JP5534699B2 - X-ray diagnostic apparatus and image processing apparatus - Google Patents

Description

  The present invention relates to an X-ray diagnostic apparatus and an image processing apparatus used for X-ray imaging using a dual energy subtraction method.

  In the digital subtraction method, which is one of the X-ray imaging methods by the X-ray diagnostic apparatus, two images of X-rays with different quality are taken by changing the tube voltage at the same imaging position, and the density value of each image Is multiplied by a weighting factor (w value) (adding a weighting factor or putting on clogs is also possible), and subtraction is performed for each corresponding pixel, so that, for example, X-ray absorption can be performed from the captured image. There is a so-called dual energy (DE) subtraction method that obtains an image from which large bones are erased, or an image from which soft tissues with small X-ray absorption are erased.

  The X-ray diagnostic apparatus can acquire an image of only the bone from which the soft tissue has been removed or a DE image of only the soft tissue from which the bone has been removed by changing the weighting factor. In the X-ray diagnostic apparatus, weighting factors corresponding to the energy of irradiated X-rays are determined in advance as a table.

  As an X-ray diagnostic apparatus using the dual energy subtraction method, a triode X-ray tube is used, and the filament current is set to a current value that allows an allowable maximum current during low tube voltage imaging, and the grid is negative during high tube voltage imaging. There is a device that applies a voltage to control the current to be equal to or less than the allowable maximum current for the high tube voltage, and causes the allowable maximum current for the low tube voltage to flow by setting the voltage applied to the grid to 0 during low tube voltage imaging. (For example, refer to Patent Document 1).

  Moreover, there exists an apparatus like patent document 2 as an X-ray diagnostic apparatus using a dual energy subtraction system.

JP 2008-73115 A Japanese Patent Laid-Open No. 2002-359781

  When a DE image is generated using a table of weight coefficients determined in advance, a DE image with varying luminance is generated depending on individual differences such as the body thickness of the subject, so that the diagnosis may vary depending on the skill of the diagnostician. was there.

  The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide an X-ray diagnostic apparatus and an image processing method capable of displaying a DE image suitable for diagnosis of a target site.

In order to solve the above-described problems, an X-ray diagnostic apparatus according to the present invention uses X-ray imaging using a first radiation quality and a second radiation quality smaller than the first radiation quality for a subject. A control means for performing control so as to perform X-ray imaging, and a pixel value of a direct line based on a histogram of a first image generated by X-ray imaging using the first radiation quality and a maximum in the subject. Pixel values for obtaining respective pixel values and obtaining pixel values of direct lines and highest pixel values in the subject based on a histogram of a second image generated by X-ray imaging using the second radiation quality A first width which is a width of the pixel value of the direct line and the highest pixel value based on the first image , and a pixel value of the direct line and the width of the highest pixel value based on the second image ; width calculating means for determining a certain second width respectively, the first width及 Has a ratio calculating means for calculating a ratio of said second width as a weighting factor, and an image generating means for generating a difference image of the first image and the second image using the weighting factor.

In order to solve the above-described problem, an image processing apparatus according to the present invention uses a pixel value of a direct line based on a histogram of a first image generated by X-ray imaging using a first radiation quality for a subject, A pixel value of a direct line and the subject are obtained based on a histogram of a second image generated by X-ray imaging using a second radiation quality smaller than the first radiation quality, respectively , by obtaining a highest pixel value in the subject. A pixel value calculating means for respectively obtaining the highest pixel value, a pixel value of the direct line based on the first image , a first width which is a width of the highest pixel value, and the direct line based on the second image the width calculating means for determining a second width, respectively the width of the pixel value and the maximum pixel value, a ratio calculating means for calculating a ratio of said first width and said second width as a weighting factor, the weighting factor Using the first image and the second It includes an image generating means for generating a difference image of the image, a.

  The X-ray diagnostic apparatus and image processing apparatus according to the present invention can display a DE image suitable for diagnosis of a target site.

