Ultrasound diagnostic imaging system with TGC control

Abstract

A TGC control system for an ultrasound diagnostic imaging system has a TGC control configured as a single elongated module with periodic expansion regions spaced along the elongated module. The number of expansion regions is equal to the number of TGC zones being controlled. Touch sensors are located on either side of each expansion region such that a user can touch one side of the expansion region to increase the gain in the TGC zone and the other side of the expansion region to decrease the TGC gain in the zone. The amount of gain adjustment is determined by the height at which the user touches the expansion region.

Description

[Technical field]

[0001] The present invention relates to improvements in ultrasonic diagnostic imaging systems, and more particularly to techniques for controlling signal gain as a function of depth during reception of ultrasonic echo signals. [Background technology]

[0002] Ultrasound imaging systems generate images of a patient's body from echoes received in response to the transmission of ultrasound waves into the patient's body. Ultrasound pulses are transmitted through a field of interest within the body along multiple beam directions, causing echoes to return along each beam direction as the transmitted pulses encounter tissue structures and interfaces within the body. By mapping the received echoes as a function of their return time and direction, an image of the interior of the body can be assembled and displayed.

[0003] It is well known that as ultrasound waves propagate through the body, they are constantly attenuated and scattered by passing through the tissues of the body. Echoes are similarly affected during their return. Thus, echoes returning from increasing depths within the body exhibit constantly increasing attenuation. To compensate for this attenuation, ultrasound systems conventionally have returning echoes amplified as a function of depth. As echoes return from increasing depths, they are processed by increasing amplification. As the transmitted pulse travels through the body over time, and echoes return from increasing depths at increasing time periods following the transmission of each pulse, this amplification is typically controlled by varying the gain of an amplifier in the ultrasound receiver as a function of time following the pulse transmission. This form of gain control is called time gain compensation, or TGC.

[0004] It has been customary for ultrasound systems to have a row of gain setting switches that can be set by the user to adjust the TGC. Each switch is an input to a TGC function generator that generates a TGC function over a portion of the receive period following a pulse transmission. For example, if there are five switches, five different variations in gain can be applied sequentially over the receive period during which echoes are received from the shallowest to the deepest depth. TGC adjustments are generally made to a starting TGC gain characteristic provided by the ultrasound system for a particular examination type. The TGC switches are traditionally sliding potentiometers with a central reference position that are then used to fine-tune the starting TGC characteristic provided by the ultrasound system. Summary of the Invention [Problem to be solved by the invention]

[0005] Slide switches, or slide pots as they are called, are mechanical components. Thus, they are subject to wear, deterioration, and mechanical breakdown over time. Additionally, the sliders of the slide pots move along slots in the ultrasound system control panel. These slots are openings through which dust and other particles can accumulate, providing a source of contaminants in an otherwise clean hospital environment. Therefore, it is desirable to provide a TGC control that avoids these shortcomings while still providing the sonographer with a tactile sensation during TGC adjustment. [Means for solving the problem]

[0006] In accordance with the principles of the present invention, a time gain compensation system is provided for an ultrasound system in which the controller is configured as a single modular unit. Multiple enlarged regions are positioned along the structure, one for each TGC zone to be controlled. The sides of the enlarged regions have multiple touch sensors that the sonographer can touch with a finger to increase or decrease the gain of a particular TGC depth zone. This configuration eliminates the mechanical drawbacks of slide pots and their openings in the control panel while still providing a tactile adjustment for the sonographer. In the drawings: [Brief description of the drawings]

