressed. In the variants of FIGS. 5, 6 and 7, two opposite parts of the rim each have a conformation 18 having an opening. The openings are preferably symmetrical with respect to a parallel axis and equidistant from the opposite parts of the rim each having the opening. The plate 14 then has a strip extending from one opening to the other, the resistance to bending of the strip being less than the resistance to bending of the rest of the plate 14. The flange 16 may also have a series openings along one of its parts, reducing the flexural strength of the plate 14 in several zones along the rim. Preferably, these series are also symmetrical.

FIG. 5 shows the ball 12 in which the parts 16c and 16d have a slit with a closed contour, the largest dimension of each of the slits being parallel to the plate 14. The slits through the parts of the rim 16c and 16d are extend on either side of the end of the fold 20 over the parts 16c and 16d. The advantage of the shape of these openings is to increase the size of the strip in which the flexural strength is reduced. At least one of these slots opens into part 16b.

FIG. 6 shows the ball in which the parts 16c and 16d have an opening 18 in the form of a slit which is offset with respect to the end of the fold 20 on the parts 16c and 16d in the direction of the patient.

FIG. 7 shows yet another variant of the compression pad 12. The openings 18 are a notch. This form has the advantage of being easily machined and of offering greater flexibility to the portion of the ball 12 comprised between the patient and the notches. This is advantageous for patients sensitive to compression. The notch may have a substantially rectangular shape; the notch may have a V shape, the width of the notch narrowing in the direction of the plate 14 and the bottom of the notch having a round shape. The notch can be made between the ends of the parts of the rim 16, when the parts of the rim 16 are considered in a longitudinal direction; the notch can also be made along the entire length of part of the rim 16. The notch extends from the edge of the rim 16 opposite to the plate 14 and in the direction of the plate 14. The depth of the notches varies according to reducing the resistance of the desired plate 14. The depth of the notch can be interrupted before the intersection of the rim 16 and the plate 14. The depth of the notches can also extend to the bottom of the ball 12; in this case, the depth corresponds to the height of the rim 16. The rim 16 is interrupted, and the resistance to bending of the plate 14 at the level of the notch corresponds to the resistance to bending of the plate 14 without rim.

FIG. 8 shows a second embodiment of the compression device 10. In this embodiment, the ball 12 is made of different materials. The choice of materials is such that the materials have different rigidities. Thus, during compression of the breast, the ball has zones which deform differently depending on the material constituting the zones.

FIG. 8 represents the device 10 with the ball 12 and the support 54. The ball 12 comprises the plate and on its periphery, the rim 16. The rim 16 comprises the parts 16a, 16b, 16c, 16d. The part 16a is in contact with the rib grill of a patient, the part 16b is held by the holding member 56 of the support 54. The parts 16c, 16d extend between the parts 16a and 16b.

