JP2008113699A - Ultrasonic diagnostic apparatus and catheter navigation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic apparatus capable of providing ultrasonic images permitting excellent visual recognition of the present position of a catheter, the blood vessel into which the catheter is inserted and the position to which the catheter should be advanced in the vascular intervention under the ultrasonic guidance. <P>SOLUTION: A navigation image, in which the present position of the catheter and a predetermined planned route of insertion of the catheter are clearly visualized on an ultrasonic image obtained real time, is created and displayed. In addition, whether the present position of the catheter is correct or not is determined based on the position in the planned route of insertion of the catheter and the present position of the catheter, and the result of the determination is displayed in a prescribed mode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is used when a catheter is inserted into a blood vessel under an ultrasonic guide, and is particularly used for easily and accurately inserting a catheter into a desired blood vessel.

  Ultrasound diagnosis can be performed repeatedly by simply touching the ultrasound probe from the body surface, and the heart beats and fetal movements can be obtained in real time, and it is highly safe. . In addition, it can be said that this is a simple diagnostic method in which the scale of the system is smaller than other diagnostic devices such as X-rays, CT, and MRI, and inspection can be easily performed while moving to the bedside. Ultrasound diagnostic devices used in this ultrasound diagnosis vary depending on the types of functions that they have, but small ones that can be carried with one hand have been developed. Thus, there is no influence of exposure, and it can be used in obstetrics and home medical care.

  In recent years, in the treatment with an intravascular catheter (vascular intervention), in addition to angiography using X-rays, ultrasound is also used as a method for monitoring the position of the catheter in the body. This is because, in an ultrasound image, images of both the blood vessel wall (that is, the blood flow and its surrounding tissues) and the catheter can be visualized. For example, when a blood vessel branch exists, the catheter is placed in the target blood vessel. This is because it is possible to easily determine whether it is inserted (True) or whether it is inserted into another branched blood vessel (Sub), and there are advantages such as easy advancement of the catheter. The vascular intervention is applied to many blood vessels such as the carotid artery, renal artery, aorta, coronary artery, upper limb artery / vein, lower limb artery / vein.

In addition, as a well-known document relevant to this application, there exist the following, for example.
JP 2004-283373 A Japanese Patent Laid-Open No. 11-318884 JP 2003-305039 A

  However, when a monitoring image in blood vessel intervention is acquired using a conventional ultrasonic diagnostic apparatus, the operator moves the probe in order to obtain a scan section passing through the blood vessel, for example, FIG. Appropriate angles, positions, etc. as shown in) must be sought. Therefore, the operation is complicated in the blood vessel intervention for performing the catheter operation, and the work load during the operation is large. In addition, blood vessels have a three-dimensional structure such as bent or branched, and when a one-dimensional array probe is used, it is difficult to extract an ultrasonic cross-sectional image along the traveling direction of the blood vessels.

  In order to solve the above problem, for example, the blood vessel traveling in the ultrasonic volume data is determined using Doppler information or blood vessel wall information, an ultrasonic cross-sectional image along the central axis of the blood vessel traveling direction is drawn, and the blood vessel When is bent, there is a method of drawing a two-dimensional tomographic image as a curved surface. However, in this method, in order to insert a catheter into a living body under ultrasound guidance and reach a desired site, the blood vessel containing the catheter is artificially determined from a plurality of blood vessels on the image. I have to do it. Therefore, it can be said that the work burden on the surgeon is still large.

  The present invention has been made in view of the above circumstances, and in the vascular intervention under the ultrasound guide, the current position of the catheter, the blood vessel in which the catheter is inserted, and the position where the catheter should be advanced are visually recognized. An object of the present invention is to provide an ultrasonic diagnostic apparatus and a catheter navigation system capable of providing an ultrasonic image that can be performed.

  In order to achieve the above object, the present invention takes the following measures.

