Transducer Construction, Care, and Damage

This course will help you understand transducer construction, care, and detection of internal and external damage. Included is a discussion of how each transducer component contributes to the final image quality. Sections include a high-level review of daily transducer care as well as results of damage. Each learning activity concludes with a quiz to test your retention of the presented content. A score of 80% or higher is required to pass the quiz. You have three attempts to pass this course. This tutorial contains additional information in the form of links placed on the page. To successfully complete this course, please view all available content.    We hope you enjoy our tutorial. Upon completion of this tutorial you will be able to: Identify the internal and external components of the transducer, Describe the piezoelectric effect, Generalize the importance of transducer components to image resolution, Explain the difference between detail (axial and lateral), contrast, temporal, and elevational resolution, and Describe external transducer damage. The first section of the tutorial describes the construction and basic function of a transducer.  In its simplest form, a transducer merely converts one type of energy to another.  When we listen to music on an iPod or mp3 player, a transducer converts the electrical signal to sound. This is a single direction transducer as the electrical current only converts to sound. The same process occurs within an ultrasound transducer, electricity stimulates a piezoelectric element that changes shape creating the high-frequency sound waves that travel into the body.  Once the tissues in the body have reflected the sound wave, the piezoelectric element, again changes shape creating the electrical current used by the ultrasound system to create an anatomic image.1 This is a bidirectional transducer. Any damage to the components results in changes to the transducer function.  A transducer changes one type of energy to another.   Input Transducer Output Electric current Microphone Sound Flashlight Light Motor Mechanical energy Radio waves Antenna Sound Weight Scale Digital readout Radiation Geiger counter Sound Heart movement EKG lead Oscillation graph Examples of transducers.   Depending on the task, the ultrasound transducer has many different shapes, uses, and simply converts one type of energy to another. First, we will look at the different parts of the ultrasound transducer.   Transducers may look different depending on the manufacturer or the intended use; however, there are common components. Externally we see the strain relief that decreases damage to flexible connection points such as where the cable inserts to the transducer and the connector.2 Connectors have a locking mechanism to ensure a secure connection with the ultrasound system. After viewing the material on the tabs, check your knowledge with the Test Your Understanding questions. Strain Relief and Connectors Learn More about Strain Relief and Connectors Tab TitleTextStrainRelief   The strain relief (red arrow) helps decrease damage to the areas that connect the cable, transducer, and connector. The locking mechanism on the connector (yellow arrow) ensures the transducer correctly attaches to the  ACUSON P500™ ultrasound system.    TEEStrain Relief The Z6Ms transesophageal (TEE) transducer  has a third strain relief area (arrow) where the flexible, catheter-like transducer connects to the handle.   Pin-type Connector This is a pin-type connector transducer. The transducer side (left) has pins that fit into the system port (right) (orange arrow). This Canon-type connector has a rotating locking mechanism3 (green arrow) to ensure a snug, secure connection. Cartridge-typeConnector To attach the cartridge-type transducer connector, as seen on the ACUSON P500™ ultrasound system, FROSK edition, insert the transducer side of the connector (top) into the system port. A lever-type lock ensures a snug connection (bottom). Pinless-typeConnectorThis pinless-type connector has 512 fine wires embedded in a base material providing the electric current between two circuit boards.4 Removing the pins from the transducer connector (the micropinless (MP) transducer), results in a decrease in the signal-to-noise ratio (SNR).  This increases the quality of the electrical signal traveling between the transducer and ultrasound system, thus decreasing the possibility of electronic noise on the image.   Electronic noise on the image appears as an artifact on the beam axis as patterns of radiating lines or echogenic streaks.5       The left image shows the inside of the transducer side of the connector while the right side shows inside the ultrasound system connector port. Beam narrowing, called focusing, increases all types of resolution, lateral, axial, and elevational. Each transducer component affects resolution in a different manner. We begin with the lens of the transducer. A lens, known as external focusing,6 helps focus and narrow the sound beam transmitted by the transducer.1   Each lens differs depending on the transducer design and use. Any type of focusing that decreases beam width, increases lateral resolution by decreasing the near field diameter, focal zone depth, and size.1, 7   Lateral resolution is the ability to resolve structures perpendicular to the transmitted beam.1, 8 If a structure lies outside of the beam, they blend into a single structure.8 This demonstrates the importance of using a focused beam and centering the beam to the imaged structure. Click on the information icon to view additional explanations. Lateral Resolution Explainations Learn More about Lateral Resolution Tab TitleTextLateral Resolution PlaneThe section of the beam that extends the width of the transducer (left) is the lateral resolution plane.  On the transducer, the lateral resolution is the longest plane (right) as seen on this 9L4 linear array transducer. Tissue Phantom ImageThis image of a tissue phantom demonstrates lateral resolution of structures located next to each other and perpendicular to the ultrasound beam.     The pins located close to the transducer lens (green arrowheads) at the narrowest part of the beam have a clear appearance.  The pins further from the lens (orange arrowheads) have a oval appearance due to beam spreading that occurs further from the transducer.1 The space between the circular cystic to solid structures (white arrow) also demonstrates lateral resolution.  Ultrasound ImageThis longitudinal trapezoid image of a thyroid is taken with the VF13-5 linear array transducer demonstrates good lateral resolution as seen by the separation of calcifications (arrows).   