Advantageously, the rim 16 is partially made of a material different from the plate 14. The ball 12 is produced in two parts, for example by means of a bi-material injection. Preferably, the material B of the part 16a in contact with the rib rib of a patient is more flexible than the material A of the plate 14. This makes it possible to adapt to the curvature of the patient's chest which gives better comfort of the patient in contact with the ball during the radiography procedure. According to an example of distribution, the parts 16c and 16d adjacent to the part 16a in contact with the rib grill are partially of the same material B as the part 16a and partially of the same material A as the plate 14. This allows the bet 16a and the parts 16c and 16d of the same material as part 16a to be less rigid than the rest of the rim; this allows a portion of the plate 14 supporting the part 16a and the parts 16c and 16d made of the same material to be capable of being deformed by bending in a direction peφendicular to the plate 14 under the action of a force applied according to this direction. During compression of the breast, this portion of plate 14 close to the rib grill and compressing a greater thickness of the breast is more flexible and leaves the plane of the rest of the plate. The plate 14, and therefore the ball 12, deforms and adapts to the breast anatomy. Furthermore, the construction of such a ball is simple and inexpensive because it can be done by molding. FIG. 8 shows the separation 17 between the materials A and B. The separation between the two materials is positioned so as to control the deformation of the ball 12 as a function of the compression force and the anatomy of the patient but independently of the force with which the patient leans against the ball. The partition 17 extends along the bottom of the part 16a, at the border between the rim 16 and the plate 14. The partition 17 also extends across the parts 16c and 16d to the fork 56. Thus the portion of plate 14 between part 16a and the end of the fork 56, turned towards the patient, is more flexible than the portion of plate 14 on the side of the support and can deform during compression. The shape of the partition 17 is not limited to the example given in FIG. 8. For the choice of the material A constituting the plate 14, a person skilled in the art may take the following elements into account. Material A is transparent to allow precise positioning of the patient's breast, distinguishing the folds of the skin. The material A absorbs the least possible radiation emitted by the mammography apparatus so as not to reduce the quality of the shooting. Preferably, the material A does not include fiberglass, as this would reduce the quality of the shot. The material A preferably has a good fluidity at the injection to facilitate the homogeneity of thickness of the plate 14 and allow a good homogeneity of material with a portion of the rim 16. Also, the material A has a rigidity allowing a good spreading of the breast to favor its exposure to radiation (Young's modulus of the order of 1000 to 2400 MPa). For the choice of the material B constituting the plate 14, a person skilled in the art may take the following elements into account. The material B has no transparency constraint or even an X-ray absoφtion, since this material is only on the rim 16. Preferably, the material B has a high flexibility (same order of magnitude as above) to follow the shape of the costal grill. For this, the material B has a large deformation before plastic deformation and rupture, even at low thicknesses. This makes it possible to manufacture a ball with a thin and light rim but with a high elastic limit tension.

The most rigid material ensures the structural hold of the ball, while the most flexible material ensures the controlled deformation of the plate. According to an embodiment of the ball not shown in the figures, the part 16a of the rim 16 in contact with the rib rib of the patient can be more inclined towards the patient than previously described. The part 16a can be inclined at an angle between 2 ° and 10 ° with a plane peφendicular to the plate 14 to avoid asking for a systematic support force on the part of the patient. Preferably, the part 16a can be inclined by more than 5 ° with a plane peφendicular to the plate 14. The part 16a of the flange flares as one moves away from the plate 14. This part 16a is oriented towards the outside of the ball so as to compensate for the force of support of the patient against the ball. Another advantage is that part 16a requested by the patient and the tissues of the costal grill do not enter the field of view.

An advantage of these embodiments is that the contact surface between the skin of the breast and the underside of the plate 14 is increased, without risking masking part of the image of the tissues of the breast by the penetration of the part 16a in the field of shooting.

In addition, the movements of bending of the ball described can be accompanied by a movement of torsion of the ball so as to improve the adaptation to the anatomy and the compression of the breast. This also makes it possible to adapt to the location of the breast on the mammography device.

Advantageously, the support 54 is deformed. The ball can be rigid, in the sense that it is not subjected to a controlled deformation, or can be deformed in a controlled manner and described above. Thus, the support 54 makes it possible to orient the ball 12 so as to conform to the shape of the patient's breast while retaining control of the position of the part 16a by a more complex movement than a rotation about a fixed axis. The complex movement can be a rotation whose center and amplitude are variable according to the anatomy of the patient's breast and the compression force applied, but not according to the support force exerted by the patient on part 16a in the plane peφendicular to the rib grill and peφendicular to the direction of propagation of the X-rays - that is to say from front to back and from left to right for the patient.

FIG. 9 shows a third embodiment of the compression device in which the support deforms. In this embodiment, the holding member 56 is capable of being deformed by bending in a direction peφendicular to the plate 14 under the action of a force applied in this direction. In the example of a holding member 56 in the form of a fork, the latter is capable of being deformed by bending in a direction peicendicular to the plate 14 under the action of a force applied in this direction.