  A first aspect of the present invention relates to an ultrasonic scanning region in which the first position information, which is position information related to a planned insertion path of a catheter to be inserted into a subject, is stored, and the subject is ultrasonically scanned. Data acquisition means for acquiring image data, position information acquisition means for acquiring second position information that is position information relating to the ultrasonic scanning region, the first position information, and the second position information; Corresponding means for associating with the third position information which is the position information of the catheter supplied from the catheter position detecting device, the associated first to third position information and the ultrasonic wave Image generation means for generating a navigation image, which is an ultrasound image in which the planned insertion path of the catheter and the current position of the catheter are clearly shown based on image data relating to a scanning region; An ultrasonic diagnostic apparatus characterized by comprising a display means for displaying the navigation image.

  According to a second aspect of the present invention, there is provided storage means for storing first position information, which is position information related to a catheter insertion planned route, and data for ultrasonically scanning the subject to obtain image data related to an ultrasonic scanning region. An acquisition unit, a position information acquisition unit that acquires second position information that is position information related to the ultrasonic scanning region, and a catheter position that detects third position information that is the position information of a catheter inserted into the subject. Detecting means; association means for associating the first position information; the second position information; and the third position information; and the associated first to third information Based on the position information and the image data related to the ultrasonic scanning region, a navigation image, which is an ultrasonic image in which the planned insertion path of the catheter and the current catheter position are specified, is generated. An image generating means, a catheter navigation system characterized by comprising a display means for displaying the navigation image.

  As described above, according to the present invention, in the vascular intervention under the ultrasound guide, the ultrasound image that can favorably visually recognize the current position of the catheter, the blood vessel in which the catheter is inserted, and the position where the catheter should be advanced is obtained. An ultrasonic diagnostic apparatus and a catheter navigation system that can be provided can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

  FIG. 1 is a diagram showing a configuration of a catheter navigation system 1 according to the present embodiment. As shown in FIG. 1, the catheter navigation system 1 includes a catheter system 2 and an ultrasonic diagnostic apparatus 3.

  The catheter system 2 includes a catheter 2a and a catheter position detection device 2b provided at a predetermined position (for example, the distal end) of the catheter. The catheter 2a is used for blood vessel intervention, and is provided with a balloon, a cutter, or the like at the tip thereof according to the purpose, and is inserted into a predetermined position through the blood vessel. The catheter position detection device 2b is connected to the ultrasonic diagnostic device 3 by wire or wirelessly, and transmits information (catheter position information) for specifying the spatial position of the distal end of the catheter 2a to the ultrasonic diagnostic device 3.

  In this embodiment, for the sake of specific explanation, as shown in FIG. 2, a blood vessel intervention of the lower limbs (a catheter is inserted into the blood vessel from the base of the left foot and advanced to the toe to reach the ankle periphery) For example, vascular intervention in which a catheter is advanced to a position is taken as an example, however, the technical idea of the present invention is only to insert a catheter into a subject under an ultrasonic guide, for example, the type of catheter and the insertion site. Is not bound by

  FIG. 3 shows a block configuration diagram of the ultrasonic diagnostic apparatus 3 of the system 1. As shown in the figure, the ultrasonic diagnostic apparatus 3 includes a main body 11, an ultrasonic probe 12, an input device 13, and a monitor 14.

  The ultrasonic probe 12 generates ultrasonic waves based on a drive signal from the apparatus main body 11, converts a reflected wave from the subject into an electric signal, a matching layer provided in the piezoelectric vibrator, It has a backing material that prevents the propagation of ultrasonic waves from the piezoelectric vibrator to the rear. When ultrasonic waves are transmitted from the ultrasonic probe 12 to the subject P, the transmitted ultrasonic waves are successively reflected by the discontinuous surface of the acoustic impedance of the body tissue and received by the ultrasonic probe 12 as an echo signal. . The amplitude of this echo signal depends on the difference in acoustic impedance at the discontinuous surface that is supposed to be reflected. In addition, the echo when the transmitted ultrasonic pulse is reflected by the moving blood flow or the surface of the heart wall or the like depends on the velocity component in the ultrasonic transmission direction of the moving object due to the Doppler effect, and the frequency deviation. Receive a move. Note that an area scanned by ultrasonic transmission / reception from the ultrasonic probe 12 is referred to as an ultrasonic scanning area. The ultrasonic scanning region is, for example, a two-dimensional scanning surface in the case of acquiring a two-dimensional image, and a three-dimensional scanning space in the case of acquiring a three-dimensional image.

