(19)
(11)EP 2 974 662 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
27.02.2019 Bulletin 2019/09

(21)Application number: 14763661.7

(22)Date of filing:  12.03.2014
(51)Int. Cl.: 
A61B 6/04  (2006.01)
A61B 6/00  (2006.01)
(86)International application number:
PCT/KR2014/002053
(87)International publication number:
WO 2014/142544 (18.09.2014 Gazette  2014/38)

(54)

DIGITAL MAMMOGRAPHY DEVICE

DIGITALE MAMMOGRAFIEVORRICHTUNG

DISPOSITIF DE MAMMOGRAPHIE NUMÉRIQUE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 12.03.2013 KR 20130026175

(43)Date of publication of application:
20.01.2016 Bulletin 2016/03

(73)Proprietor: GENERAL ELECTRIC COMPANY
Fairfield, CT 06828 (US)

(72)Inventors:
  • LEE, Chang Hwa
    Hwaseong-si Gyeonggi-do 445-170 (KR)
  • NAM, Tae Woo
    Hwaseong-si Gyeonggi-do 445-170 (KR)

(74)Representative: Bedford, Grant Richard 
GPO Europe GE International Inc. The Ark 201 Talgarth Road Hammersmith
London W6 8BJ
London W6 8BJ (GB)


(56)References cited: : 
DE-A1- 3 227 258
JP-A- 2003 310 594
JP-A- 2010 179 030
US-A1- 2008 080 668
FR-A1- 2 681 521
JP-A- 2010 110 571
KR-A- 20120 087 751
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Technical Field



    [0001] The present invention relates to a digital mammography device photographing a breast using X-ray, and more particularly, to a digital mammography device capable of preventing pain or inconvenience of a patient by monitoring and adjusting strength of force applied to the breast of the patient from a pressure pad.

    Background Art



    [0002] X-ray is generally defined as an electromagnetic wave having a short wavelength corresponding to wavelengths of 0.01nm to 10nm, and an X-ray photographing is referred to as a radiography that transparently displays an inside of a photographing target by the high penetrable X-rays.

    [0003] As well known, the X-ray involves an attenuation phenomenon depending on a material, a density, and a thickness of an object such as Compton scattering, a photoelectric effect, or the like during a process in which the X-ray penetrates through the object. Therefore, the X-ray photographing projects and displays the inside of the photographing target on a plane based on an amount of attenuation of the X-ray accumulated during the process in which the X-ray penetrates through the photographing target, and to this end, a dedicated X-ray system is used.

    [0004] Recently, an X-ray imaging technology has rapidly evolved to a digital X-ray imaging technology having various advantages such as relatively high resolution, a wide dynamic region, an easy generation of an electrical signal, simple data process and storage, and the like, instead of a conventional analog scheme using a film while being grafted to a semiconductor field. A digital based imaging technology meets the clinical and environmental requirements of an early diagnosis of diseases based on excellent diagnostic ability of a digital image.

    [0005] Therefore, "digital mammography", which is a breast dedicated X-ray photographing technology capable of detecting a lesion and a micro-calcification for detection and early diagnosis of a breast cancer by expressing an internal structure of the breast in a high resolution image utilizing unique contrast ability of biological tissues of the X-ray has been proposed. The above-mentioned digital mammography has rapidly propagated due to unique characteristics such as an image expansion, a reduction in the number of photographs, an increase in resolution, and minimization of exposure through an adjustment of brightness and contrast ratio, together with various advantages of the digital X-ray imaging technology.

    [0006] A general mammography device includes a column of a column shape which is perpendicular to a bottom; a C-arm that generally shows a C letter or a shape similar to the C letter at both end portions which are bent in arc shapes facing each other in a state in which a middle portion is connected so as to be elevatable and rotatable along the column; an X-ray generator mounted in one end portion of the C-arm to irradiate X-ray toward the other end portion facing one end portion; a detector mounted in the other end portion of the C-arm to face the X-ray generator; and a pressure pad performing a straight-line reciprocating motion between the X-ray generator and the detector along an internal surface of the C-arm.

