JPH04117081A - X-ray diagnostic device - Google Patents

Abstract

PURPOSE:To prevent deterioration of picture by determining the amount of smear generated in elements for each matrix of element based on a TV video signal and performing the processing of subtracting the amount of smear from the TV video signal. CONSTITUTION:The X-ray transmitting a reagent is converted into a fluorescent image, the fluorescent image is picked up by a two-dimensional solid-state image pickup element 11 to convert it into electric charge information and the electric charge information is transmitted to a TV monitor 19 as the TV video signal. The two-dimensional solid-state image pickup element 11 generates the different amount of smear for each matrix due to a transmission system, and a smear correction means 20 determines the amount of the smear for each matrix of the element 11 based on the TV video signal transmitted horizontally, performs the processing of subtracting the amount of the smear from the TV video signal and outputs a signal which is not affected by the smear. Thus, deterioration of picture arising from the smear can be prevented.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention is an image intensifier.

Using a two-dimensional solid-state image sensor, the X-rays that have passed through the subject are
The present invention relates to an X-ray diagnostic apparatus that converts a fluoroscopic image of a subject into a V video signal and displays it on a TV monitor.

(Prior art) An X-ray diagnostic device irradiates a subject with X-rays, converts the transmitted X-rays into a fluorescent image, converts this fluorescent image into a TV video signal, and displays it as a fluoroscopic image on a TV monitor. It is to be displayed.

That is, according to this X-ray diagnostic apparatus, when an X-ray tube irradiates a subject with X-rays, the X-rays are converted into a fluorescent image by an image intensifier. The fluorescent image from this image intensifier is then inputted to a TV camera via an optical system and converted into a TV video signal, which is then converted into a digital signal by an A/D converter and sent to the TV.
Displayed as a transparent image on the monitor.

On the other hand, as a TV camera that inputs an optical image from the image intensifier described above, CCD cameras using a two-dimensional side body image sensor in which elements are arranged two-dimensionally have recently become mainstream.

This two-dimensional side body imaging device converts the fluorescence image into photo-charges and provides it as a diagnostic image. Generally, a two-dimensional side body image sensor uses a single image sensor, and the resolution of an image is determined by the number of pixels of this image sensor. For this reason, since the number of pixels in a single image sensor is limited due to space limitations, there has been a problem in that image resolution cannot be significantly improved.

Therefore, in order to improve image resolution, an X-ray diagnostic apparatus as shown in FIG. 12 has conventionally been used.

That is, this X-ray diagnostic apparatus includes an image intensifier 1 (hereinafter referred to as 1 and 1), lenses 2a to 2C as an optical system, a half mirror 3°, and imaging plates 4 and 5 as two-dimensional side body imaging elements. It is composed of: The fluorescent image from 1.1.1 above is transferred to the lens 2a and the half mirror 3.
, I, I, output images are formed on the lower end of the imaging plate 4 via the lens 2b.

In addition, the fluorescent image from I.1.1 is transferred to the left end of the imaging plate 5 via the lens 2a, the half mirror 3, and the lens 2C.
, 1. Form an output image. The overlapping portions 4a and 5a of the output images formed on the image pickup plate 4.5 are overlapped to double the number of pixels, thereby improving resolution. was.

(Problem to be Solved by the Invention) However, the overlapping portion 4a of the imaging plates 4 and 5 described above
, 5a are stacked one on top of the other, there is a problem in that the image quality deteriorates because the photo-charge conversion characteristics of the image pickup plates 4 and 5 are somewhat different.

Furthermore, when transferring the charge information converted by the two-dimensional side body image sensor, the fluorescence image light output from the image intensifier continues to be irradiated, so smear occurs on the image sensor, causing incorrect It was not possible to output a TV video signal, which caused further image deterioration.

Therefore, an object of the present invention is to provide an X-ray diagnostic apparatus that can reduce image deterioration.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention converts X-rays transmitted through a subject into a fluorescent image by an image intensifier,
In an X-ray diagnostic apparatus, this fluorescent image is focused on a two-dimensional side body image sensor, converted into charge information, and further this charge information is transmitted as a TV video signal to a TV monitor to display a fluoroscopic image of the subject. , characterized in that it has a smear correction means that calculates the amount of smear generated in the element for each column of the elements based on the horizontally transferred TV video signal, and subtracts the amount of smear from the TV video signal. It is something.