  The ultrasonic probe 12 is provided with a probe position detection device 120. The probe position detection device 120 detects the spatial position of the ultrasonic probe 12. The detected spatial position of the ultrasonic probe 12 is transmitted to the ultrasonic device 3 by wire or wirelessly.

  The input device 13 is connected to the device main body 11, and various switches, buttons, and tracks for taking various instructions, conditions, region of interest (ROI) setting instructions, various image quality condition setting instructions, etc. from the operator into the device main body 11. It has a ball, mouse, keyboard, etc. For example, when the operator operates the end button or the freeze button of the input device 13, the transmission / reception of the ultrasonic wave is ended, and the ultrasonic diagnostic apparatus is temporarily stopped. Further, for example, by operating a predetermined switch, the operation of the ultrasonic diagnostic apparatus 3 shifts to a navigation mode in which navigation image generation and incidental information to be described later are displayed.

  The monitor 14 displays in vivo morphological information and blood flow information as an image based on the video signal from the apparatus main body 11. The monitor 14 also displays navigation image generation and supplementary information, which will be described later, in a predetermined form.

  The apparatus main body 11 includes an ultrasonic transmission unit 21, an ultrasonic reception unit 22, a B-mode processing unit 23, a Doppler processing unit 24, an image generation unit 25, a navigation image generation unit 26, an image composition unit 27, and a control processor (CPU). 28, a storage unit 29, and an interface unit 30 are provided. Hereinafter, the function of each component will be described.

  The ultrasonic transmission unit 21 includes a trigger generation circuit, a delay circuit, a pulsar circuit, and the like (not shown). In the pulsar circuit, a rate pulse for forming a transmission ultrasonic wave is repeatedly generated at a predetermined rate frequency fr Hz (period: 1 / fr second). Further, in the delay circuit, a delay time necessary for focusing the ultrasonic wave into a beam shape for each channel and determining the transmission directivity is given to each rate pulse. The trigger generation circuit applies a drive pulse to the probe 12 at a timing based on this rate pulse.

  The ultrasonic transmission unit 21 has a function capable of instantaneously changing a transmission frequency, a transmission drive voltage, and the like in order to execute a predetermined scan sequence in accordance with an instruction from the control processor 28. In particular, the change of the transmission drive voltage is realized by a linear amplifier type transmission circuit whose value can be instantaneously switched or a mechanism for electrically switching a plurality of power supply units.

  The ultrasonic receiving unit 22 has an amplifier circuit, an A / D converter, an adder and the like not shown. The amplifier circuit amplifies the echo signal captured via the probe 12 for each channel. The A / D converter gives a delay time necessary for determining the reception directivity to the amplified echo signal, and then the adder performs addition processing. By this addition, the reflection component from the direction corresponding to the reception directivity of the echo signal is emphasized, and a comprehensive beam for ultrasonic transmission / reception is formed by the reception directivity and the transmission directivity.

  The B-mode processing unit 23 receives the echo signal from the transmission / reception unit 21, performs logarithmic amplification, envelope detection processing, and the like, and generates data in which the signal intensity is expressed by brightness.

  The Doppler processing unit 24 performs frequency analysis on velocity information from the echo signal received from the transmission / reception unit 21, extracts blood flow, tissue, and contrast agent echo components due to the Doppler effect, and obtains blood flow information such as average velocity, dispersion, and power. Ask for multiple points. The obtained blood flow information is sent to the image generation unit 25 and displayed in color on the monitor 14 as an average velocity image, a dispersion image, a power image, and a combination image thereof.

  The image generation unit 25 converts the signal sequence from the B-mode processing unit 23 (scanning line signal sequence for ultrasonic scanning) into a scanning line signal sequence in a general video format typified by a television or the like, and performs ultrasonic diagnosis. Image data (two-dimensional tomographic image data, volume image data) is generated. At this time, various image filters such as edge enhancement, temporal smoothing, and spatial smoothing are also applied to provide image quality according to user preferences. Note that data before entering the image generation unit 25 may be referred to as “raw data”.

