Abstract:
An ultrasonic diagnostic apparatus and method are disclosed for enabling identification of a type of reference deformable body. The ultrasonic diagnostic apparatus includes an ultrasonic probe to which the reference deformable body is attached, a tomographic image constructing unit, and a display unit. The ultrasonic diagnostic apparatus further includes a storing unit configured to store the relationship between the ID given to the reference deformable body and a type of the reference deformable body, and a type identifying unit configured to specify the type of the reference deformable body corresponding to the inputted ID. A tomographic image can then be constructed based on the type of reference deformable body specified.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a reference deformable body to be attached on an ultrasonic wave transmission/reception surface of an ultrasonic probe, an ultrasonic diagnostic apparatus and ultrasonic diagnostic method for displaying a tomographic image of an imaging target portion in an object to be examined using ultrasonic waves or an elasticity image which presents hardness or softness of biological tissues. 
     DESCRIPTION OF RELATED ART 
     An ultrasonic diagnostic apparatus transmits an ultrasonic wave to the inside of an object to be examined using an ultrasonic probe, receives the reflected echo signal of the ultrasonic wave from the inside of the object according to the structure of the biological tissue, and constructs a tomographic image such as a B-mode image to display for diagnosis. 
     Ultrasonic diagnostic apparatuses of recent years measure an ultrasonic wave receiving signal by pressing an object using an ultrasonic probe manually or mechanically, acquire displacement of the tissues, and display an elasticity image of the biological tissues based on the acquired displacement data. At this time, the method has been disclosed wherein a reference deformable body is attached to the ultrasonic probe via a fixing member, the border between the object and the reference deformable body is detected from the RF signal frame data acquired by transmission and reception of the ultrasonic waves, and the pressure applied to the object is measured from the positional information of the border (for example, Patent Document 1). 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: WO2005/120358 
       
    
     There are various types of reference deformable bodies to be attached to an ultrasonic probe. For example, since there are different sizes or shapes of ultrasonic probes, the size or shape of the reference deformable body best suited to each of those probes would be also different. For a linear-type ultrasonic probe, a linear-type reference deformable body is to be attached. For a convex-type of ultrasonic probe, a curved reference deformable body is to be attached. Also, when depth or size of a measuring portion or physical attribute of the object is different, hardness or thickness of the reference deformable body needs to be changed. In this manner, it is necessary to switch types of the reference deformable body to have optimal feature according to the measurement condition. 
     However, if the type of the reference deformable body is not identified, elasticity modulus calculation or ultrasonic wave transmission/reception setting cannot be executed properly. 
     The objective of the present invention is to identify the type of a reference deformable body to be attached to an ultrasonic probe. 
     SUMMARY OF THE INVENTION 
     In order to achieve the objective of the present invention, the ultrasonic diagnostic apparatus comprises: 
     an ultrasonic probe having the ultrasonic wave transmitting/receiving surface on which a reference deformable body is attached; 
     a tomographic image constructing unit configured to transmit/receive an ultrasonic wave to/from an object to be examined via the reference deformable body, and generate a tomographic image based on the RF signal frame data of the cross-sectional region of the object; and 
     a display unit configured to display the tomographic image, 
     characterized in further comprising: 
     a storing unit configured to store the relationship between an ID given to the reference deformable body and the type of the reference deformable body; and 
     a type identifying unit configured to read out the type of the reference deformable body corresponding to the ID of the reference deformable body attached to the ultrasonic probe and to identify the type of the reference deformable body. Consequently, the type of the reference deformable body can be identified. 
     It also comprises an image analyzing unit configured to analyze feature quantity of the reference deformable body in the tomographic image, wherein: 
     the storing unit stores the relationship between the analyzed feature quantity of the reference deformable body and the type of the reference deformable body; and 
     the type identifying unit reads out the type of the reference deformable body corresponding to the feature quantity of the reference deformable body in the newly-obtained tomographic image, and identifies the type of the reference deformable body. Consequently, the type of the reference deformable body can be identified. 
     Furthermore, it comprises an image processing means configured to shift a tomographic image or an elasticity image toward the ultrasonic probe side in accordance with the thickness of the reference deformable body identified in the type identifying unit. Furthermore, it comprises an ultrasonic wave transmission/reception control unit configured to control the focus of the ultrasonic wave in accordance with the thickness of the reference deformable body identified by the type identifying unit, so that the ultrasonic wave will not be focused on the reference deformable body. 
     In the present invention, the type of a reference deformable body can be identified, and the information thereof can be reflected to calculation of elasticity or displayed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows the general configuration of the present invention. 
         FIG. 2  shows the attachment pattern of a reference deformable body related to the present invention. 
         FIG. 3  shows the display pattern of an ID related to the present invention. 
         FIG. 4  shows the first embodiment of the present invention. 
         FIG. 5  shows an embodiment of pressure measurement related to the present invention. 
         FIG. 6  shows the second embodiment of the present invention. 
         FIG. 7  shows a tomographic image of a reference deformable body in which scatterer is included, which is related to the present invention. 
         FIG. 8  shows a tomographic image of a reference deformable body formed by a plurality of different layers, which is related to the present invention. 
         FIG. 9  shows a tomographic image of a reference deformable body including bar code, which is related to the present invention. 
         FIG. 10  shows the third embodiment of the present invention. 
         FIG. 11  shows tomographic images before and after receiving correction process. 
     
