FR2881337A1 - Breast imaging method for premature screening of e.g. cancerous tumors, involves determining, before acquisition of image, X-field and compression plate positions based on angle between patient longitudinal axis and breast support normal - Google Patents

Abstract

The method involves determining, before acquisition of a radiography image, position of X-ray field and/or position of compression plate (13) along proximal edge of an image receiver (2) and/or an image receiver zone that is analyzed for determining exposition parameters. The positions are determined based on an angle formed between longitudinal axis of the patient and normal at breast support (3). The zone is considered as containing the radiography image for acquiring, processing, storing, displaying or transmitting the image. An independent claim is also included for a mammography apparatus for implementing imaging method.

Description

TITLE

  FIELD OF THE INVENTION The present invention relates to the field of radiological imaging which makes it possible to visualize a breast of a patient. . The invention more particularly relates to a radiological imaging method in which certain parameters of the mammography apparatus are determined prior to the acquisition of the radiographic image according to a predefined function of the angle called angulation formed between the longitudinal axis of the patient and the breast support plane of said mammography apparatus.

  The present invention further relates to a mammography apparatus for carrying out said method.

  BACKGROUND OF THE INVENTION In the field of medical imaging, breast radiography or mammography is known for its effectiveness in the early detection of mammary diseases and in particular in that of cancerous tumors. X-ray of the breast is obtained by means of a mammographic X-ray machine with an X-ray source, a breast support positioned between the X-ray source and an image receptor consisting of either X-ray film or a digital image receiver, said image receiver and the X-ray source being integral with an arm mounted sliding on a column and rotating about an axis, control means, data acquisition means, a radiographic image and image display means, at least one radiofrequency compression plate mounted on a slide carriage between the X-ray source and the image receiver, and control means. The compression plate, also known as the compression pad, compresses the breast against the breast support to improve image quality and reduce radiation doses absorbed by the patient. The compression plates are interchangeable and have various shapes and sizes to meet specific needs such as for example perforated compression plates for biopsies or small plates to strongly compress an area of the breast in which the presence of a tumor is suspected, or more generally to be adapted to the dimensions of the patient's breast while facilitating access to the operator when positioning the breast between the breast support and the plate compression and during breast compression.

  The compression plate may advantageously be movable not only in a direction parallel to the direction of the X-rays, but also in a direction parallel to the proximal edge of the image receptor intended to bear on the costal grill of the patient. Such a characteristic makes it possible to adjust the positioning of the compression plate when using specific compression plates making it possible to promote access to the axillary areas of the patient. The proximal edge of the image receptor is the edge closest to the central axis of the patient. This is the case, for example, of the Senographe 2000D mammography machine marketed by the company General Electric Medical System.

  The image receptor of the mammography apparatus consists of either a removable cassette comprising, for example, an X-ray intensifying screen held in contact with a photographic film, said cassette being in different dimensions depending on the size of the breast to be radiographed, or, since recently, in a digital sensor. These removable cassettes are housed in a cassette holder comprising the breast support tablet, an anti-scattering grid type Bucky grate and a drawer adapted to receive the cassettes. Typically, the removable cassette mammography machines are able to alternately receive cassettes holders of two sizes, each allowing the use of the corresponding size cassette. The smaller of the two sizes, intended for films of a size of approximately 18 cm x 24 cm, and usually used with a compression plate of the same dimensions 18 cm x 24 cm, is intended for the examination of small or medium sized breasts. . This size is sufficient for breast examination of about two-thirds of the female population. The larger of the two cassette holders, provided for films of dimensions substantially 24 cm x 30 cm, and usually used with a compression plate of the same dimensions 24 cm x 30 cm allows the examination of larger breasts.

  Digital mammography devices have the advantage of providing contrast resolution of the superior X-ray image, especially for dense breasts, to allow radiographic images to be archived on a computer medium, to reduce the dose of radiation, accelerate mammography and no longer require a delicate chemical treatment and subject to drift radiographic films.

  However, this type of device has the disadvantage of imposing a single sensor size, because of technical constraints such as the accuracy of the alignment, the connection or the weight, but above all economic, these detectors having a cost Student. A first possibility is to optimize the examination of the majority of patients using a format corresponding substantially to that of small cassettes of dimensions substantially 18 cm x 24 cm. If we want format compatibility with almost all the population, it is necessary to use a detector whose dimensions correspond substantially to those of large cassettes. On the other hand, it results from this choice an increase in weight and a lengthening of the procedure resulting from the need to carry out additional steps, particularly for radiographic imaging of small breasts, that is to say the majority of patients, in mediolateral (MLO) or lateral view. In fact, there are three distinct types of views: craniocaudal shooting, which consists of irradiating the breast from above so as to obtain a view of the gland in the axis from the head to the foot of the patient; side view which consists of irradiating the breast by the side so as to obtain a view of the gland in an axis transverse to the body of the patient and finally oblique medio-lateral shooting (MLO) which consists of irradiating the breast at an angle of oblique view. However, for a mid-lateral shooting (MLO) of a small breast, the operator places the upper angle of the image receptor in the patient's axillary hollow and, so as to have good access to the breast. during set-up and compression, use the standard compression plate (18 cm x 24 cm). As a result, it is generally impossible to center the breast between the compression plate and the breast support extending to the right of the image receptor which is larger (24 cm x 30 cm) than the plate compression.