The conceptual diagram which shows the production | generation method of DE image. Schematic which shows the whole structure of the X-ray diagnostic apparatus of this embodiment. The figure which shows the structure of an image processing apparatus. The block diagram which shows the function of the X-ray diagnostic apparatus of 1st Embodiment. The figure which shows the histogram of the pixel value about each of a high energy image and a low energy image. The figure for demonstrating how to obtain | require the pixel value in the peak of the linearity as a representative value on the histogram of a low energy image. The figure for demonstrating how to obtain | require the highest and lowest pixel value of the chest as a representative value on the histogram of a low energy image. The figure for demonstrating how to obtain | require the width | variety between the representative value groups based on a high energy image. The figure for demonstrating how to obtain | require the width | variety between the representative value groups based on a low energy image. The block diagram which shows the function of the X-ray diagnostic apparatus of 2nd Embodiment. The block diagram which shows the function of the X-ray diagnostic apparatus of 3rd Embodiment.

  Embodiments of an X-ray diagnostic apparatus and an image processing apparatus according to the present invention will be described with reference to the accompanying drawings.

  First, a method for generating a DE (Dual Energy) image will be described.

The energy (radiation quality, transmission power) I of the transmitted X-ray transmitted through the substance (transmission coefficient μ, thickness x) is expressed by the following formula using the energy I0 of the monochromatic X-ray irradiated from the X-ray tube. I can express.

A signal s obtained by LOG-converting a value proportional to the energy I of the transmitted X-ray can be expressed as the following equation (1).

Further, monochromatic X-rays of high energy I0 _H are transmitted through an object in which soft tissue (permeability coefficient μ _aH , thickness x _a ) and bone (permeability coefficient μ _bH , thickness x _b ) are mixed and LOG converted. and the signal _{S H} has a monochromatic X-ray of low energy I0 _L transmitted through soft tissue (transmission coefficient mu _aL, thickness _{x a)} and bone (transmission coefficient mu _b, thickness _{x b)} and is subject to coexist the LOG-converted signal _{S L} Te, expressed as the following equation (2) and (3). The transmission coefficient depends on the energy of incident X-rays.

When the weight coefficient w is added and the difference between the above formulas (2) and (3) is taken, it can be expressed as the following formula (4).

Here, if the weighting coefficient w as shown in the following equation (5) is obtained, the bone (x _b ) is canceled based on the above equation (4) and a DE image of the soft tissue is obtained. If the weighting coefficient w as shown in the equation (6) is obtained, the soft tissue (x _a ) is canceled based on the equation (4), and a bone DE image is obtained.

  FIG. 1 is a conceptual diagram illustrating a DE image generation method.

As shown in FIG. 1, a high-energy image I _H generated by imaging using high-energy X-rays (X-rays with a high tube voltage) and low-energy X-rays (X-rays with a low tube voltage) are used. on the other hand have low energy image I _L generated by the photographing was Tonouchi, for example, low-energy image I _L of the data by differential processing is multiplied by the weighting coefficients w, DE images I _DE as the difference image is generated.

The X-ray diagnostic apparatus according to the present embodiment accurately _obtains the ratio of μ _bH and μ _{bL in} the above formula (5) to obtain the weight coefficient w, and accurately _obtains the DE image I _DE of the soft tissue from which the bone has been canceled. Is to be generated. In addition, the X-ray diagnostic apparatus of the present embodiment _obtains the weight coefficient w by accurately _obtaining the ratio of μ _aH and μ _{aL in} the above formula (6), and _obtains the bone DE image I _{DE in} which the soft tissue has been canceled. It is generated with high accuracy.

  FIG. 2 is a schematic diagram illustrating the overall configuration of the X-ray diagnostic apparatus according to the first embodiment.

  FIG. 2 shows the X-ray diagnostic apparatus 10 of the first embodiment. The X-ray diagnostic apparatus 10 includes an X-ray tube 11, an X-ray detection apparatus 12, an image memory 13, an image processing apparatus 14, a controller 15, and a high voltage supplier 16.