A sound wave returning from the body causes the piezoelectric element to vibrate and helps in the creation of a radiofrequency or RF signal that stores in an ultrasound system.9 Unwanted radiofrequencies and vibrations result in noise on the image, decreasing resolution.10 Many patient systems, such as respirators, create noise on the image due to RF signals. Other interfering systems include cell phones, and elevators.  To prevent the creation of noise from these external systems a shield lies between the lens and matching layer of the transducer.11 A matching layer decreases the impedance difference between the tissue and the piezoelectric element.12 Tissue has a lower impedance, or resistance to the movement of sound, than the element.  This results in reflection at the tissue / transducer interface reducing the amount of sound traveling into the patient.10 Without this layer, both the sent and received sound would reduce by as much as 80 percent!1, 12   The thickness of the matching layer depends on the transducer wavelength.  Optimally, the layer is one-quarter of the wavelength9, 10 maximizing sound transmission,11 and reception.10 The use of multiple matching layers that correspond to the transducer bandwidth decrease the impedance mismatch further.1, 10 An added benefit is an increase in sensitivity with a decrease in reverberation artifacts.9  Dicing, cutting into small cubes, of the matching layer helps to decrease unwanted transfer of signals (crosstalk) between the piezoelectric rods.13   Modern transducers produce multiple frequencies to provide an optimal image.  This requires the use of multiple matching layers as each frequency has its own wavelength. As many as three matching layers decrease the tissue / transducer mismatch1 resulting in efficient sound transfer to the tissue.12 Epoxy or polyimides compose the low impedance layer. Metal powders such as tungsten, copper and hafnia are added to the epoxy to create mid to high impedance matching layer.14 The use of glass, graphite or non-piezoelectric ceramics results in a very high impedance matching layer.14, 15 Click on the information icon for photographs of the matching layer.     Learn about Matching Layers Learn about Matching Layers Tab TitleTextMicroscopic ViewThis cutaway photo of the transducer layers demonstrates the multiple matching layers (ML) placed between the lens and piezoelectric element. The impendence changes with the ML composite.   <--Low impedence ML <--Low to high impedence ML <--Very high impedence ML <--Ground foil <--Piezoelectric element       Damaged TransducerThis transducer shows damage-related removal of the lens and shield layer exposing the matching layer. A – lens; B – shield; C – matching layer.   The grounding foil provides a pathway for external vibration and RF signals safely direct the signal around the sensitive electrical components and route to the grounding wire.16 This is a part of the transducer’s circuitry. In addition to being a key component of the transducer’s receiver circuitry, the grounding foil is the electrical pathway by which high-voltage RF signals from system transmitters return safely to ground.11 The flex circuit provides a connection between the piezoelectric crystal and the ultrasound system via the transducer cable. Rows of copper18 connections extend from the flex circuit to each crystal rod within the piezoelectric composite. A gold or nickel coated electrode lies within the flex circuit and in contact with the PZT elements providing the connection with wiring.18  In turn, the flex circuit wires travel through the transducer cable to the system.11, 25, 26   Epoxy adhesive glues this thin sandwich consisting of the matching layer, PZT, flex circuit, and backing material.18 There is no need for matching layers between the crystal, flex circuit, and the backing material as the flex circuit is ‘acoustically transparent’.26  This allows the backing material to do its job of decreasing ring down time.26   Click on the information icon to view additional explanations. Learn more about the Flex Circuit Learn More about the Flex Circuit Tab TitleTextElement Construction - Diagram ←LIML ←HIML   ←Sub-diced PZT                                                                              ←Receive Flex ←Backing Material   This figure shows the connections to individual elements. The elements here are the four-pronged structures that are light grey on the bottom and have the four gold spots on top.  There are also two matching layers, which act as acoustic transformers to help couple the sound from the piezoelectric material (PZT) to the patient.  The subdiced elements control unwanted acoustic modes so each element is actually four prongs as shown.  The elements shown in this diagram are 400 microns.  For comparison, a sheet of generic copy paper is 80 microns thick,27 so each element is as wide as five sheets of paper are thick! LIML – low impedance matching layer; HIML – high impedance matching layer.Element Construction - Photo This is a photograph of the double-sided bottom or receive flex (top arrow).  The shiny copper traces are the connection to the bottom of the elements on the edge. (bottom arrow)  The faint traces between the shiny copper ones are on the underside of the flex circuit and run under the rest of the elements.Transmit Flex This is an array with the top or transmit flex in place.  The little lines you see on each module are a collection of individual traces running over the tops of the elements and connecting to each individual element.  Also in this picture, you can see that we build the array as a group of modules, rather than one large group.  These common, modular building blocks change the dimensions and frequency of the modules. This allows stacking and the creation of additional arrays. We know that a pulsed wave transducer has cycles of sending and listening.1, 12 The crystal vibrates or rings with the application of the electrical current. Similar to a bell, the crystal would continue vibrating until stopped.8 If ringing continues in the transducer, the returning signal becomes degraded.11 In the case of a transducer this additional ringing degrades the image requiring the use of a dampening layer.    A dampening or backing layer decreases how long (pulse length) and the pulse duration.1 As a result, the transducer axial resolution11 and bandwidth increase; 1 however, the tradeoff is a decrease in sensitivity in detection of weak echoes.1   Continuous wave transducers do not need dampening material because they do not pulse.1 Click on the information icon to view additional explanations. Learn more about Axial Resolution Learn More about Axial Resolution Tab TitleTextAxial Resolution – DiagramThis diagram demonstrates the axial resolution plane within the transducer beam.    