An advantage of this embodiment is that the contact surface between the skin of the breast and the underside of the plate 14 is increased, without risking masking part of the image of the tissues of the breast by the penetration of the part 16a in the field of shooting.

In FIG. 9, the arms 56c and 56d undergo a deformation by bending in a direction peφendicular to the plate 14. In this embodiment, the fork 56 is held in a recessed manner by the heel which allows the arms 56c and 56d to flex more easily. In the case where the holding member is a fork extending on either side of the ball 12, the ball and the support 54 are preferably both capable of deformation as is the case in Figure 9. If the holding member is U-shaped, only the support can be deformed to tilt the ball and adapt it to the anatomy of the breast.

By way of example, the holding member 56, for example in the form of a fork, is made of plastic material reinforced with glass fibers. This allows the holding member to deform elastically during compression.

The choice of plastic is guided by its elasticity for the desired bending, and which is compatible with the desired deflection of the plate 14. In addition, given the significant bending moment which is exerted on the support 54, it will be possible to choose the plastic material taking into account the maximum material tension before plastic deformation and the maximum deformation before plastic deformation and rupture. Furthermore, impact resistance properties can also be sought since the compression device can be a removable element of the mammography device and can escape from the hands of the manipulator and fall.

A material such as ULTEM 2200 brand material from GE Plastics can be used. It is loaded with 20% fiberglass. It allows a deflection of 25 mm between the parts 16a and 16b of the ball 12 at a compression force of 300N, with a safety margin of 2.7 relative to the breaking limit of the material.

Advantageously, the support 54 is liable to be deformed either by the flexion of the arms 56c and 56d, or by the torsion of the heel 55. At the junction of the heel 55 and the retaining member 56, a deformation combined by flexion and torsion takes place. This allows the compression device 10 to adapt to a breast disposed eccentrically relative to the ball.

Figures 10 to 13 show a fourth embodiment of the compression device in which the support is deformed.

According to this embodiment, the support 54 comprises a blade 61 fixed by embedding on one side to the holding member 56 and on the other to the heel 55. The blade 61 is liable to deform by bending under the action of a force applied in a direction peφendicular to the plate 14. Thus, the support 54 is deformed to improve the compression of the breast by the ball.

When a compressive force is applied and the breast is placed substantially in the middle of the ball, the blade 61 works in flexion. If the breast is off-center, the blade can deform by torsion under the action of a force applied in a direction peφendicular to the plate 14. Thus the compression device also adapts to the position of the breast on the mammography. The blade 61 may have a dimension parallel (width) to the part 16b equivalent to that of the heel 55. By choosing the thickness and the width of the blade 61, it is possible to control the orientation of the ball in the plane peφendicular to the rib grill and peφendicular to the direction of X-ray propagation - that is, back to front and left to right for the patient.

Alternatively, the support 54 may include a stop 60, the blade 60 being able to deform in contact with the stop 60. FIG. 11, detail D of FIG. 10, shows the stop 60. FIG. 11 also shows the blade 61 in different positions. The blade in solid lines is the rest position, without compression. The dotted position is a position under intermediate compression. The dashed position is the position under maximum compression in contact with the stop 60. Thus, the blade 61 comes to rest against the stop 61 as the compression force increases; the blade 61 follows the shape of the stop. This makes it possible to control the movement of the support as a function of the compression force. In particular, this makes it possible to control the forward / backward movement of the ball with respect to the patient and to prevent the penetration of the part 16a into the field of view.