  The X-ray tube 11 receives supply of high voltage power from the high voltage supplier 16 and emits X-rays toward the subject (a predetermined part of the patient P) according to the condition of the high voltage power. The X-ray tube 21 can expose imaging X-rays for imaging the subject.

  The X-ray detection device 12 is provided on the emission side of the X-ray tube 11 and detects X-rays transmitted through the subject. The X-ray detection apparatus 12 includes a flat panel detector (FPD) 12a, a gate driver 12b, and a data generation unit 12c. Note that the X-ray detection apparatus 12 may be a CR (computed radiography) system, an I.D. I. (Image intensifier) -TV system may be used.

  The flat detector 12a converts X-rays that have passed through the subject into charges and accumulates them. The gate driver 12b reads out the electric charge accumulated in the flat detector 12a as an X-ray image signal. The data generation unit 12c converts the read charges into image data. The data generation unit 12c includes a charge / voltage converter (not shown) that converts the charge read from the flat detector 12a into a voltage, and an A / D converter that converts the output of the charge / voltage converter into a digital signal. (Not shown) and a parallel / serial converter (not shown) for converting an image signal read in parallel from the flat detector 12a in line units into a serial signal.

  The image memory 13 stores the X-ray image from the data generation unit 12c.

  FIG. 3 is a diagram illustrating a configuration of the image processing apparatus 14.

  The image processing device 14 includes a CPU 21, a comprehensive memory 22, an HDD (hard disk drive) 23, a communication control device 24, a display 25, and an input device 26.

  The CPU 21 is a control device having a configuration of an integrated circuit (LSI) in which an electronic circuit made of a semiconductor is enclosed in a package having a plurality of terminals. The CPU 21 executes a program stored in the comprehensive memory 22 when a command is input by operating the input device 26 by an operator such as a doctor or a technician. Alternatively, the CPU 21 stores a program stored in an HD (hard disk) of the HDD 23, a program transferred from the network N, received by the communication control device 24 and installed in the HD, or a recording medium drive (not shown). The program read from the attached recording medium and installed in the HD is loaded into the comprehensive memory 22 and executed.

  The comprehensive memory 22 is a storage device having a configuration that combines elements such as a ROM (read only memory) and a RAM (random access memory). The comprehensive memory 22 is a storage device that stores an initial program loading (IPL), a basic input / output system (BIOS), and data, or a work memory of the CPU 21 and a temporary storage of data.

  The HDD 23 is a reading device having a configuration in which an HD, which is a metal disk coated or vapor-deposited with a magnetic material, is detachably incorporated. The HD stores a program (including an OS (operating system) in addition to an application program) installed in the image processing apparatus 14 and data. In addition, the OS can be provided with a graphical user interface (GUI) that can use the graphics for displaying information to the user and perform basic operations by the input device 26.

  The communication control device 24 performs communication control according to each standard. The communication control device 24 has a function of being able to connect to the network N, whereby the X-ray diagnostic device 10 can be connected from the communication control device 24 to the network N network.

  The display 25 is configured by a liquid crystal display, a CRT (Cathode Ray Tube), or the like. The display 25 has a function of displaying a DE image together with character information and scales of various parameters based on the video signal.

  The input device 26 includes a keyboard and a mouse that can be operated by an operator. An input signal according to the operation by the input device 26 is sent to the CPU 21.

  The controller 15 shown in FIG. 2 includes a CPU and a memory (not shown). The controller 15 controls the operation of the high voltage supplier 16 in accordance with an instruction from the CPU 21 of the image processing apparatus 14.

  The high voltage supplier 16 supplies high voltage power to the X-ray tube 11 under the control of the controller 15.

  FIG. 4 is a block diagram illustrating functions of the X-ray diagnostic apparatus according to the first embodiment.

  When the CPU 21 shown in FIG. 3 executes the program, the X-ray diagnostic apparatus 10 functions as an X-ray imaging control unit 31, a coefficient setting unit 32, and a coefficient processing unit 33. Note that each of the units 31 to 33 is described as being provided as a function of the X-ray diagnostic apparatus 10, but the X-ray diagnostic apparatus 10 may be provided as hardware.