Axial Resolution - Image This image of the large quadriceps muscle located in anterior thigh shows a linear image using the trapezoid feature.       This extends the image laterally (yellow arrows). Using a depth of 6.5 cm allows for imaging to the echogenic femoral shaft (double arrowhead). The good axial resolution allows separation of the muscle fibers (single arrowheads). Earlier we learned about the internal and external components of the transducer.  We also know that the piezoelectric element is made of a fragile crystal vulnerable to breakage if dropped or loss of polarity if sterilized. These factors highlight the importance of proper storage and cleaning of the transducer. The next sections contain information on storing, general cleaning procedures, and visual inspection.   Important! Always refer to the system specific transducer guides located in the User Manual. Storage of the transducer occurs in many different ways.  One is to place the transducer into the ultrasound system while placing the cables in the holders. This is the appropriate method for daily storage between patients; however, other methods help reduce damage for shared or specialized transducers.   Do Place unused transducers in system holders. Hang transducers vertically. Store transducers with the lens up. Dry before storage. Store transducers separate from other medical equipment. Protect the TEE tip from striking any surfaces. Use a Tip Protector on the TEE transducer. Coil the transducer cables loosely. Do Not Leave transducers where they can be dropped or knocked over. Drop the transducers into a sink or disinfectant container lens first. Immerse transducers above the suggested depth. Immerse the cables or connectors. Pull on the cord. Store in any disinfectant. Click on the information icon to view types of transducer storage.   Learn more about Transducer Storage Learn More about Transducer Storage Tab TitleTextOn the Ultrasound System The ACUSON S3000™ ultrasound system provides storage on both sides of the control panel for the transducers. The connectors store on the front of the system. The ACUSON SC2000™ ultrasound system, PRIME edition transducer holders allow for storage of the Z6Ms while waiting for an exam to begin.  Do not use the holders with a TEE transducer when moving the system. Wall-type A storage rack for general purpose and endocavity transducers helps prevent damage to the transducer. Make sure to anchor both the transducer and connector in the holder. Placing the transducer in the holder and the connector on the floor stresses the connection points.   Photo compliments of CIVCO Medical Solutions, Coralville, IA. Closet-typeThis type of transducer storage combines filtered airflow, clean storage, plus the ability to lock the cabinet.   Examples of a TEE (left) and general imaging (right) transducer GUS Storage system. Photos compliments of CIVCO Medical Solutions, Coralville, IA. The cleaning method varies depending on the transducer and use.  Clean transducers before and after every use to prevent nosocomial transfer of pathogens between patients. There are three levels of transducer cleaning, critical, semi-critical, and noncritical. These levels vary on the degree of risk for infection, and the type of tissue involved while imaging.   Important! Check the Siemens Transducer Disinfection Guide specific to your ultrasound system. Click the icons to learn more about transducer cleaning and disinfection. Note: The following general procedures do not include biopsy attachments.   Learn More about Transducer Cleaning Learn More about Transducer Cleaning Tab TitleTextCritical DisinfectionUse critical disinfection in cases where the transducer could spread disease when used in a sterile environment.  Equipment included in this category would be catheters, implants, surgical instruments, and ultrasound transducers. Since steam sterilization harms the transducer, we must use liquid chemical sterilants. Usually requiring soaking for a predetermined time, this type of disinfection results in a sterile, organism-free, transducer. 29, 30High-level DisinfectionContact of the transducer with nonintact skin or mucous membranes, require cleaning to remove most infectious organisms.  The removal of all pathogens, except for a small number of bacterial spores, defines high-level disinfection. Using a shorter soaking time or manufacturer-approved disinfectant wipes is an appropriate cleaning procedure for this level of disinfection. 29, 30  Low-level DisinfectionEquipment that has a low chance of transmitting disease require low-level cleaning.  Disinfection solutions provide adequate cleaning for items such as a blood pressure cuff, ultrasound system surfaces, and transducers that only contact intact skin. 29, 30  Transducer Disinfection Click the transducer to view a video demonstrating the cleaning of the 6C1 HD transducer. When decontaminating the transducer consider the following: 1. Determine the proper decontamination level based on both the transducer     type and intended use. 2. Choose a manufacturer-recommended decontaminant. 3. Pre-clean the transducer to remove all foreign materials. 4. Disinfect or sterilize the transducer according to Siemens instructions. Review the following tables to ensure you understand transducer disinfection categories and decontamination processes.   Disinfection Category Uses Transducer Type Required Minimum Decontamination Level Critical Enter sterile tissue or the vascular system Intraoperative, laparoscopic or catheter-type Cleaning and sterilization disinfection or liquid chemical sterilants Semi-critical Contact mucous membranes or non-intact skin Endocavity Cleaning and high-level disinfection Noncritical Contact intact skin but not mucous membranes & non-intact skin External Cleaning and low-level or intermediate-level disinfection Transducer Classification for Decontamination29, 30 * The recommended decontamination level for various types of Siemens medical ultrasound transducers.   Bleach Soaking transducers in bleach (Sodium Hypochlorite), even diluted, will cause damage. Wiping transducers with a cloth dampened with < 10 % bleach solution is an acceptable pre-cleaning process. Isopropyl Alchohol (IPA) Soaking transducers in Isopropyl Alcohol will cause damage to the transducer. Wiping transducers with a cloth dampened with Isopropyl Alcohol is an acceptable pre-cleaning process.31   Notes on some very common chemicals V5M Care and Handling To extend the useful life of the transducer, withdraw the TEE transducer from the stomach acid environment when not actively acquiring a transgastric view. Move the TEE transducer to the neutral position, moved out of the stomach, and “parked” in the esophagus until needing additional transgastric views. The most damaged component of an ultrasound system is the transducer.32 A study done by Mårtensson32  showed that radiology departments had the highest damage rate, followed by obstetrics and gynecology, with the transesophageal transducer showing the lowest rate of damage.  