Figures 12 and 13 show the movement of part 16a of the ball relative to the rest position without compression. On the abscissa is shown the compression force and on the ordinate the displacement of the part 16a in height. FIG. 12 shows the movement without stop 60. On the graph, a limit 30 indicates a maximum movement for the part 16a before entering the field of view. This limitation is advantageous for small breasts to prevent the tissues from being pushed towards the outside of the ball on the side of the wall 16a, which would reduce the quantity of tissues imaged. This limitation allows the same ball to be used for all breast sizes. We see that for a MAX compressive force, the part 16a exceeds the displacement threshold, which is interesting for larger breasts. FIG. 13 shows the displacement with stop 60. It can be seen that for a MAX compression force, the part 16a does not exceed the displacement threshold, which is advantageous for smaller breasts.

Figures 14 to 16 show a fifth embodiment of the compression device in which the support is deformed.

In this embodiment, the support 54 further comprises a set of links 61 to 64 articulating the retaining member 54 relative to the heel 55, the set of links deforming under the action of a force applied according to a direction peφendicular to the plate 14. The deformation of this assembly is the deformation of the support 54. An advantage is to allow the ball 12 to have a movement composed of a rotation and a translation of the ball. This movement is equivalent to a rotation with variable center and axis. Another advantage of this embodiment is that the contact surface between the skin of the breast and the underside of the plate 14 is increased, without the risk of masking part of the image of the tissues of the breast by the penetration of part 16a in the field of shooting. Figure 14 shows an example of this set of links. The support comprises a set of four links 61 to 64. The links are articulated at the heel 55 and at the holding member 56. The links are not all of the same length and are articulated at the heel 55 and at the member holding 56 at different heights and in different places. On the member 56, the rods are attached one on the upper face, the other on the opposite facing face, in a vertical direction. The foundry of part 56 may include local protuberances to reinforce the attachment point where fairly significant stresses are exerted. From this point of view, we set aside the attachment points as much as possible. On the heel 55, the links are attached to the rear face on reinforcement points of the foundry, respectively in the vicinity of the highest point and the lowest point of the foundry. The precise positioning of the rods determines the path of the plate 12. Thus, when the breast is compressed, the articulated rods will allow the movement of the part 16a near the rib grill to compress the breast with the largest possible area of the ball. Furthermore, if the breast is off-center with respect to the ball, the articulated links at different heights allow a rotational movement of the ball which adapts to the position of the breast.

Alternatively, the support 54 comprises a set of blades 65, 66 articulated between the retaining member 56 and the heel 55, articulating the retaining member 56 relative to the heel 55, the assembly deforming under the action of a force applied in a direction peφendicular to the plate 14. The deformation of this assembly is the deformation of the support 54. According to FIGS. 15 and 16, the assembly comprises two blades 65 and 66 each articulated according to two edges at the heel 55 and at the holding member 56. Preferably, the blades do not deform by bending but can pivot when a compressive force is exerted.

A blade 65 is capable of coming into contact with a stop 67. The stop is preferably flexible in elastomer with a hardness, for example of 70-80 Shore. The other blade 66 can advantageously be connected to a return spring 68 to bring the compression device to a rest position after shooting.

Figure 15 shows a rest position. Figure 16 shows a compression position in which the ball is deflected to compress the breast with the largest possible area of the ball. The deflected position of the ball is shown in dotted lines. During compression, the blade 65 gradually abuts against the stop 67 which limits the movement of the blades and the inclination of the ball. The flexibility of the stop allows you to adjust the inclination of the ball: the higher the hardness of the stop, the less the ball will be inclined.