  In order to overcome this drawback, international patent application WO 03/037046 proposes a method for performing a mammography of a patient consisting in providing a digital image receiver and an X-ray emitting X-ray source on said receiver, position the patient's breast between the X-ray source and the receiver, eccentrically along the proximal edge of the receiver, to compress the breast against the receiver by means of a compression plate which is also eccentrically mounted along the edge proximal to the receiver and to take a radiographic image of the breast. In particular, the automatic exposure control and X-ray beam collimation parameters are defined according to the position of the compression plate which can be adjusted laterally, i.e., along the proximal edge of the X-ray beam. receiver.

  In order to remedy this same drawback, US Pat. No. 6,816,569 discloses a radiodiagnostic device for mammography comprising an arm for an X-ray emission tube, a fixation for an image receptor and a support table. the breast support, which is slidable laterally with respect to the image receptor, and a compression plate which is connected to the arm and can: slide along the latter between the X-ray emission tube and the image receiver, the arm being rotatably mounted around a horizontal shaft mounted in a stand. The breast support table is slidably formed laterally with respect to the image receiver from a first central position in which the two short sides of the image receptor are at the same distance from the sides of the breast support table until two eccentric positions in which one of the short sides of the image receiver is substantially aligned with one of the short sides of the breast support table and the compression plate.

  These solutions, while allowing the use of a single size image receiver regardless of the dimensions of the compression plate used, thus improving the ergonomics of the work of the operator, do not provide sufficient ergonomics. Indeed, many parameters must be introduced manually by the operator. The latter, after having chosen and put in place the appropriate compression plate, must adjust the X-ray field, the position of the compression plate along the proximal edge of the image receptor by moving the compression plate parallel to the edge proximal to said receiver, selecting the area of the image receptor considered to contain the image for acquisition, processing, recording, display or transmission of the radiographic image, and finally selecting the area of the analyzed receptor to determine the exposure parameters. The operator must, moreover, introduce the characteristics of the compression plate such as its shape and dimensions. It is also necessary to inform the type of shooting performed, namely a cranio-caudal (CC), lateral or medio-lateral (MLO).

  All these operations and these parameters introduced by the operator by control means in the control means of the mammography machine are sources of waiting for the patient. Moreover, the operator is likely to make seizure or adjustment errors that may require the taking of a new radiographic image involving a new dose of radiation or be confusing when analyzing images that may eventually lead to on a wrong diagnosis. Finally, since this parameterization must be carried out for each new patient, the routine nature of these parameterization operations may induce a phenomenon of fatigue for the operator which increases the probability of errors when entering these parameters.

BRIEF DESCRIPTION OF THE INVENTION

  One of the aims of the invention is thus to remedy these drawbacks by proposing a method of imaging a breast of a patient and a mammography apparatus for carrying out said method.

  According to the invention, there is provided a method of imaging a breast of a patient by X-ray radiography using a mammography apparatus having an X-ray source, a breast support positioned between the source of X-ray and an image receiver, said image receiver and the X-ray source being integral with an arm mounted in rotation about an axis, control means, acquisition means and display means radiographic image, at least one transparent radio compression plate positioned between the X-ray source and the image receiver and slidably mounted on a carriage so as to perform compression of the breast of the patient, and control means, said method comprising at least positioning the patient's breast between the x-ray source and the receiver and compressing the breast between the breast support and the compression plate; said method is remarkable in that the position of the X-ray field and / or the position of the compression plate along the proximal edge of the image receiver and / or the area of the image receiver analyzed to determine the parameters of the exposure and / or the image receptor area considered to contain the image for acquisition, processing, recording, display or transmission of the radiographic image, so-called geometric configuration parameters of the image apparatus, are determined prior to the acquisition of the radiographic image according to a predefined function of the angulation angle formed between the longitudinal axis of the patient and the normal to the breast support passing through the focus of the ray source X. The values of these geometric configuration parameters of the apparatus as a function of angulation are prerecorded in the control means of said apparatus.