The X-ray imaging control unit 31 captures two X-ray images (a high energy image I _H and a low energy image I _L ) using the high energy X-ray and the low energy X-ray for the same subject. Thus, the controller 15 has a function of controlling.

Coefficient setting unit 32, high-energy image I _H stored in the image memory 13 under the control of the X-ray imaging control unit _31, based on the low-energy image I _L, the weighting factor w that is added to the equation (4) Has the function to set. The coefficient setting unit 32 includes a histogram generation unit 321, a representative value calculation unit 322, a width calculation unit 323, and a ratio calculation unit 324.

Histogram generation unit 321 includes a high-energy image I _H generated by the control of the X-ray imaging control unit _31, a function of generating a histogram of pixel values for each of the low-energy image I _L (shown in FIG. 5). In the histogram shown in FIG. 5, generally, the pixel value of the output image data is LOG-converted with respect to the dose. Therefore, the pixel values on the horizontal axis of these histograms are values proportional to the dose LOG.

Representative value calculation unit 322 shown in FIG. 4, while obtaining a high energy image I representative pixel values on the histogram of the _H (typical) group, the function of obtaining a representative value group on the histogram of the low-energy image I _L Have. The representative value includes a pixel value at the peak of the direct line on the histogram, the highest pixel value in the subject, the lowest pixel value in the subject, and the like.

6, FIG. 7 is a diagram showing a histogram of a chest of an example of a method of determining the representative value group on the histogram of the low-energy image I _L. Figure 6 is a diagram for explaining how to determine the pixel value in the linearity of the peak as a representative value of the histogram of the low-energy image I _L. Figure 7 is a diagram for explaining how to determine the highest and lowest pixel values of the chest as a representative value of the histogram of the low-energy image I _L.

  As shown in FIG. 6, the pixel value at the first peak exceeding the threshold value A1 as viewed from the high pixel value side (right side) of the histogram, or the pixel value at the most frequent peak is set as the pixel value at the peak of the direct line.

  As shown in FIG. 7, the portion of the histogram excluding the direct line can be said to be a chest histogram. Then, when viewed from the high pixel value side of the histogram of the chest, the pixel value corresponding to the frequency at which the frequency first exceeds the threshold value A2 is set as the highest pixel value. Further, as shown in FIG. 7, the pixel value corresponding to the frequency that first exceeds the threshold value A3 when viewed from the low pixel value side (left side) of the chest histogram is set as the lowest pixel value.

The width calculating unit 323 shown in FIG. 4 has a function of determining the width between the representative value group based on a histogram of the high-energy image I _H, and a width between the representative value group based on the histogram of the low-energy image I _L .

Figure 8 is a diagram for explaining how to determine the width between the representative value group based on high-energy image I _H. Figure 9 is a diagram for explaining how to determine the width between the representative value group based on a low-energy image I _L.

  As shown in FIGS. 8 and 9, the highest pixel value in the chest can be regarded as representing a relatively thin soft tissue in the chest, and the lowest pixel value can be regarded as representing a relatively thick soft tissue in the chest. . Strictly speaking, the minimum pixel value of the histogram includes a pixel value such as bone, but even if the minimum pixel value of the histogram is determined to be a thick portion of the soft tissue of the chest, there is almost no influence.

The width calculating unit 323, a first example of obtaining the width between the representative value group based on a histogram of the high-energy image I _H, and a width between the representative value group based on the histogram of the low-energy image I _L, high the width of the pixel value of the relatively thin soft tissue and the pixel value of the direct line based on the histogram of the energy image I _H, the low-energy image I pixel values of relatively thin soft tissue and the pixel value of the direct line based on the histogram of _L Find the width.