Further, the two-dimensional side body image sensor is provided with a plurality of sets, and is arranged so as to divide and form the fluorescent image on each set of the two-dimensional side body image sensor with an overlapping portion, and It may also include a sensitivity correction means for correcting differences in photo-charge conversion characteristics between the respective coarse side image sensors.

(for production) The operation of the device having the above configuration will be explained.

A two-dimensional side body image sensor generates a different amount of smear from column to column due to the transfer method. The smear correction means calculates the amount of smear generated in each element for each row of the elements based on the horizontally transferred TV video signal, and subtracts the amount of smear from the TV video signal to produce a signal free from the influence of smear. Output. This prevents image deterioration caused by smear.

Further, by using a plurality of sets of two-dimensional side body image sensors, the number of pixels can be increased, resolution can be improved, and image deterioration caused by smear can be prevented.

(Example) Examples of the present invention will be described in detail below.

FIG. 1 shows a schematic block diagram of an X-ray diagnostic apparatus 10 according to a first embodiment of the present invention.

The present device 10 includes two systems of frame transfer type two-dimensional surface solid imaging devices 11.
CCD camera 12゜12' with 11' and each CCD
Each amplifier 13. connected after the camera 12.12'.
13', each A/D converter 14, 14', and each A/D converter 14.
smear correction means 20 and 20' that perform smear correction to remove the amount of smear included in the digital signal converted by the D converter 14, 14', and the two-dimensional side body image sensor 1.
Sensitivity correction coefficient calculation means 15 for correcting differences in photo-charge conversion characteristics, etc. of the two systems including 1.11', and smear correction means 2
0.20' and sensitivity correction coefficient calculation means 15 and multiplier M
, M', a selector 17 that alternately selects the image data stored in each memory 16, 16' and outputs it to a subsequent stage, and a D/A converter 18. The TV monitor 19 displays image information converted into an analog signal by a TV monitor 19.

FIG. 2 shows a block diagram of the smear correction means 20 (or 20'). Since the smear correction means 20 of one system and the smear correction means 20' of the other system are constructed in the same way, the smear correction means 20 of one system will be explained.

This smear correction means 20 has a multiplier 21 that multiplies the image data input from the A/D converter 14 by (1+τ/T), and a multiplier 21 that multiplies the image data input from the A/D converter 14 by (τ/T). T) a multiplier 22 for multiplication, an adder 23 connected after the multiplier 22, a line memory 24 for storing one line of image data of the two-dimensional image sensor 11, a subtracter 25, and a switch. It has an element 26.

Here, the charge transfer method of the two-dimensional surface solid imaging device 11, 11' will be explained with reference to FIG. Element 11 and element 1
Since element 1' has the same structure, element 11 will be explained. 3(a) to 3(f) show the operation of the two-dimensional side body image sensor 11, and FIGS. 3(a) to 3(c)
shows the external transfer stage, and (d) to (f) in the same figure show the internal transfer stage.

This element 11, as shown in FIG.
Light receiving unit 1 that receives the fluorescent image from the intensifier 1
1a, a memory section 11b for storing charge information accumulated in the light receiving section 11a, and an output register llc, and both the light receiving section 11a and the memory section 11b have respective elements 11d.

11e arranged in a matrix.

The symbols shown as “○” or “x” in the same figure (a) to (f) are
This shows the charge between two consecutive frames. Same figure (
A) shows a state in which charges indicated by "x" are accumulated in the light receiving element lid of the light receiving section 11a, and charge information indicated by "◯" is stored in the memory element 11e of the memory section 11b.

The light-receiving section 11a is configured to constantly receive fluorescence and image light without being blocked, and accumulate electric charges therein. on the other hand,
In the memory section 11b, as shown in FIG.
The charge information "○" transferred to the output register 11c is transferred to the amplifier 13.c by the horizontal transfer H. The signal is transferred to the smear correction means 20 via the A/D converter 14.