  According to a first variant embodiment, the operator selects an angulation which is transmitted to the control means which determine the geometric configuration parameters of the apparatus and rotate the arm carrying the image receiver and the X-ray source. until angulation is reached.

  According to another variant embodiment, the geometrical configuration parameters of the apparatus are determined in real time during the rotation of the arm provided by motorized drive means controlled by the control means.

  According to a last variant of the method according to the invention, the geometrical configuration parameters of the apparatus are determined when the arm, driven in rotation manually or not, stops in a defined position during a predefined time interval.

  Of course, the values of these geometric configuration parameters of the apparatus thus determined are then transmitted to the various means of the apparatus to bring the various means of the apparatus into conformity with these values.

  All the geometric configuration parameters of the apparatus determined as a function of the angulation are advantageously transmitted to display means and the operator can modify said parameters prior to the acquisition of the radiographic image.

  Another subject of the invention relates to a mammography apparatus for carrying out the method, comprising an X-ray source, a breast support positioned between the X-ray source and an image receptor, said image receptor. and the X-ray source being integral with an arm mounted in rotation about an axis, control means, acquisition means and means for viewing the radiographic image, at least one transparent radio compression plate positioned between the X-ray source and the image receptor and slidably mounted on a carriage so as to effect compression of the patient's breast, and control means, remarkable in that it comprises means for determining, prior to the acquisition of the X-ray image, the position of the X-ray field and / or the position of the compression plate along the proximal edge of the image receptor and / or the area of the image receptor analyzed to determine the exposure parameters and / or the area of the image receptor considered to contain the image for the acquisition, processing, recording, display or transmission of the radiographic image called geometric configuration parameters of the mammography apparatus according to a predefined function of the angulation angle formed between the longitudinal axis of the patient and the normal to the breast support passing through the focus of the X-ray source.

BRIEF DESCRIPTION OF THE DRAWINGS

  Other advantages and features will become more apparent from the following description, of several variant embodiments, given by way of non-limiting examples, of the method of imaging an organ or an organ part by radiography. digital and mammography apparatus embodying said method according to the invention, from the attached drawings in which: - Figure 1 is a schematic perspective view of a mammography apparatus according to the invention, - FIG. 2 is a perspective view of a large compression plate of the mammography apparatus according to the invention, FIG. 3 is a perspective view of an alternative embodiment of a small compression plate of FIG. FIG. 4 is a schematic front view of the mammography apparatus according to the invention in oblique medio-lateral shooting position, FIG. 5 is a diagrammatic representation of the mammography apparatus according to the invention. above a small compression plate mounted on a support provided with means for driving said compression plate parallel to the proximal edge of the image receptor of the mammography apparatus according to the invention; FIGS. 6B are representations in projection on the image receptor of the mammography apparatus according to the invention of a large breast and a small breast respectively during a craniocaudal shooting, FIGS. 7A and 7B are representations in projection on the image receiver of the mammography apparatus according to the invention of a large breast and a small breast respectively during an oblique medio-lateral shooting.

  DETAILED DESCRIPTION OF THE INVENTION

  With reference to FIG. 1, the mammography apparatus 1 according to the invention conventionally consists of a digital image receiver 2, approximately of dimensions 24 cm × 30 cm for example, a breast support plate 3 extending between the image receiver 2 and an X-ray source 4 emitting X-rays on the image receiver 2, said image receiver 2 and the X-ray source 4 being respectively positioned at the ends of a shaped arm The image receptor 2 comprising a bucky gate, not shown in FIG. 1, and provided with a protective cover whose upper surface forms the breast support plate 3, is integral with the end of the arm 5, said breast support 3 being advantageously removable and extending just above the image receptor 2. This arm 5 is able to be moved along a vertical column 6. In addition, this arm 5 is rotatably mounted about an axis 7 orthogonal to said neck The mammography apparatus 1 comprises an adjustable collimator 8 positioned at the exit of the X-ray source 4. The mammography apparatus 1 further comprises control means 9 connected to the X-ray source 4 , collimator 8, image receiver 2, acquisition means 10 and display means 11. Control means 12 such as a keyboard, a mouse, control buttons or the like are connected to means of control 9.