    [0007] In the mammography device as described above, when a patient enters a photographing position, the C-arm is elevated and rotated along the column to adjust a height and an angle so that the breast of the patient is placed at a target position on the detector, and when the pressure pad is moved in a direction of the detector to pressurize the breast, the X-ray is irradiated from the X-ray generator and is received at the detector. The detector generates an electrical signal for each position which is proportional to an incident amount of X-ray, and when the electrical signal and position information are read and are processed by an image processing algorithm, an X-ray image of the breast for the corresponding angle may be obtained. If necessary, the above-mentioned process may be repeated while the X-ray generator and the detector are rotated to face each other while having the breast therebetween, and as a result, the mammography device may obtain high resolution images for the breast of the patient at various angles. See FR 2 681 521 and DE 32 27 258, for example.

    [0008] In the general mammography device showing the above-mentioned photographing principle, a key driving mechanism for minimizing inconvenience of the patient and obtaining a high quality X-ray image is a pressure operation of the pressure pad. That is, since the pressure pad directly applies pressure to the breast during the X-ray photographing, it is directly related to pain or inconvenience which is felt by the patient. According to the related art, when the pressure pad pressurizes the breast placed on an inspection plate, more pressure than necessary may be applied, and as a result, there is a possibility that the patient undergoes more pain than necessary. Particularly, since sizes, densities, and the like of the breast of the patients are different from each other, suitable pressure should be applied accordingly, but there is a problem that the suitable pressure is not accurately and reliably controlled. An improvement method capable of increasing reliability for the pressure operation of the pressure pad and precisely and accurately controlling the pressure operation is required.

    [Disclosure]


    [Technical Problem]



    [0009] An object of the present invention is to provide a digital mammography device capable of performing a control so that suitable pressure is applied using a monitored electrical signal while monitoring pressure applied to a patient through a pressure pad in real time, and protecting the patient by interrupting driving force of the pressure pad in the case in which excessive pressure is applied.

    [0010] Another object of the present invention is to prevent a risk that the excessive pressure is suddenly applied to a body of the patient even in the case in which a malfunction due to error of an electronic control device occurs, by transferring force using a mechanical mechanism including a spring between the pressure pad and a pressure pad driving part.

    [Technical Solution]



    [0011] According to an exemplary embodiment of the present invention, there is provided a digital mammography device as defined by appended claim 1.

    [0012] The applied pressure transferring part may include: a spring disposed between the coupling block and the moving block and deformed depending on the relative movement displacement; and a load cell disposed at one end portion of the spring to provide the electrical signal according to a deformation of the spring. The digital mammography device may further include: a piston member configured to be installed between one end portion of the spring and the load cell.

    [0013] The digital mammography device may further include: a controller configured to control the motor with the electrical signal and may further include: a safety switch configured to control the motor when the relative movement displacement exceeds a preset range regardless of whether or not the controller is functioned.

    [Advantageous Effects]



    [0014] The digital mammography device according to the present invention may perform the control so that suitable pressure is applied using the monitored electrical signal while monitoring the pressure applied to the patient through the pressure pad in real time, and may protect the patient by interrupting the driving force of the pressure pad in the case in which excessive pressure is applied.

    [0015] In addition, the digital mammography device according to the present invention may prevent the risk that excessive pressure is suddenly applied to the body of the patient even in the case in which the malfunction due to the error of the electronic control device occurs, by transferring the force using the mechanical mechanism including the spring between the pressure pad and the pressure pad driving part.

    Description of Drawings



    [0016] 

    FIG. 1 is a perspective view showing a mammography device according to an exemplary embodiment of the present invention.

    FIG. 2 is a partial exploded perspective view showing configurations of a pressure pad driving part and an applied pressure transferring part in the digital mammography device according to an exemplary embodiment of the present invention.

    FIG. 3 is a front perspective view showing the applied pressure transferring part of the digital mammography device according to an exemplary embodiment of the present invention.

    FIG. 4 is an exploded perspective view showing a configuration of the applied pressure transferring part in the digital mammography device according to an exemplary embodiment of the present invention.

    FIG. 5 is a schematic diagram showing the configuration of the applied pressure transferring part in the digital mammography device according to an exemplary embodiment of the present invention.