In fact, up to 40 percent32, 33 of transducers show some sort of damage highlighting the importance of careful handling. Image quality directly links to the transducer33 warranting routine visual inspection to detect damage before the image becomes degraded. Keeping the transducer in optimal condition begins with the visual inspection and the ability to recognize image changes due to transducer, system error, artifacts, or technical errors.   Click on the information icon to view transducer protection. Learn More about Protecting the TEE Transducer Learn More about Protecting the TEE Transducer Tab TitleTextTEE Tip Protector The TEE tip guard protects the transducer from damage during storage or transport.  Remove these non-latex, single-use devices before imaging. Photo compliments of CIVCO Medical Solutions, Coralville, IA.   Placement of the tip potector Slide protector over the end of the transducer ensuring complete coverage of the tip. Removal of the tip protector   Gently pull the transducer protector to remove. TEE Bite GuardThe bite guard serves a dual purpose of providing safe passage of the TEE transducer and preventing the patient from damaging the transducer.   This is an example of an approved bite guard. Photo compliments of CIVCO Medical Solutions, Coralville, IA. Here we see the TEE bite guard positioned in the mouth of an imaging phantom. Photo compliments of Blue Phantom, Redmond, WA.   This section covers the visual inspection, which includes all portions of the transducer. Though the damage may be slight, progression may result in malfunction. To ensure a thorough inspection, your facility may develop a protocol or checklist. Especially in the case of a defect that requires monitoring. Damage can result in not only image degradation, but also possibly place the patient in peril due to poor image quality34, 35 and infection transfer.35 In this section, you will see examples of damage to the transducer, cables, and connector.   Complete a daily transducer, cable, and connector inspection for the following:36 Handle cracks Nose piece cracks Cuts or gouges of the lens Swelling or bubbling of the lens Strain relief connection Connector cracks or damage Pins with damage or bending Ensure cleanliness of the pinless transducer connector Flexibility and continuity of the cable Bite marks on the TEE transducers Depth marker visibility on the TEE transducers In the event of damage to the transducer, or any other component of the ultrasound system, contact your local Customer Care Center. Download and print a copy of the Key Considerations for Transducer Repair white paper. The lens helps focus the ultrasound beam increasing axial and lateral resolution in the image.1 When damaged, not only is the focus changed, but, in severe cases, may harm the patient through misdiagnosis or even electrical shock.  Click the tabs to see examples of lens damage.   Click on the information icon to view additional explanations. Learn More about Lens Damage Learn More about Lens Damage Tab TitleTextGouged Lens This photograph shows a gouged lens that is due to improper storage and handling. The damage to the lens will have a severe impact on the transducer’s imaging capabilities. Ensuring that transducers are properly stored when not in use and that all personnel handle transducers cautiously can reduce the likelihood of this type of damage.  This image demonstrates the effect on the B-mode image of a gouged lens on an 8C3 HD transducer. The defect area (arrow) creates linear artifacts on the image obscuring the tissue phantom pins and internal structures. Dry Lens Use of disinfection, such as alcohol or bleach can result in the lens becoming dry and shrinking. Image compliments of LBN Medical A/S, Aalborg, Denmark TEE Bite Marks    These transesophageal (TEE) transducer tips demonstrate bite marks extending into the lens material. To help prevent this type of damage, always use a bite guard.  DelaminationLamination of multiple components results in the transducer used in the clinical setting. If these layers separate, or delaminate, the seal fails resulting in the introduction of air between the layers. Mårtenssons32 study found that a quarter of transducer failure was due to delamination.     These TEE transducers demonstrate the appearance of air under the lens.       Air under the lens of a linear and phased array transducer appears as raised, bubbled areas.     This dual image using the 9L4 linear array transducer demonstrates the effect of air (arrows) under the lens on the left image that extends from the transducer. The use of compression removed the bubble artifact as seen on the right image. It is important to differentiate a transducer artifact from an imaging artifact such as the edge artifact1 seen here (arrowheads).   Once inspecting the lens for any signs of damage, look at the transducer casing and seams to ensure intact seals. Click on the information icon to view additional explanations. Learn More About Seal / Case Damage Learn More About Seal / Case Damage Tab TitleTextSeal Damage   These two transducers show seals that have become detached. The absence of seals allows external debris and fluids to enter the case possibly resulting in damage to the internal electronics. Compromised seals allow fluids to enter the transducer allowing damage to the internal components. Though important for all transducers, a broken seal becomes critical in endocavity and TEE transducers.Case Damage   These photos demonstrate damage to the transducer case. Damage to the housing is usually due to dropping or banging against another object such as a sink or counter. An important part of the transducer assembly, the strain relief helps to minimize damage to a vulnerable section that fits over the connection point.37 The design of the strain relief at the transducer and connector ends allows movement without damage of the cable. This type of damage shows up as areas called ‘dropout’ where the image demonstrates linear, dark areas.38   Click on the information icon to view additional explanations. Learn More about Strain Relief Damage Learn More about Strain Relief Damage Tab TitleTextConnector   This is an example of a damaged strain relief at the connector end of the transducer cable.Transducer   The strain detachment on this transducer would occur with pulling or yanking if the cable catches in the ultrasound system wheels.   