JP2013212318A - Medical image processing apparatus and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an operation for two-point specification to be easily and accurately performed when the operation for two-point specification necessary for a bone mineral measurement examination is performed on a medical image.SOLUTION: In a medical image processing apparatus 3, a control unit 31 displays an image for interpretation of radiogram, which is created by applying image processing, including frequency enhancement processing, to a medical image obtained by roentgenographing a second metacarpal of a left hand, as an image for two-point specification on a two-point specification field 352g of a bone mineral measurement screen 352.

Description

  The present invention relates to a medical image processing apparatus and a program.

  Conventionally, a bone mineral density examination is performed for diagnosis of osteoporosis and determination of therapeutic effect. There are various bone mineral quantitative tests. Among them, the DIP (Digital Image Processing) method is widely used as a simple and highly accurate test. In the DIP method, an aluminum slope and the left second metacarpal bone are simultaneously radiographed, and the bone mineral density is measured by comparing the shadow density of the aluminum slope and the left second metacarpal bone in the obtained X-ray image. It is a technique.

  As a flow of bone mineral density examination by the DIP method, X-ray imaging of the left second metacarpal bone is performed at a hospital or clinic, and the X-ray image (recording medium on which film or electronic data is recorded) is passed to the clinical laboratory center. In general, the X-ray image is analyzed at a clinical laboratory center to measure the bone mineral content, and the result is returned to the requesting hospital or clinic.

  For example, Patent Document 1 describes an image forming apparatus including a bone mineral content quantification unit that performs bone mineral content measurement based on X-ray image data. According to this image forming apparatus, bone mineral quantitative measurement at a hospital or clinic becomes possible.

JP 2010-200844 A

  By the way, in order to measure bone mineral density from an X-ray image, the most protruding portion at the upper end of the second metacarpal bone of the left hand and the most depressed portion at the lower end (end on the patient side) in the X-ray image. You need to specify a point.

When measuring bone mineral quantification at a clinical laboratory center, these two designated operations are performed by specialized operators. On the other hand, when bone mineral content is measured at a hospital or clinic, an operator such as a doctor who has not designated two points so far performs two designated operations.
However, unlike a medical image for interpretation (see FIG. 7) that is familiar to doctors, the medical image used for bone mineral content measurement (see FIG. 13) is dark overall and the edges are not clear. Therefore, if the operator is unfamiliar with this operation, it may be difficult to see and it may not be possible to specify two points correctly.

  An object of the present invention is to enable easy and correct designation of two points when performing two designations necessary for bone mineral quantitative examination on a medical image.

In order to solve the above-mentioned problem, a medical image processing apparatus according to claim 1 is provided.
A bone mineral quantitative optimization image that creates a bone mineral quantitative optimization image optimized for bone mineral quantitative measurement by performing image processing on the medical image obtained by radiographing the second metacarpal bone of the left hand Creating means;
An image processing unit that performs image processing for emphasizing an edge on the medical image, and an image creating unit for designating an image for designating an operator to designate two predetermined points of the second metacarpal bone of the left hand;
Display means for displaying the designation image created by the designation image creation means;
Operating means for an operator to specify the predetermined two points from the designation image displayed on the display means;
Bone mineral content measurement means for measuring bone mineral content based on the coordinates of the two points designated by the operation means and the bone mineral content optimization image,
Is provided.

The invention according to claim 2 is the invention according to claim 1,
Image interpretation image creation means for creating an image for interpretation by performing image processing including gradation conversion processing and frequency enhancement processing on the medical image,
The image interpretation image creating means creates an image for image interpretation whose edges are emphasized by performing frequency enhancement processing on the medical image as the image creation device for designation.
The display means displays the interpretation image created by the interpretation image creation means as the designation image.

The program of the invention described in claim 3 is:
Computer
A bone mineral quantitative optimization image that creates a bone mineral quantitative optimization image optimized for bone mineral quantitative measurement by performing image processing on the medical image obtained by radiographing the second metacarpal bone of the left hand Creation means,
Image designating means for performing an image processing for emphasizing an edge on the medical image, and creating an image for designation for an operator to designate two predetermined points of the left second metacarpal;
Display means for displaying the designation image created by the designation image creation means;
Operation means for an operator to designate the two predetermined points from the designation image displayed on the display means;
Bone mineral content measurement means for measuring bone mineral content based on the coordinates of the two points designated by the operation means and the bone mineral content optimization image,
To function as.

  According to the present invention, when two point designation operations necessary for bone mineral quantitative examination are performed on a medical image, the two point designation operations can be easily and correctly performed.

It is a figure which shows the whole structure of the system in a facility in embodiment of this invention. It is a block diagram which shows the functional structure of a medical image processing apparatus. It is a figure which shows the example of data storage of an image information table. It is a figure which shows the example of data storage of bone mineral quantitative determination DB. It is a figure for demonstrating the method of the X-ray imaging in a bone mineral quantitative examination. It is a flowchart which shows the diagnostic assistance process performed by the control part of a medical image processing apparatus. It is a figure which shows an example of a viewer screen. It is a figure for demonstrating G value which is a parameter of a gradation conversion process. It is a figure for demonstrating the S value which is a parameter of a gradation conversion process. It is a flowchart which shows the bone mineral quantitative measurement process performed in step S8 of FIG. It is a figure which shows an example of a bone mineral fixed quantity screen. It is a figure for demonstrating L value. It is a figure for demonstrating the bone width D and the bone marrow width d. It is a figure which shows an example of the bone mineral quantitative screen after a bone mineral quantitative measurement. It is a figure which shows an example of the viewer screen on which the graph which is a bone mineral quantitative measurement result was displayed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