  With reference to FIGS. 1 and 2, the mammography apparatus comprises a rectangular compression plate 13, obtained in an X-ray transparent material, such as polycarbonate, for example, and having a peripheral rim 14. A U-shaped stirrup 15 is secured on the peripheral rim along the distal edge of the compression plate 13 and on a portion of the lateral edges of said compression plate 13. The stirrup 15 is secured to the end of an arm 16 whose another end comprises appropriate securing means to a support 17 fixed to a carriage 18 movable between the x-ray source 4 and the image receptor 2 so that the compression plate 13 extends parallel to the image receptor 2 and is able to be moved between the image receiver 2 and the X-ray source 4, in the X-ray propagation direction as indicated by the arrows a of FIG. 1. This compression plate 13 rectangular has dimensions substantially 24 cm x 30 cm, identical to the dimensions of the image receptor 2, and is used for large breasts. Note that, for taking a radiographic image of a large breast requiring the use of a compression plate 13 of the same dimensions as the image receptor 2, the position of the X-ray field remains unchanged , the compression plate 13 is centered, its lateral edges extending to the right of the lateral edges of the image receptor 2, the zone of the image receptor 2 considered to contain the image for the acquisition, the treatment, the The recording, display or transmission of the X-ray image consists of the entire surface of the image receiver 2.

  Referring to Figures 1 and 3, the mammography apparatus comprises, for small breasts, a compression plate 13 having dimensions substantially 18 cm x 24 cm and a substantially rectangular shape. The arm 16 is secured to the U-shaped stirrup 15 fixed along the distal edge of the compression plate 13 by a slideway 19 so as to cause said plate 13 to translate parallel to the proximal edge of the image receptor 2, that is to say in a direction perpendicular to the direction of propagation of X-rays, as indicated by the arrow b of FIGS. 1 and 3. In order to translate the compression plate 13 in translation parallel to the proximal edge of the receiver of image 2, the mammography apparatus advantageously comprises means for driving the compression plate 13 which may consist of a motor provided with a toothed pinion cooperating with a rack integral with the distal edge of the compression plate 13 by example.

  According to a preferred embodiment of the mammography apparatus 1 according to the invention, with reference to FIGS. 1 and 5, the drive means of the compression plate 13 are housed in the support 17 fixed to the carriage 18. These drive means consist of a mass 20 slidably mounted on a rail 21 extending parallel to the proximal edge of the image receptor 2 and provided with ball bushings 22 to limit friction. This mass 20 is connected by two cables 23a and 23b cooperating with a pulley 24a and 24b respectively to a guide 25 sliding on a second rail 26, which extends parallel to the first rail 21, and carrying the arm 16 of the compression plate 13 so that the angulation of the arm 5 provides a displacement of the mass 20 along its rail 21 which drives in translation the guide 25 and, thus, the compression plate 13 parallel to the proximal edge of the image receptor 2 in the opposite direction to mass 20.

  It goes without saying that the mass 20 can be connected to the guide 25 by any appropriate means such that the displacement of the mass 20 causes the displacement of the guide 25 without departing from the scope of the invention.

  Note that said mass 20 is greater than the mass of the assembly formed by the compression plate 13, its arm 16 and the guide 25. The latter advantageously comprises ball sockets 27 or similar to reduce friction. In addition, the rail 26 comprises at its free ends a stop 28 and 29, respectively, to limit the displacement of the compression plate 13.

  It is obvious that the drive means of the compression plate 13 may consist of any other means well known to those skilled in the art such as, for example, a belt and pulleys or gears, a screw without end or the like, without departing from the scope of the invention.

  According to an alternative embodiment, not shown in the figures, the compression plate 13 can be driven in translation along the proximal edge of the image receptor 2 by the arm 16 which is able to slide on the support 17, preferably by motorized means. In the same way as above, the drive means of the arm 16 relative to the support 17 may consist of any suitable means well known to those skilled in the art.

  Moreover, alternatively and not preferentially, the compression plate 13 can be driven manually by the operator parallel to the proximal edge of the image receptor 2, and then be locked in translation, when the compression plate 13 has reached the position desired, by a locking wheel 30 (Figure 3) or by any suitable locking means. These suitable locking means may for example consist of a spring system on which bears a ball that is housed in a recess formed in the compression plate 13, the latter having a plurality of recesses corresponding to the different positions of the compression plate in position. cranio-caudal (CC) and mid-lateral positions (MLO), or even in an electromagnetic locking system. Preferably, each compression plate 13 intended to be manually moved by the operator comprises a set of stops or notches in such a way that said operator moves the compression plate 13 until it comes to bear on said stop or that the locking means are housed in said notch corresponding to the position along the proximal edge of the image receptor 2 determined by the control means 9.

  According to the preferred embodiment of the invention in which the compression plate is driven in translation by motorized means, the position of the compression plate 13 is determined by the control means 9 according to the angulation, c that is to say according to the angle 8 formed between the longitudinal axis of the patient and the normal to the breast support 3 passing through the focus of the X-ray source 4. In the particular embodiment, the angle 8 corresponds to the angle formed between the column 6 and the arm 5 which carries the image receiver 2 and the X-ray source 4. This angle 8 is, moreover, equal to the angle formed between the surface of the image receiver 2 and the horizontal H as shown in FIG. 4.