Among the high-energy image I _H and the low energy image I _L of the chest, when the pixel value of the relatively thin soft tissue to the highest pixel value in the chest, the width calculating unit 323, by each histogram, direct line of the pixel values And the width of the pixel value of the relatively thin soft tissue. On the other hand, if the soft tissue (thickness x _a1 , transmission coefficient μ _a ) is relatively thin, the signal s ′ attenuated by transmitting the relatively thin soft tissue according to the above equation (1) is expressed by the following equation (7). It can be expressed as follows.

Here, the signal s ′ attenuated by the relatively thin soft tissue and the width of the pixel value of the direct line and the pixel value of the relatively thin soft tissue can be regarded as equivalent. Therefore, the width calculation unit 323 sets the transmission coefficient μ _a in the above formula (7) to μ _aH and the width between the pixel value of the direct line and the pixel value of the relatively thin soft tissue based on the histogram of the high energy image I _H. (mu _aH × x _a1) is calculated, also the transmission coefficient mu _a of the equation (7) as mu _aL, relatively thin soft tissue and the pixel value of the direct radiation on the basis of the histogram of the low-energy image I _L The width (μ _aL × x _a1 ) with the pixel value is calculated.

The ratio calculation unit 324, based on the width between the representative value group based on a histogram of the high-energy image I _H calculated by the width calculation unit 323, and a width between the representative value group based on the histogram of the low-energy image I _L , Has the function of determining the ratio. For example, the ratio calculation unit 324, as shown in the following equation (8), the high-energy image I pixel values of the direct line based on the histogram of _H and a relatively thin width of the pixel values of the soft tissue (mu _aH × x _a1 ) and, determining the ratio between the low-energy image I _L of the width of the pixel values of the direct line of the pixel value and a relatively thin soft tissue based on the histogram (μ _aL × x _a1).

According to the above formulas (6) and (8), the ratio calculation unit 324 includes the pixel value of the direct line based on the high energy image I _H and the width of the pixel value of the relatively thin soft tissue (μ _aH × x _a1 ), by calculating the ratio of the low-energy image I width of the pixel values of the direct line of the pixel value and a relatively thin soft tissue based on _{L (μ aL × x a1)} , bone soft tissue is canceled DE image I _DE Can be obtained.

The width calculating unit 323, a second example of obtaining the width between the representative value group based on a histogram of the high-energy image I _H, and a width between the representative value group based on the histogram of the low-energy image I _L, high energy the width of the pixel values of a relatively thick soft tissue and the pixel value of the relatively thin soft tissue based on the histogram of the image I _H, relatively thick as the pixel value of the relatively thin soft tissue based on the histogram of the low-energy image I _L The width with the pixel value of the soft tissue is obtained.

Among the high-energy image I _H and the low energy image I _L of the chest, when the pixel values of a relatively thick soft tissue to a minimum pixel value in the chest, the width calculation unit 323, by each histogram, relatively thin soft tissue The width of the pixel value of the thick soft tissue can be obtained. On the other hand, if the thickness of the relatively thin soft tissue is x _a1 , the thickness of the relatively thick soft tissue is x _a2 , and the soft tissue transmission coefficient is μ _a , the signal attenuated by transmitting through the relatively thin soft tissue. And Δs ′ between the signal attenuated by passing through the relatively thick soft tissue and expressed by the following equation (9).

  Strictly speaking, a relatively thick soft tissue and a relatively thin soft tissue may not have exactly the same transmission coefficient. However, what is important is the difference in the permeability coefficient between the bone and the soft tissue. Therefore, the soft tissue may have the same permeability coefficient.

Here, the difference Δs ′ between the signal attenuated by transmitting through the relatively thin soft tissue and the signal attenuated by transmitting through the relatively thick soft tissue, and the pixel value of the relatively thin soft tissue and the relatively thick The width of the soft tissue pixel value can be regarded as equivalent. Therefore, the width calculation unit 323 sets the transmission coefficient μ _a in the above formula (9) to μ _aH and the pixel value of the relatively thin soft tissue and the pixel value of the relatively thick soft tissue based on the histogram of the high energy image I _H. calculates the width _{(μ aH × (x a2 -x} a1)) and, also, the above expression transmission coefficient mu _a (9) as mu _aL, relatively thin soft based on the histogram of the low-energy image _{I L} The width (μ _aL × (x _a2 −x _a1 )) between the pixel value of the tissue and the pixel value of the relatively thick soft tissue is calculated.