Next, in the external transfer stage shown in FIG. 2(b), the charge information "○" stored in the lowest stage of the memory element 11e is transferred to the external transfer stage shown in FIG.
As shown in C), the data is similarly vertically transferred V and horizontally transferred H, and then transferred to the smear correction means 20. When the charge information rOJ stored in the memory section 11b is sequentially transferred in this way, the memory section 11b is transferred as shown in FIG.
The state is such that no charge information is stored.

From (d) in the figure, the internal transfer stage begins, and from (a) to (
The charge "x" accumulated in the external transfer stage shown in C) is first transferred to the light receiving element l of the light receiving section 11a, as shown in FIG.
The charge “x” accumulated in the bottom row of id is the memory element l
The charge information "x" vertically transferred to the top stage of the memory element ie is vertically transferred to the top stage of the memory element ie, and then, although not shown, the charge information "x" vertically transferred to the top stage of the memory element lie is vertically transferred to the next lower stage memory element 11e. At the same time, the charge "x" accumulated in the light receiving element 11d at the bottom stage is vertically transferred to the top stage of the memory element 11e. When the charge "x" is vertically transferred in this internal transfer stage, the charge "x" to be vertically transferred is successively influenced by the charge received by the light receiving element lid on the vertical transfer path. This affected bone is the amount of smear. As shown in FIG. 3(f), while including the amount of smear, when all the charges "x" accumulated in the light receiving section 11a are vertically transferred to the memory section 11b, the charges " While performing the vertical transfer V of “×”,
The light receiving portion 11a is in a state where charges "◯" are accumulated. After that, the process moves to the external transfer stage again as shown in FIG. 6(b), and the charge information "x" is vertically transferred V in the same way as described above.

Horizontal transfer H is performed. In this way, charge information, ie, image data, horizontally transferred from the memory element lie of the two-dimensional surface image sensor 11 includes a different amount of smear for each column of the memory element lie.

Next, smear correction will be explained using a calculation formula.

FIG. 4 shows the coordinates of pixels in the memory section 11b where the number of pixels is NXM. .

Under a situation where it can be assumed that the intensity of light incident on the two-dimensional body image sensor 11.11' does not change between two consecutive frames, the output voltage of any pixel P (i, j) of the memory section 11b ■1. It can be expressed as a pigeon. Here, (i, j): Coordinates of pixel P■1. : Light intensity incident on pixel P (i, j)■1. : Output voltage of pixel P (i, j) (corresponding to accumulated charge) Vl, : True value when no smear occurs τ : Charge accumulation time: Vertical transfer time per pixel.

In the equation (1), the second term on the right side represents the amount of smear, and Σ in the second term represents the sum of the amounts of smear for all pixels in the first column. The charge accumulation time T and the transfer time τ are determined by the driving conditions of the two-dimensional surface imaging device 11, and since Vl is the charge information itself, the true value vI without the influence of smear is determined from equation (1).

can be found.

Moreover, since the above formula (1) is 0×(τ/T)<1, (
τ/T)24 or more can be used as an approximate expression, VIl"= (1+r/T)Vi, -(r/T) ΣV
.

k-1...(2) get.

The smear correction means 20, 20' realizes this equation (2). That is, when digital image data vI is input from the A/D converter 14, the multiplier 2
2 is performed, and the amount of smear is stored in the line memory 24 for each M columns. At this time, the switch element 26 is connected to the line memory 24 during the period b during which the digital image data of the first line of the frame is output from the A/D converter 14, 14'.

On the other hand, image data v1. is multiplied by the multiplier 21, and (1+τ/T)V, , (the first term of equation (2)) is input to the subtracter 25, and from the first term of equation (2), equation (2)
) is subtracted to obtain the true value v1. is output to the sensitivity correction coefficient calculation means 15.

The two systems of image data imaged on the two-dimensional mouth image sensor 11.11' are captured by the optical system of the CCD camera 12°12',
The difference in sensitivity is caused by the photo-charge conversion characteristics, gain, etc. of the two-dimensional surface image sensor 11° 11'.

the sensitivity correction coefficient calculating means 15 and the multiplier M;

M' is for correcting the difference in sensitivity between these two systems. 2
A correction coefficient al+a2 is obtained from the image data of the overlapping portion commonly received by the two CCD cameras 12, 12', and multipliers M and M' multiply the image data by this. An example of how to calculate the correction coefficient al+a2 is as follows, where the sum of the output values of the overlapping portion is ml and m2, al=(myo+m2)/2'myoa2=
(ml 10 m2)/2·m2 may be used.