  According to an alternative embodiment of the mammography apparatus 1 according to the invention, the latter comprises at least one indicator light whose position along the distal edge of the compression plate 12 is determined as a function of the angulation. operator manually moving or using the motorized drive means the compression plate 13 until said indicator light is aligned with a reference mark affixed to the compression plate 13, along the distal edge of said plate 13 for example.

  The compression plates 13, shown in FIGS. 2 and 3, may advantageously comprise identification means capable of cooperating with reading means connected to the control means 9 in order to adjust the dimension of the X-ray field. These means identification, not shown in the figures consist of a relay actuator and the reading means consist of a mechanical relay, magnetic or optical as described in the French patent application FR 2 844 985 for example According to an alternative embodiment of the mammography apparatus 1 according to the invention, the identification means consist of a bar code 31, such as a self-adhesive label provided with a bar code in one or two dimensions, such as the bar codes known under the names 3-DI, ArrayTag, Aztec, Code Codablock, Code 1, Code 16K, Code 49, CP Code, Data Matrix and PDF 417 for example, applied on the arm 16 of the compression plate 13, readable by a manual reader bar code 32 (Figure 1) connected to the control means 9 of the mammography apparatus 1. Thus, after placing the compression plate 13, the operator reads the bar code 31 by means of the reader 32 which transmits the information to the control means 9. The characteristics of the compression plate 13 such that its shape, its dimensions and its mechanical characteristics corresponding to the bar code 31 read are recorded in the means of control 9.

  It is obvious that the bar code reader 32 may consist of a fixed fixed reader, for example of the column 6 of the mammography apparatus 1, the operator presenting the bar code 31 of the compression plate 13 in front of the reader of bar code 32 prior to its positioning between the x-ray source 4 and the image receiver 2. Particularly advantageously, the bar code reader 32 is secured to the support 17 carrying the compression plate 13 so that when the operator positions the compression plate 13 on the support 17, the bar code 31 is read automatically.

  Moreover, it goes without saying that the position and the dimension of the X-ray field as a function of the characteristics of the compression pad 13 used may be indicated by the operator using the control means 12.

  According to another variant embodiment, not shown in the figures, the identification means consist of a memory unit in which the information relating to the type and the dimensions of the compression plate 13 that can be read by the means is recorded. control 9 through a wired link or not. The memory unit consists for example of a USB key secured to the compression plate 13 in which are recorded either a reference or the shape, dimensions and mechanical characteristics of the compression plate 13 and adapted to be introduced into a port USB connected to the control means 9. These recorded mechanical characteristics will allow the control means 9 to manage the reliability of the compression plate 13 which, over time, given the successive uses, presents a risk of fatigue that can lead to the broken.

  Particularly advantageously, information relating to the number of operations and / or the compression force used and / or the calibration data used 1 to improve the accuracy of the determination of the position of the compression plate 13 or the like are suitable for be recorded in the memory unit integral with said compression plate 13. This information can be transmitted to the control means 9 and / or received, said information being transmitted by said control means 9, by any appropriate means well known to the user. Those skilled in the art such as, for example, means for receiving and transmitting data connected to the memory unit able to cooperate with means for transmitting and receiving data connected to the control means 9 or still more wired means provided with connectors. These connectors are preferably incorporated in the attachment means of the arm 14 carrying the compression plate 13 and in the complementary fastening means secured to the support 17 on which the compression plate 13 is fixed. It will be observed that the memory unit can for example consist of a chip card incorporated the free end of the arm 16 of the compression plate 13 and whose terminals are supported on a connector incorporated in the support 17.

  In order to be able to determine the geometric configuration parameters of the mammography machine, it is necessary to measure the angulation. In this regard, the measurement of the angulation is preferably determined from a control software, from the means for controlling the rotation of the arm 5 or even from the motor and the rotary drive servomotor. the arm 5 of the mammography apparatus 1 provided with motorized means for rotating the arm 5. The measurement of the angulation is then transmitted to the control means 9 either in real time or when the arm 5 reaches a position d predefined angulation, the operator having introduced this angulation position using the control means 12, or when the arm 5 stops in a defined position for a predefined time interval, the operator controlling the rotation of the arm 5 until it reaches a satisfactory angulation for taking the X-ray.

  According to an alternative embodiment, in order to measure the angulation, the mammography apparatus 1 comprises, with reference to FIG. 1, means for measuring the angulation consisting of an angular sensor 33 such as a potentiometer or an optical coder , for example, integral with the axis of rotation 7 of the arm 5 and connected to the control means 9.

  It goes without saying that the angular sensor 33 may be substituted by any other means of measuring an angle such as an inclinometer for a mammography apparatus consisting of an arm 5 mounted on a vertical bracket.