[0007] [Figure 1] 1 shows an ultrasound display screen having an ultrasound image and TGC features according to the present invention. [Diagram 2] 1 shows the ultrasound system control panel with slide pot TGC control switch. [Diagram 3] A close-up view of the slide pot TGC control set and the slider slot. [Figure 4] 1 illustrates, in block diagram form, an ultrasound system constructed in accordance with the principles of the present invention. [Diagram 5] FIG. 2 is a plan view of the TGC control module of the present invention. [Figure 6] FIG. 2 is a side view of the TGC control module of the present invention. [Figure 7] 2 illustrates, in block diagram form, the control signal path for one of the depth zones of the TGC control system of the present invention. [Figure 8] 1 illustrates an exemplary method for generating an ultrasound image adjusted for depth-dependent ultrasound attenuation with TGC control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 1, an ultrasound image display 40 is shown. At the center of the display is an ultrasound image 112 that indicates the tissue structure or flow conditions of the patient being examined. In the upper left corner of the display is alphanumeric information regarding the patient and / or other characteristics of the examination being performed. To the right of the ultrasound image 112 is a depth scale 114 aligned with the image, indicating the depth within the body that the image extends to. Typically, the markers on the depth scale are calibrated in centimeters of depth.

[0009] To the right of the depth scale 114 is a graphical representation 116 of the TGC characteristic. The TGC characteristic is shown as a series of line segments connected by dots on the display. The relative slope of each line segment indicates the variation in gain applied to the echo signal received over the depth covered by that line segment. As described below, the slope of each line segment is changed by adjusting the individual TGC switches. Each line segment and its switches may have a predefined constant depth for which it is effective, or the segments may be scaled to the maximum depth for a particular image. An initial gain adjustment is used to change the gain of the entire TGC characteristic, moving the displayed characteristic 116 to the left or right, as indicated by arrows 118.

[0010] Each segment of the TGC profile is set by one of the TGC switches 20 shown on the control panel in FIG. 2. Conventionally, the TGC switches are slide switches, as shown by the first switch 22 sliding horizontally along a slot 24 in the close-up of the TGC control area in FIG. 3. The switch 22 controls the gain over an initial depth portion of the image, as shown by the first segment 117 of the TGC profile 116. Moving the slide switch 22 to the right increases the gain over this initial depth, causing the first line segment 117 on the display to slope more steeply toward the right. Turning the global gain control adjustment knob 26 changes the gain over the entire depth, moving the TGC profile to the right or left, as shown by the arrows 118. When all of the TGC switches 20 are vertically aligned along the centerline 29, as shown in FIG. 3, there is no variation in gain over the depth of the image other than that imposed by the starting nominal TGC gain profile. When various of the TGC switches 20 are moved progressively to the right, as shown on the user control console in FIG. 2, an increasingly sloped TGC characteristic 116 results, as shown in FIG.

[0011] When a user wishes to perform a particular ultrasound examination, such as imaging the liver, the user selects the desired procedure by using controls on the control panel 28. This may involve interaction with a menu of parameters and performance options shown on the display monitor 62. If the user selects an abdominal scan of the liver with a particular transducer probe, this information is communicated from the control panel to the system setup controller. The setup controller then retrieves the control parameters for such procedure in the setup memory and initializes the system to control the probe and echo signal processing specifically for this procedure. The system beamformer is set up by the setup controller, for example, to activate and receive echo signals from the selected probe. The setup memory also provides the setup controller with information regarding the nominal TGC characteristic to be used in scanning the liver. The setup controller then controls the gain of the system's TGC amplifiers according to this nominal TGC characteristic. The setup controller also provides graphic information to the system's graphics processor such that a visual representation of the nominal TGC characteristic is shown on the image display, as shown at 116 in FIG. 1.

[0012] As the ultrasound examination progresses, the user may find that the ultrasound image is not optimal at a particular depth. If the user finds that a variation from the predetermined TGC characteristic is necessary to better image a particular patient, the user moves the slide switch right or left to adjust the slope segment of the TGC characteristic. As the switch is moved, the change is communicated from the control panel 28 to the TGC controller, which applies incremental changes to the predetermined characteristic. The effect of these changes is indicated by a visual change to the displayed TGC characteristic 116. When the user finishes adjusting the TGC switch 20, the change from the predetermined characteristic is indicated by the new physical position of the switch, and the final TGC characteristic is shown on the display. A uniform gain adjustment across the entire image depth is applied as previously described by adjusting the gain control adjustment 26.