[Configuration of in-facility system 1]
FIG. 1 is a block diagram showing a system configuration of an in-facility system 1 according to the present embodiment.
The in-facility system 1 is a system applied to a relatively small-scale medical facility such as a medical practitioner or a clinic. As shown in FIG. 1, the modality 2, the medical image processing device 3, the reception device 4, the i A major 5, a general-purpose printer 6, and a client PC (Personal Computer) 7 are included. Each device constituting the in-facility system 1 is connected to a communication network (hereinafter simply referred to as “network”) 8 such as a LAN (Local Area Network) via a switching hub (not shown), for example. The medical image processing apparatus 3 is preferably a WS (workstation) provided in an examination room where a doctor is resident. The WS that operates as the medical image processing apparatus 3 may be configured to control the activation of the modality 2, processing conditions, and the like.

  In general, DICOM (Digital Image and Communications in Medicine) standard is used as a communication method in a hospital, and DICOM MWM (Modality Worklist Management) or DICOM MPPS (DICOM MPPS) is used for communication between devices connected to a LAN. Modality Performed Procedure Step) is used. Note that the communication method applicable to this embodiment is not limited to this.

[Device configuration of each device of the in-facility system 1]
Hereinafter, each apparatus which comprises the in-facility system 1 is demonstrated.
The modality 2 is an image generation apparatus that performs imaging using a patient's diagnosis target region as a subject and digitally converts the captured image to generate a medical image.

  Examples of the modality 2 include a CR (Computed Radiography) apparatus, an ultrasonic diagnostic apparatus, an endoscope apparatus, a CT (Computed Tomography) imaging apparatus, and a magnetic resonance imaging apparatus (MRI). In the present embodiment, modality 2 is described as a CR device, but a configuration having other modalities may be used.

In the present embodiment, the modality 2 is a CR device that includes an X-ray imaging device, a CR cassette, and a reading device. The modality 2 arranges a subject between the X-ray imaging apparatus and the CR cassette to perform X-ray imaging, and reads a radiographic image recorded on the CR cassette with a reading apparatus to acquire digital image data.
Here, the CR cassette has a built-in radiation image conversion plate including a stimulable phosphor sheet that accumulates radiation energy, for example, and when irradiated with radiation, an amount of radiation according to the radiation transmittance distribution of the subject is emitted. The stimulable phosphor sheet is accumulated in the stimulable phosphor layer, and a radiographic image of the subject is recorded on the stimulable phosphor layer.
The reading device irradiates the stimulable phosphor sheet in the CR cassette with excitation light, photoelectrically converts the stimulated light emitted from the sheet, and A / D converts the obtained image signal to obtain image data. Is generated.

  In the present embodiment, the modality 2 has a function of giving image attribute information such as a UID, an imaging date / time, an examination ID, and an imaging site to each medical image in a format conforming to the DICOM standard. The UID is a unique ID for specifying a medical image in the in-facility system 1.

The modality 2 includes an input unit (not shown) such as a keyboard having character input keys, numeric input keys, and the like, and inputs patient information for specifying a patient to be imaged from the input unit.
The patient information input here is, for example, patient ID, patient name (kanji), patient name (Kana), patient name (ASCII), gender, date of birth, and the like. Note that it is not necessary to input all of them in the modality 2, and it is possible to not input any patient information. When the modality 2 has a specification for inputting only a patient ID as patient information, the input unit of the modality 2 may be a numeric keypad, for example.

  The image attribute information and the patient information are incidental information attached to the medical image generated by the modality 2. Modality 2 generates a medical image in a DICOM file format that conforms to the DICOM standard. The DICOM file is composed of an image part and a header part. In the image portion, image data of a medical image is written, and in the header portion, incidental information related to the medical image is written.

The medical image processing apparatus 3 is installed, for example, in an examination room. The medical image processing apparatus 3 stores the medical image generated by the modality 2 in the database in association with the patient information, or performs image processing on the medical image and displays it on the display unit for diagnosis by the doctor. And may be provided with a monitor with higher definition than a monitor used in a general PC (Personal Computer).
Further, the medical image processing apparatus 3 has a bone mineral density inspection function. The bone mineral density examination is an examination for measuring bone mineral density from a medical image in which a left hand and an aluminum slope (described later in detail) are taken.

  As shown in FIG. 2, the medical image processing apparatus 3 includes a control unit 31, a RAM 32, a storage unit 33, an operation unit 34, a display unit 35, a communication unit 36, a media drive 37, a timing unit 38, and the like. Each part is connected by a bus 39.

  The control unit 31 is configured by a CPU (Central Processing Unit) or the like, reads various programs such as system programs and processing programs stored in the storage unit 33, expands them in the RAM 32, and performs diagnosis support described later according to the expanded programs. By executing various processes including processing and bone mineral quantitative measurement processing, it functions as an interpretation image creating means, a bone mineral quantitative optimized image creating means, a designation image creating means, and a bone mineral quantitative measuring means.

The RAM 32 temporarily stores a work area for temporarily storing various programs, input or output data, parameters, and the like that can be executed by the control unit 31 read from the storage unit 33 in various processes controlled by the control unit 31. Form.
The RAM 32 stores the patient information list received from the receiving device 4.

  The storage unit 33 includes an HDD (Hard Disk Drive), a semiconductor nonvolatile memory, or the like. The storage unit 33 stores various programs as described above, and image processing parameters for adjusting a medical image to an image quality suitable for interpretation diagnosis (lookup defining a gradation curve used for gradation processing). Table (LUT) etc. are stored. In addition, fixed values (for example, LUT, G value, S value, etc. used for creating a bone mineral quantitative optimization image) stored in bone mineral quantitative measurement are stored.