  The operation of the mammography apparatus 1 implementing the method according to the invention will now be explained with reference to FIGS. 1 to 8.

  The operator previously defines the shooting of the radiographic images that he wishes to produce, namely a cranio-caudal (CC), lateral or medio-lateral (MLO) and chooses the appropriate compression plate 13 according to the size of the patient's breast and / or depending on the examination phase.

  The operator firstly secures the compression plate 13 chosen on the support 17, said compression plate 13 used being identified by the control means 9 by means of the bar code 31 read by the bar code reader 32. Said means control 9 thus take into account the characteristics of the compression plate 13 such as its shape, dimensions and mechanical characteristics. In this case, the compression plate 13 chosen is approximately 18 cm x 24 cm as shown in FIG.

  It is obvious that the compression plate 13 used can be automatically identified by any suitable means such as, for example, a relay actuator and a mechanical, magnetic or optical relay forming reading means as described in the French patent application. FR 2,844,985, a memory unit and a transceiver or the like.

  In addition, it goes without saying that the compression plate 13 used can be identified manually, the operator entering in the control means 9 the reference of said plate 13 by means of a keyboard or a command button or by connecting a USB key, integral with the compression plate 13, in which is recorded the identification of said plate 13 in a USB port connected to the control means 9 by

example.

  The operator, with reference to FIGS. 1 and 5, then adjusts the angulation as a function of the radiographic images that he wishes to produce. The operator can either select predetermined angulations such as an angulation of 8 = 0 corresponding to a cranio-caudal shooting, an angulation of e = 90 corresponding to a lateral shooting or even an angulation 8 substantially equal to 45 corresponding to a medio-lateral shooting, or control the rotation of the arm 4 until the desired angulation is reached.

  The measurement of the angulation is determined by means of the angular sensor 33 that the mammography apparatus 1 comprises means for rotating the arm 5 or not. However, the measurement of the angulation will preferably be deduced from the means for rotating the arm 5. This measurement of the angulation makes it possible to determine the parameters of the mammography apparatus in real time during the rotation of the arm 5 provided by drive means controlled by control means.

  According to a third variant of the method, the parameters of the mammography apparatus are determined when the arm 5 reaches a predefined angulation position.

  According to a last variant of the method according to the invention, the parameters of the mammography apparatus are determined when the arm 5, driven in rotation manually or motorized, stops in a defined position during a time interval. predefined, of the order of the second for example.

  It will be observed that the parameters of the mammography apparatus can be determined after the positioning of the compression plate 13 if the latter is secured to the support 17 mounted on the carriage 18 after the rotation of the arm 5.

  For lateral or mid-lateral shooting, the compression plate 13 is moved parallel to the proximal borcl of the image receptor 2, as indicated by the arrows b in FIGS. 1 and 3, towards the highest edge of the receiver. image 2. Said compression plate 13 is moved by motorized drive means or manually until it reaches a stop positioned or determined according to the angulation, or until a marker placed on the compression plate 13 is aligned with a light mark whose position is determined by the control means 9 according to the angulation.

  The dimensions of the X-ray beam are then adjusted by the operator and / or by the control means 9 as a function of the type of compression plate 13 used, said compression plate 13 used being identified by the control means automatically or manually as it was described previously.

  On the other hand, the position of the X-ray beam is displaced as a function of angulation in the same direction as said compression plate 12, i.e. towards the highest edge of the image receiver 2, by the collimator 8 controlled by the control means 9 to cover the compression plate 13 so that the X-ray field is tangent to the lateral edge of the image receptor 2 in contact with the axillary hollow of the patient is i.e. with the side edge of the highest image receiver 2.

  The operator then positions the patient. For this purpose, the operator positions the upper angle of the image receptor 2 in the axillary hollow of the patient and the patient's breast between the x-ray source 4 and the breast support 3 and compresses the breast between the support breast 3 and the compression plate 13.

  The position of the image receptor area 2 which collects information relating to the radiographic image of the patient's breast can be adjusted by manual selection by the operator who defines said image receptor area by means of the keyboard. or by an automatic selection according to the size of the X-ray beam and the position of said beam which depends on the angulation as previously described.

  It will be recalled that the dimensions of said area of the image receiver 2 are determined by a manual selection by the operator or by an automatic selection during the installation of the compression plate 13 on its support 17.

  The overall area of the radiographic image in which an evaluation is performed to determine the exposure parameters is shifted as a function of angulation. The effective evaluation of the image content to feed the automatic exposure control mechanism of the mammography apparatus is obtained from the method described in US Patent Applications US 6,292,536 and US 6,556,655. It will be observed that the information of the position of the compression plate 13 is not necessary.

