JP4400263B2 - X-ray equipment - Google Patents

Description

  The present invention relates to an X-ray imaging apparatus that performs X-ray imaging, and in particular, a technique for performing subtraction processing using a mask image that is a normal fluoroscopic image and a live image that is a fluoroscopic image in which a contrast agent is imprinted. About.

  Conventionally, as a device of this type, the delay time from when the contrast agent is injected until the mask image is collected is “pre-set before imaging”, and the mask image is automatically set when the delay time elapses. That are controlled to start the collection of In this apparatus, a delay time until a live image is collected is also set in advance before shooting.

In addition, there is an apparatus configured to automatically detect that the contrast agent has reached the imaging region based on the detected value of the collected fluoroscopic image and start capturing a live image from the time of detection (for example, , See Patent Document 1). Since the live image requires that the contrast medium reaches the imaging region, this apparatus can prevent the previous imaging from being wasted. The mask image is automatically collected when a predetermined delay time elapses from the timing when the contrast medium is injected, as in the above-described apparatus.
JP-A-6-54256

  However, the conventional example having such a configuration has the following problems.

  That is, the time from when the contrast agent is injected until the actual imaging region is imaged varies depending on the blood vessel diameter of the subject, the running state of the blood vessel, the diameter and length of the catheter, and the like. Therefore, depending on conditions, it may occur that the contrast agent has already reached when the delay time for mask image collection has elapsed. Then, although the mask image is premised on that no contrast agent is imprinted, the subtraction between the mask image imprinted with the contrast agent and the live image imprinted with the flowing contrast agent Therefore, there is a problem that the image quality of the obtained subtraction image is deteriorated.

  In order to avoid the inconvenience described above, it is conceivable to set the mask image collection delay time short. However, if this is done, the interval between the time when the mask image is collected and the time when the live image is collected becomes longer, which causes another problem that the subject is easily affected by the body movement of the subject. When affected by such body movement, the image quality of the subtraction image is deteriorated as described above.

  The present invention has been made in view of such circumstances, and by selecting a mask image based on the detection of the arrival of a contrast agent, a constant image quality can be stabilized while avoiding adverse effects due to body movement. An object of the present invention is to provide an X-ray imaging apparatus that can be obtained automatically.

  In order to achieve such an object, the present invention has the following configuration.

  That is, the invention described in claim 1 is directed to X-ray fluoroscopic means for irradiating a predetermined imaging region of a subject with X-rays and capturing an X-ray transmission image of the imaging region, and the X-ray transmission image as digital data. In an X-ray imaging apparatus, comprising: a data conversion means for converting into: a storage means for storing the digital data as an image; and a calculation means for performing a subtraction process between a plurality of images stored in the storage means. Based on the image stored in the storage means, the timing detection means for detecting the timing at which the contrast medium arrives at the imaging site, and the timing detection means stored in the storage means based on the timing detected by the timing detection means Selecting means for selecting an image before the timing as a mask image in the subtraction process from among the existing images. It is a feature.

[Operation / Effect] According to the invention described in claim 1, since the timing detection means detects that the contrast medium has reached the imaging region, the image stored in the storage means before this timing is masked. The selection means selects an image. Therefore, since the contrast agent is not projected on the mask image and is difficult to be influenced by the body movement of the subject, it is ideal as a mask image in the subtraction process and has a certain image quality. It can be obtained stably. Further, since the path through which the contrast medium flows varies depending on the imaging region of the subject, the detection area setting means can set which part of the path is determined as the timing. For example, when the position of the lesion is at the end of the imaging region, the contrast agent reaches the vicinity of the lesion rather than timing when the contrast agent reaches the imaging site on the opposite side of the lesion. There are cases where it is better to set the timing as the timing, which is advantageous in such a case. Thereby, a region useful for diagnosis can be set as a detection region. Furthermore, when a preset live image acquisition start delay time elapses or an event is detected by the timing detection means, a signal is sent that the contrast agent has reached the imaging region. Output and select the mask image accordingly. As a result, even if a situation where the arrival of the contrast agent cannot be detected by the timing detection means occurs, the live image collection start delay time acts as a backup, so that a situation where the mask image is not selected can be prevented.