    
    
     DESCRIPTION OF REFERENCE NUMERALS 
       1 : ultrasonic wave transmission/reception control circuit,  2 : transmitting circuit,  3 : ultrasonic probe,  4 : receiving circuit,  5 : phasing and adding circuit,  6 : signal processing unit,  7 : black and white scan converter,  8 : RF signal frame data selecting unit,  9 : displacement/strain calculating unit,  10 : elasticity modulus calculating unit,  11 : elasticity data processing unit,  12 : color scan converter,  13 : switching and adding unit,  14 : image display unit,  15 : pressure calculating unit,  16 : reference deformable body,  30 : reference deformable body information acquiring unit,  32 : control unit,  34 : input unit,  36 : cine memory 
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present invention will be described referring to the diagrams.  FIG. 1  shows a block diagram of the ultrasonic diagnostic apparatus related to the present invention. An ultrasonic diagnostic apparatus is for acquiring a tomographic image of a measuring portion in an object to be examined using ultrasonic waves and displaying an elasticity image that presents hardness or softness of biological tissues. 
     The ultrasonic diagnostic apparatus is Configured comprising ultrasonic wave transmission/reception control circuit  1 , transmitting circuit  2 , ultrasonic probe  3 , receiving circuit  4 , phasing and adding circuit  5 , signal processing unit  6 , black and white scan converter  7 , RF signal frame data selecting unit  8 , displacement/strain calculating unit  9 , elasticity modulus calculating unit  10 , elasticity data processing unit  11 , color scan converter  12 , switching and adding unit  13 , image display unit  14 , pressure calculating unit  15 , reference deformable body  16 , reference deformable body information acquiring unit  30 , control unit  32 , input unit  34  and cine memory  36  as shown in  FIG. 1 . 
     Ultrasonic probe  3  is formed by disposing multiple strips of transducers therein, for transmitting and receiving ultrasonic waves to/from an object by scanning beams mechanically or electronically. Each transducer generally has the function that converts incoming pulse waves or continuous transmitting signals into ultrasonic waves and discharges the converted ultrasonic waves, and the function that converts the reflected echoes discharged from inside of the object into electronic signals (reflected echo signals) and outputs the converted signals. 
     Reference deformable body  16  is attached on the ultrasonic wave transmitting/receiving surface of ultrasonic probe  3 . Reference deformable body  16  is to be applied on the body surface of the object to give compression. Compressing motion renders transmission/reception of ultrasonic waves via ultrasonic probe, and provides stress distribution to the measuring portion in the body cavity. 
     Ultrasonic wave transmission/reception control circuit  1  controls the timing or focus for transmitting and receiving ultrasonic waves. Transmitting circuit  2  produces transmission pulses for generating ultrasonic waves by driving ultrasonic probe  3 , and sets the convergent point (focus) of the ultrasonic waves transmitted by an internal transmission phasing and adding circuit at a certain depth. Receiving circuit  4  amplifies the reflected echo signal received by ultrasonic probe  3  at a predetermined gain. The number of reflected echo signals which corresponds to the number of the amplified respective transducers is inputted to phasing and adding circuit  5 . Phasing and adding circuit  5  controls the phase of the reflected echo signal amplified in receiving circuit  4 , and forms RF signal frame data. 
     Signal processing unit  6  and black and white scan converter  7  are provided on one end of the output side of phasing and adding circuit  5 . Signal processing unit  6  inputs the RF signal frame data from phasing and adding circuit  5 , and executes various signal processing such as gain compensation, log compensation, detection, edge enhancement and filtering. 
     Black and white scan converter  7  obtains the RF signal frame data signal processed in signal processing unit  6  at a predetermined cycle, and reads out the tomographic image data based on the RF signal frame data at TV system cycle. 
     Also, RF signal frame data selecting unit  8 , displacement/strain calculating unit  9 , pressure calculating unit  15  and elasticity modulus calculating unit  10  are comprised on the output side of the other end of phasing and adding circuit  5 . Also, elasticity data processing unit  11  and color scan converter  12  are comprised on the latter part of elasticity modulus calculating unit  10 . 
     On the output side of black and white scan converter  7  and color scan converter  12 , switching and adding unit  13  is comprised. Image display unit  14  is a monitor for displaying a tomographic image based on the tomographic image data obtained by black and white converter  7  and an elasticity image based on the elasticity image data obtained by the color scan converter. Cine memory  36  on the output side of switching and adding unit  13  is for storing tomographic image data and elasticity image data with time information. The tomographic image data and elasticity image data stored in cine memory  36  are displayed on image display unit  14  according to the command from input unit  34 . 
     RF signal frame data selecting  8  sequentially stores the RF signal frame data outputted from phasing and adding circuit  5  (the currently stored RF signal frame data is set as RF signal frame data N) in the frame memory provided in RF frame data selecting unit  8 , selects one set of RF signal frame data from among the past RF signal frame data N−1, N−2, N−3, . . . N−M (the selected data is set as RF signal frame data X), and outputs a pair of RF signal frame data N and RF signal frame data X to displacement/strain calculating unit  9 . While RF signal frame data is described above as the signal to be outputted from phasing and adding circuit  5 , it may also be the form of I,Q signal which is the complex-demodulated RF signal. 
     Displacement/strain calculating unit  9  executes one-dimensional or two-dimensional correlationship process based on the pair of RF signal frame data selected by RF signal frame data selecting unit  8 , measures displacement or moving vector (direction and size of displacement) of the respective measurement points on a tomographic image, generates displacement frame data, and calculates the strain from the generated strain frame data. The strain is to be calculated, for example, by performing spatial differentiation on the displacement. The moving vector is to be detected, for example, using the block matching method or the gradient method. Block matching method divides an image into blocks formed by, for example, N×N pixels, searches the block which is most approximated to the target block in the current frame from the previous frame, and performs encoding referring to the searched blocks. 
     Elasticity modulus calculating unit  10  calculates elasticity modulus from the strain information outputted from displacement/strain calculating unit  9  and from the pressure information outputted from pressure calculating unit  15 , generates numerical data of the elasticity modulus (elasticity frame data), and outputs the generated data to elasticity data processing unit  11  and color scan converter  12 . One of elasticity modulus, for example, Young&#39;s modulus Ym is to be obtained by dividing the stress (pressure) in each calculation point by the strain in each calculation point, as shown in the equation below. In the equation below, the index of i,j represents the coordinate of the frame data.
 