Another example of damaged strain relief at the transducer end of the cable. Damage to the cable not only jeopardizes patient care, image quality may also suffer. This type of damage appears as noise or lines on the image with cable movement.39 Click the tabs to see examples of cable damage.   Click on the information icon to view additional explanations. Learn More about Cable / Instertion Tube Damage Learn More about Cable / Instertion Tube Damage Tab TitleTextBruising   This is an example of insertion tube ‘bruising’ due to crushing (i.e., between the system and patient cart). Inside the cable-like tube, the fine round wires move over each other; however, repeated crushing may result in a change in the wires and thus reducing movement.39Squashed   This cable demonstrates the result of both cable bruising and squashing.Run Over   This type of damage occurs when the ultrasound system runs over the cable. Cut   An example of a cut cable sheath.Metallic Sheath Exposure This damaged transducer cable allows exposure of the woven metallic sheath or armor40 of the cable. This is an example of the type of artifact seen with cable damage with the color mode active. Damage to the transducer connector may be cosmetic or add artifacts to the image.   Click on the information icon to view additional explanations. Learn More about Connector Damage Learn More about Connector Damage Tab TitleTextConnector Case Rough handling and dropping of the transducer connector increases the chance of damage Connector pins This photograph shows a transducer connector with bent electrical contact pins. This kind of damage occurs when the transducer has been connected or disconnected forcefully.   Dirty Connector This image demonstrates a triple image artifact due to a dirty transducer connector. Check the connector to check for dirt and clean with a soft cloth. The internal components of a transducer also have a direct effect on image quality.  All have a role in the creation of the image but none is more visible than the malfunctioning PZT element. Each element is part of a line within the transducer array. A damaged element disrupts the steering,33, 34, 41 focus,34 accuracy,32, 34 overall efficiency,34 and sensitivity 32, 42 of the entire array. Weigang and others34 studied the effect of dead elements on image quality using side-by-side images (functional versus damaged) with tissue-mimicking phantoms, transducer testing systems, and live imaging. Testing revealed: An increase in side-lobes More image noise Decreased dynamic range Decreased lateral resolution A decrease in Doppler flow sensitivity Decreased depth penetration due to a decrease in power These changes occur with as few as four elements!34   Click on the information icon to view additional explanations. Learn More about Element Damage Learn More about Element Damage Tab TitleText34 Elements Missing   This series of images demonstrates the large area of noise from 34 missing elements (arrow; left image). Placement of the color box within the liver (middle image) shows the artifact created by the missing elements. Though a vessel with flow away from the transducer images (right image), the artifact obscures not only B-mode information but also vascular anatomy.29 Missing Elements   These images demonstrate the loss of 29 elements at the edge of the transducer (Left image: arrow). The loss of image information becomes more evident with the activation of color (right image).   So far, we have discussed imaging issues due to transducer error. Other imaging problems relate to system artifacts or technique errors. Recognition of these types of errors aid in determining the need for repair of the ultrasound system. System errors are image problems due to either a software or a hardware problem. A technique error is one due to feature or technique maladjustments.   Click on the information icon to view examples of system artifacts or technique errors. Learn More about System Error Artifacts Learn More about System Error Artifacts Tab TitleTextStalactite Artifact This is an image demonstrating a stalactite artifact. Occurring intermittently on the zoomed image (not HD) with Dynamic TCE™ tissue contrast technology (DTCE) active, multiple hyperechoic artifacts extend posteriorly from the transducer. To correct this system error, deactivate DTCE, increase the overall gain, and activate DTCE.   Triple Cone Artifact   This triple cone artifact (left) is not to be confused with the triple image artifact (right) seen earlier. A dirty connector creates the triple image artifact while the triple cone artifact is the result of a faulty transmit receive (TR) board. To differentiate the two, look at the underlying image. Replicated anatomy (left) indicates the triple cone artifact. In the case of the triple image artifact (right), the system’s hardware channels three times for each sweep of the transducer resulting in three identical structures.    The first step to eliminating these artifacts is to change transducer ports. If the problem persists, check the connector for dirt and clean with a soft cloth. Call the service engineer if the imaging problem continues.  HD Zoom Exit   This system error begins when entering high definition zoom (HD Z) using a linear transducer as seen on the left image. Activating color (right), the image may intermittently exit HD zoom (arrow); however, this behavior only occurs with the first color activation in a new exam.Image Stall   The image may ‘stall’ when moving the color region of interest (ROI) twice in a short time span. With the first move, the color stops, and waits for the ROI to settle (left).  The color then fills in at the new position. The stall reoccurs with a second ROI movement as the color moves to the original location. Pressing Freeze and scrolling the CINE wheel, the color ROI updates and fills with a saturated speckle artifact (right). Note: These images are for demonstration purposes only.  During color Doppler imaging, you would need to angle the ROI either right or left to obtain the optimal signal.  Learn More about Technique Error Artifacts Learn More about Technique Error Artifacts Tab TitleTextVertical Doppler Artifact   The vertical artifacts (arrows) seen during spectral Doppler appear with gain adjustment with an active trace.  This due to slight interruptions in the signal leading to the spikes. This is not a system error. To avoid the artifact, adjust the Doppler gain as needed then allow the waveform to continue until it is smooth without spikes, then freeze. ROI Linear Color Artifacts   The left image demonstrates an ROI filled with linear color artifacts.  