In addition, the storage unit 33 includes an image DB (Data Base) 331 and a bone mineral content determination DB 332.
The image DB 331 is a database for storing a medical image and a bone mineral quantitative graph image. The image DB 331 has an image information table 331a for storing various information related to images stored in the image DB 331.
As shown in FIG. 3, the image information table 331 a includes “UID”, “imaging date / time”, “examination ID”, “imaging region”, “patient ID”, “patient name”, “age”, “sex”, It has items such as “image storage destination”, and stores examination information, patient information, image storage destination path, and the like related to each image stored in the image DB 331. As an image storage destination, a medical image (referred to as an original image) transmitted from the modality 2, a processed image created from the original image, a thumbnail image created from the original image, and a graph image created by a bone mineral quantitative examination , And a graph thumbnail image created from the graph image, each image storage destination path is stored. Based on the information stored in the image information table 331a, medical images and graph images are associated with patient information, examination information, and the like, and are stored so as to be searchable using patient information, imaging date and time as keys.

  The bone mineral content determination DB 332 is a database for storing the results of bone mineral content inspection, parameters used for bone mineral content inspection, and the like. As shown in FIG. 4, the bone mineral content determination DB 332 includes “examination ID”, “measurement date / time”, “patient ID”, “patient name”, “age”, “gender”, “result value”, “parameter”, etc. This information is stored for each bone mineral quantitative examination. The result value is, for example, an L value, a DIP value, an MCI, or the like. The parameters are, for example, the coordinates of two points designated at the time of inspection ((X1, Y1), (X2, Y2)), the coordinates of the measurement target area (upper left (X3, Y3), lower right (X4, Y4)), The coordinates of the aluminum slope (upper left (X5, Y5), lower right (X6, Y6)). Details of the result values and parameters will be described later.

  The operation unit 34 includes a keyboard having cursor keys, numeric input keys, various function keys, and the like, and a pointing device such as a mouse, and a key pressing signal pressed by the keyboard and an operation signal by the mouse. Is output to the control unit 31 as an input signal.

  The display unit 35 is configured to include a monitor such as a CRT (Cathode Ray Tube) or an LCD (Liquid Crystal Display), for example, and displays various screens according to instructions of display signals input from the control unit 31.

  The communication unit 36 is configured by a network interface or the like, and transmits / receives data to / from an external device connected to the network 8 via a switching hub.

  The media drive 37 is a device that reads or writes data from / to a portable recording medium M such as a CD-R (Compact Disk Recordable), DVD-R (Digital Versatile Disk Recordable), or MO (Magnet Optical) disk. .

  The reception device 4 is a computer device for performing registration, accounting, insurance score calculation, etc. of patients who come to the hospital, and is composed of a storage unit composed of a CPU, ROM, RAM, etc., an input composed of a keyboard, a mouse, etc , A display unit configured by a CRT, an LCD, and the like, a communication unit (none of which is shown) that controls communication with each device connected to the network 8, and the like. When receiving a reception input screen is instructed from the input unit, the reception device 4 displays a reception input screen (not shown) on the display unit by software processing in cooperation with the CPU and a program stored in the storage unit. When reception information (reception number + patient name, etc.) is input by the input unit via this reception input screen, a patient information list of the received patients is created (updated), stored in the storage unit, and transmitted by the communication unit. It transmits to the medical image processing apparatus 3 as appropriate.

  The imager 5 records a latent image by laser exposure on a transmissive recording medium (film) based on the medical image transmitted from the medical image processing apparatus 3, and visualizes the latent image by thermal phenomenon processing. It is a salt printer.

  The general-purpose printer 6 is a printer that records an image on a reflective recording medium (paper medium, sticker, etc.) by an ink jet method or a laser method.

  The client PC 7 is a computer device that displays a medical image or a graph image transmitted from the medical image processing device 3, for example.

[Flow of bone mineral quantity inspection]
Next, the flow (1) to (5) of the bone mineral density inspection in the medical facility where the in-facility system 1 is installed will be described.
(1) First, a patient is accepted at the reception. The received patient information of the patient is input by the receiving device 4, and a patient information list including this patient information is transmitted to the medical image processing device 3. In the medical image processing apparatus 3, the patient information list transmitted from the reception apparatus 4 is stored in the RAM 32.
(2) Next, in the examination room, examinations and necessary examination decisions are made. The examination is performed by an inquiry, a patient's past medical record, browsing of images and reports, and the like.
(3) When it is determined that the bone mineral content quantitative examination is necessary, X-ray imaging of the patient's left hand is performed by the modality 2 in the imaging room.
In the present embodiment, it will be described as performing a bone mineral density examination by the DIP method. In the DIP method, as shown in FIG. 5, the aluminum slope AL and the left hand second metacarpal bone B are arranged side by side and X-ray photographed at the same magnification, and the aluminum slope AL and the second metacarpal bone B in the obtained medical image This is a comparative analysis of shadow density. The aluminum slope AL is a slope member made of aluminum having an inclination of 1 cm in thickness and 1 mm in the longitudinal direction. At the time of radiography, the aluminum slope AL is arranged right next to the patient's left hand so that the thick side is in front, and X-ray imaging is performed by the modality 2.
As will be described later, the medical image processing apparatus 3 creates an image for interpretation that is suitable for interpretation regardless of individual differences in the body type of the subject patient and changes in the irradiation X-ray dose due to changes in apparatus characteristics of the modality 2. can do. Therefore, it is possible to perform shooting under fixed shooting conditions without performing individual adjustments during shooting.
(4) After the X-ray imaging of the left hand, the medical image obtained by the imaging is captured by the medical image processing apparatus 3 and bone mineral quantification is measured, and the measurement results (inspection results) such as result values and graphs are obtained. Is output.
(5) Diagnosis and treatment are performed based on the measurement result.