    FIG. 6 is a schematic diagram showing a configuration of an applied pressure transferring part in a digital mammography device according to another exemplary embodiment of the present invention.


    Best Mode



    [0017] Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. A scope of the present invention may be clearly understood through the exemplary embodiments. However, the present invention is not limited to the exemplary embodiments described below and may be modified in various forms within the scope to which the present invention pertains. Meanwhile, like reference numerals used in several drawings denote a component having the same characteristics, and a description of the component having the same reference numeral as the component described with reference to any one drawing may be omitted from the description of another drawing.

    [0018] FIG. 1 is a perspective view showing a mammography device according to an exemplary embodiment of the present invention and FIG. 2 is a partial exploded perspective view showing configurations of a pressure pad driving part and an applied pressure transferring part in the digital mammography device according to an exemplary embodiment of the present invention.

    [0019] The digital mammography device according to the present invention includes a column 10 which stands to be perpendicular to a ground and supports a load of the device; a C type arm 20 that generally shows a C letter or a shape similar to the C letter by both end portions which are bent in arc shapes facing each other in a state in which a middle portion is connected so as to be elevatable and rotatable along the column 10; an X-ray generator 30 mounted in one end portion of the C type arm 20 to irradiate X-ray toward the other end portion facing one end portion; a detector 40 mounted in the other end portion of the C type arm 20 to face the X-ray generator 30; a pressure pad 60 performing a straight-line reciprocating motion between the X-ray generator 30 and the detector 40; a pressure pad driving part 70 driving the pressure pad 60; and an applied pressure transferring part 100 installed between the pressure pad 60 and the pressure pad driving part 70, transferring applied pressure from the power transferring part of the pressure pad driving part 70 to the pressure pad 60, and measuring the transferred applied pressure to provide an electrical signal.

    [0020] The column 10 has a column shape which is perpendicular to a bottom, and an extension part 21 extended from the middle portion of the C type arm 20 is elevatably coupled to the column 10. A vertical connection part 22 connecting one end portion and the other end portion facing each other of the C type arm 20 is rotatably coupled to the extension part 21.

    [0021] The X-ray generator 30 collides electrons having high kinetic energy with a metal target to generate X-ray, and preferably includes a collimator that controls an irradiation direction and an irradiation area of the X-ray, or the like.

    [0022] The detector 40 is a device that receives the X-ray penetrating through a subject, that is, penetrating through a breast of a patient to generate an electrical signal accordingly, and according to an exemplary embodiment of the present invention, a general technique such as a direct transforming scheme that directly obtains the electrical signal from the X-ray without a separate intermediate operation according to an X-ray transforming scheme, an indirect transforming scheme that transforms the X-ray into visible ray and indirectly obtains the electrical signal by the visual ray, or the like may be widely used.

    [0023] The pressure pad 60 pressurizes the breast on a support fixture which is separately installed at a front side of the detector 40 or the support fixture including the detector 40 to the support fixture side, and the breast in the pressurized state is photographed using the X-ray generator 30 and the detector 40. The pressure pad driving part 70 is configured to vertically move the pressure pad 60 and provide applied pressure, and may be installed at the vertical connection part 22 of the C type arm 20.

    [0024] The applied pressure transferring part 100 transfers a motion and force generated by the pressure pad driving part 70 to the pressure pad 60, measures applied pressure applied to the breast of the patient, that is, a strength of repulsive force transferred to the pressure pad 60 from the breast of the patient, and generates the electrical signal using the measured strength of repulsive force, such that a controller may control an operation of the pressure pad driving part 70 based on the electrical signal. For example, the strength of the applied pressure itself or a change trench thereof may be detected in order to be used to generate a control signal driving a motor of the pressure pad driving part 70. If the strength of the applied pressure exceeds a preset value, it is also possible to interrupt power of the pressure pad driving part 70, drive the pressure pad driving part 70 in an opposite direction, or the like.

    [0025] The pressure pad driving part 70 includes a motor which is electrically controlled, and a power transferring part transforming power of the motor into a vertical reciprocal movement form. The power transferring part may include a gear box and a pulley which are connected to the motor, a belt wound around the pulley to be rotated, and the like.