  Here, “before the timing” is immediately before the above timing (immediately before the contrast agent reaches the imaging region), but also includes a little before that. In other words, it includes an image taken immediately before the timing and a plurality of images continuously collected before that. However, the previous time is not included in view of the above-mentioned timing in which only the mask image is taken prior to the injection of the contrast agent as in the conventional example. That is, when the mask image and the live image are continuously collected, all images taken before the timing can be mask images.

In the present invention, it is preferable that the image processing apparatus further includes mask image generation means for generating a new mask image by performing predetermined arithmetic processing on one or a plurality of mask images selected by the selection means. Item 2 ). The image quality of the mask image can be improved by performing predetermined arithmetic processing by the mask image generating means and generating a new mask image, so that the image quality of the subtraction image can be improved.

  Examples of the predetermined arithmetic processing include edge enhancement processing for one mask image and averaging processing for a plurality of mask images.

Further, in the present invention, the detection area setting means sets a plurality of determination areas, and the timing detection means detects the timing based on whether any one of the plurality of determination areas exceeds a threshold value. (Claim 3). When imaging a complex blood vessel, the mask image selection timing can be set appropriately.

  The present specification also discloses an invention relating to the following X-ray imaging apparatus.

  In order to stably obtain a subtraction image with high image quality, it is necessary to improve the accuracy of the mask image. Therefore, when the mask image and the live image are collected continuously, it is detected that the contrast agent has reached the imaging region, and an image collected a little before is selected as the mask image. However, in the case of such a configuration, for example, an unexpected situation such as a contrast agent flowing out from a part of a blood vessel branched due to a vascular disorder or the like, or an imaging region being displaced due to body movement of the subject, etc. If this occurs, the contrast medium may not be detected. In such a case, since the arrival of the contrast agent cannot be detected, there is a problem that X-ray exposure to the subject is continued unnecessarily.

  Therefore, if the contrast agent is not detected even after the expected arrival time of the contrast agent, the imaging is stopped.

  (1) X-ray fluoroscopic means for irradiating a predetermined imaging part of the subject with X-rays and taking an X-ray transmission image of the imaging part; and data conversion means for converting the X-ray transmission image into digital data; An X-ray imaging apparatus comprising a storage unit that stores the digital data as an image and a calculation unit that performs subtraction processing between a plurality of images stored in the storage unit, and is stored in the storage unit Based on the image, the timing detection means for detecting the timing at which the contrast medium reaches the imaging region, and the timing detected from the images stored in the storage means based on the timing detected by the timing detection means Selection means for selecting an earlier image as a mask image in the subtraction process, and a contrast-enhanced image as a live image in the storage means The live image acquisition start delay time until the start of recollection is compared with the elapsed time from the time when the contrast medium starts to be injected, and the elapsed time until the timing detection unit detects the timing starts the live image acquisition. An X-ray imaging apparatus comprising: a control unit that stops imaging by the X-ray fluoroscopic means when a condition that the delay time is exceeded is satisfied.

  According to the invention described in (1) above, when the condition that the elapsed time exceeds the live image acquisition start delay time is satisfied, the imaging by the X-ray fluoroscopic means is stopped by the control unit, so that X-rays are unnecessarily performed. Can be prevented from being continued.

  (2) The X-ray imaging apparatus according to (1), wherein the control unit further stops injection of a contrast agent when the condition is satisfied.

  According to the invention described in (2), when the above condition is satisfied, the imaging is stopped and the injection of the contrast agent is stopped, so that it is possible to prevent waste of imaging using the contrast agent. it can.

  (3) The X-ray imaging apparatus according to (1) or (2), wherein the control unit further issues a warning when the condition is satisfied.

  According to the invention described in (3) above, an alarm is also issued when the above condition is satisfied, and the photographer can be notified that a problem has occurred. Can be done quickly.

  According to the X-ray imaging apparatus of the present invention, since the timing detection means detects that the contrast medium has reached the imaging region, the image stored in the storage means before this timing is selected as the mask image. Select. Therefore, the mask image does not reflect the contrast agent and can be hardly affected by the body movement of the subject. Therefore, the mask image is ideal as a mask image in the subtraction process. As a result, a constant image quality can be obtained stably.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram illustrating a schematic configuration of the X-ray imaging apparatus according to the first embodiment.