The ratio calculation unit 324, as shown in the following equation (10), the pixel of the distribution range of pixel values of a relatively thin soft tissue based on a histogram of the high-energy image I _H and a relatively thick soft tissues (observation target tissue) the width of value _{(μ aH × (x a2 -x} a1)), the pixels of the pixel value and a relatively thick soft tissue distribution range of the low energy image I _L thinner soft tissue based on a histogram of the (observation target tissue) The ratio to the value width (μ _aL × (x _a2 −x _a1 )) is obtained.

According to the above formulas (6) and (10), the ratio calculation unit 324 calculates the width of the pixel value of the relatively thin soft tissue and the pixel value of the relatively thick soft tissue based on the high energy image I _H (μ _aH × (x and _a2 -x _a1)), the ratio of the width of the pixel value of the pixel values and the relatively thick soft tissue of a relatively thin soft tissue based on the low energy image _{I L (μ aL × (x} a2 -x a1)) by determining, it is possible to obtain the weighting coefficient w for generating a DE images I _DE bone soft tissue is canceled.

Coefficient processing unit 33, by difference from the higher energy image I _H is multiplied by a weighting factor w that is set to the data of a low-energy image I _L by the coefficient setting unit 32 has a function of generating a DE images I _DE. DE images I _DE bone soft tissue generated by the coefficient processing unit 33 is canceled is displayed on the display 25.

Note that the coefficient setting unit 32 generates a weight coefficient w (the above equation (6)) for generating a bone DE image I _DE in which the soft tissue is canceled based on the signal s ′ attenuated by passing through the soft tissue. However, the present invention is not limited to this case. Coefficient setting unit 32 generates a weighting factor to generate a DE images I _DE of attenuated signal s'soft tissue bone is canceled based on by passing through w (the formula (5)) bone May be.

According to the X-ray diagnostic apparatus 10 of the first embodiment, the weighting factor w is appropriately obtained based on the X-ray image of each subject without using a table of weighting factors w determined in advance. A suitable DE image _ID can be displayed.

  FIG. 10 is a block diagram illustrating functions of the X-ray diagnostic apparatus according to the second embodiment. The configuration of the X-ray diagnostic apparatus according to the second embodiment is the same as that of the X-ray diagnostic apparatus according to the first embodiment shown in FIGS.

  When the CPU 21 shown in FIG. 3 executes the program, the X-ray diagnostic apparatus 10A of the second embodiment includes an X-ray imaging control unit 31, a coefficient setting unit 32A, a coefficient processing unit 33, and a ROI (region of interest) setting unit. 34 functions. Note that each of the units 31 to 34 is described as being provided as a function of the X-ray diagnostic apparatus 10A, but may be provided as hardware in the X-ray diagnostic apparatus 10A. The coefficient setting unit 32A includes a histogram generation unit 321, a representative value calculation unit 322A, a width calculation unit 323A, and a ratio calculation unit 324A.

ROI setting unit 34, a high-energy image I _H generated by imaging using the X-ray of high energy, if it is identical with the low-energy image I _L generated by imaging using the low energy X-rays It has a function of setting an ROI as a region of interest in each portion considered.

Coefficient setting unit 32A sets the average value of the pixel values within the ROI of the higher energy image I _H set by the ROI setting unit 34 as a representative value group, the pixels within the ROI of the low-energy image I _L An average value of values is set as one of the representative value groups.

Representative value calculation unit 322A of the coefficient setting unit 32A calculates the pixel values of the direct radiation based on the histogram of the average value and the higher energy image I _H of the pixel values within the ROI of the higher energy image I _H, also, low-energy calculating a pixel value of the direct line based on the histogram of the average value and the low energy image I _L of the pixel values within the ROI of the image I _L.