    [0026] The exemplary embodiment shown in FIG. 2 will be described in more detail. The pressure pad driving part 70 includes a pair of horizontal brackets 71; a pair of guide shafts 72 which are perpendicular to the horizontal brackets 71 and installed so as to be in parallel to each other; a guide block 73 of which a movement is guided by the pair of guide shafts 72 and to which a component of the applied pressure transferring part 100 is coupled; a belt 74 moving the guide block 73 and the applied pressure transferring part 100; and a driving motor and a gear box 75 driving the belt 74.

    [0027] FIG. 3 is a front perspective view showing the applied pressure transferring part of the digital mammography device according to an exemplary embodiment of the present invention and FIG. 4 is an exploded perspective view showing a configuration of the applied pressure transferring part in the digital mammography device according to an exemplary embodiment of the present invention.

    [0028] The applied pressure transferring part 100 includes a moving block 120 fixed to the belt 74, which is a member substantially performing a vertical reciprocal motion as a part of the power transferring part; and a coupling block 110 having the moving block 120 which is coupled to one side thereof to be relatively movable and the pressure pad 60 fixed to the other side thereof. The coupling block 110 is installed with guide rails 152 and guide protrusions 151 are formed on sides of the moving block 120 corresponding to the guide rails 152, such that a relative movement of the coupling block 110 and the moving block 120 may be guided. In addition, the coupling block 110 is provided with pressure pad coupling parts 112, to which the pressure pad 60 is fastened.

    [0029] A spring 140 deformed depending on a relative movement displacement between the coupling block 110 and the moving block 120 and transferring force; and a load cell 170 disposed at one end portion of the spring 140 and measuring a strength of force transferred through the spring 140 to provide the electrical signal may be included between the coupling block 110 and the moving block 120. In addition, a piston member 160 transferring all of the force across the spring 140 to a measuring part of the load cell 170 may be further included between the spring 140 and the load cell 170.

    [0030] The piston member 160 may include a piston body 162 which is directly in contact with the spring 140 and the load cell 170, and a piston rod 161 extended from the piston body 162 into the spring 140 to hold a position of the spring 140.

    [0031] FIG. 5 is a schematic diagram showing the configuration of the applied pressure transferring part in the digital mammography device according to an exemplary embodiment of the present invention.

    [0032] The spring 140 may be installed in a spring housing part 124 provided in the moving block 120, for example. An operation range of the spring 140 may be limited by the piston member 160 described above. For example, an initial state of the spring 140 may be adjusted by allowing the piston rod 161 to penetrate through an upper end portion of the spring housing part 124 and coupling an adjustment nut 163 to an upper end portion of the piston rod 161. Minimum applied pressure at which a relative movement starts to be generated between the moving block 120 and the coupling block 110 depending on the initial state of the spring 140 is mechanically set.

    [0033] The load cell 170 has a bottom surface supported by the coupling block 110 and a measuring part which is directly in contact with the piston body 162, and receives the applied pressure from the spring 140. When the breast of the patient is photographed, a deformation no longer occurs after the deformation in which the breast of the patient is compressed to a predetermined degree occurs by the pressure pad 60 which is vertically moved. In this case, when the pressure pad driving part 70 continues to operate and the belt 74 presses down the moving block 120 in an arrow direction, a relative displacement occurs between the coupling block 110 and the moving block 120 while the spring 140 receiving repulsive force from the pressure pad 60 which is no longer descended by receiving the repulsive force from the breast of the patient is compressed. In other words, the spring 140 receiving the applied pressure from the pressure pad driving part 70 stores energy through an elastic deformation and transfers the applied pressure to the coupling block 110, and the load cell 170 provides the electrical signal by measuring the applied pressure in real time.