 Ymi,j =pressure(stress) i,j /(strain  i,j )( i,j= 1, 2, 3 . . . )  [Equation 1]
 
     Here, the pressure given to the object is measured in pressure measuring unit  15 . Pressure measuring unit  15  obtains the pressure given to reference deformable body  16  by calculation, and outputs it as the pressure given to the object. The detail on this step will be described later. 
     Elasticity data processing unit  11  executes various image processing such as smoothing process in the coordinate plane of the calculated elasticity frame data, contrast optimization process, or smoothing process among the frames in the time axis direction. 
     Color scan converter  12  provides color information on light&#39;s three primary colors that are red(R), green(G) and blue(B) to the elasticity frame data outputted from elasticity data processing unit  11 . For example, large elasticity modulus is converted into red color code, and small elasticity modulus is converted into blue color code. 
     Also, object pressing mechanism  18  moves ultrasonic probe  3  in vertical directions using a device such as motor or wire so as to press the object, or an operator may manually move ultrasonic probe  3  in vertical direction. 
     First Embodiment 
     Manual Input of ID 
     Here, the first embodiment will be described referring to  FIGS. 1˜5 . In the first embodiment, an operator inputs an ID to make an ultrasonic diagnostic apparatus to identify the type of a reference deformable body, for reflecting the type to elasticity calculation or displaying the type. This ID is to be the index for identifying the type of the reference deformable body. 
     The ultrasonic diagnostic apparatus of the first embodiment mainly comprises input unit  34  configured to input an ID of reference deformable body  16 , control unit  32  configured to make the ID inputted by input unit  34  to be outputted to reference deformable body information acquiring unit  30 , reference deformable information acquiring unit  30  configured to acquire the type of reference deformable body  16  corresponding to the outputted ID and to reflect the type of reference deformable body  16  to calculation in pressure calculating unit  15  or elasticity modulus calculating unit  10 . 
     First, attachment pattern of reference deformable body  16  will be described using  FIG. 2 . As shown in  FIG. 2(   a ), fixing member  17  is formed by frame body  20  having airspace in the center thereof and a pair of holding units  21  extended downward from the bottom surface of frame body  20 . Frame body  20  and holding units  21  are formed being integrated with each other. On holding unit  21 , a protruded portion is provided so as to fit in the slot on the side portion of ultrasonic probe  3  (not illustrated in the diagram). Accordingly, fixing member  17  can be mounted to ultrasonic probe  3  through one-touch operation. Also, on the inner-peripheral surface of the airspace in frame body  20 , slot portion  22  is provided for holding reference deformable body  16 . The width of lot portion  22  is about 3 mm, and the depth thereof is about 5 mm. 
     As shown in  FIG. 2(   b ), reference deformable body  16  has a form wherein rectangle body  26  is provided to the central portion on the upper surface of a square-shaped flat-plate body  25 . Rectangle body  26  of reference deformable body  16  has the size which can be protruded from the airspace in fixing member  17 . Also, flat-plate body  25  has about 3 mm of thickness which can be fit in slot portion  22  of fixing member  17 . 
     Reference deformable body  16  is formed based on oil-based gel material, water-based gel material such as acrylamide or silicon, etc. Acrylamide is formed as acrylamide gel wherein cross-linking agent (BIS) is polymerized in the presence of catalytic agent. This is polymer gel having 3-dimensional meshed structure, and has texture like agar or gelatin. In this manner, the material that is a liquid solution and gets coagulated over time into a gel after coagulating agent is mixed in is preferable for reference deformable body  16 . If it is constituted by the material such as acrylamide having low viscosity, it is suited for pressure measurement since it responds to pressing operation quickly. Also, reference deformable body  16  may also be formed by a material based on aqueous resin gelled substance which is to be used as a phantom for diagnosis using ultrasonic waves. 
       FIG. 2(   c ) shows a pattern wherein reference deformable body  16  is attached to fixing member  17 . The end portion of flat-plate body  25  is inserted into slot portion  22  formed on the inner-peripheral surface of frame body  20 , and reference deformable body  16  is attached to fixing member  17 . Since flat-plate body  25  which is reference deformable body  16  is an elastic body, flat-plate body  25  can be mounted in slot portion using the elasticity. Accordingly, when reference deformable body  16  is attached to fixing member  17 , rectangle body  26  of reference deformable body  16  is protruded from frame body  20  of fixing member  17 . 