  The navigation image generation unit 26 generates a navigation image based on the volume data corresponding to the ultrasonic scanning region, the positional information of the ultrasonic scanning region, the positional information of the catheter, and the positional information of the planned catheter insertion route. The generation of the navigation image will be described in detail later.

  The image synthesizing unit 27 synthesizes the image received from the image generating unit 25 or the navigation image generating unit 26 together with character information of various parameters, scales, and the like and outputs them as a video signal to the monitor 14. In particular, the image composition unit 27 displays the navigation image and the result of the current catheter position correct / incorrect determination executed in the control processor 28 in a predetermined form.

  The control processor 28 has a function as an information processing apparatus (computer) and controls the operation of the main body of the ultrasonic diagnostic apparatus. The control processor 28 reads out a control program for executing image generation / display, etc. from the storage unit 29, a dedicated program for realizing the catheter navigation function, etc., expands it on its own memory, and calculates / Execute control etc. In particular, the control processor 28 determines position information (ultrasonic) based on the spatial position of the ultrasonic probe 12 and the position of the ultrasonic scanning area with respect to the ultrasonic probe. Position information of the acoustic scanning region) is calculated. Further, the control processor 28 associates the position information of the ultrasound scanning region, the catheter position information, the position information of the planned catheter insertion route (or the position information of the volume data acquired in advance), and generates the additional information described later. Etc.

  The storage unit 29 includes a control program for executing transmission / reception conditions, image generation, and display processing, diagnostic information (patient ID, doctor's findings, etc.), diagnostic protocol, probe scanning line angle information, probe position information, body A mark generation program, a dedicated program for realizing a catheter navigation function, and other data groups are stored. Further, the storage unit 29 stores image data related to the ultrasound scanning region, catheter position information, position information on the catheter insertion planned route, volume data related to the region R acquired in advance, and the like. The data in the storage unit 29 can also be transferred to another device via the interface unit 80.

  The interface unit 30 is an interface related to the input device 13, the network, a new external storage device (not shown), the catheter position detection device 2 b, and the probe position detection device 120. Note that data such as ultrasonic images and analysis results obtained by the apparatus can be transferred by the interface unit 30 to another apparatus via a network.

(Catheter navigation function)
Next, the catheter navigation function of the ultrasonic diagnostic apparatus 3 will be described. This function is roughly divided into a navigation image generation function and an accompanying information provision function. Each function will be described below.

[Navigation image generation function]
The navigation image generation function is a function for generating and displaying in real time a two-dimensional or three-dimensional ultrasound image (navigation image) including information on the catheter insertion planned route and the current catheter position as shown in FIG. The planned catheter insertion path is obtained by collecting in advance volume data relating to an area including at least the catheter insertion start position (to the blood vessel) from the catheter insertion planned position to the catheter arrival planned position, and using this, the catheter insertion planned path is created on the volume data. specify. The volume data may be collected by any modality. Therefore, it may be collected by, for example, an X-ray computed tomography apparatus or a magnetic resonance imaging apparatus without being limited to the ultrasonic diagnostic apparatus. In this embodiment, for the sake of specific description, it is assumed that volume data in a range including the region R shown in FIG. 2 is collected by a predetermined modality.

  In addition to this volume data, (spatial) position information of the volume data with respect to a predetermined reference position is also collected in advance. There is no particular limitation on the method of collecting the position information of the volume data, and for example, a magnetic method or an optical method can be employed. As for the reference position, it is preferable to employ a predetermined part (eg, umbilicus) of the subject. If it is a subject part, even if the subject's posture or position with respect to the apparatus is different between when volume data is acquired and when the catheter is inserted (at the time of monitoring with an ultrasonic image), it can be accurately associated. Because.

  It should be noted that the planned catheter insertion path (that is, the path planned to move the catheter from the catheter insertion start position to the catheter arrival planned position) is based on the volume data of the region R acquired in advance as shown in FIG. In advance. More specifically, for example, by designating a desired catheter insertion planned path with a mouse or the like on a three-dimensional image (for example, a volume rendering image) obtained using volume data of the region R, the catheter insertion planned path is determined. Can be set.