The bed 1 includes a top board 3 on which a subject M is placed. The top plate 3 is made of a material that transmits X-rays. An X-ray tube 5 and an X-ray imaging device 7 are disposed at opposing positions sandwiching the top plate 3. These X-ray tube 5 and X-ray imaging device 7 are controlled by X-ray fluoroscopy means 9 . That is, under the control of the X-ray fluoroscopic means 9, the X-ray tube 5 emits X-rays, and the X-ray imaging device 7 captures a transmitted X-ray image. Examples of the X-ray imaging device 7 include a device composed of an image intensifier and a TV camera, and a device composed of a flat panel detector.

  An injector 11 is disposed at a position adjacent to the bed 1. A catheter 13 is connected to the injector 11, and a contrast agent is injected into the subject M through the catheter 13. The injection is started, for example, when a signal is given from a control unit (25) described later, and is similarly stopped by a signal from the control unit (25).

  An analog signal (video signal) from the X-ray imaging device 7 is converted into digital data by an A / D converter 15 which is a data conversion unit, and sequentially output to a storage unit 17. The storage unit 17 sequentially stores the given digital data as an image (image data) for each collection frame.

  The computing unit 19 performs a subtraction process between a plurality of images stored in the storage unit 17 and outputs a subtraction image generated by the process to the display unit 21. Specifically, one or a plurality of images are processed into a mask image, an image collected after timing described later is a live image, and a subtraction image is obtained by taking a difference between the images. Generate.

  The timing detection unit 23 has a function of detecting whether or not the contrast agent from the injector 11 has reached the imaging region based on the image stored in the storage unit 17. When the contrast agent reaches the imaging region, it can be determined according to the measurement value corresponding to the pixels constituting the image (analog signal output from the X-ray imaging device 7 converted into digital data). Specifically, the threshold T set as described later is compared with the above measured value, and the timing at which the contrast agent reaches the time when the measured value exceeds the threshold T or coincides with the threshold T. Detect as. Therefore, by monitoring the measurement value stored in the storage unit 17, it can be determined that the contrast agent has reached the imaging region. When the timing detection means 23 detects the arrival of the contrast agent at the imaging site, it notifies the control unit 25 of the timing.

  Note that the above measured values include, for example, an average of all measured values corresponding to all pixels constituting the imaging region.

  When the timing at which it is detected that the contrast agent has arrived is output from the timing detection means 23, the timing is notified to the selection means 27 via the control unit 25. Receiving this, the selection means 27 selects a mask image from the images stored in the storage means 17 so far. Further, a new mask image is generated using a plurality of images stored so far and selected as a mask image. The timing may be notified directly from the timing detection unit 23 to the selection unit 27.

  Further, the threshold T for determining whether or not the timing detection means 23 has reached the contrast medium is appropriately set in advance by the photographer or the like from the input device 29.

  Next, the operation of the apparatus configured as described above will be described with reference to FIG. FIG. 2 is a time chart showing an operation sequence, where (a) shows a collected frame and (b) shows a measured value.

  The injection of the contrast agent is performed, for example, after a predetermined time has elapsed after the photographer presses a hand switch (not shown). Specifically, the injector 11 starts injecting contrast medium into the subject M under the control of the control unit 25. In FIG. 2A, the time point at which the injection of contrast medium is started is indicated by a time axis “0”.

  In this example, a mask image collection delay time Tmst is set, and image collection is not performed until the mask image collection delay time Tmst elapses from the start of contrast agent injection. Thereby, the X-ray exposure amount to the subject M can be suppressed. This mask image collection delay time Tmst needs to be set shorter than the timing described later. However, without setting the mask image acquisition delay time Tmst, the image acquisition may be started immediately after the start of the injection of the contrast agent or after a predetermined time has elapsed after the start of the injection of the contrast agent.