Width calculating unit 323A is a pixel within the ROI of the higher energy image I and the width of the average value and the pixel value of the direct line based on the histogram of the high-energy image I _H of the pixel values within the ROI of _H, lower energy image I _L determining the width of the pixel value of the direct line based on the histogram of the average value and the low energy image I _L value.

The ratio calculation unit 324A includes a width of the pixel values of the direct radiation based on the histogram of the average value and the higher energy image I _H of the pixel values within the ROI of the higher energy image I _H, the pixels within the ROI of the low-energy image I _L by determining the ratio between the width of the pixel values of the direct radiation based on the histogram of the average value and the low energy image I _L values can be obtained weighting coefficients w that is set portion in ROI is canceled .

  In the X-ray diagnostic apparatus 10A shown in FIG. 10, the same functions as those in the X-ray diagnostic apparatus 10 shown in FIG.

According to the X-ray diagnostic apparatus 10A of the second embodiment, the weighting factor w is appropriately obtained based on the X-ray image of each subject without using the predetermined weighting factor w table. A suitable DE image _ID can be displayed.

  FIG. 11 is a block diagram illustrating functions of the X-ray diagnostic apparatus according to the third embodiment. The configuration of the X-ray diagnostic apparatus of the third embodiment is the same as the configuration of the X-ray diagnostic apparatus of the first embodiment shown in FIGS.

  When the CPU 21 shown in FIG. 3 executes the program, the X-ray diagnostic apparatus 10B of the third embodiment functions as an X-ray imaging control unit 31, a coefficient setting unit 32B, a coefficient processing unit 33, and an ROI setting unit 34. The respective units 31 to 34 are described as being provided as functions of the X-ray diagnostic apparatus 10B, but may be provided as hardware in the X-ray diagnostic apparatus 10B. The coefficient setting unit 32B includes a histogram generation unit 321, a representative value calculation unit 322B, a width calculation unit 323B, and a ratio calculation unit 324B.

Coefficient setting unit 32B, the high energy image and through the input device 26 in a portion that appear to be single, and low energy images that manual ROI are input, manual ROI within high-energy image I _H an average value of pixel values, etc. set as a representative value group, and sets the average value of pixel values in the manual ROI low energy image I _L as a representative value group.

Representative value calculation unit 322B of the coefficient setting unit 32B calculates the pixel values of the direct radiation based on the histogram of the average value and the higher energy image I _H of the pixel values in the manual within the ROI of the higher energy image I _H, also, low calculating a pixel value of the direct line based on the histogram of the average value and the low energy image I _L of the pixel values in the manual within the ROI of the energy image I _L.

Width calculating unit 323B, a high average value of pixel values in the manual within the ROI of the energy image I _H and the width of the pixel values of the direct radiation based on a histogram of the high-energy image I _H, the low-energy image I manual ROI within _L determining the width of the pixel value of the direct line based of the histogram of the average value and the low energy image I _L of the pixel values.

The ratio calculation unit 324B, a high-energy average of the pixel values in the manual within the ROI of the image I _H and the width of the pixel values of the direct radiation based on a histogram of the high-energy image I _H, the low-energy image I _L manual ROI in weights such as by obtaining the ratio of the width of the pixel values of the direct radiation, the portion is deemed to be within the same manual ROI is canceled based on the average value and the low energy image I _L of the pixel value histogram The coefficient w can be obtained.

  In the X-ray diagnostic apparatus 10B shown in FIG. 11, the same functions as those in the X-ray diagnostic apparatus 10 shown in FIG.

According to the X-ray diagnostic apparatus 10B of the third embodiment, the weighting factor w is appropriately determined based on the X-ray image of each subject without using the predetermined weighting factor w table. A suitable DE image _ID can be displayed.