FIG. 21 shows a mammography apparatus 38. It makes it possible to carry out an x-ray of the breast of a patient. The mammography apparatus comprises a tube 40 emitting X-rays in one direction and an image receptor 42 adapted to receive the rays coming from the tube 40. The compression device 10 comprising the ball 12 and the support 54 is mounted movably between the tube 40 and the receiver 42. The compression device is movable in translation between the tube 40 and the receiver 42. The support 54 makes it possible to translate the ball 12 in the direction of the X-rays so as to compress the patient's breast against the image receptor 42. The ball makes it possible to transform the translational movement of the compression device into a pressure applied to the breast, with a homogeneous distribution of the pressure over the breast. In this way, the breast is spread over a larger area. Thus compression of the breast makes it possible to reduce the thickness of the breast, under conditions that can be supported by the patient, and thus to reduce the time of exposure to X-rays. Furthermore, compression causes spreading of the glandular structures inside. breast, reducing the risk of image supeφosition of these structures. The readability of the image and the detectability of possible lesions are improved. In addition, compression of the breast ensures its immobility during delivery, the duration of which can reach or exceed a duration of one or even several seconds. The device also makes it possible to use the mechanical position of the compression pad to deduce therefrom the mechanical thickness of the compressed breast, this data being able to be used in an automatic exposure device.

When the breast is placed on the receiver 42, the compression device 10 is activated. In particular, the ball 12 is moved to the receiver 42 to compress the breast. During compression of the breast, the ball 12 or the support 54 deforms. The deformation of the ball can be obtained by the conformation 18 or by different constituent materials of the ball. For example, according to conformation 18, the ball undergoes a bending movement so as to adapt the compression of the breast to the shape and size of the latter. The difference in height between different portions of the ball 12 can however be controlled so as to be less than the standards in force. The deformation of the support 54 can be obtained by the deformation of the holding member 56, by the deformation of the fork, by the deformation of the set of links or of the articulated blades or by the deformation of the blade 61.

The compression device 10 allows the ball 12 to be tangent to the costal grill of the patient without the edge of the ball entering the field of the image carried out during the mammography. The ball 12 is chosen according to the characteristics (dimensions, stiffness, etc.) of the breast so as to have a ball size 12 allowing optimal compression of the breast from the rib grill to the nipple and transversely. For example, the ball 12 has a part 16b of the rim 16, opposite to the part 16a of the rim 16 in contact with the rib rib of a patient, which has the conformation 18. The conformation 18 of the part 16b of the rim 16 can lead to at least one part 16c, 16d of the rim 16, adjacent to the part 16b. According to another ball, the ball 12 has at least a part 16c, 16d of the rim 16 between the rib grill and the support 54 which has the conformation 18 opening into the part 16b of the rim 16 opposite the rib grill.

Only the ball 12 can be removed from the support 54 and replaced by another. Advantageously, the compression device 10 is removable, and in particular the support 54 is removable. This makes it possible to replace the compression device to adapt it to the size of the breast as well as to the characteristics of the latter. The mammography apparatus may include a set of compression devices, the conformations of which give these devices properties adapted to the characteristics of the breast. The support 54 is for example mounted on the device 38 using a slide link. The connection can be made in a dovetail or by a tenon and a mortise between the mammography apparatus and the heel 55. The image receiver 42 is for example a cassette containing a reinforcing screen film assembly or by an electronic receiver ensuring the conversion of the radiant image into a signal used in digital form.

Of course, the present invention is not limited to the embodiments described by way of example. Thus, the various embodiments of deformation of the ball or of the support can be considered independently of each other or in combination.

Claims

1. A compression device of a mammography apparatus comprising: - a compression ball (12) having a plate (14) and a flange (16) projecting around the periphery of the plate (14)

- A support (54) adapted to connect the ball (12) to the mammography apparatus, the ball (12) or the support (54) being liable to deform under the action of a force applied in a peφendicular direction to the plate.

2. The device according to claim 1, characterized in that the ball (12) is capable of being deformed by bending in a direction peφendicular to the plate (14) under the action of a force applied in this direction.

3. The device according to claim 2, characterized in that the flange (16) has a conformation (18) locally reducing the resistance to bending of the plate (14) in a direction peφendicular to the plate (14).

4. The device according to claim 3, characterized in that the conformation (18) has an opening through the flange (16).

5. The device according to claim 3 or 4, characterized in that the conformation (18) has a slot through the flange (16).

6. The device according to one of claims 2 to 5, characterized in that the ball

(12) is made of different materials.