       FIG. 2(   d ) shows the cross-sectional view in the longitudinal direction of the condition that reference deformable body  16  and fixing member  17  are fixed on ultrasonic probe  3 . In the condition that reference deformable body  16  is attached to fixing member  17  as shown in  FIG. 2(   c ), fixing member  17  is fixed on ultrasonic probe  3  via holding unit  22 . When fixing member  17  is fixed on ultrasonic probe  3 , reference deformable body  16  comes to contact transducers  19  provided on the upper part of ultrasonic probe  3 . In this condition, the upper surface of reference deformable body  16  is applied to an object, and executes transmission/reception of ultrasonic waves from/to transducers  19 . 
     Also, as shown in  FIG. 3 , reference deformable body  16  or package  40  of reference deformable body  16  has ID  40 . 
     (1-1: ID on a Reference Deformable Body) 
     Concretely, as shown in  FIG. 3(   a ), ID  40  formed by letters is appended on the side surface of reference deformable body  16 . ID  40  is, for example, “BBAC” formed by four alphabetical letters. ID  40  is appended on the side surface (the part which does not contact the object) of reference deformable body  16  to avoid the influence thereof in transmission and reception of ultrasonic waves to/from the object. An operator can identify ID  40  by the order of alphabetical letters through checking ID  40  on the side surface of reference deformable body  16 . ID  40  may be presented also by numbers, symbols, figures, colors, and so on. 
     Also, as shown in  FIG. 3(   b ), by providing concavity and convexity for imprinting ID  40  in advance on a metal mold to form reference deformable body  16  and inpouring gel material of reference deformable body in the metal mold, ID  40  formed by concavity and convexity can be formed on the side surface of reference deformable body  16 . The operator can identify ID  40  by seeing or touching the concavity and convexity of ID  40  formed on the side surface of reference deformable body  16 . Also, surface treatment such as sawtooth or wave pattern may be worked on the side surface of reference deformable body  16 . 
     Also, ID  40  may be identified by dyeing reference deformable body  16 . For example, if reference deformable body  16  is white ID  40  is set as “BBAC”, and if reference deformable body  16  is yellow ID  40  is set as “AAAA”. 
     (1-2: ID on a Package) 
     As shown in  FIG. 3(   c ), ID  40  may be appended on case  42  which is for packaging reference deformable body  16 . Case  42  has case part  46  having airspace therein and cover part  44 , and reference deformable body  16  is contained and sealed between case part  46  and cover part  44 . By sealing and containing reference deformable body  16  inside of case  42 , deterioration of reference deformable body  16  can be minimized by keeping out dust or air. 
     The operator can identify the alphabetical letters, i.e. ID  40  of reference deformable body by seeing ID  40  on the case for packaging reference deformable body  16 . 
     (1-3: Manual Input of ID) 
     Next, as shown in  FIG. 4 , the operator inputs ID  40  of reference deformable body  16  or ID  40  described on case  42  for containing reference deformable body  16  to input unit  34 . Control unit  32  outputs ID  40  inputted by input unit  34  to reference deformable body information acquiring unit  30 , and gives a command to identify the type of reference deformable body  16 . Then reference deformable body information acquiring unit  30  identifies the type of reference deformable body  16  from the outputted ID  40 , and reflects the type of reference deformable body  16  to calculation to be executed by pressure calculating unit  16  and elasticity modulus calculating unit  10 . Also, reference deformable body information acquiring unit  30  displays the type of reference deformable body  16  on image display unit  14 . 
     In concrete terms, reference deformable body information acquiring unit  30  is formed by ID information receiving unit  50  for receiving the inputted ID  40  of reference deformable body  16 , memory  52  for storing a plurality of relationships between IDs  40  of reference deformable body  16  and types of reference deformable body  16  in advance, and type identifying unit  54  for identifying the type of reference deformable body  16  corresponding to the inputted ID  40  based on the information stored in memory  52 . Also, in memory  52 , one type of reference deformable body (such as thickness, elasticity characteristic, acoustic characteristic and type of the probe) is stored corresponding to one ID  40  as shown in chart 1 below. 
     