    [0034] In addition, strong safety measures for protecting the patient may also be taken such as a relative movement range of the moving block 120 in a housing of the coupling block 110 being limited or the initial state of the spring 140 being adjusted by installing a support bolt 165 between the coupling block 110 and the moving block 120 as well as power supplied to the pressure pad driving part 70 being shut-down in the case in which the relative movement displacement exceeds a predetermined value by installing a safety switch 180 at a predetermined position, and the like. The reason that the safety switch 180 is operated depending on the relative movement displacement is that a strength of applied pressure applied to the breast of the patient becomes strong in proportion to the relative movement displacement between the coupling block 110 and the moving block 120 due to the existence of the spring 140 between the coupling block 110 and the moving block 120. The safety switch 180 may be installed at a position at which the moving block 120 arrives when the spring 140 is deformed as much as maximum applied pressure which may be typically applied to the patient is transferred. In addition, as the safety switch 180, a mechanical switch may be employed so that the patient may be protected under any situation.

    [0035] FIG. 6 is a schematic diagram showing a configuration of an applied pressure transferring part in a digital mammography device according to another exemplary embodiment of the present invention.

    [0036] The configuration of the digital mammography device shown in FIG. 6 is substantially equal to that shown in FIG. 5, and only a difference therebetween will be described.

    [0037] A tensile load cell 190 is installed between the coupling block 110 and the moving block 120 so as to be tensioned as the moving block 120 is relatively moved in the housing of the coupling block 110. Therefore, the piston body 162 is installed so that the bottom surface thereof is supported by the coupling block 110.

    [0038] Similar to the load cell 170, the tensile load cell 190 provides an electrical signal by measuring tensile force generated according to the movement of the moving block 120 in real time.


    Claims

    1. A digital mammography device comprising:

    a pressure pad (60) configured to be movably installed between an X-ray generator (30) for irradiating X-ray and a detector (40) for receiving the X-ray penetrating through a subject, and configured to compress the subject;

    a pressure pad driving part (70) configured to include a motor and a power transferring part for moving the pressure pad using power of the motor; and

    an applied pressure transferring part (100) configured to include a coupling block (110) to which the pressure pad is fixed and a moving block (120) fixed to the power transferring part and relatively and movably connected to the coupling block, and configured to provide an electrical signal depending on a relative movement displacement between the coupling block (110) and the moving block (120), characterized in that:

    the pressure pad driving part (70) comprises a pair of vertical and parallel guide shafts (72), configured to enable only vertical movement of a guide block (73) configured to be guided by the guide shafts (72) and coupled to the applied pressure transferring part (100).


     
    2. The digital mammography device according to claim 1, wherein the applied pressure transferring part (100) includes:

    a spring (140) disposed between the coupling block (110) and the moving block (120) and deformable depending on the relative movement displacement; and

    a load cell (170) disposed at one end portion of the spring (140) to provide the electrical signal according to a deformation of the spring.


     
    3. The digital mammography device according to claim 2, further comprising: a piston member (160) configured to be installed between one end portion of the spring (140) and the load cell (170).
     
    4. The digital mammography device according to any preceding claim, further comprising: a controller configured to control the motor with the electrical signal.
     
    5. The digital mammography device according to any preceding claim, further comprising: a safety switch (180) configured to control the motor when the relative movement displacement exceeds a preset range.
     


    Ansprüche

    1. Digitales Mammographiegerät, umfassend:

    ein Druckkissen (60), das dazu konfiguriert ist, beweglich zwischen einem Röntgenstrahlengenerator (30) zum Ausstrahlen eines Röntgenstrahls und einem Detektor (40) zum Empfangen des Röntgenstrahls, der einen Patienten durchdringt, eingerichtet zu sein, und zum Komprimieren des Patienten konfiguriert ist;

    ein Druckkissenantriebsteil (70), das zum Enthalten eines Motors und eines Leistungsübertragungsteils zum Bewegen des Druckkissens unter Nutzung von Leistung des Motors konfiguriert ist; und

    ein Anwendungsdruckübertragungsteil (100), das zum Enthalten eines Kopplungsblocks (110), an dem das Druckkissen befestigt ist, und eines beweglichen Blocks (120), der am Leistungsübertragungsteil befestigt ist und relativ und beweglich mit dem Kopplungsblock verbunden ist, konfiguriert ist, und zum Zuführen eines elektrischen Signals abhängig von einer relativen Bewegungsverschiebung zwischen dem Kopplungsblock (110) und dem beweglichen Block (120) konfiguriert ist, dadurch gekennzeichnet, dass:
    das Druckkissenantriebsteil (70) ein Paar vertikaler und paralleler Führungsschäfte (72) umfasst, die zum Ermöglichen nur von vertikaler Bewegung eines Führungsblocks (73) konfiguriert sind, der dazu konfiguriert ist, durch die Führungsschäfte (72) geführt zu werden, und an das Anwendungsdruckübertragungsteil (100) gekoppelt ist.