[Operation of Medical Image Processing Device 3]
Next, the operation of the medical image processing apparatus 3 will be described.
FIG. 6 shows a flowchart of a diagnosis support process executed by the control unit 31 of the medical image processing apparatus 3. The diagnosis support process is executed in cooperation with the control unit 31 and the program stored in the storage unit 33.

  First, the viewer screen 351 for the patient to be diagnosed is displayed on the display unit 35 (step S1). The viewer screen 351 is a screen for taking a medical image from the modality 2 and displaying it for interpretation. The viewer screen 351 can instruct execution of bone mineral content measurement and display the measurement result. . The viewer screen 351 is displayed on the patient list screen of the patient to be diagnosed by the operation unit 34 from the patient list screen (screen on which the patient information list transmitted from the receiving device 4 is displayed) displayed on the display unit 35 by a predetermined operation of the operation unit 34. Displayed by selecting patient information.

  FIG. 7 shows an example of the viewer screen 351. As shown in FIG. 7, the viewer screen 351 has an image display field 351a for displaying an image, an image capture button 351b, a measurement button 351c, various tool buttons 351d, a print button 351e, a patient display field 351f, and a thumbnail display. A column 351g, a display image selection column 351h, and the like are provided.

The image display column 351a is a column for displaying a medical image captured from the modality 2, a graph image of a test result, a past image of the same patient, and the like. FIG. 7 shows an example in which an image is displayed in the image display field 351a, but no image is displayed yet in step S1 (the image for interpretation in FIG. 7 is displayed in step S4).
The image capture button 351b is a button for instructing to capture a medical image transmitted from the modality 2 as an image of a patient currently being diagnosed (a patient displayed in the patient display field 351f). When the image capture button 351b is pressed, the modality 2 is displayed until the image capture button 351b is pressed next to cancel capture or the viewer screen 351 is closed or transitions to another screen. The medical image received from is captured as an image of the patient currently being diagnosed.
The measurement button 351c is a button for instructing display of a measurement menu. The measurement menu includes bone mineral quantitative measurement.

  The various tool buttons 351d are buttons for performing image processing such as density contrast adjustment processing and image quality adjustment processing on the displayed medical image, for example. When a button of a desired item of the tool button 351d is pressed, an input field, a button, a toolbar, or the like corresponding to the item is displayed. When an input to the displayed input field or an operation of a button or a toolbar is performed by the operation unit 34, processing corresponding to the operation is performed on the displayed image. For example, when the density contrast button is pressed, a slide bar for density adjustment, a slide bar for contrast adjustment, and the like are displayed. When the slide bar is operated by the operation unit 34, the control unit 31 sets the density and contrast according to the operation. The image displayed in the image display field 351a is adjusted.

The print button 351e is a button for instructing to print the selected image from the general-purpose printer 6.
The patient display column 351f is a column for displaying patient information of a patient currently selected as a diagnosis target.
The thumbnail display column 351g is a column for displaying thumbnail images of medical images (including images taken in the past) of the same patient in order to select a medical image to be displayed in the image display column 351a.
The display image selection field 351h is a field for selecting the classification (CR, bone mineral content determination (graph)) of the images displayed in the thumbnail display field 351g.

When the image capturing button 351b is pressed by the operation unit 34 and photographing is performed in the modality 2, a medical image obtained by photographing is captured (step S2).
In step S2, when a medical image is received from the modality 2 by the communication unit 36, the received medical image is associated with the patient information of the patient selected on the patient list screen, and stored in the image DB 331 as an original image. Is done. In the image information table 331a, the UID written in the header part of the received image, the photographing date and time, the examination site, the original image storage destination path, and the like are written. A thumbnail image is created from the original image and stored in the image DB 331. Further, the storage destination path of the created thumbnail image is written in the image information table 331a.

Next, an interpretation image creation process is executed, and an interpretation image is created from the original image (step S3).
Here, in the modality 2, shooting is performed under fixed shooting conditions without performing individual adjustments at the time of shooting each time. For this reason, the original image varies depending on the variation of the irradiation X-ray dose due to the patient's body shape (the thickness of the hand in the case of bone mineral quantitative examination), the change in apparatus characteristics of the modality 2, and the like. However, if there are variations in the images to be interpreted, stable interpretation diagnosis cannot be performed. Therefore, in order to stably output an image suitable for interpretation, the medical image processing apparatus 3 performs image processing on the original image to create an interpretation image that satisfies a predetermined standard for interpretation. The Examples of the contents of the image processing include gradation conversion processing, frequency enhancement processing, dynamic range compression processing, and the like. The created image for interpretation is stored in the image DB 331 and the storage destination path is written in the image information table 331a.

Hereinafter, the contents of the image interpretation image creation process will be described.
<Irradiation field recognition processing>
As a premise for gradation conversion processing, frequency enhancement processing, etc., irradiation field recognition processing is first executed on the input original image. The irradiation field refers to an area where X-rays have reached through the subject. In the irradiation field recognition processing, the irradiation field area is distinguished from an irradiation field outside area (an area other than the irradiation field). This is because appropriate processing cannot be performed if gradation conversion processing or the like is performed including an irradiation field region with a biased signal value (pixel digital density signal value).