The correction coefficients a and a2 may be determined for each frame and multiplied by the image data of the next frame, or the coefficients a and a2 may be determined at a certain time and the same coefficient al+22 may be used thereafter.

Next, the operation of the device 10 of the first embodiment will be explained.

The image data of the first frame based on the images taken by the two CCD cameras 12.12' are each sent to the smear correction means 20.2.
0', the amount of smear is calculated and stored.

Next, in the next frame, each smear correction means 20.2
Based on the smear-corrected signal output from 0', the sensitivity correction coefficient calculation means 15 calculates a correction coefficient al+a: for correcting the sensitivity difference between the two systems. Furthermore, for the image data of the subsequent frame, the already calculated correction coefficient al+a
2 is multiplied by multipliers M and M', and the smear-corrected and sensitivity-corrected image data is output to the subsequent stage, and high-resolution image information with little image deterioration is displayed on the TV monitor 19.

According to the embodiment device 10 configured in this way, image deterioration caused by smear is prevented, so when the number of pixels is increased using a plurality of two-dimensional solid-state image sensors,
It is possible to provide an X-ray diagnostic apparatus that can improve resolution and prevent image deterioration. Furthermore, since the overlapping portion does not appear as a boundary between images, diagnostic performance is improved.

FIG. 5 shows a schematic block diagram of an X-ray diagnostic apparatus 30 according to a second embodiment of the present invention.

Components having the same functions as those of the device 10 of the first embodiment will be described with the same reference numerals.

This device 30 includes a CCD camera 12. similar to the device 10 of the first embodiment. Amplifier 13. A/D converter 14, D/A converter 18. When the pixel values converted into digital signals by the TV (-), the smear correction means 20, the memories 31 and 32 provided before and after the smear correction means 20, and the A/D converter 14 are saturated. and a saturated pixel address memory 34 configured to correspond to the pixels in the memory section 11b of the element 11 and to store the address of the pixel corresponding to the element that outputs saturated charge information. , a saturated pixel column re-correction section 40 as a saturation correction means for re-correcting data after smear correction for a column containing saturated pixels, a saturated pixel pixel value replacement section 35 for replacing the pixel value of the saturated pixel, and an address. It has address generators 36 and 37 that generate signals, and a CPU 38 that controls each part of this device 30.

The memories 32.16 each have a pair of frame memories 32a and 32a, respectively, in order to adjust the timing deviation of data transfer.
32b, frame memory 16a.

16b.

The saturated pixel detection means 33 detects a saturated pixel based on whether the transmitted pixel value is the maximum value. For example, if the resolution is 12 bits and the transmitted pixel value is the maximum value of 4095, that pixel is determined to be saturated. This determination is made for all pixels.

As shown in FIG. 6, the saturated pixel address memory 34 includes a memory 34a having a number of pixels (NxM) corresponding to the number of NxM pixels in the memory llb of the CCD 12, and a memory 34a that determines the presence or absence of saturated pixels in each column. Saturated column memo IJ to memorize information
34b, and a saturated row memory 34c that stores information on the presence or absence of saturated pixels in each row. In the memory 34a, when a saturated pixel is detected by the saturated pixel detection means 33, "1" is written in the position corresponding to the coordinates by the CPU 38, and in other cases, "0" is written. There is. In addition, the saturated column memory 34b
, the CPU 38 stores the logical sum of the values stored in the memory 34a for each column.
If there is even one "1" in 4a, "1" is written into the memory of the saturated column memory 34b corresponding to that column. In the case of the figure, since "1" is included in the second and third columns, "1" is written in the corresponding position. Similarly, the logical sum is stored in the saturated row memory 34c. In the case of the same figure, "1" is written in the second line.
is included, so "1" is written in the corresponding position.

The saturated pixel column re-correction unit 40 includes a line memory 41 that stores pixel values for one row, a re-correction value calculation unit 42 that calculates a re-correction value Δj, and a re-correction unit that stores the calculated re-correction value Δj. It includes a value memory 43 and a subtracter 44.