To correct this problem simply reduce the ROI (right image).  Another technique to increase the image detail is to ensure contact between the patient and the transducer.  The lag results in an area of decreased echoes (arrows; right) on the image.    1.  Kremkau, F.W. (2016). Sonography principles and instruments. St. Louis, MO: Elsevier. 2.  Moore, G.W. (2006).Common Ultrasund Probe Failures. Retrieved  from http://www.faculty.pnc.edu/jlerne00/advanced/Common%20Probe%20Failures.pdf   3.  Marian Jr., V.R., and Mullen, D.R. (1996). U.S. Patent No. 5,865,650. Washington, DC: U.S. Patent and Trademark Office.   4.  Ayala-Esquilin, J., Beaman, B.S., Harin, A., Hedrick, J.L., Shih, D., et. al. (1993). U.S. Patent No. 5,441,690. 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Single element transducers: Properties, in Technology for diagnostic sonography. Elsevier: St. Louis, MO, USA.   13   Guo, X., and Houck, G. (2002). U.S. Patent No. 6,359,375 B1. Washington, DC: U.S. Patent and Trademark Office.   14. Oliver, N.H. (2005). U.S. Patent No. US 2005/0225211 A1. Washington, DC: U.S. Patent and Trademark Office.   15. Thiagarajan, S., Martin, R.W., Procotor, A., Jayawadena, I., & Silversteien, F. (1997). Dual layer matching (20 MHz) piezoelectric transducers with glass and parylene. In IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 44(5), 1172-1174.   16. Morrison, R. (2007). Hardware, in Grounding and shielding circuits and interfearence. John Wiley & Sons, Inc.: Hoboken, NJ, USA.   17. Frey, G.W. (2009). U.S. Patent No. US 7,518,290 B2. Washington, DC: U.S. Patent and Trademark Office.   18. Hanafy, A.M. (1999). U.S. Patent No. 5,894,646. Washington, DC: U.S. Patent and Trademark Office. 19. Tutala, W.A., and Weber, D.J. (2008). Guideline for disinfection and sterilization in healthcare facilities. Retrieved from http://www.cdc.gov/hicpac/Disinfection_Sterilization/3_1deLaparoArthro.html   20. Hanafy, A.M. (1999). U.S. Patent No. 5,976,091. Washington, DC: U.S. Patent and Trademark Office.   21. Whittingham, T., & Martin, K. (2010). Transducers and beam-forming, in diagnostic ultrasound: physics and equipment. In P. Hoskins, K. Martin, & A. Thrush (Eds.) Diagnostic ultrasound: physics and equipment (p. 23-46). Cambridge University Press: Cambridge, NY.   22. Hedrick, W. (2013). Real-time ultrasound transducers, in Technology for diagnostic sonography (p. 65-82). Elsevier Mosby: St. Louis, MO.   23.  Del Prince, B. (2016). Doppler and color flow principles. In  R. C. Sanders & B. Hall-Terracciano (Eds.), Clinical sonography: A practical guide (p. 7-20). Wolters Klewer: Philadelphia, PA.   24. Florin, G.R., & Timisoara, V.B. (2016). A review for the advances in medical ultrasound investigation. Retrieved from http://smj.medicalinfo.ro/arhiva/download/smj_no_001/smj_no1_022006_scientific_06.pdf   25. Lay, H.S., Simpson, E.A., Griffin, G., & Lockwood, G.R. (2012). High-Frequency Annular Array. Ultrasonic Imaging, 34(3), 196-204.   26. Strole, J., Corbett, S., Lee, W., Light, E., & Smith, S. (2002). A Novel Flex Circuit Area-Array Interconnect System for a. in IMAPS 2002. Denver: International Microelectronics And Packaging Society. 27. Ives, R. (2016). Converting paper weights. Retrieved from http://www.dummies.com/how-to/content/converting-paper-weights.html   28. Eaton, J.W., Schlesinger, R.L., Ikeda, M.H., Brummer, C.W., Pacheco, X.L., et al. (1998). U.S. Patent No. 5,795,299. Washington, DC: U.S. Patent and Trademark Office.   29. Phillips, R., and Harris, G. (2015). Guidance for industry and FDA staff - Information for manufacturers seeking marketing clearance of diagnostic ultrasound systems and transducers - Sections 4 through 6 and Appendix A through H, U.S.D. of Health and Human Services: Silver Spring, MD.   30. Rutala, W.A., and Weber, D.J. (2008). Guideline for disinfection and sterilization in healthcare facilities, 2008. Retrieved from http://www.cdc.gov/hicpac/pdf/guidelines/Disinfection_Nov_2008.pdf   31. Chuan, A., Tiong, C., Maley, M., Descallar, J., and Ziochos, H. (2013). Decontamination of ultrasound equipment used for peripheral ultrasound-guided regional anaesthesia. Anaesthesia & Intensive Care, 41(4), 529-534.   32. Mårtensson, M. (2011). Evaluation of errors and limitations in ultrasound imaging systems (Doctoral dissertaion). Retrieved from Digitala Vetenskapliga Arkivet. (DiVA ORCID iD: 0000-0001-9419-910X)   33. Gistvik, H., and Pettersson, S. (2013). Effects of dead elements in ultrasound transducers (Master’s thesis). Retrieved from Digitala Vetenskapliga Arkivet. (DiVA: diva2:638244) 34.     Weigang, B., Moore, G. W., Gessert, J., Phillips, W.H., and Schafer, M. (2003). The methods and effects of transducer degradation on image quality and the clinical efficacy of diagnostic sonography. Journal of Diagnostic Medical Sonography, 19(1), 3-13.   35. Acute Communicable Disease Congrol Program. (2006).Transesophageal echocardiography, insufficient cleaning practices and lax equipment maintenance, and Escheria coli—a breakdown in infection control. Retrieved from http://publichealth.lacounty.gov/acd/reports/spclrpts/spcrpt06/ecoli_ss06.pdf   36. Moore, G.W. (2006). Common ultrasound probe failures. Retrieved from http://www.faculty.pnc.edu/jlerne00/advanced/Common%20Probe%20Failures.pdf   37. tecopedia. (2016). Strain relief. Retrieved from https://www.techopedia.com/definition/2301/strain-relief.   38. LLC, P.M.E. (2016). Ultrasound probe repair.  Retrieved from http://www.providianmedical.com/ultrasound-probe-repair/   39. Medical, L. (2015). How to protect your ultrasound probes. Retrieved from http://lbnmedical.com/fix-broken-ultrasound-probe/   40. Open Electical. (2012).Cable construction. Retrieved from http://www.openelectrical.org/wiki/index.php?title=Cable_Construction   41. Powis, R.L., and Moore, G.W. (2004). The silent revolution: catching up with the contemporary composite transducer. Journal of Diagnostic Medical Sonography, 20(6), 395-405. 42. Mårtensson, M., Olsson, M., Segall, B., Fraser, A.G., Winter, R., et. al. (2009). High incidence of defective ultrasound transducers in use in routine clinical practice. European Heart Journal - Cardiovascular Imaging, 10(3), 389-394. Click ◄ for previous page                                                                              Click ► to continue Acoustic lens – A lens used to focus or diverge an ultrasound beam. Artifact – Image characteristics, such as shadowing or enhancement, which do not represent real anatomic structures. Axial resolution (Linear, range, longitudinal or depth resolution) – The ability to separate two structures parallel to the ultrasound beam.  