  FIG. 5 is a flowchart showing a flow of processing (navigation image generation processing) according to the navigation image generation function. As shown in the figure, the control processor 28 acquires the spatial position of the ultrasonic probe 12 from the probe position detection device 120 and the catheter position information from the catheter position detection device 2b (step S1). The control processor 28 calculates the position information of the ultrasonic scanning region using the spatial position of the ultrasonic probe 12 and the position of the ultrasonic scanning region with respect to the probe 12, and then the catheter position information and the position information of the ultrasonic scanning region. Then, the position information of the catheter insertion scheduled route set in advance is associated (step S2).

  Next, the navigation image generation unit 28 generates a navigation image, which is an ultrasound image in which the current position of the catheter 2 and the planned catheter insertion route are specified (for example, superimposed and displayed) (step S3). That is, the navigation image generation unit 28 specifies the current position of the catheter 2 and the planned catheter insertion path on the two-dimensional ultrasonic image or the three-dimensional ultrasonic image using each piece of associated position information, and plans to insert the catheter. A navigation image is generated in which the blood vessel corresponding to the route and the current position of the catheter 2 are individually highlighted (for example, high-intensity display, color-specific display, clarification with an arrow, line drawing of a region, etc.). The generated navigation image is displayed in a predetermined form (step S4).

[Attached information provision function]
The supplementary information providing function provides supplementary information useful for vascular intervention or the like (for example, a determination result as to whether or not the current catheter position is on the planned catheter insertion route) together with the generated navigation image. is there.

  6 and 7 are diagrams showing examples of incidental information displayed together with the navigation image N. FIG. For example, as shown in FIG. 6, when the current catheter position is out of the planned catheter insertion path, the user is notified that the current catheter position (or course) is out of the planned catheter insertion path. Information (for example, a message indicating that the current catheter position is incorrect) is displayed together with the navigation image N. Further, for example, as shown in FIG. 7, when the current catheter position exists on the planned catheter insertion path, the user is notified that the current catheter position (or course) exists on the planned catheter insertion path. Information (for example, a message indicating that the current catheter position is correct) is displayed together with the navigation image N. Further, the output of the message is not limited to the video, and for example, the message may be output using audio alone or together with the video.

  In this determination, for example, the control processor 28 monitors the deviation between the current catheter position and the position of the planned catheter insertion path, and if the deviation does not exceed a predetermined threshold, the current catheter position (or If the deviation exceeds a predetermined threshold, it is determined that the current catheter position (or path) is not appropriate, and a message corresponding to the determination result is displayed at the same time as the navigation image. It can be realized by controlling the image composition unit 27 so as to be displayed. The deviation between the current catheter position and the position of the planned catheter insertion path may be monitored on the navigation image, or directly on the volume data corresponding to the ultrasonic scanning region or on the volume data acquired in advance. You may make it perform.

  The determination in the incidental information provision process can be executed as a background process using the catheter position information and the position information of the catheter insertion planned route. Therefore, it is not always necessary to generate a navigation image. Therefore, provision of the supplementary information can be performed even under the guidance of a normal ultrasonic image.

  According to the configuration described above, the following effects can be obtained.

  According to the present catheter navigation system, a navigation image is generated and displayed by explicitly imaging the current position of the catheter and a preset catheter insertion route on an ultrasonic image acquired in real time. can do. Therefore, the user can observe the displayed navigation image to see how far the current catheter position has reached the planned route, whether the current catheter position is correct, and in what direction the catheter will be moved from now on. It is possible to easily and quickly determine whether or not to move.

  Further, according to the catheter navigation system, it is determined whether or not the current position of the catheter is correct based on the position of the planned catheter insertion path and the current position of the catheter, and the determination result is displayed in a predetermined form. Display. Therefore, the user can continue to operate the catheter with peace of mind, for example, if the current position of the catheter is determined to be correct, while quickly determining that the current position of the catheter is incorrect. Can be corrected. As a result, in addition to the user's human judgment, the device determines whether or not the current position of the catheter is appropriate, so that it is possible to prevent erroneous operation of the catheter during vascular intervention and contribute to improving the quality of medical practice. be able to.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Specific examples of modifications are as follows.