10, 10A, 10B X-ray diagnostic apparatus 13 Image memory 14 Image processing apparatus 21 CPU
31 X-ray imaging control units 32, 32A, 32B Coefficient setting unit 33 Coefficient processing unit 34 ROI setting unit 321 Histogram generation units 322, 322A, 322B Representative value calculation units 323, 323A, 323B Width calculation units 324, 324A, 324B Ratio calculation Part

Claims (6)

Control means for controlling the subject to perform X-ray imaging using a first radiation quality and X-ray imaging using a second radiation quality smaller than the first radiation quality;
Based on the histogram of the first image generated by X-ray imaging using the first radiation quality, the pixel value of the direct line and the highest pixel value in the subject are respectively determined , and the second radiation quality is used. Pixel value calculation means for respectively obtaining a pixel value of a direct line and a maximum pixel value in the subject based on a histogram of a second image generated by X-ray imaging;
A first width that is a width of the pixel value of the direct line and the highest pixel value based on the first image , and a second width that is a width of the pixel value of the direct line and the highest pixel value based on the second image width calculating means for determining bets respectively,
Ratio calculating means for calculating a ratio of the first width and the second width as a weighting factor;
Image generating means for generating a difference image between the first image and the second image using the weighting factor;
An X-ray diagnostic apparatus comprising: Control means for controlling the subject to perform X-ray imaging using a first radiation quality and X-ray imaging using a second radiation quality smaller than the first radiation quality;
Interested in portions that are considered to be the same in the first image generated by X-ray imaging using the first radiation quality and the second image generated by X-ray imaging using the second radiation quality. A region of interest setting means for setting a region ;
A pixel value of the direct line and an average value of the pixel value group in the region of interest are obtained based on the histogram of the first image, respectively, and a pixel value of the direct line and the region of interest are calculated based on the histogram of the second image. Pixel value calculating means for respectively obtaining an average value of the pixel value groups of
A first width that is a pixel value of the direct line based on the first image and a width of the average value, and a second width that is a width of the pixel value of the direct line and the average value based on the second image. width calculating means for determining each
Ratio calculating means for calculating a ratio of the first width and the second width as a weighting factor;
Image generating means for generating a difference image between the first image and the second image using the weighting factor;
An X-ray diagnostic apparatus comprising: X-ray diagnostic apparatus according to claim 2, characterized in Rukoto further having a region of interest input means for inputting a region of interest. Based on the histogram of the first image generated by X-ray imaging using the first radiation quality for the subject, the pixel value of the direct line and the highest pixel value in the subject are obtained , respectively , from the first radiation quality Pixel value calculation means for respectively obtaining a pixel value of a direct line and a highest pixel value in the subject based on a histogram of a second image generated by X-ray imaging using a small second radiation quality;
A first width that is a width of the pixel value of the direct line and the highest pixel value based on the first image , and a second width that is a width of the pixel value of the direct line and the highest pixel value based on the second image width calculating means for determining bets respectively,
Ratio calculating means for calculating a ratio of the first width and the second width as a weighting factor;
Image generating means for generating a difference image between the first image and the second image using the weighting factor;
An image processing apparatus comprising: The first image generated by X-ray imaging using the first radiation quality for the subject is the same as the second image generated by X-ray imaging using the second radiation quality smaller than the first radiation quality. A region-of-interest setting means for setting a region of interest in each portion considered to be ,
A pixel value of the direct line and an average value of the pixel value group in the region of interest are obtained based on the histogram of the first image, respectively, and a pixel value of the direct line and the region of interest are calculated based on the histogram of the second image. Pixel value calculating means for respectively obtaining an average value of the pixel value groups of
A first width that is a pixel value of the direct line based on the first image and a width of the average value, and a second width that is a width of the pixel value of the direct line and the average value based on the second image. width calculating means for determining each
Ratio calculating means for calculating a ratio of the first width and the second width as a weighting factor;
Image generating means for generating a difference image between the first image and the second image using the weighting factor;
An image processing apparatus comprising: The image processing apparatus according to claim 5, characterized in Rukoto that Yusuke further region of interest input means for inputting a region of interest.