       
         
               
               
               
               
               
             
           
               
                 CHART 1 
               
               
                   
               
               
                   
                   
                 Elasticity 
                 Acoustic 
                 Kind of probe 
               
               
                   
                 Thickness 
                 characteristics 
                 characteristics 
                 (Applying 
               
               
                 ID 
                 (mm) 
                 (N/m) 
                 (N · s/m 3 ) 
                 part) 
               
               
                   
               
             
             
               
                 AAAA 
                 8 
                 100 
                 1.5 × 10 6   
                 Linear type 
               
               
                 BAAA 
                 7 
                 100 
                 1.5 × 10 6   
                 Linear type 
               
               
                 BBAA 
                 7 
                  50 
                 1.5 × 10 6   
                 Linear type 
               
               
                 . 
                 . 
                 . 
                 . 
                 . 
               
               
                 . 
                 . 
                 . 
                 . 
                 . 
               
               
                 . 
                 . 
                 . 
                 . 
                 . 
               
               
                 DDDD 
                 5 
                  30 
                 1.0 × 10 6   
                 Intracavitary 
               
               
                   
                   
                   
                   
                 type 
               
               
                   
               
             
          
         
       
     
     Here, the thickness of reference deformable body  16  is the thickness of reference deformable body in the transmitting/receiving direction of ultrasonic waves, and is the initial thickness before applying pressure. Elasticity characteristics indicate elasticity modulus, viscoelasticity modulus, nonlinearity, Poisson&#39;s ratio, etc. of reference deformable body  16 . In the present embodiment, elasticity modulus is used as elasticity characteristic. Also, acoustic characteristics indicate acoustic velocity, rate of decrease, acoustic impedance, etc. of reference deformable body  16 . In the present embodiment, acoustic impedance is used as acoustic characteristic. The type of probe indicates the type of ultrasonic probe  3  to which reference deformable body  16  is attached. For example, there are different types such as linear type of ultrasonic probe  3  for pressing from outside of the body or a convex type of ultrasonic probe  3 , or an intracavitary type of ultrasonic probe  3  for pressing from inside of the object&#39;s body, and the applying part is to be determined. 
     The four alphabetical letters which indicate ID  40  respectively correspond to the type of each reference deformable body  16 . The far-left alphabet corresponds to the thickness of each reference deformable body  16 . For example, if the far left alphabet is A, it means that the thickness of the reference deformable body is 8 mm, B indicates that the thickness of the reference deformable body is 7 mm, C indicates that the thickness of the reference deformable body is 6 mm, and D indicates that the thickness of the reference deformable body is 5 mm. In this manner, the operator can recognize the thickness of reference deformable body  16  by only looking at ID  40 . In the same manner, the second left alphabet corresponds to the elasticity characteristics. The third left alphabet corresponds to the acoustic characteristic, and the far-right alphabet corresponds to the type of ultrasonic probe to which reference deformable body  16  is attached. 
     Then kind identifying unit  54  identifies the kind of reference deformable body  16  corresponding to the inputted ID  40  by reading it out from memory  52 . Input unit  34  may also input the information on characteristics (for example, elasticity characteristics, etc. of reference deformable body  16 ) of reference deformable body  16  instead of ID  40 . 
     (1-4: Pressure Measurement) 
     Type identifying unit  54  outputs the type of reference deformable body  16  to pressure calculating unit  15 . Pressure calculating unit  15  detects the thickness and the elasticity modulus in particular from among the types of reference deformable body  16  (thickness, elasticity characteristics, acoustic characteristics, type of probe, etc.) outputted from reference deformable body information acquiring unit  30 . The detected thickness is the initial thickness of reference deformable body  16  before pressure is applied to the object. 
     Pressure calculating unit  15  obtains the strain of reference deformable body  16  deformed by the pressure applied to the object, from the RF signal frame data outputted from RF signal frame data selecting unit  8 . In concrete terms, pressure calculating unit  15  first extracts the RF signal frame data in the region including the border between the object and reference deformable body  16 . Then it obtains the coordinate of the border between the object and reference deformable body  16  based on the extracted RF signal frame data. For example, the threshold value is set with respect to the amplitude of the signal wave pattern of the RF signal frame data including the border, the threshold value is set as original point 0 in the depth direction (contact plane of the transducer and reference deformable body  16 ), and the coordinate wherein the amplitude of the waveform of the RF signal frame data first surpasses the threshold value from in the depth direction from the original point is detected as the coordinate of the border. 
     While the border between the object and reference deformable body  16  is detected above based on the RF signal frame data, the tomographic image data outputted from black and white scan converter  16  may also be used for detecting the border.  FIG. 5(   a ) shows the condition of reference deformable body  16  before pressure is applied on the object.  FIG. 5(   b ) shows the condition of reference deformable body  16  after pressure is applied on the object. Pressure calculating unit  15  detects the coordinate of the border in the tomographic image based on the difference of the acoustic characteristics (acoustic velocity, rate of decrease and acoustic impedance) between tissue  1  and reference deformable body  16 . 
     Then pressure calculating unit  15  associates the initial thickness of reference deformable body  16  before pressure is applied with the coordinate of the border. Also, pressure calculating unit  15  calculates the displacement of reference deformable body  16  from the coordinate of the border after pressure is applied, based on the association between the initial thickness and the coordinate of the border. Pressure calculating unit  15  then calculates the strain from the calculated displacement and the initial thickness. 
     Also, elasticity modulus (a part of elasticity characteristics) of reference deformable body  16  is identified by type identifying unit  54  based on ID  40 . Consequently, by setting P as (pressure(stress)), Y as (elasticity modulus) and δd as (strain), their relationship can be expressed by the following equation.
 
 P (pressure(stress))= Y (elasticity modulus)×δ d (strain)  [Equation 2]
 