The higher the frequency the better the axial resolution on the image. B-mode – Grayscale imaging. Bandwidth – The range of frequencies transmitted or received by the transducer. Curie temperature – The temperature when the positive and negative charges of a ferroelectric, such as a piezoelectric crystal, change direction. Continuous wave transducer – Uninterrupted send and receive of a sound wave. Dipole – Molecules with polar positive and negative charges. Elevational resolution (slice thickness resolution) – Dependent on the piezoelectric element height, elevational resolution is the ability to separate structures that lie vertically on the axis of the beam. The best elevational resolution is at the focal point of the beam. Far field (Fraunhofer zone) – The area of the sound beam that begins at the focal zone to include the diverging beam. Impedance – Resistance of tissue to the transmission of sound. Measured in Rayls, each tissue type has a different impedance.   Lateral resolution (azimuthal resolution) – The ability of the system to separate reflectors perpendicular to the ultrasound beam. The best lateral resolution is at the focal point of the beam.   Near field (Fresnel zone) – The area of the sound beam from the transducer face to the focal zone.   Piezoelectric effect – The conversion of electricity to sound and vice versa.   Polarization – Aligning the magnetic poles (positive and negative) of a material.   Pulse repetition frequency (PRF) – How many pulses per second a system sends into the body.   Ring down time – The time it takes for a vibrating piezoelectric crystal to decrease to a insignificant level.   Slice thickness – The thickness of the ultrasound beam.   Slice thickness artifact – The production of low-level echoes within a cystic structure due to the interaction of the ultrasound beam.   Side lobes – Portions of the ultrasound beam that extend from the central beam that result in misregistration of the returning signal. Transducer (also called a probe or scanhead) – a part of the ultrasound system that contains the acoustic lens, matching layer, piezoelectric element, backing material and associate electronics within a case.   Wavelength – The distance between the highest or lowest points of a sound wave. Click ◄ for previous page                                                                              Click ► to continue   Internal components include the acoustic lens, which helps to focus the sound beam, a shield layer, the matching layer, grounding foil, piezoelectric element, and the backing materials. Lamination of these layers creates the transducer ‘stack’. Congratulations! You have completed the Transducer Construction, Care and Damage Online Training course. Listed below are the key points that have been presented. Take time to review the material before you proceed to the final quiz.     Download and print a copy of the Course Review. In this tutorial you have learned to: Identify the internal and external components of the transducer, Generalize the importance of transducer components to image resolution, Describe the piezoelectric effect, Explain the difference between detail (axial and lateral), contrast, temporal, and elevational resolution, and Describe external transducer damage. Earlier in this tutorial we learned that the piezoelectric crystal generates sound by changing shape with applied pressure whether electrical or sound waves.  This expansion and contraction of the crystal results in the creation of sound waves into the body or an electrical signal when a signal returns from the body.  This property of the piezoelectric crystal is called the piezoelectric effect.1   Originally, diagnostic ultrasound transducers contained piezoelectric materials, such as quartz and tourmaline.8  Modern day transducers are more likely to be a piezo-composite of lead zirconate titanate or PZT and a non-piezoelectric polymer.1 This type of construction results in a lighter weight crystal due to the alternating rods of crystal and polymer.17, 18 Did you know that a kerf is the space between the piezoelectric rods?17, 18 Click on the information icon for a photograph of the rod / matrix configuration. Learn More about Construction Learn More about Construction   Epoxy Matrix   This image shows the rod / matrix configuration of a high-density (HD) piezoelectric element.  These HD arrays, often described as having a fine pitch, have smaller rods, increasing the number of elements used to create the image. As a result, there is an improvement in color sensitivity, image detail and contrast resolution as well as the ability to increase compounding of the image. PZT Rod Amin Hanafy designed and developed the transducer array known as the Hanafy lens. Originally intended to increase transducer bandwidth for use in contrast imaging, the Hanafy lens, provides focusing on the elevation plane of the ultrasound beam.  Additionally, the array configuration allows for transmission of a high-frequency signal at the center with lower frequencies with the thicker, outer crystals.20   Click on the information icon for more information on the Hanafy Lens.   Learn More about the Hanafy Lens Learn More about the Hanafy Lens Tab TitleTextTransducer Stack   Referred to as a ‘stack’ the Hanafy lens includes multiple laminated matching layers, and an overlying external lens. We learned earlier that matching layer thickness is one-quarter of the wavelength.9, 10 Since the Hanafy lens produces a broad range of frequencies due to the different crystal thicknesses, there is a matching layer for each frequency (yellow and orange layers).  The gray area in this diagram represents an area filled with either inert material or additional focusing lenses.Slice ThicknessThe perpendicular elevation plane (z-plane) determines the slice thickness of the ultrasound beam.21 The left graphic demonstrates the elevation plane with a traditional linear transducer array.  This plane corresponds to the thickness of the transducer (right graphic; yellow arrow) demonstrated on the 18L6 HD transducer that uses the Hanafy lens.   To understand the importance of configuring the transducer array with different thicknesses, we must remember some basic ultrasound principles.  Higher frequency transducers provide higher resolution images with less penetration.  The opposite is true of the low frequency transducers; there is more penetration but less detail.  