[0013] An ultrasound system constructed in accordance with the principles of the present invention is shown in block diagram form in FIG. 4. A transducer array probe 10 includes an array transducer 12 for transmitting ultrasound waves and receiving echo signals. The transducer array 12 in this embodiment is a one-dimensional (1D) array of transducer elements that can scan an azimuth plane in front of the row of elements by steering and focusing a beam in the plane. The transducer array may alternatively be a 1.5D (or 1.xD) array transducer with several elements on either side of a central row for elevation aperture geometry. A 2D array is used for three-dimensional scanning. The elements of the transducer array are coupled by a probe cable to a transmit / receive switch 18 to switch between transmit and receive and to protect the beamformer 42 from high energy transmit signals. FIG. 1 shows the main components of the receive signal path of the ultrasound system. The received echo signals are amplified by a TGC amplifier 14, which amplifies the signals in a time-gain controlled manner. Typically, there is a separate TGC amplifier for each channel of the beamformer to amplify the echo signal from a particular transducer element or group of elements (patch). The TGC amplifiers are gain controlled by control signals provided by the TGC gain processor 16, as described more fully below. The TGC gain processor adjusts the gain in response to gain adjustments made by the user with a TGC gain control module on the control panel 28, as described more fully below. The TGC gain processor also generates gain values ​​for processing by the TGC display processor 38 and display of the TGC characteristics 116 on the display 40 by the graphics processor 34 and the display processor 36. The TGC gains are initialized by a nominal TGC gain characteristic stored with other setup parameters in a setup memory, and in this description is part of a setup controller 80, which includes a processor for selecting the appropriate initial parameters for the desired ultrasound procedure and providing them to other elements of the system.

[0014] The amplified echoes received by the elements of the array are beamformed by the beamformer 42 by appropriately delaying them and then combining them to generate coherent echo signals. For example, the beamformer 42 may have 128 channels, each of which controls transmission by and delays signals received from a particular element of the 128-element array transducer. The beamformer may process the echo signals in the received analog form, or may digitize the signal samples and digitally process the echo signals.

[0015] The coherent echo signals undergo signal processing by a signal processor 24, which includes filtering by digital filters, such as by spatial or frequency compounding, and noise (speckle) reduction. The digital filters in the signal processor 24 may be, for example, filters of the type disclosed in U.S. Pat. No. 5,833,613 (Averkiou et al.). The echo signals are then coupled to a quadrature bandpass filter (QBP) 46. The QBP filter performs three functions: band limiting the RF echo signal data, generating in-phase and quadrature pairs (I and Q) of echo signal data, and decimating the digital sample rate. The QBP filter comprises two separate filters, one generating in-phase samples (I) and the other generating quadrature samples (Q), each filter being digitally implemented by multiple multiplier-accumulators (MACs) implementing FIR filters.

[0016] The beamformed and processed coherent echo signals are coupled to a pair of image data processors. The B-mode processor 32 generates image data for B-mode images of structures within the body, such as tissue. The B-mode processor (I 2 +Q 2 ) 1 / 2The system performs amplitude (envelope) detection of the quadrature demodulated I and Q signal components by calculating the echo signal amplitude in the form: The quadrature echo signal components are also coupled to a Doppler processor 30. The Doppler processor 30 stores an ensemble of echo signals from discrete points in the image field, which are then used to estimate the Doppler shift at the points in the image using a Fast Fourier Transform (FFT) processor. The speed at which the ensemble is acquired determines the range of velocities of motion that the system can accurately measure and depict in the image. The Doppler shift is proportional to the motion at the points in the image field, e.g., blood flow and tissue motion. For color Doppler image data, the estimated Doppler flow values ​​at each point in the vessel are filtered and converted to color values ​​using a look-up table. The wall filter has an adjustable cutoff frequency above or below which motion, such as low frequency motion of the vessel wall when imaging blood flow, will be rejected. The B-mode image data and Doppler flow values ​​are coupled to a display processor 36 which scan converts the B-mode and Doppler samples from their acquired R-θ coordinates to Cartesian (x,y) coordinates for display in a desired display format, e.g., a rectilinear display format or a sector display format. Either the B-mode image or the Doppler image may be displayed alone, or the two images shown together in anatomical registration with a color Doppler overlay showing blood flow in the B-mode processed tissues and blood vessels in the image. The color Doppler values ​​may also be coupled to the graphics processor 34 to assemble a motion or flow color map to overlay in anatomical registration on the B-mode image. Another display possibility is to display side-by-side images of the same anatomical structure that have been processed differently. This display format is useful when comparing images. The ultrasound images and their associated information are displayed on an image display 40.