  Any method of irradiation field recognition may be adopted. For example, as disclosed in Japanese Patent Application Laid-Open No. 5-7579, an original image is divided into a plurality of small areas, a variance value is obtained for each divided area, and an irradiation field area is determined based on the obtained variance value. Also good. Usually, since the reaching X-ray dose is substantially uniform in the irradiation field region, the dispersion value of the small region becomes small. On the other hand, in a small region including the edge of the irradiation field region, a portion having a large arrival X-ray dose (outside the irradiation field region) and a portion (irradiation field region) in which the arrival X-ray dose is somewhat reduced by the subject are mixed, and thus the variance value is growing. Therefore, assuming that an edge is included in a small region having a variance value greater than a certain value, the region surrounded by such a small region is determined as an irradiation field region.

<Area of interest setting and reference signal value setting>
When the irradiation field region is determined, a region of interest (hereinafter referred to as ROI: Region Of Interest) is set from this irradiation field region. At this time, the reference signal value is set together with the ROI setting.
For example, the ROI can be specified based on the signal value profile by sequentially scanning the horizontal direction and the vertical direction of the original image to create a signal value profile in each direction. Further, the ROI may be specified by pattern matching, and any method may be applied.

  Then, a histogram of the signal values of the specified ROI region is created, and the signal values having a predetermined frequency from the maximum value side and the minimum value side in the histogram are determined as the maximum reference value H and the minimum reference value L, respectively. To do. The maximum reference value H and the minimum reference value L are used as reference values when the signal value range of the original image is converted into the signal value range (maximum value SH, minimum value SL) in the image for interpretation.

<Tone conversion processing>
When the preprocessing is completed as described above, gradation conversion processing is performed.
The gradation conversion process is a process for adjusting the density and contrast of the original image. When a doctor diagnoses the presence or absence of a human body structure disease by interpretation of an X-ray image, the presence or absence of the disease is determined based on the density and contrast (gradation) of the structure on the X-ray image. Therefore, by adjusting the density and contrast suitable for interpretation, a doctor's disease detection operation can be supported.

  The gradation conversion processing is performed in two stages: (1) normalization processing and (2) conversion processing using a basic LUT (lookup table), and finally a signal value range predetermined as an image for interpretation. Gradation conversion is performed so as to obtain gradation characteristics.

  Conventionally, since a screen / film method has been adopted for photographing, input signal (reading signal) conversion processing is performed with a target of gradation characteristics (contrast) cultivated by the screen / film method. The gradation characteristic obtained by the screen / film system is an S-shaped curve. In the gradation conversion processing, an LUT indicating this gradation characteristic is prepared as a basic LUT for each part, and after performing individual signal adjustment on the original image by normalization processing, the signal value is calculated using this basic LUT. Perform conversion.

FIG. 8A and FIG. 8B show the relationship between the X-ray dose detected by the modality 2 and the signal value of the interpretation image that is finally output in accordance with the X-ray dose.
In the coordinate systems of FIGS. 8A and 8B, the fourth quadrant indicates the relationship between the X-ray dose reaching the photostimulable phosphor plate of modality 2 and the signal value of the original image (reading characteristics of modality 2). . The third quadrant shows the relationship (normalization characteristic) between the signal value of the original image and the normalized signal value after the normalization process is performed. The second quadrant shows the relationship (tone conversion characteristics) between the normalized signal value and the signal value (digital density signal value) of the image for interpretation read out by the basic LUT. Here, the signal value of the image for interpretation is set to 12-bit resolution of 0 to 4095.

  In the third quadrant, the straight line indicating the normalization characteristic can adjust the range of the signal value of the image (size between SH and SL) by changing the slope of the straight line and change the contrast of the entire image. it can. This slope is defined as a G value. Also, by changing the intercept of the straight line indicating the normalization characteristic, the height (SH-SL movement) of the entire signal value range of the image can be adjusted, thereby changing the density of the entire image. Let this intercept be an S value.

  For example, as shown in FIG. 8A, when a patient Pa having a standard body shape and a patient Pb having a large body thickness are imaged, the range of the X-ray dose is widened in the patient Pb, and as a result, compared with the patient Pa. The image has a wide density distribution. When the patient Pb image is to be an image having the same density and contrast as the patient Pa, the patient Pb G value is adjusted to be larger than the patient Pa G value (the normalized characteristic line of the patient Pa is shown in FIG. 8A). La, the normalized characteristic line of the patient Pb is Lb), and the density range (SH-SL range) and contrast image (normalized image) equivalent to the patient Pa can be obtained. Therefore, if the patient Pa and the patient Pb are subjected to gradation conversion processing using the same basic LUT, an equivalent image can be obtained.

  Further, for example, as shown in FIG. 8B, when patients Pc and Pd of the same body type are photographed with different X-ray doses, the patient Pd with a large dose has an overall high-density image compared to the patient Pc. Since it falls outside the effective density range when it is output, the contrast is lowered and the image is not suitable for interpretation. When the patient Pd image is to be an image having the same density as the patient Pc, the patient Pd S value is adjusted to be larger than the patient Pc S value (the normalized characteristic straight line of the patient Pc is shown in FIG. 8B). Lc, the normalized characteristic line of the patient Pd is Ld), and an image (normalized image) in the density range (SH-SL range) equivalent to the patient Pc can be obtained. Therefore, even if the gradation conversion processing is performed on the patient Pc and the patient Pd using the same basic LUT, an equivalent image can be obtained.

  That is, by controlling the slope G value and intercept S value of the straight line indicating the gradation conversion characteristics as gradation conversion parameters, an image having a density range and contrast satisfying a predetermined standard as an image for interpretation is obtained. Can be adjusted.