7. The device according to claim 6, characterized in that the flange (16) is partially made of a material different from the material of the plate (14).

8. The device according to claim 6 or 7, characterized in that the material of the part (16a) of the rim (16) in contact with the rib rib of a patient is more flexible than the material of the plate (14).

9. The device according to one of claims 6 to 8, characterized in that the flange (16) comprises parts (16c, 16d), adjacent to a part (16a) in contact with the rib grill of a patient, which are partially of the same material as the part (16a) in contact with the rib rib of a patient and partially of the same material as the plate (14).

10. The device according to one of the preceding claims, characterized in that the support (54) comprises: - a holding member (56) of the ball, and

- a heel (55), connected to the holding member and which is adapted to be connected to a mammography device.

11. The device according to claim 10, characterized in that the holding member is capable of being deformed by bending in a direction peφendicular to the plate (14) under the action of a force applied in this direction.

12. The device according to claim 11, characterized in that

the holding member (56) is a fork,

- the ball (12) is fixed to the support (54) by parts (16c, 16d) of the rim (16) adjacent to a part (16a) in contact with the rib rib of a patient, the parts (16c, 16d) adjacent being partially supported by the fork (56),

- The fork (56) is capable of being deformed by bending in a direction peφendicular to the plate (14) under the action of a force applied in this direction.

13. The device according to claim 12, characterized in that the fork (56) is made of plastic material reinforced with glass fibers.

14. The device according to one of claims 11 to 13, characterized in that the ball

(12) comprises a fold (20) projecting from the rim (16).

15. The device according to claim 14, characterized in that the holding member (56) comprises a groove (57) for receiving the fold (20) of the ball (12).

16. The device according to one of claims 10 to 15, characterized in that the support (54) further comprises a blade (61) fixed by embedding on one side to the holding member (56) and the 'other to the heel (55), the blade being capable of being deformed by bending under the action of a force applied in a direction peφendicular to the plate (14).

17. The device according to claim 16, characterized in that the blade (61) is liable to deform by torsion under the action of a force applied in a direction peφendicular to the plate (14).

18. The device according to claim 16 or 17, characterized in that the support (54) comprises a stop (60), the blade (61) being capable of deforming in contact with the stop

(60).

19. The device according to one of the preceding claims, characterized in that the support (54) further comprises a set of connecting rods articulating the retaining member with respect to the heel, the assembly deforming under the action of a force applied in a direction peφendicular to the plate (14).

20. The device according to one of the preceding claims, characterized in that the support (54) further comprises a set of blades articulated between the heel and the retaining member, articulating the retaining member with respect to the heel, the whole deforming under the action of a force applied in a direction peφendicular to the plate (14).

21. The device according to one of the preceding claims, characterized in that the ball (12) and the support (54) are liable to deform under the action of the force applied in a direction peφendicular to the plate.

22. A mammography device comprising:

- a tube (40) emitting X-rays in one direction, - an image receptor (42) adapted to receive the rays coming from the tube,

- The compression device of one of the preceding claims movable between the tube (40) and the receiver (42).

23. The apparatus of claim 22, characterized in that the ball (12) has a part (16b) of the rim (16), opposite to the part (16a) of the rim (16) in contact with the costal grill of a patient, who has the conformation (18).

24. The apparatus of claim 23, characterized in that the configuration (18) of the part (16b) of the flange (16) opens into at least one part (16c, 16d) of the flange (16), adjacent to the part (16b).

25. The apparatus of claim 24, characterized in that the ball (12) has at least a portion (16c, 16d) of the flange (16) between the rib grill and the support (54) which has the conformation (18 ) opening into the part (16b) of the rim (16) opposite the rib grill.

26. The apparatus of one of claims 22 to 25, characterized in that the apparatus comprises a set of compression devices, the conformations of which confer on these devices properties adapted to the characteristics of the organ.