     Pressure calculating unit  15  can obtain the pressure in the border between the object and reference deformable body  16  based on the above-mentioned equation 2. 
     (1-5: Calculation of Elasticity Modulus) 
     Elasticity modulus calculating unit  10  calculates elasticity modulus based on the above equation 1 from the strain information outputted from displacement/strain calculating unit  9  and the pressure information outputted from pressure calculating unit  15 , and generates numerical data (elasticity frame data) of the elasticity modulus. Elasticity modulus calculating unit  10  outputs the elasticity frame data to elasticity data processing unit  11 . 
     Color scan converter  12  appends hue information to the elasticity frame data outputted from elasticity data processing unit  11 , and image display unit  14  displays the elasticity image based on the elasticity image data acquired by the color scan converter. Though not shown in the diagram, image display unit  14  may also display the elasticity modulus outputted from elasticity modulus calculating unit  10  by numerical values. 
     As described above, in accordance with the present embodiment, it is possible to identify the type of reference deformable body  16  by ID  40 , and to reflect the identified information on elasticity calculation, whereby calculation of elasticity can be more stable. 
     (1-6: ID Display) 
     Also, type identifying unit  54  outputs the type of reference deformable body  16  or ID  40  to cine memory  36 . Cine memory  36  stores the type of reference deformable body  16  or the information on ID  40  along with the elasticity image or tomographic image. Image display unit  14  outputs the type of reference deformable body  16  or the information on ID  40  along with the elasticity image or tomographic image from cine memory  36  and displays them. In this manner, the type of the reference deformable body or ID  40  can be displayed. 
     The operator can execute the setting of ultrasonic waves properly since the type of reference deformable body  16  or ID  40  can be identified. Also, after performing the ultrasonic diagnosis, he/she can identify which type of reference deformable body was used for obtaining the elasticity image or tomographic image upon reviewing the elasticity image or tomographic image obtained by applying reference deformable body  16 . 
     Also, dedicated information on ultrasonic probe  3  is appended to ID  40  as shown in chart 1. Though not shown in the diagram, it is possible to set the procedure to display the warning or to make sounds when reference deformable body  16  is applied to a nondedicated ultrasonic probe  3  and transmission/reception of ultrasonic waves is executed. 
     Second Embodiment 
     ID Automatic Identification 
     (2-1: Echo Luminance) 
     Here, the second embodiment will be described using  FIG. 6˜FIG .  9 . The difference from the first embodiment is that ID  40  of reference deformable body  16  is automatically identified. 
     Reference deformable body information identifying unit  30  is formed by image analyzing unit  60  configured to the tomographic image stored in cine memory  36 , memory  52  configured to store the relationship between a plurality of IDs  40  of reference deformable body  16  and feature quantity of the tomographic image of reference deformable body  16  in advance, and type identifying unit  54  configured to identify the type of reference deformable body  16  corresponding to the inputted tomographic image based on the information stored in memory  52 . 
     Reference deformable body  16  includes, for example, a scatterer. Image analyzing unit  60  analyses the echo luminance in the tomographic image of reference deformable body  16  in which the scatterer outputted from cine memory  36  is included. The memory  52  stores plural echo luminance (0˜255) of reference deformable body  16  by associating them with ID  40  respectively. For example, as shown in chart 2, it is assumed that there are two kinds (ID  40 : α,β) of reference deformable bodies  16  having different elasticity modulus or scatterer concentration that are stored in memory  52 . It is also assumed that the ultrasonic waves are transmitted/received to/from the respective reference deformable bodies  16  in the same condition. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 CHART 2 
               
               
                   
               
               
                   
                 Elasticity 
                 Scatterer 
                 Echo 
                   
               
               
                   
                 modulus 
                 concentration 
                 luminance 
                 Thickness 
               
               
                 ID 
                 (kPa) 
                 (%) 
                 (0~255) 
                 (mm) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 α 
                 10 
                 1 
                 50 
                 8 
               
               
                 β 
                 20 
                 3 
                 100 
                 7 
               
               
                   
               
             
          
         
       
     