[0017] A TGC control module 50 constructed in accordance with the principles of the present invention is shown in plan view in FIG. 5 and in side view in FIG. 6. The module is a continuous elongated structure with periodically enlarged regions 52 that are wider and taller than the intermediate regions. A typical module may be 10-15 cm long and 2-4 cm tall. The module is constructed as a polymer base of the shape and configuration shown in the drawings. A touch sensor 60, shown in FIG. 7, is attached to the side of the enlarged region 52. The entire assembly is covered with a smooth polymer coating such as polystyrene or polycarbonate. Beneath the TGC control module 50 in FIG. 5 are two lighted buttons 54 and 56. When button 54 is pressed, the control module can control the TGC characteristics. When button 56 is pressed, the control module can adjust the lateral gain control (LGC) characteristics when the ultrasound system is so equipped. Double tapping a button resets the corresponding gain curve to the nominal TGC or LGC gain characteristics. The color of the button lights may be changed to provide additional user information. For example, green may indicate that no adjustments have been made to the nominal TCG curve, orange may indicate that the nominal TCG curve has been altered, etc. Such indicator lights may be attached to or correspond to each of the expansion areas 52, as desired.

[0018] The number of expansion regions 52 on the TGC control module is equal to the number of TGC depth zones that can be controlled. In the illustrated example of Figs. 5 and 6, there are eight expansion regions 52 for controlling eight depth zones. The touch sensors 60 located on the sides of the expansion regions may be capacitive or resistive sensors. Those located closer to the base of the module will cause a larger increase or decrease in the TGC gain of the particular zone when touched. Touching a sensor near the top of the expansion region will cause the gain adjustment to be made in smaller increments than those caused by touching the bottom, and continuous adjustments can be made by touching the sensor rather than just a quick touch of a finger, with the amount of gain adjustment being proportional to the length of time the sensor is touched. The periodically changing shape of the control module allows the user to sense the controls tactilely by placing a hand on the top of the module to feel its raised areas and then sliding the hand down to the expansion region for the region of interest. This allows the user to adjust the TGC gain of various zones while keeping their eyes focused on the ultrasound image that should be improved by the results of the adjustment.

[0019] For patient health and safety, the TGC control module 50 does not require slots or other openings in the ultrasound system control panel as traditional slide pot controls do. With its polymer coating, the entire module can be wiped down with disinfectant during cleaning. From a reliability standpoint, the module 50 has no mechanical or moving parts and is therefore not subject to the mechanical destruction of slide pot devices.

[0020] The signal paths for processing the TGC control signals generated by the TGC control module of the present invention are shown in FIG. 7. On the left side of the figure is a cross-sectional view of the expanded area 52 of the control module, showing touch sensors 60 on either side of the expanded area. In this example, the touch sensors closest to the base of the module when touched result in a 10% change in TGC gain. The sensors directly above them cause a 5% change, and the two topmost sensors cause a 2% and 1% change, respectively. The sensor on the right side of the expanded area causes an increase in TGC gain, and the sensor on the left side causes a decrease in gain. For example, when two adjacent sensors are touched simultaneously, the gain applied is a blend of the gains controlled by the two sensors. Although this example shows separate sensors, one skilled in the art will understand that continuous sensors on each side could be used, and positional detection of the touch location could be used to determine the magnitude of the gain adjustment.

[0021] In the separate sensor example of FIG. 7, conductors 63 from each sensor 60 are coupled to the inputs of a TGC decoder 64, as indicated by the arrows in the figure. The TGC decoder generates a gain signal appropriate to the touch sensor from which the signal is received. The gain signal may be one of four possible magnitudes (e.g., 10%, 5%, 2%, 1%) and may either increase or decrease the gain. Each new gain signal increment is added to or subtracted from the current gain control signal by a TGC gain accumulator 68. The TGC gain accumulator starts with a gain value provided by a TGC memory 66, which is the gain of the zone provided by the nominal starting TGC gain characteristic. The TGC gain of the zone is then incremented or decremented from the initial gain value.