  It will be observed that for cranio-caudal shooting, the compression plate need not be moved along the proximal edge of the image receiver 2, only the area of the image receiver analyzed to determine the parameters of the image. exposure and the area of the image receptor considered to contain the image for the acquisition, processing, recording, display or transmission of the radiographic image are modified as a function of the dimensions of the compression plate 13 used and secondly the measured angulation.

  Referring to Figure 6A, schematically showing the position of the image of a large breast 34 of a patient relative to the image receptor 2 of the mammography apparatus 1 during a cranio-caudal shooting , the zone 35 of the image receptor 2 considered to contain the image has the same dimensions as the image receptor 2. Note that in this case the compression plate 13 used has dimensions (24 cm x 30 cm) identical to the dimensions of the image receiver 2. When the patient has a breast of smaller size, with reference to Figure 6B schematically showing the position of the image of a small breast 34 relative to the receiver of image 2 of the mammography apparatus 1 during a cranio-caudal shooting, the compression plate 13 then used has dimensions (18 cm x 24 cm) smaller than the dimensions of the image receptor 2, the area 35 of the image receptor 2 considered to contain the image and determined in particular according to the angulation, which in this case is equal to e = o, has dimensions smaller than those of the image receptor 2.

  In the same way for an oblique medio-lateral shooting (MLO), that is to say as ee] -75, 10 [x] 10, 75 [, or for lateral shooting, it is that is 8 = 90 15, of a large breast 34 of a patient, with reference to FIG. 7A schematically showing the position of the image of a large breast 34 relative to the image receptor 2 of the mammography apparatus 1, the zone 35 of the image receptor 2 considered to contain the image has the same dimensions as the image receptor 2. It will be noted that in this particular case the compression plate 13 used has dimensions (24 cm x 30 cm) identical to the dimensions of the image receiver 2. When the patient has a breast 34 of small size, with reference to Figure 7B schematically representing the position of the image of a small breast 34 relative to the image receptor 2 of the mammography apparatus 1 during oblique medio-lateral shooting (MLO), the compression plate sion 13 then used has dimensions (18 cm x 24 cm) smaller than the dimensions of the image receiver 2, the area 35 of the image receptor 2 considered to contain the image and determined in particular according to the angulation has dimensions smaller than those of the image receiver 2 and is moved to the highest edge of said image receiver 2.

  Thus, as previously described, the geometrical configuration parameters of the mammography apparatus are determined prior to the acquisition of the radiographic image according to a predefined function of the angle called angulation formed between the column 6 and the arm 5 carrying the image receiver 2 and the x-ray source 4.

  These parameters of the radiographic apparatus as a function of angulation are, for example, pre-recorded in the control means 9 of the radiographic apparatus 1.

  All the parameters of the radiographic apparatus determined according to the angulation are advantageously displayed on display means 11 of said radiographic apparatus 1 and the operator can modify said parameters prior to the acquisition of the radiographic image. In particular, the operator can first change the size, shape and position of the X-ray beam to match the characteristics of the X-ray beam with the dimensions of the compression plate 13 used.

Claims (1)