       FIG. 7  are tomographic images in the case that reference deformable body  16  (α,β) in which scatterer is included is attached.  FIG. 7(   a ) is a tomographic image in the case that reference deformable body  16  having α as ID  40  is attached, and  FIG. 7(   b ) is a tomographic image in the case reference deformable body  16  having β as ID  40  is attached. 
     The echo luminance of reference deformable body  16  is displayed in the region where is shallow in depth (for example, 0˜5 mm) in the tomogaphic image. Image analyzing unit  60  analyzes the echo luminance in the shallow region of the tomographic image stored in cine memory  36 . For example, image analyzing unit  60  sets ROI  70  in reference deformable body  16  of the tomographic image, and analyzes the luminance information in ROI  70 . This ROI  70  is set via input unit  34  as one chooses. Also, it may be set so that ROI  70  is automatically set in the region which is shallow in depth (for example, 0˜5 mm) in the tomographic image. 
     Image analyzing unit  60  analyzes statistical characteristics of the echo luminance such as the average value or dispersion value of the echo luminance in ROI  70 . Then type identifying unit  54  reads out the type of reference deformable body  16  corresponding to the characteristics of the echo luminance in the analyzed tomographic image from memory  52  and identifies it. 
     In concrete terms, if the average value of the echo luminance in ROI  70  is “50”, type identifying unit  54  identifies that ID  40  of reference deformable  16  is α. Also, if the average value of the echo luminance in ROI  70  is “100”, type identifying unit  54  identifies that ID  40  of the reference deformable body is β. 
     Then type identifying unit  54  outputs the type (here, elasticity modulus, scatterer concentration, echo luminance and thickness) or ID  40  of reference deformable body  16  to cine memory  36 . Cine memory  36  stores the information on the type or ID  40  of reference deformable body  16  along with the elasticity image or tomographic image. Image display unit  14  outputs the information on the type or ID  40  of reference deformable body  16  along with the elasticity image or tomographic image from cine memory  36 , and displays them. Accordingly, the operator can identify the type or ID  40  of reference deformable body, and set ultrasonic waves appropriately. Also, he/she can identify the type of reference deformable body  16  used for obtaining the elasticity image or tomographic image. 
     Also, as in the same manner as the first embodiment, elasticity modulus may be calculated based on the type of reference deformable body  16 . Type identifying unit  54  outputs the type of reference deformable body  16  to pressure calculating unit  15 , and pressure calculating unit  15  calculates the pressure. Then elasticity modulus calculating unit  10  calculates elasticity modulus from the strain information outputted from displacement/strain calculating unit  9  and the pressure information outputted from pressure calculating unit  15 , and generates the numerical data (elasticity frame data) of the elasticity modulus. Image display unit  14  displays the elasticity image or elasticity modulus based on the generated elasticity frame data. 
     (2-2: Attenuation Characteristics) 
     While the type of reference deformable body  16  is identified above from the average value of the echo luminance in reference deformable body  16 , there are cases, for example, that approximately average echo luminance is distributed even when the scatterer concentration of reference deformable body  16  is greatly different. 
     Given this factor, type identifying unit  54  may identify the type of reference deformable body  16  from attenuation characteristic of reference deformable body  16 . Attenuation characteristic is the feature that ultrasonic waves attenuate in proportion to the scatterer concentration. Image analyzing unit  60  analyzes the attenuation characteristics from distribution of the intensity of echo luminance in reference deformable body  16 . The intensity of echo luminance in reference deformable body  16  has the characteristic that it attenuates as moving from the shallow depth portion to the deep portion. 
     When the ultrasonic waves having low transmitting voltage are transmitted/received to/from ultrasonic probe  3  and the scatterer concentration of reference deformable body  16  is high, attenuation rate is great and the intensity of echo luminance attenuates drastically. ID  40  in this condition is set as α. Also, when the ultrasonic waves having high transmitting voltage are transmitted/received to/from ultrasonic probe  3  and the scatterer concentration is low, attenuation rate is small and the intensity of echo luminance attenuates gradually. ID  40  of this reference deformable body  16  is set as β. The relationship between the attenuation of reference deformable body  16  and ID  40  is stored in memory  52 . 
     Image analyzing unit  60  analyzes the attenuation rate from the distribution of the intensity in echo luminance of the scatterer in ROI  70 . Then type identifying unit  54  reads out and identifies the type of reference deformable body  16  corresponding to the attenuation rate from memory  52 . Type identifying unit  54 , in the case that the attenuation rate in ROI  70  is high, identifies that ID  40  of reference deformable body  16  is α. In the case that the attenuation rate in ROI is low, it identifies that ID  40  of reference deformable body  16  is β. 
     (2-3: Pattern of Scatterer) 
     Also, type identifying unit  54  may identify the type of reference deformable body  16  from density distribution (rarefaction density) of scatterer in reference deformable body  16 . 
     For example, in the case that density distribution of the scatterer of reference deformable body  16  gets higher as it moves from the shallow region to the deep region, ID  40  of reference deformable body  16  is set as α. In the case that the density distribution of the scatterer of reference deformable body  16  gets lower as it moves from the shallow region to the deep region, ID  40  of reference deformable body  16  is set as β. The relationship between the scatterer distribution of reference deformable body  16  and ID  40  is to be stored in memory  52 . 
     Image analyzing unit  60  analyzes density distribution of the scatterer from the echo luminance in ROI  70 . Then type identifying unit  54  reads out and identifies the type of reference deformable body  16  corresponding to the density distribution of the analyzed scatterer from memory  52 . 
     Type identifying unit  54 , in the case that the echo luminance in ROI  70  gets lower as it moves from the shallow region to the deep region, identifies that ID  40  of reference deformable body  16  is α. Type identifying unit  54 , in the case that the echo luminance in ROI  70  gets higher as it moves from the shallow region to the deep region, identifies that ID  40  of reference deformable body  16  is β. Type identifying unit  54  may also identify the type of reference deformable body  16  based on discreteness (dispersion in normal distribution) of the echo luminance distribution in the scatterer of reference deformable body  16 . 
     (2-4: Size and Form of Scatterer) 
     Also, deformable body type identifying unit  54  may identify the type of reference deformable body  16  from the size of the scatterer. For example, when the size of the scatterer included in reference deformable body  16  is 5 μm, ID  40  of reference deformable body  16  is set as α. When the size of the scatterer included in reference deformable body  16  is 10 μm, ID  40  of reference deformable body is set as β. At this time, it is to be assumed that a plurality of scatterers having even size are included in reference deformable body  16 . The relationship between the size of the scatterer in reference deformable body  16  and ID  40  is stored in memory  52 . 