The Hanafy lens stack uses the thinner central crystals to transmit the high frequency signal and the thicker outer crystals to transmit the lower frequency increasing the bandwidth and narrowing the slice thickness of the beam.20, 22   The clinical benefits of a transducer with a Hanafy lens stack includes a broad bandwidth,22 a narrow slice thickness12 which results in a reduction of slice thickness (also known as partial volume) artifacts,24 and increased elevational detail20 due to a uniform elevation plane.23 Click on the information icon to view additional explanations.   Learn More about Element Thickness Learn More about Element Thickness Tab TitleTextFrequency Effects High frequency focus Medium frequency focus Low frequency focus  Composite Changing the transmitted frequency also affects the natural focus or aperture.  A higher frequency focuses closer to the transducer and the lower frequency focuses further from the transducer. Called a variable aperture the result is a narrower beam width.1 In this diagram, you see the focal zone (yellow arrowheads) depth changes with frequency differences due to the transducer stack.  The resulting beam (composite) has a longer focal zone. 1Slice Thickness Artifact   This is an image of a tissue phantom, obtained during the pre-release research phase, using conventional, fixed aperture focusing (left) and the dynamic aperture (Hanafy lens) array (right). A slice thickness artifact appears as a filling of a cystic structure due to side lobes (left; arrowhead).1 The beam profile demonstrates side lobes (left; blue); however, focusing the beam eliminates or reduces this artifact (right). Ceramic composite crystals need polarization, as the materials are not piezoelectric naturally. The molecules have a weak positive and negative charge, which is a dipole.12 Placing the crystal in a strong electrical current when at a high temperature results in the creation of piezoelectric capabilities. A temperature in excess of 365 degrees Celsius, the Curie temperature, allows the positive and negative poles in the crystal molecules to align when the current passes through.  The placement of charged plates, either negative or positive, cause the molecules to orient with the charge.12  As the electrical current passes through the crystal, the positive and negative sides align in a process called polarization.1, 8   Important! Heat and steam sterilization of a transducer risks depolarization of the crystal due to excessive heat.  Though usually below the Curie temperature, steam is at 121 – 132 degrees Fahrenheit,19 damage occurs to not only the crystal but also other transducer materials.8 Important! Use only sterilization processes outlined in the ultrasound User Manual. Learn More about Polarization Learn More about Polarization Instructions:Flash File:/content/generator/Course_90016939/SWF_SI3121ULTRATransducerInteraction1_20160920/interactive_03.swfHTML5 File:/content/generator/Course_90016939/HTML5_SI3121ULTRATransducerInteraction1_20160920/index.htmlPDF File: We have talked about three types of resolution: axial, lateral, and elevational.  Two other types, spatial and temporal, become important when imaging moving structures such as the heart. Temporal resolution depends more on system parameters than on the design of the transducer. Dependent on lateral and axial resolution, spatial resolution, is a combination of transducer and sonographer dependent selections. This table provides a summary of resolution types.  Take a few moments to review the material. Create your own transducer! Create Your Own Transducer! Instructions:Flash File:/content/generator/Course_90016939/interactive_2Rev2/interactive_2Rev2.swfHTML5 File:/content/generator/Course_90016939/interactive_2Rev2/index.htmlPDF File: Resolution Review Learn More about Resolution Resolution  Definition System Component Optimization Temporal The ability to display anatomy in the correct location over time Pulse repetition frequency (PRF) High frame rate (above 25 frames per second) Decrease depth System refresh rate Decrease focal zones Decrease image width Spatial The ability to display anatomy at different locations in space Combination of lateral and axial resolution See axial and lateral resolution Axial The ability to display separate structures parallel to the ultrasound beam Transducer backing material Increase transducer frequency PZT thickness Lateral The ability to display separate structures perpendicular to the ultrasound beam.  Transducer lens (decrease beam width) Use the shallowest depth possible Place area of interest in the focal zone Increase transducer frequency Transducer PZT thickness Use the lowest gain setting necessary for a diagnostic image Line density Decrease image width Elevational Detail of cystic structures on the thickness of the ultrasound beam Transducer PZT width Focus on the elevation plane (Hanafy lens) Methods to increase resolution.1, 7, 8, 12 Please note that the learning material is for training purposes only!   For the proper use of the software or hardware, please always use the Operator Manual or Instructions for Use (hereinafter collectively “Operator Manual”) issued by Siemens Healthineers. This material is to be used as training material only and shall by no means substitute the Operator Manual. Any material used in this training will not be updated on a regular basis and does not necessarily reflect the latest version of the software and hardware available at the time of the training.   The Operator Manual shall be used as your main reference, in particular for relevant safety information like warnings and cautions. Note: Some functions shown in this material are optional and might not be part of your system. The information in this material contains general technical descriptions of specifications and options as well as standard and optional features that do not always have to be present in individual cases.   Certain products, product related claims or functionalities described in the material (hereinafter collectively “Functionality”) may not (yet) be commercially available in your country. Due to regulatory requirements, the future availability of said Functionalities in any specific country is not guaranteed. Please contact your local Siemens Healthineers sales representative for the most current information. The reproduction, transmission or distribution of this training or its contents is not permitted without express written authority. Offenders will be liable for damages.   All names and data of patients, parameters and configuration dependent designations are fictional and examples only. All rights, including rights created by patent grant or registration of a utility model or design, are reserved. Copyright © Siemens Healthcare GmbH, 2018 Selecting the ► continues this course and confirms you have read and understand this disclaimer.