  1 - Method for imaging a breast of a patient by digital X-ray radiography using a mammography apparatus (1) comprising an X-ray source (4), a breast support (3) positioned between the X-ray source (4) and an image receiver (2), said image receiver (2) and the X-ray source (4) being integral with an arm (5) rotatably mounted around an axis (7), control means (9), acquisition means (10) and display means (11) for the radiographic image, at least one transparent radio compression plate (13) positioned between the X-ray source (4) and the image receiver (2) and slidably mounted on a carriage (18) to effect compression of the patient's breast, and control means (12), said method comprising at least positioning the patient's breast between the X-ray source (4) and the image receptor (2) and compressing the breast against the breast support table (3) image sensor (2) by means of the compression plate (13), characterized in that the position of the X-ray field and / or the position of the compression plate (13) along the proximal edge of the image (2) and / or the area of the image receiver (2) analyzed to determine the exposure parameters and / or the area of the image receiver (2) considered to contain the image for acquisition, the processing, the recording, the display or the transmission of the radiographic image, called the geometric configuration parameters of the apparatus, are determined prior to the acquisition of the radiographic image according to a predefined function of the angle 8 said angulation formed between the longitudinal axis of the patient and the normal to the breast support (3) passing through the focus of the X-ray source (4).   2 - Imaging method according to claim 1 characterized in that the geometric configuration parameters of the mammography apparatus (1) as a function of angulation are pre-recorded in the control means (9).   3 - imaging method according to any one of claims 1 or 2 characterized in that the operator selects an angulation which is transmitted to the control means (9) which determine the geometric configuration parameters of the mammography apparatus and drive the rotation drive of the arm (5) carrying the image receiver (2) and the X-ray source (4) until the angulation is reached.   4 - Imaging method according to any one of claims 1 to 3 characterized in that the geometric configuration parameters of the mammography apparatus (1) are determined in real time during the rotation of the arm (5) provided by motorized drive means controlled by the control means (9).   - Imaging method according to any one of claims 1 to 3 characterized in that the geometric configuration parameters of the mammography apparatus (1) are determined when the arm (5), rotated, stops in a defined position during a predefined time interval.   6 - Imaging method according to any one of claims 1 to 5 characterized in that the geometric configuration parameters of the mammography apparatus (1) determined according to the angulation are displayed on the display means (11). ) of said apparatus.   7 - Process according to claim 6 characterized in that the geometric configuration parameters of the mammography apparatus (1) determined according to the angulation are modifiable by an operator prior to the acquisition of the radiographic image.   8 - Mammography apparatus (1) for carrying out the method, comprising an X-ray source (4), a breast support (3) positioned between the X-ray source (4) and an image receptor (2), said image receiver (2) and the X-ray source (4) being integral with an arm (5) rotatably mounted about an axis (7), control means (9), acquisition means (10) and display means (11) of the radiographic image, at least one transparent radio compression plate (13) positioned between the X-ray source (4) and the image receiver ( 2) and slidably mounted on a carriage (18) so as to effect compression of the patient's breast, and control means (12), characterized in that it comprises means for determining, prior to the acquisition of the radiographic image, the position of the X-ray field and / or the position of the compression plate (13) along the proximal edge of the image receptor (2) and / or the area of the image receiver (2) analyzed to determine the exposure parameters and / or the area of the image receiver (2) considered to contain the image for acquisition, processing, recording, display or transmitting the radiographic image, said parameters geometrical configuration of the mammography apparatus (1) according to a predefined function of the angle 8, said angulation formed between the longitudinal axis of the patient and the normal to the breast support (3) passing through the focus of the X-ray source (4).   9 - mammography apparatus according to claim 8 characterized in that it comprises means for measuring the angulation.   - Mammographic apparatus according to claim 9 characterized in that the means for measuring the angulation consist of an angular sensor (33) integral with the axis of rotation (7) of the arm (5).   11 - mammography apparatus according to any one of claims 8 to 10 characterized in that it comprises means for driving said plate (13) in translation parallel to the proximal edge of the image receptor (2) positioned in the axillary hollow from the patient to the position of the plate (13) determined according to the angulation.   12 - mammography apparatus according to claim 11 characterized in that said drive means consist of a mass (20) slidably mounted on a rail (21) extending parallel to the proximal edge of the image receptor (2) and connected a guide (25) sliding on a second rail (26), which extends parallel to the first rail (21), and carrying the compression plate (13), the mass (20) being connected to the guide (25) of such that the angulation of the arm (5) provides a displacement of the mass (20) along its rail (21) which drives in translation the guide (25) and, thus, the compression plate (13) parallel to the proximal edge of the image receptor (2) in the opposite direction to the mass (20).   13 - mammography apparatus according to claim 11 characterized in that it comprises at least one motor for moving the compression plate (13).   14 - mammography apparatus according to claim 11 characterized in that the compression plate (13) comprises at least one slide (19) and locking means (30).   - Mammographic apparatus according to claim 14 characterized in that it comprises at least one stop positioned or selected according to the angulation, the operator moving the compression plate (13) until it comes to bear on said stop.   16 - Mammographic apparatus according to claim 14 characterized in that it comprises at least one light indicator whose position is determined according to the angulation and that a reference marking affixed to the compression plate (13) must be aligned with said indicator light.   17 - mammography apparatus according to any one of claims 8 to 10 characterized in that the compression plate (13) comprises identification means adapted to cooperate with reading means connected to the control means.   18 - mammography apparatus according to claim 17 characterized in that the identification means consist of a bar code (31) adapted to be read by a manual or fixed bar code reader (32).   19 - mammography apparatus according to claim 17 characterized in that the identification means consist of a relay actuator and in that the reading means consist of a mechanical relay, magnetic or optical.   - mammography apparatus according to claim 17 characterized in that the identification means consist of a memory unit in which are recorded the information relating to the type and dimensions of the compression plate (13) readable by the means control (9) through a wired link or not.   21 - mammography apparatus according to any one of claims 8 to 20 characterized in that the compression plate (13) comprises at least one memory unit in which can be recorded information relating to the number of operations and / or to the compression force used and / or calibration data used to improve the efficiency of the determination of the position of the compression plate (13) or the like and the means for receiving and transmitting data connected to the unit memory and the control means (9).