     
    2. Digitales Mammographiegerät nach Anspruch 1, wobei das Anwendungsdruckübertragungsteil (100) enthält:

    eine Feder (140), die zwischen dem Kopplungsblock (110) und dem beweglichen Block (120) angeordnet ist und abhängig von der relativen Bewegungsverschiebung verformbar ist; und

    eine Lastdose (170), die an einem Endabschnitt der Feder (140) zum Zuführen des elektrischen Signals gemäß einer Verformung der Feder angeordnet ist.


     
    3. Digitales Mammographiegerät nach Anspruch 2, ferner umfassend: ein Kolbenglied (160), das dazu konfiguriert ist, zwischen einem Endabschnitt der Feder (140) und der Lastdose (170) eingerichtet zu sein.
     
    4. Digitales Mammographiegerät nach einem der vorstehenden Ansprüche, ferner umfassend: eine Steuerung, die zum Steuern des Motors mit dem elektrischen Signal konfiguriert ist.
     
    5. Digitales Mammographiegerät nach einem der vorstehenden Ansprüche, ferner umfassend: einen Sicherheitsschalter (180), der zum Steuern des Motors konfiguriert ist, wenn die relative Bewegungsverschiebung einen voreingestellten Bereich übersteigt.
     


    Revendications

    1. Dispositif de mammographie numérique comprenant :

    une plaquette de pression (60) configurée pour être installée de manière mobile entre un générateur de rayons X (30) pour un rayonnement de rayons X et un détecteur (40) pour une réception du rayon X pénétrant à travers un sujet, et configuré pour comprimer le sujet ;

    une partie d'entraînement de plaquette de pression (70) configurée pour inclure un moteur et une partie de transfert de puissance pour une mise en mouvement de la plaquette de pression en utilisant la puissance du moteur ; et

    une partie de transfert de pression appliquée (100) configurée pour inclure un bloc de couplage (110) auquel la plaquette de pression est fixée et un bloc mobile (120) fixé à la partie de transfert de puissance et raccordé de manière relative et mobile au bloc de couplage, et configuré pour fournir un signal électrique en fonction d'un déplacement de mouvement relatif entre le bloc de couplage (110) et le bloc mobile (120), caractérisé en ce que :

    la partie d'entraînement de plaquette de pression (70) comprend une paire d'arbres de guidage (72) vertical et parallèle,

    configurés pour permettre uniquement un mouvement vertical d'un bloc de guidage (73) configuré pour être guidé par les arbres de guidage (72) et couplé à la partie de transfert de pression appliquée (100).


     
    2. Dispositif de mammographie numérique selon la revendication 1, dans lequel la partie de transfert de pression appliquée (100) inclut :

    un ressort (140) disposé entre le bloc de couplage (110) et le bloc mobile (120) et déformable en fonction du déplacement de mouvement relatif ; et

    un capteur de force (170) disposé au niveau d'une portion d'extrémité du ressort (140) pour fournir le signal électrique selon une déformation du ressort.


     
    3. Dispositif de mammographie numérique selon la revendication 2, comprenant en outre : un élément de piston (160) configuré pour être installé entre une portion d'extrémité du ressort (140) et le capteur de force (170).
     
    4. Dispositif de mammographie numérique selon l'une quelconque des revendications précédentes, comprenant en outre : un dispositif de commande configuré pour commander le moteur avec le signal électrique.
     
    5. Dispositif de mammographie numérique selon l'une quelconque des revendications précédentes, comprenant en outre : un interrupteur de sécurité (180) configuré pour commander le moteur lorsque le déplacement de mouvement relatif dépasse une plage prédéfinie.
     




    Drawing












    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description