The G value is determined by the following equation (1).
G = (D2-D1) / (logE2-logE1) (1)
here,
D1 = 0.25 + Fog, D2 = 2.0 + Fog, Fog = 0.2,
E1 and E2 are incident X-ray doses corresponding to D2 and D1, respectively.
In the case where each part of the human body such as the chest and breast is to be observed, the G value is generally about 2.5 to 5.0 in many cases.

Further, the S value is obtained by the following formula (2).
S = QR × P1 / P2 (2)
here,
QR is a quantized region value, P1 is an X-ray dose reaching a signal value 1535 (QR = 200, output density 1.2), and P2 is a pixel of an output density 1.2 in an image after gradation conversion. Actual X-ray dose.
The value of P1 is uniquely determined by the setting of the quantization region QR value before photographing.

<Frequency enhancement processing>
As the frequency enhancement processing, for example, unsharp mask processing disclosed in Japanese Patent Publication No. 62-62373 or multi-resolution analysis disclosed in Japanese Patent Application Laid-Open No. 9-44645 can be applied. In the frequency enhancement process, a specific sharpness component of a certain mask size included in the original image is multiplied by the enhancement coefficient α to perform the calculation represented by the following expression (3), thereby enhancing the desired sharpness from the original image. Get the image.
S = So + α (So-Sus) (3)
S: frequency processed image signal
So: Original image signal
Sus: Unsharp image signal
α: Emphasis coefficient Here, the non-sharp image signal Sus is set to a square area (mask) with 2N + 1 pixels (N is a positive integer) on the side of the target pixel, and the average value of the pixel values in the mask is set as the center This is a non-sharp image signal of a pixel.
By the frequency enhancement process, an image in which the edge of a structure such as a bone is enhanced can be obtained.

<Dynamic range compression processing>
As the dynamic range compression processing, for example, a technique disclosed in Japanese Patent No. 250950 can be applied. In the dynamic range compression processing, the density of the low density area is corrected by multiplying the image signal in the low density area from a certain signal value A by the correction coefficient β by performing the calculation represented by the following equation (4). Compress gradation.
S = So + β (A−Sus) (4)
However, β = βL (Sus ≦ A)
β = βH (Sus> A)
S: Dynamic range compression processed image signal
So: Original image signal
Sus: Unsharp image signal
β: Correction coefficient
A: Constant (threshold value)
As described above, an image for interpretation is created by performing gradation conversion processing, frequency enhancement processing, and dynamic range compression processing on the original image.

  Next, the created image for interpretation is displayed in the image display field 351a of the viewer screen 351 (step S4, see FIG. 7). The doctor can confirm whether the imaging has been successful (whether re-imaging is necessary) by observing the image for interpretation. Further, in the case of an examination that does not require measurement, it is possible to make a diagnosis by interpreting an image for interpretation. At this time, the tool button 351d can be operated to adjust to a desired image quality. Although details will be described later, in measurement of bone mineral quantity, an operator such as a doctor needs to designate two points on the second metacarpal bone of the left hand. In order to easily specify these two points, the density contrast button and the image quality adjustment button of the tool button 351d are operated in advance to adjust the image so that the operator can easily specify the two points and the edge is emphasized. It can also be left.

  When an operation other than the pressing of the measurement menu button 351c and the selection of the bone mineral content measurement menu is performed by the operation unit 34 (step S5; NO), processing corresponding to the operation is executed (step S6). When the end button 351i is pressed by the operation unit 34 (step S7; YES), the diagnosis support process ends.

  On the other hand, when the measurement menu button 351c is pressed by the operation unit 34 and the bone mineral quantitative measurement menu is selected (step S5; YES), the bone mineral quantitative measurement process is executed (step S8).

  FIG. 9 shows a flowchart of the bone mineral content measurement process executed by the control unit 31. The bone mineral density measurement process is executed in cooperation with the control unit 31 and a program stored in the storage unit 33.

  In the bone mineral density measurement process, first, a bone mineral quantity optimized image creation process is executed, a bone mineral quantity optimized image is created from the created image for interpretation, and is temporarily stored in the RAM 32 (step S101).

Here, the image for interpretation is suitable for interpretation diagnosis, but is not suitable for measurement of bone mineral content. Specifically, an image required for bone mineral content measurement differs in tone, density, and contrast from an image required for interpretation. Further, in the measurement of bone mineral quantification, a correct measurement result cannot be obtained if frequency enhancement processing or dynamic range compression processing is performed. That is, if bone mineral content is measured from the image for interpretation, a correct measurement result cannot be obtained.
Therefore, in the present embodiment, when the measurement of bone mineral quantity is instructed, the bone mineral quantity quantification suitable for the measurement of bone mineral quantity is calculated from the image for interpretation by automatically executing the bone mineral quantity optimization image creation processing. By creating an optimized image and using it for measurement, it is possible to prevent an erroneous measurement result from being measured using the image for interpretation.

  In addition, since the image for interpretation is an image that satisfies a predetermined standard, it is not necessary to adjust parameters for each image, and a bone mineral quantitative optimization image is created from the image for interpretation using a fixed processing parameter. be able to. In this embodiment, for example, the image for interpretation is a fixed parameter with a gradation conversion curve (LUT) of BONE-02, a density correction value (S value) of 250, and a contrast value (G value) of 2.50. Is subjected to gradation processing. In addition, when the image for interpretation is subjected to frequency enhancement processing and dynamic range compression processing, the parameters used when the frequency enhancement processing (dynamic range compression processing) are performed are used. The inverse conversion of the conversion performed by the compression processing) is performed. Note that an image for interpretation that has not been adjusted on the viewer screen 351 is used for the bone mineral quantitative optimization image creation processing.