Here, the case where there is a saturated pixel will be explained. For example, if there is a saturated pixel, the output voltage V1. is v, = v, + (r/T) (ΣKT I , -v,
)k-1...(3) In such a case, the above formula (2) becomes y,
Clause (1+τ/T)Vi, -(τ/T) ΣKT I
,.

k-1...(4) Between equation (2) and equation (4), V, , <V,
, , Therefore, the following relationship holds true: (τ/T) ΣV, <(τ/T) ΣKTIk+where, K, proportionality constant V l &, : saturated pixel output voltage. Therefore, when correction is performed using equation (2) for an image with saturated pixels, the amount of smear may not be subtracted enough, as shown in FIG.

The shaded area in the figure is the re-correction amount Δj that is insufficient to subtract the smear amount.

Therefore, the saturated pixel row re-correction unit 40 correctly removes the amount of smear by determining the re-correction amount Δj even if there are saturated pixels. For example, as shown in FIG.
' If (i, j) is a saturated pixel, the smear amount S1 (j-11) of the (j-1) column can be expressed as , and the smear amount S'1 of the j column can be expressed as , and the smear amount S'1 of the (j+1) column can be expressed as The smear amount S1,1°1. can be expressed as follows.

i without this saturated pixel. The profile of the row pixel values is
j including the saturated pixel P' (i, j) as shown in FIG.
Only the column shows a prominent pixel value of V/1°.

This is due to saturation effects. However, assuming that there is no saturation in nature, i. The pixel value v1゜1 of column j in the row is
It should be smoothly continuous as shown by the dotted line in FIG. Therefore, the pixel value V1° of the 10-row matrix when there is no saturation in that column is the pixel P□ (io
, j-1).

Using the interpolation method from the pixel value of P2 (io, j+1),
You can ask for it. The difference between the obtained true pixel value V1°1 and the pixel value V' is Δj=V'. ,-V,. .

can be regarded as the saturation influence needle of the saturated pixel P' (i, j). Therefore, by subtracting this re-correction value Δj by the amount of smear affected by saturation, 3/1°, the influence of saturation can be removed.

The re-correction value memory 43 contains M as shown in FIG.
It is possible to store re-correction values Δj corresponding to pixels in columns. As shown in the figure, if no re-correction is performed, “0
'' is stored, and when re-correcting, a re-correction value Δj indicated by x and y is stored.

The saturated pixel pixel value replacement unit 35 replaces the pixel value V of the saturated pixel P' (i, j) after the re-correction value Δj is subtracted.
(It replaces i and D with 4095, which is the maximum resolution, so that it looks white on the screen. By doing this, for example, if the re-correction value Δj is 95, when re-correcting, the image will be saturated in the j column. Pixel values other than pixel P (i, j) are almost correct values. However, the saturated pixel P' (i
, the re-correction value Δj (95) is also obtained from the pixel value (4095) of D.
When subtracting , the error increases because most of the true values exceed 4095. In order to reduce this expansion as much as possible, the saturated pixel P' (i, j) is replaced with the maximum value of 4095. By doing this, it is possible to get the value as close to the true value as possible. Furthermore, when replacing the pixel value, the pixel value may be replaced with "0" so that the pixel value appears black on the screen. In this case, it becomes easy to distinguish between saturated pixels and other pixels.

Next, the functions and effects of the second embodiment device 30 will be explained with reference to FIG. 12.

The image data captured by the COD camera 12 is sent to the amplifier 13.
．． According to the address signal output from the address generator 36 via the A/D converter 14, the signal is taken into the memory 31 and into the saturated pixel detection means 33.

The saturated pixel detection means 33 sequentially writes the detection results, ie, "1" or "0", into the addresses of the saturated pixel address memory 34 in accordance with the address signal generated by the address generator 36. When the detection of saturated pixels of NxM pieces of image data is completed, the CPU 38 specifies one of the rows in which rOJ is written in the saturated row memory 34c and outputs the row information to the address generator 37. .

The address generator 37 sends address signals corresponding to the row information output from the CPU 38 to the frame memories 32a and 3.
2b, and sends the data of the designated row to the saturated pixel column re-correction unit 40.