[0022] The gain value for a given depth zone, when increased or decreased by touching the corresponding magnified area of ​​the control module, is coupled to a TGC segment processor 70. The segment processor also receives gain values ​​for other depth zones, as indicated by input arrows 68' and 68''. The TGC segment processor assembles a complete TGC gain characteristic from the gain segment values ​​of the different depth zones, which is applied in turn to a digital-to-analog converter 72 and used to control the gain applied to the received echo signal by the TGC amplifier 14. The TGC gain characteristic is also applied to a TGC display processor 38, which processes the TGC characteristic for display as a curve 116 on the image display 40.

[0023] Other variations will readily occur to those skilled in the art. For example, the TGC decoder can further respond to a touch on the touch sensor by sending a signal to the audio system of the ultrasonic system, which responds by producing an audible "click" sound. This provides audible feedback to the user each time the user increments or decrements the TGC gain value. A higher frequency click signifies an increase in gain and a lower frequency click signifies a decrease in gain. Alternatively, tactile feedback can be delivered to the operator by piezoelectric vibration of the touch sensor.

[0024] 8 illustrates an example method 800 for generating an ultrasound image adjusted for depth-dependent ultrasound attenuation by TGC control. The example method 800 may be implemented in the devices and systems described above.

[0025] The method 800 can adjust segments 802 of a TGC gain profile by a TGC control module 50, which includes a plurality of expansion regions 52 and at least one touch sensor for each of the plurality of expansion regions.

[0026] The method 800 can apply an adjusted TGC gain 804 to a TGC amplifier with a TGC gain processor in response to an input on at least one touch sensor used to adjust the TGC gain characteristic. Optionally, the method 800 can include displaying an ultrasound image 806 and a curve of the TGC gain characteristic.

[0027] It should be noted that the ultrasound system suitable for use in the implementation of the present invention, particularly the component structure of the ultrasound system of Figures 2, 3, and 4, may be implemented in hardware, software, or a combination thereof. Various embodiments and / or components of the ultrasound system and its controller, or components and controllers therein, may also be implemented as part of one or more computers or microprocessors. The computer or processor may include computing devices, input devices, display units, and interfaces, for example, for accessing the Internet. The computer or processor may include a microprocessor. The microprocessor may be connected to a communication bus, for example, for accessing a PACS system or a data network for importing training images. The computer or processor may also include a memory. The memory device, such as the TGC memory, may include a random access memory (RAM) and / or a read-only memory (ROM). The computer or processor may further include a storage device, which may be a hard disk drive, or a removable storage drive, such as a floppy disk drive, an optical disk drive, a solid-state drive, etc. The storage device may also be other similar technologies for loading computer programs or other instructions into the computer or processor.

[0028] As used herein, the terms "computer" or "module" or "processor" or "workstation" can include any processor-based or microprocessor-based system, including systems using microcontrollers, reduced instruction set computers (RISC), ASICs, logic circuits, and any other circuits or processors capable of performing the functions described herein. The above examples are merely illustrative and thus are not intended to limit in any way the definition and / or meaning of these terms.

[0029] The computer or processor executes a set of instructions stored in one or more storage elements to process input data. The storage elements may also store data or other information as desired or required. The storage elements may form an information source or a physical memory element in a processing machine. A set of instructions for an ultrasound system, including those that control the acquisition, processing, and display of ultrasound images as described above, may include various commands that instruct the computer or processor as a processing machine to perform certain operations, such as the methods and processes of various embodiments of the present invention. Software instructions may be used, for example, by the TGC segment processor to assemble a complete TGC characteristic. The set of instructions may form a software program. The software may be in various forms, such as system software or application software, and may be embodied as a tangible and non-transitory computer readable medium. Many ultrasound system functions are typically calculated by or under the direction of software routines. Furthermore, the software may form a collection of separate programs or modules, or a program module within a portion of a larger program or program module. The software may also include modular programming in the form of object-oriented programming. The processing of input data by the processing machine may be in response to operator commands, or in response to results of previous processing, or in response to a request made by another processing machine.