  When the above-described mask image collection delay time Tmst elapses, image data is sequentially stored in the storage unit 17 for each collection frame (FIG. 2A). And since the density | concentration of the contrast agent which flows into an imaging site | part increases gradually, the measured value which comprises the acquisition flame | frame begins to rise. Accordingly, it is assumed that the measured value reaches the threshold value T at a certain time point t1. Accordingly, the timing detection unit 23 notifies the selection unit 27 via the control unit 25 of the fact. The selection unit 27 receives a notification of the timing t1 when the contrast agent reaches the imaging region, and selects a mask image from the collection frames stored in the storage unit 17. Before this timing t1, the mask image collection Tm is performed, and after the timing t1, live image collection Tv is performed.

  As a specific mask image selection method, for example, the following may be mentioned.

  That is, the acquisition frame A immediately before the timing t1 when the contrast agent arrives is selected as a mask image. Alternatively, a predetermined calculation process may be performed on the three frames B including the collected frame A immediately before the timing t1, and a new mask image may be generated and used as a mask image. When the influence of body movement is small, a collection frame before timing t1 and immediately after the mask image collection delay time Tmst has elapsed may be used as a mask image.

  When the mask image is selected by the selection means 27 as described above, the subsequent acquired frames are handled as live images, and the subtraction processing is performed in the calculation means 19 and the subtraction images are sequentially displayed on the display means 21. .

  As described above, since the timing detection means 23 detects that the contrast medium has reached the imaging region, the selection means 27 selects an image stored in the storage means 17 before this timing as a mask image. Therefore, since the contrast agent is not projected on the mask image and is difficult to be influenced by the body movement of the subject, it is ideal as a mask image in the subtraction process and has a certain image quality. It can be obtained stably.

  Next, Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 3 is a block diagram illustrating a schematic configuration of the X-ray imaging apparatus according to the second embodiment. In addition, about the structure similar to Example 1 mentioned above, detailed description is abbreviate | omitted by attaching | subjecting a same sign.

  The second embodiment is characterized in that the detection area setting means 31 is further provided in the first embodiment. The detection area setting unit 31 has a function for the timing detection unit 23 to set an area for determining that the contrast medium has reached the imaging area.

  Specifically, the photographer or the like sets an area for the determination via the input device 29 while viewing the image of the imaging region displayed on the display means 21. Information related to the determination area set in this way is notified to the timing detection means 23 and set. Thereafter, it is detected whether or not the contrast agent has arrived based on the determination region.

  Next, the region setting for the above determination will be specifically described with reference to FIG. FIG. 4 is a diagram for explaining setting of the determination area.

  For example, in a state in which fluoroscopic imaging is performed prior to imaging and the image 33 of the imaging region is displayed on the display unit 21, the photographer or the like sets a determination area 35 that is considered appropriate for determination of arrival via the input device 21. Set. This determination area 35 is set immediately before the lesioned part 39 in the blood vessel 37 captured in the image 33 of the imaging region. This is because the state of the blood vessel 37 near the lesioned part 39 can be easily grasped. Further, instead of being manually set by the photographer or the like via the input device 21, for example, it may be configured such that it can be automatically set as follows.

  That is, when the distal end portion of the catheter 13 is imprinted on the image 33 of the imaging region, the distal end portion of the catheter 13 can be automatically identified based on the image 33. Therefore, the vicinity of the tip may be automatically set as the determination area 41.

  Further, since the position of the blood vessel can be easily identified from the image 33 of the imaging region, any of the blood vessels may be automatically set as the determination region. Furthermore, not only blood vessels but also barium imaging may be used to automatically set the vicinity of the esophagus and the upper part of the stomach. As a result, it is possible to save the trouble of the photographer and the like determining the determination area 35. Note that this setting need not be performed in advance by performing fluoroscopic imaging before imaging, and may be set via the input device 29 immediately after imaging is started, for example.

  By adopting the configuration as described above, in addition to the effect in the first embodiment, there is an effect that the vicinity of a region useful for diagnosis can be appropriately set as a detection region.

  Next, Embodiment 3 of the present invention will be described with reference to the drawings.

Figure 5 is a block diagram showing an outline of an X-ray imaging apparatus according to the third embodiment. In addition, about the structure similar to Example 1 mentioned above, detailed description is abbreviate | omitted by attaching | subjecting a same sign.

  The third embodiment is characterized in that the mask image generating means 43 is further provided in the first embodiment. The mask image generation unit 43 has a function for performing a predetermined arithmetic process on one or a plurality of mask images selected by the selection unit 27 and generating a new mask image.