On the other hand, the image data taken into the memory 31 is subjected to smear correction by the smear correction means 20 as shown in the first embodiment apparatus 10, and the smear correction data obtained by subtracting the amount of smear from the image data is stored in the frame memory. 32a. Next, when image data for one frame is sent out, it is written into the frame memory 32b by a switch operation.

One row of data output from the frame memory 32a to obtain the re-correction value Δj is transferred to the line memory 41. The re-correction calculation unit 42 selects “
Re-correction value Δj for column information in which “1” is written
Calculate. This calculated re-correction value Δj is stored in the re-correction value memory 43.

Next, all of the image data stored in the frame memory 32a is transferred to the saturated pixel row re-correction unit 40 under the control of the CPU 38.
The subtraction unit 44 takes in the subtraction unit 44 .

The subtraction unit 44 extracts the re-correction value Δ stored in the re-correction value memory 43 for each column from the image data from the frame memory 32a.
j is subtracted and output to the saturated pixel pixel value replacement section 35.

The saturated pixel pixel value replacement unit 35 replaces the address information of the saturated pixel in the saturated pixel address memory 34 sent by the CPU 38 with the maximum pixel value, and writes all image data to the frame memory 16a.

When writing image data for the next frame, it is written to the frame memory 16b by a switch operation.

The CPU 38 alternately transfers the image data written to the memories 16a and 16b to the D/A converter 18 by switch control.
to display an accurately smear-corrected image with little image deterioration even if there are saturated pixels on a TV monitor 19.

Note that the present invention is not limited to the above-mentioned embodiments, and can be implemented in various modifications. For example, although the frame transfer method has been described as a charge information transfer method, the incline transfer method also generates a different amount of smear for each column of image sensors, so the present invention is similarly applicable to this case as well.

[Effects of the Invention] According to the present invention described in detail above, since the smear component is removed by the smear correction means, it is possible to provide an X-ray diagnostic apparatus that can reduce image deterioration.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a device according to a first embodiment of the present invention;
FIG. 2 is a schematic block diagram of the smear correction means of this device.
3(a) to (f) and FIG. 4 are explanatory diagrams showing the action of the smear correction means shown in FIG. 2, and FIG.
6 to 11 are diagrams showing the functions of each part of this device, and FIG. 12 is a schematic diagram showing the main parts of a conventional device using a plurality of two-dimensional surface image sensors. , FIG. 13 shows 1.1. FIG. 3 is a schematic diagram showing a composite image in which output images are superimposed. 0.30... X-ray diagnostic device, 1.11'... Two-dimensional surface image sensor, 5... Sensitivity correction coefficient calculation means, 9... TV monitor, 0.20'... Smear correction Means, 3...Saturated pixel detection means, O...Saturated pixel row re-correction unit (saturation correction means) agent
Patent Attorney Sanzawa Masayoshi Diagram M1 ↑ Is it a lie? Figure 1.1 Bore 7 Gravels\ Figure

Claims (3)

[Claims] (1) Convert the X-rays transmitted through the object into a fluorescent image using an image intensifier, focus this fluorescent image on a two-dimensional solid-state image sensor and convert it into charge information, and then convert this charge information into T
In an X-ray diagnostic apparatus that displays a fluoroscopic image of the subject by transmitting it as a V video signal to a TV monitor, the amount of smear generated in each element column is determined based on the horizontally transferred TV video signal. An X-ray diagnostic apparatus comprising: a smear correction means for calculating the amount of smear and subtracting the amount of smear from the TV video signal. (2) a saturated element detection means for detecting a saturated element that outputs saturated charge information among the two-dimensional solid-state image sensor; and smear correction for the column including the saturated element based on the unsaturated charge information. The X-ray diagnostic apparatus according to claim 1, further comprising saturation correction means for removing the influence of the saturation element from the amount of smear determined by the means. (3) The two-dimensional solid-state image sensor is provided in a plurality of sets, and is arranged so as to divide and form the fluorescent image on each set of the two-dimensional solid-state image sensor with an overlapping portion, and the two-dimensional solid-state image sensor is 3. The X-ray diagnostic apparatus according to claim 1, further comprising a sensitivity correction means for correcting a difference in photo-charge conversion characteristics between each set of solid-state image sensors.