     Image analyzing unit  60  analyzes the size of the scatterer from echo luminance in ROI  70 . Then type identifying unit  54  reads out and identifies the type of reference deformable body  16  corresponding to the size (5 μm or 10 μm) of the analyzed scatterer. Also, deformable body type identifying unit  54  can also identify the form of the scatterer in reference deformable body  16  using the pattern matching method. It is set so that the form of the scatterer is different for each ID  40  of reference deformable body  16 . 
     The relationship between the form of the scatterer of reference deformable body and ID  40  is stored in memory  52 . Image analyzing unit  60  analyzes the form of the scatterer from the echo luminance in ROI  70 . Then type specifying unit  54  executes the pattern matching method between the form of the scatterer stored in memory  54  and the form of the analyzed scatterer. Type identifying unit  54  reads out and identifies the type of reference deformable body  16  including the best matched scatterer stored in the memory. 
     (2-5: Layer and Barcode) 
     Also, deformable body type identifying unit  54  may identify the type by the pattern or barcode of reference deformable body  16 . As shown in  FIG. 8 , reference deformable body  16  is assumed to be formed by a plurality of different kinds of layers (layer  1  and layer  2 ). Layer  1  is on the side of ultrasonic probe  3 , and layer  2  is on the side of the object. 
     As shown in  FIG. 8(   a ), in the case that the ratio between layer  1  and layer  2  of reference deformable body  16  is (layer  1 :layer  2 =1:2), ID  40  of reference deformable body  16  is set as α. As shown in  FIG. 8(   b ), in the case that the ratio thereof is (layer  1 :layer  2 =1:1), ID  40  of reference deformable body is set as β. The relationship between the ratio between the layers of reference deformable body  16  and ID  40  is stored in memory  52 . 
     Image analyzing unit  60  analyzes the ratio between layer  1  and layer  2  of reference deformable body  16  from the echo luminance of an elasticity image. In concrete terms, image analyzing unit  60  detects the border between layer  1  and layer  2 , and the border between layer  2  and tissue  1  based on the echo luminance. Then image analyzing unit  60  detects the height of layer  1  and layer  2  in the depth direction from the respective borders. Type identifying unit  54  then reads out and identifies ID  40  of reference deformable body  16  corresponding to the detected ratio between layer  1  and layer  2  from memory  52 . 
     Also, as shown in  FIG. 9 , it is assumed that mark  72  formed by barcodes is appended to the side of reference deformable body  16 . As shown in  FIG. 9(   a ), in the case that reference deformable body  16  includes one strip of barcode, ID  40  of reference deformable body  16  is set as α. As shown in  FIG. 9(   b ), in the case that reference deformable body  16  includes two strips of barcodes, ID  40  of reference deformable body  16  is set as β. The relationship between the number of strips in barcode and ID  40  of reference deformable body  16  is stored in memory  52 . The echo luminance of barcode should be different from the echo luminance of reference deformable body  16 . The array direction of the barcode is the major-axis direction or minor-axis direction of reference deformable body  16 . 
     Image analyzing unit  60  analyzes the number of strips of barcode in reference deformable body  16  from the echo luminance of the elasticity image. Then type identifying unit  54  reads out and identifies ID  40  of reference deformable body  16  corresponding to the analyzed number of strips of barcode from memory  52 . 
     While barcode is used as mark  72  here, a concave portion or notch may also be used. Also, by stretching a very thin string (for example, a fish line) inside of reference deformable body  16  along the minor-axis direction of reference deformable body  16 , the information on the number of the strings or interval between the strips may be also used as mark  72 . 
     Third Embodiment 
     Image Processing 
     The third embodiment will now be described referring to  FIGS. 10 and 11 . The difference from the first embodiment and the second embodiment is that image processing is executed by identifying the type of reference deformable unit  16 . 
     As shown in  FIG. 10 , reference deformable body information acquiring unit  30  has image processing unit  62  for executing image processing with respect to the tomographic image (or elasticity image) stored in cine memory  36 , in addition to the above-described image analyzing unit  60 , memory  52  and type identifying unit  54 . 
     Type identifying unit  54  outputs ID  40  of reference deformable body  16  (includes thickness, elasticity characteristics, acoustic characteristics, kind of probe, etc.) to image processing unit  62 . Image processing unit  62  detects thickness from ID  40 . 
     As shown in  FIG. 11 , image processing unit  62  shifts the tomographic image toward the upper direction (the side of ultrasonic probe  3 ) according to the “thickness” of reference deformable body  16  so as not to display reference deformable body  16 .  FIG. 11(   a ) shows the tomographic image before the correction, and  FIG. 11(   b ) shows the tomographic image after the correction. 
     In concrete terms, as shown in Chart 1, if ID  40  identified in type identifying unit  54  is AAAA, the thickness of reference deformable body  16  is 8 mm. Image processing unit  62  loads the thickness information of the reference deformable body from type identifying unit  54 , and shifts the tomographic image stored in cine memory  36  in the upper direction by 8 mm. If ID  40  is BAAA, the thickness of reference deformable unit  16  is 7 mm. Image processing unit  62  loads thickness information of the reference deformable body from type identifying unit  54 , and shifts the tomographic image stored in cine memory  36  in the upper direction by 7 mm. 
     In this manner, as shown in  FIG. 11(   b ), since reference deformable body  16  is not displayed on image display unit  14 , it is possible to broaden the display region of tissue  5  in the deep portion. 
     Fourth Embodiment 
     Focus Only on the Thickness Portion 
     Here, the fourth embodiment will be described. The difference from the first embodiment˜the third embodiment is that transmission and reception of ultrasonic waves is controlled by identifying ID  40  of reference deformable body  16 . 
     In the present embodiment, though not shown in the diagram, reference deformable body information acquiring unit  30  is connected with ultrasonic-wave transmission/reception control circuit  1 . 
     Type identifying unit  54  outputs ID  40  of reference deformable body  16  (includes thickness, elasticity characteristics, acoustic characteristics, kind of probe, etc.) to ultrasonic-wave transmission/reception control circuit  1 . Ultrasonic-wave transmission/reception control circuit  1  detects “thickness” from ID  40 . Then ultrasonic-wave transmission/reception control circuit  1  controls focus of the ultrasonic waves according to the thickness so that the ultrasonic waves will not be focused on reference deformable body  16 . 
     In concrete terms, as shown in Chart 1, if ID  40  identified in type identifying unit  54  is AAAA, the thickness of reference deformable body  16  is 8 mm. Ultrasonic-wave transmission/reception circuit  1  loads the thickness information of the reference deformable body from type identifying unit  54 , and controls transmission circuit  2  and receiving circuit  4  so that ultrasonic waves will be focused at the depth deeper than 8 mm to avoid ultrasonic waves from being focused on reference deformable body  16 . 
     Accordingly, since ultrasonic waves are focused on tissues  1 ˜ 5  of the object, image display unit  14  can display the tomographic image appropriately.