Next, the bone mineral content screen 352 is displayed on the display unit 35 (step S102).
FIG. 10 shows an example of the bone mineral content screen 352. On the bone mineral content determination screen 352, patient information 352a, imaging region 352b, measurement date and time 352c, measurement value 352d, comment field 352e, confirmation button 352f, and the like of the patient to be diagnosed are displayed. In step S102, the final result value of the patient to be diagnosed (that is, the previous result value) stored in the bone mineral quantification DB 332 is read as the measurement value 352d and initially displayed.
In addition, the bone mineral amount determination screen 352 is provided with a two-point designation field 352g. In bone mineral quantitative measurement, it is necessary to designate two points, the most protruding part at the upper end of the second metacarpal bone of the left hand and the most depressed part at the lower end, and this two-point designation field 352g has two points. The image for designation to designate is displayed.

  Here, it is preferable to display an image for interpretation (or an adjusted image for interpretation) as the image displayed in the two-point designation field 352g. The bone mineral quantification optimized image is generally darker than the image for interpretation (see FIG. 13), and processing for enhancing the edge of the bone portion such as frequency enhancement processing applied to the image for interpretation is performed. It has not been. Therefore, depending on the shape and arrangement of the bone of the patient's left hand, it may be very difficult to specify two points.

  When two points of the left second second core bone are designated from the two-point designation field 352e by the operation unit 34 (for example, clicked with the mouse of the operation unit 34), the coordinates of the designated two points (X1, Y1) , (X2, Y2) are temporarily stored in the RAM 32 (step S103), and the bone mineral quantification is performed using the coordinates (X1, Y1), (X2, Y2) of these two points and the bone mineral quantification optimized image. Is measured (step S104).

The measurement of the bone mineral amount in step S104 is performed by the DIP method. As described above, the DIP method is a known method for measuring the bone mineral density by comparing the shadow density of the aluminum slope in the image and the left second metacarpal bone. Hereinafter, measurement of bone mineral content measurement using the DIP method will be described with reference to FIGS. 11A to 11B.
First, as shown in FIG. 11A, a distance between coordinates of two designated points (X1, Y1) and (X2, Y2) is calculated as an L value (bone length). Next, a range of 10% of the bone length in the center between the two points in the bone mineral quantitative optimization image with the vertical width and the horizontal width as fixed values is determined as the measurement region, and in the image by pattern matching etc. The position of the aluminum slope is detected. Then, based on the density of the aluminum slope image, the bone density GS is calculated based on which thickness part of the aluminum slope the bone density in the measurement region matches, and the integrated value of the calculated bone density A value obtained by dividing ΣGS by the bone width D (ΣGS / D (mmAl)) is calculated as the DIP value (bone mineral content). Further, an average bone cortex width MCI (MCI = (D−d) / D) is calculated. D is the bone width and d is the bone marrow width d. FIG. 11B is a diagram showing a tomographic plane and a concentration profile of the central portion of the left second metacarpal bone B. The bone width D and the bone marrow width d can be calculated based on, for example, the concentration profile of the center portion of the left second metacarpal bone B as shown in FIG. 11B.
Calculated L value, DIP value, MCI, measurement area coordinates (upper left (X3, Y3), lower right (X4, Y4)), detected aluminum slope position coordinates upper left (upper left (X5, Y5), lower right (X6, Y6)) is temporarily stored in the RAM 32.

  When the measurement of the bone mineral content is finished, the result value is displayed on the bone mineral content screen 352 (step S105). FIG. 12 shows a bone mineral content screen 352 after bone mineral content measurement. As shown in FIG. 12, in step S105, the L value, ΣGS / D, and MCI, which are the results obtained by the measurement in step S104, are displayed on the measurement value 352d of the bone mineral quantitative screen 352. In addition, on the image displayed in the two-point designation field 352g, the coordinates P1, P2 of the designated two points, the measurement region R1, and the detected position R2 of the aluminum slope are displayed as annotations.

Next, it is determined whether or not the operation unit 34 has instructed to move the coordinates P1 and P2 of the two points on the bone mineral amount determination screen 352 (step S106). P1 and P2 can be moved by dragging and dropping the annotation using the operation unit 34. If it is determined that the movement of the two coordinate points P1 and P2 is instructed by the operation unit 34 (step S106; YES), the process returns to step S104, and the newly designated two points (after the movement) are used. Measurement is executed again.
When the operation unit 34 does not instruct the movement of the two coordinates P1 and P2 (step S106; NO) and the confirm button 352f is pressed (step S107; YES), the measurement result is confirmed and the bone mineral quantity quantification is optimal. The converted image, the result value, and the parameters used for measurement are stored (step S108), and the process proceeds to step S9 in FIG. Specifically, in step S108, a new record is added to the bone mineral quantification DB 332, and the result value and parameters used for measurement (calculated L value, DIP value, MCI, two-point designation coordinates ((X1, Y1), (X2, Y2)), measurement area coordinates (upper left (X3, Y3), lower right (X4, Y4)), detected aluminum slope position coordinates upper left (upper left (X5, Y5), lower right ( X6, Y6)) is written, the bone mineral quantitative optimization image is stored in the image DB 331, and the storage destination path of the processed image of the record of the examination in the image information table 331a is the bone mineral quantitative optimization image. Changed to a path.