  Specific calculation processing includes frequency conversion processing by performing template filter processing or the like on one mask image, temporal filtering processing on a plurality of mask images, and averaging processing on a plurality of mask images. Etc. The selection of the mask image to be processed at this time is the same as the example of the collection frame A and the three frames B described in the first embodiment (see FIG. 2). By generating a new mask image by performing processing in this way, noise components and artifacts can be reduced, so that the image quality can be improved, and consequently the image quality of the subtraction image obtained by the subtraction processing using the mask image can be improved. it can.

  Next, a fourth embodiment of the present invention will be described with reference to the drawings.

  FIG. 6 is a block diagram illustrating a schematic configuration of the X-ray imaging apparatus according to the fourth embodiment, FIG. 7 is a time chart illustrating an operation sequence, (a) illustrates a collection frame, and (b) illustrates measurement. Indicates the value. The detailed description of the same configuration as that of the first embodiment is omitted as described above.

  The fourth embodiment further includes live image collection start delay time setting means 45 and contrast timing synthesis means 47. The live image collection start delay time setting unit 45 sets a live image collection start delay time from the start of contrast agent injection when the contrast agent starts to be stored until the storage unit 17 starts storing the contrasted image as a live image. It has a function to do. The contrast timing synthesizing unit 45 has a function of outputting a signal to the control unit 35 when either a signal indicating that the live image collection start delay time has elapsed or a timing detected by the timing detecting unit 23 occurs. I have. That is, the mask image is selected based on one of the timing when the contrast medium arrives from the timing detection means 23 and the live image collection start delay time elapses.

  The photographer or the like operates the live image collection start delay time setting means 45 prior to shooting, and sets in advance a time as indicated by a symbol Tlst in FIG. 7B. As a measure of this time, it is a time exceeding the time when the contrast agent is expected to reach the imaging region sufficiently, and the time when most of the contrast agent is expected to finish passing through the imaging region. It is preferable to be within a shorter time range.

  With the above configuration, even if a situation in which the arrival of the contrast agent cannot be detected by the timing detection means 23 occurs, the situation that the mask image is not selected is obviated because the live image collection start delay time Tlst works as a backup. Can be prevented. Such a situation may occur, for example, because the imaging region is displaced due to body movement, or a blood vessel in the imaging region is faulty and the contrast agent does not sufficiently flow into the imaging region. .

  The control unit 25 compares the live image collection start delay time Tlst with the elapsed time from the time when the contrast medium starts to be injected, and the elapsed time until the timing detection unit 23 detects the timing collects the live image. When the condition that the start delay time Tlst is exceeded, each unit may be controlled so as to stop the imaging by the X-ray fluoroscopic means 5. Thereby, it is possible to prevent unnecessary X-ray exposure from continuing.

  In addition, when the above condition is satisfied, the control unit 25 may further perform an operation of stopping the injection of the contrast agent by the injector 11. Thereby, it is possible to prevent waste of photographing using a contrast agent.

  Further, when the above condition is satisfied, the control unit 25 may perform a display for alerting the display unit 21 so as to further issue an alarm, or may issue an alarm from a lamp or a speaker (not shown). Good. By configuring in this way, it is possible to notify the photographer that a problem has occurred, so it is possible to quickly stop shooting or re-shoot.

  The present invention is not limited to the above-described embodiment, and can be modified as follows.

  (1) In each of the above-described embodiments, the case where the average value exceeds the threshold T is set as the mask image selection timing based on the image of the imaging region. However, a profile cross section may be used for a specific part (for example, a blood vessel or the like) located in the imaging part, and the time when the measured value exceeds the threshold T on the profile may be set as the timing.

  Reference is now made to FIG. FIG. 8A shows an imaging region, and FIG. 8B is a diagram for explaining detection based on a profile cross section.