  (1) Each function according to the present embodiment can also be realized by installing a program for executing the processing in a computer such as a workstation and developing the program on a memory. At this time, a program capable of causing the computer to execute the technique is stored in a recording medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), or a semiconductor memory. It can also be distributed.

  (2) When the current position of the catheter is out of the planned catheter insertion path, the supplementary information provided together with the navigation image includes, for example, the shortest distance (deviation amount) between the current position of the catheter tip and the planned catheter insertion path. ) May include quantitative information. This quantitative information can be easily calculated using the current position of the catheter tip and the position of the planned catheter insertion path.

  In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  As described above, according to the present invention, in the vascular intervention under the ultrasound guide, the ultrasound image that can favorably visually recognize the current position of the catheter, the blood vessel in which the catheter is inserted, and the position where the catheter should be advanced is obtained. An ultrasonic diagnostic apparatus and a catheter navigation system that can be provided can be realized.

FIG. 1 is a diagram showing a configuration of a catheter navigation system 1 according to the present embodiment. FIG. 2 is a diagram showing a catheter insertion planned route and a region R in which volume data is acquired in advance. FIG. 3 shows a block configuration diagram of the ultrasonic diagnostic apparatus 3 of the catheter navigation system 1. FIG. 4 is a diagram showing volume data related to the region R. FIG. 5 is a flowchart showing the flow of the navigation image generation process. FIG. 6 is a diagram for explaining an example of the incidental information providing function. FIG. 7 is a diagram for explaining another example of the incidental information providing function. FIG. 8 is a diagram for explaining a normal ultrasonic monitoring technique in vascular intervention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic diagnostic apparatus 31 ... Apparatus main body, 12 ... Ultrasonic probe, 13 ... Input device 13, 14 ... Monitor, 21 ... Ultrasonic transmission unit, 22 ... Ultrasonic reception unit, 23 ... B mode processing unit, 24 ... Doppler processing unit, 25 ... image generation unit, 26 ... navigation image generation unit, 27 ... image composition unit, 28 ... control processor (CPU), 29 ... storage unit, 30 ... interface unit

Claims (5)

Storage means for storing first position information which is position information related to a planned insertion path of a catheter to be inserted into a subject;
Data acquisition means for ultrasonically scanning the subject and acquiring image data relating to an ultrasonic scanning region;
Position information acquisition means for acquiring second position information which is position information relating to the ultrasonic scanning region;
Association means for associating the first position information, the second position information, and the third position information that is the position information of the catheter supplied from the catheter position detection device;
A navigation image which is an ultrasound image in which the planned insertion path of the catheter and the current catheter position are specified based on the associated first to third position information and image data related to the ultrasound scanning region Image generating means for generating
Display means for displaying the navigation image;
An ultrasonic diagnostic apparatus comprising: Based on the first position information and the second position information, further comprising a determination means for determining whether or not the catheter is present on a planned insertion path of the catheter;
The display means displays a determination result by the determination means;
The ultrasonic diagnostic apparatus according to claim 1.   The ultrasonic diagnosis according to claim 1, wherein the display unit displays the planned insertion path of the catheter on the navigation image as a high luminance area or an area assigned with a color different from other areas. apparatus.   The position information acquisition unit acquires the second position information based on a spatial position of an ultrasonic probe used for the ultrasonic scanning and a spatial position of the ultrasonic scanning region with respect to the ultrasonic probe. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3, wherein Storage means for storing first position information which is position information related to a catheter insertion planned path;
Data acquisition means for ultrasonically scanning the subject and acquiring image data relating to an ultrasonic scanning region;
Position information acquisition means for acquiring second position information which is position information relating to the ultrasonic scanning region;
Catheter position detecting means for detecting third position information which is position information of the catheter inserted into the subject;
Association means for associating the first position information, the second position information, and the third position information;
A navigation image which is an ultrasound image in which the planned insertion path of the catheter and the current catheter position are specified based on the associated first to third position information and image data related to the ultrasound scanning region Image generating means for generating
Display means for displaying the navigation image;
A catheter navigation system comprising:

Images