In step S9 of FIG. 6, a graph image and its thumbnail image are created based on the result value obtained by measurement (step S9).
In step S9, first, for example, a graph area is drawn with the horizontal axis representing the date and the vertical axis representing ΣGS / D (mmAl). Next, a past record having the same patient ID is searched from the bone mineral density DB 332, and ΣGS / D of the searched record is plotted in the graph area in order of date. In addition to the graph, a result list is created that lists changes over time in the values of ΣGS / D and MCI of the retrieved records. Furthermore, based on the result values stored in the bone mineral quantitation DB 332, what percentage of the average value of the same age (the same age ratio), what percentage of the young adult average value (YAM) (YAM ratio), Is calculated, and one graph image including the patient information, the numerical value of the current result value, the age ratio, the YAM ratio, the graph, and the result list is created. The file format of the image may be any of PNG, JPEG, PDF, and the like. The created graph image is stored in the image DB 331, and the storage path of the graph image is stored in the record of the examination in the image information table 331a. Also, a thumbnail image of the graph image is created and stored in the image DB 331, and the storage path of the graph thumbnail image is stored in the record of the examination in the image information table 331a.

When the creation of the graph is completed, a viewer screen 351 displaying the created graph image is displayed on the display unit 35 (step S10).
FIG. 13 shows an example of the viewer screen 351 on which a graph is displayed. In the image display field 351a, the graph image created in step S9 and the bone mineral quantitative optimization image serving as the measurement source are displayed side by side.
The doctor can grasp the change in the bone mineral content of the patient by checking the graph screen, and can make the necessity and policy of treatment. In addition, since the graph and the measurement source image are displayed side by side, if there is a significant change from the previous result, observing the measurement source image to determine whether the result is correct, the shooting conditions (shooting magnification, shooting angle) It is easy to determine whether it is caused by the arrangement of hands or the like.

When the print button 351c is pressed by the operation unit 34 (step S11), the graph image data is transmitted to the general-purpose printer 6 by the communication unit 36, and the graph image is printed out from the general-purpose printer 6 (step S12).
When the end button 351i is pressed by the operation unit 34 (step S13; YES), the diagnosis support process ends.

  As described above, according to the medical image processing apparatus 3 in the present embodiment, the control unit 31 stores the second-point designation image 352g on the bone mineral amount determination screen 352 as a two-point designation image. An image for image interpretation created by performing image processing including frequency enhancement processing on a medical image obtained by X-ray imaging of a hand bone is displayed. Therefore, since the image in which the edge of the second metacarpal bone of the left hand is emphasized is displayed as a two-point designation image, even an operator who is not familiar with the two-point designation operation can easily perform the designation operation. It can be done correctly.

  In addition, the description in this Embodiment mentioned above is an example of the suitable system in a facility which concerns on this invention, and is not limited to this.

  For example, in the above-described embodiment, the case where an interpretation image is used as the designation image for designating two points has been described as an example. However, as the designation image, processing for enhancing edges on a medical image is performed. The image is not limited to the image for interpretation. For example, an image obtained by adjusting the image quality of the image for interpretation using the tool button 351d on the viewer screen 351 may be used as the designation image.

  For example, in the above-described embodiment, the measurement result of the bone mineral amount is displayed and output on the display unit 35 and output from the general-purpose printer 6 as necessary. However, the recording medium M is recorded by the media drive 37. Or may be transmitted to the client PC 7 or the like connected to the network 8 via the communication unit 36.

  For example, in the above description, an example in which a hard disk, a semiconductor non-volatile memory, or the like is used as a computer-readable medium of the program according to the present invention is disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. Further, a carrier wave is also applied as a medium for providing program data according to the present invention via a communication line.

  In addition, the detailed configuration and detailed operation of the medical image processing apparatus can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Facility system 2 Modality 3 Medical image processing apparatus 4 Reception apparatus 5 Imager 6 General-purpose printer 7 Client PC
8 Network 31 Control unit 32 RAM
33 storage unit 331 image DB
331a Image information table 332 Bone mineral content determination DB
34 Operation unit 35 Display unit 351 Viewer screen 352 Bone mineral determination screen 36 Communication unit 37 Media drive 38 Timekeeping unit 39 Bus

Claims (3)

A bone mineral quantitative optimization image that creates a bone mineral quantitative optimization image optimized for bone mineral quantitative measurement by performing image processing on the medical image obtained by radiographing the second metacarpal bone of the left hand Creating means;
An image processing unit that performs image processing for emphasizing an edge on the medical image, and an image creating unit for designating an image for designating an operator to designate two predetermined points of the second metacarpal bone of the left hand;
Display means for displaying the designation image created by the designation image creation means;
Operating means for an operator to specify the predetermined two points from the designation image displayed on the display means;
Bone mineral content measurement means for measuring bone mineral content based on the coordinates of the two points designated by the operation means and the bone mineral content optimization image,
A medical image processing apparatus comprising: Image interpretation image creation means for creating an image for interpretation by performing image processing including gradation conversion processing and frequency enhancement processing on the medical image,
The image interpretation image creating means creates an image for image interpretation whose edges are emphasized by performing frequency enhancement processing on the medical image as the image creation device for designation.
The medical image processing apparatus according to claim 1, wherein the display unit displays the interpretation image created by the interpretation image creation unit as the designation image. Computer
A bone mineral quantitative optimization image that creates a bone mineral quantitative optimization image optimized for bone mineral quantitative measurement by performing image processing on the medical image obtained by radiographing the second metacarpal bone of the left hand Creation means,
Image designating means for performing an image processing for emphasizing an edge on the medical image, and creating an image for designation for an operator to designate two predetermined points of the left second metacarpal;
Display means for displaying the designation image created by the designation image creation means;
Operation means for an operator to designate the two predetermined points from the designation image displayed on the display means;
Bone mineral content measurement means for measuring bone mineral content based on the coordinates of the two points designated by the operation means and the bone mineral content optimization image,
Program to function as.