  For example, it is assumed that the photographer identifies the specific part 49 of the blood vessel 37 as a position to obtain a profile cross section as shown in FIG. 8A while looking at the display unit 21 through the input device 29. Since the specific portion 49 is a cross section of the blood vessel 37, the measured value of the blood vessel wall portion is high as shown in FIG. 8A, and the measured value is generally low between the blood vessel walls. Therefore, the determination area 51 is set so that the detection of the contrast medium can be determined at that portion. Then, the measured value rises as shown by a two-dot chain line in FIG. 8B in accordance with the inflow of the contrast agent, and the timing can be determined based on this. Therefore, by considering the profile cross section in this way, it is possible to select a mask image at a suitable timing according to the inflow degree of the contrast agent.

  (2) Each of the above Examples 1 to 4 may be carried out independently, but the above (1) may be combined with various combinations of Examples 1 to 4.

  (3) The determination area in FIG. 4 referred to in the above description may be one or a plurality of combinations.

  That is, the timing may be determined based on any one of the determination areas 35 and 41 in FIG. 4, but by combining these, whether both exceed the threshold value T, or whether either one exceeds the threshold value T The timing may be determined based on the above. Further, a branching blood vessel is also set as in the determination area 53, and a logical expression is formed by a logical sum or logical product of a plurality of determination areas 35, 41, 53, and the timing is determined based on the result. It may be.

Thus to set the determination region at a plurality of points, by setting the timing on the basis of the logical expression, freely selected timing of the mask image even in the case of imaging a complex vascular, yet it is properly configured to it can. As a result, it is possible to easily obtain a clinically meaningful subtraction image.

1 is a block diagram illustrating a schematic configuration of an X-ray imaging apparatus according to Embodiment 1. FIG. It is a time chart which shows an operation | movement sequence, (a) shows a collection frame, (b) shows a measured value. 6 is a block diagram illustrating a schematic configuration of an X-ray imaging apparatus according to Embodiment 2. FIG. It is a figure where it uses for description of the setting of a judgment area. 6 is a block diagram illustrating a schematic configuration of an X-ray imaging apparatus according to Embodiment 3. FIG. 6 is a block diagram illustrating a schematic configuration of an X-ray imaging apparatus according to Embodiment 4. FIG. It is a time chart which shows an operation | movement sequence, (a) shows a collection frame, (b) shows a measured value. (A) shows an imaging part, (b) is a figure which uses for description of the detection based on a profile cross section.

Explanation of symbols

M ... subject 1 ... bed 9 ... X-ray fluoroscopy means 11 ... injector 13 ... catheter 15 ... A / D converter (data conversion means)
DESCRIPTION OF SYMBOLS 17 ... Memory | storage means 19 ... Calculation means 21 ... Display means 23 ... Timing detection means 25 ... Control part 27 ... Selection means 29 ... Input device T ... Threshold value Tmst ... Mask image collection delay time

Claims (3)

X-ray fluoroscopy means for irradiating a predetermined imaging part of the subject with X-rays and taking an X-ray transmission image of the imaging part, data conversion means for converting the X-ray transmission image into digital data, and the digital data In an X-ray imaging apparatus comprising a storage means for storing an image as an image and an arithmetic means for performing a subtraction process between a plurality of images stored in the storage means, based on the image stored in the storage means Timing detection means for detecting the timing at which the contrast medium arrives at the imaging region; detection area setting means for setting a determination area in which the timing detection means determines arrival; and contrast medium injection at which the contrast medium has started to be injected A live image acquisition start time for setting a live image acquisition start delay time from the start time until the contrasted image starts to be stored in the storage means as a live image. A contrast setting timing for outputting a signal when one of the timing detected by the timing setting means and the timing detected by the timing detection means and the live image acquisition start delay time elapses before the timing is detected; Based on one of the synthesizing unit and the signal indicating the timing and the signal indicating that the live image acquisition start delay time has elapsed, the image stored in the storage unit is preceded by the previous timing. An X-ray imaging apparatus comprising: selecting means for selecting an image as a mask image in subtraction processing. 2. The X-ray imaging apparatus according to claim 1 , further comprising mask image generation means for performing a predetermined arithmetic process on one or a plurality of mask images selected by the selection means to generate a new mask image. An X-ray imaging apparatus characterized by comprising: 3. The X-ray imaging apparatus according to claim 1, wherein the detection area setting unit sets a plurality of the determination areas, and the timing detection unit has one of the plurality of determination areas exceeding a threshold value. An X-ray imaging apparatus characterized in that the timing is detected on the basis thereof.

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