[0030] Moreover, the following claim limitations are not written in means-plus-function form and are not intended to be construed under 35 U.S.C. 112, sixth paragraph, unless such a claim limitation expressly uses the phrase "means for" followed by a recitation of a function lacking further structure.

Claims

1. An ultrasonic diagnostic imaging system for generating an ultrasonic image adjusted for depth-dependent ultrasonic attenuation by TGC (Time Gain Compensation) control, a TGC amplifier located in the received echo signal path of the imaging system, a source of TGC gain characteristics, a TGC control module adapted to enable adjustment of the TGC gain characteristics, the TGC control module having a plurality of enlarged regions for adjusting each segment of the TGC gain characteristics, and further having a plurality of touch sensors disposed on both sides of the enlarged regions, respectively, a TGC gain processor adapted to apply the adjusted TGC gain to the TGC amplifier and responsive to the touch sensors and the TGC gain characteristics, further comprising, the enlarged regions being wider and higher than the intermediate region of the TCG control module, an ultrasonic diagnostic imaging system.

2. The TGC gain processor is further adapted to adjust the TGC gain characteristics in response to the touch sensors, The ultrasonic diagnostic imaging system according to claim 1, further comprising an image display adapted to display an ultrasonic image and a curve of the TGC gain characteristics.

3. The ultrasonic diagnostic imaging system according to claim 1, wherein the touch sensor further comprises a capacitive touch sensor.

4. The ultrasonic diagnostic imaging system according to claim 1, wherein the touch sensor further comprises a resistive touch sensor.

5. The TGC control module further comprises an elongated structure having enlarged regions spaced periodically apart, The ultrasonic diagnostic imaging system according to claim 1, wherein the number of the enlarged regions is equal to the number of controlled TGC depth zones.

6. The touch sensor on one side of each enlarged region is further adapted to decrease the TGC gain, and the touch sensor on the opposite side of each enlarged region is further adapted to increase the TGC gain, the ultrasonic diagnostic imaging system according to claim 5.

7. The received echo signal path further comprises a beamformer, The TGC amplifier is disposed in front of the beamformer in the received echo signal path, The ultrasonic diagnostic imaging system according to claim 1.

8. Further comprising light associated with one or more of the enlarged regions, The color of the light indicates whether the nominal TGC gain characteristics have been changed, The ultrasonic diagnostic imaging system according to claim 1.

9. The ultrasonic diagnostic imaging system according to claim 1, wherein the source of the TGC gain characteristic further comprises a TGC memory.

10. The ultrasonic diagnostic imaging system according to claim 9, wherein the TGC memory is further adapted to provide nominal initial TGC characteristics at the start of an ultrasonic procedure.

11. The ultrasonic diagnostic imaging system according to claim 10, wherein the nominal initial TGC characteristics are further adapted to be adjusted by the TGC control module during the ultrasonic procedure.

12. The ultrasonic diagnostic imaging system according to claim 1, wherein the plurality of touch sensors are further adapted to provide different amounts of TGC gain adjustment.

13. The ultrasonic diagnostic imaging system according to claim 12, wherein a lower touch sensor on the enlarged area is adapted to provide a greater TGC gain adjustment than a higher touch sensor on the enlarged area.

14. The ultrasonic diagnostic imaging system according to claim 12, wherein a touch sensor on one side of the enlarged area is adapted to increase the TGC gain, and a touch sensor on the opposite side of the enlarged area is adapted to decrease the TGC gain.

15. A method of generating an ultrasonic image adjusted for depth-dependent ultrasonic attenuation by TGC (time gain compensation) control, comprising: Adjusting segments of TGC gain characteristics using a TGC control module, the TGC control module comprising a plurality of enlarged areas and at least one touch sensor for each of the plurality of enlarged areas; Applying an adjusted TGC gain to a TGC amplifier using a TGC gain processor in response to an input at the at least one touch sensor used to adjust the TGC gain characteristics; The enlarged area being wider and higher than an intermediate area of the TCG control module; An ultrasonic diagnostic imaging system.

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