The document discusses general-purpose ultrasound scanners used in hospitals. It describes the key components of an ultrasound system including the transducer probe, ultrasound monitor, and image storage system. It explains the imaging principles of ultrasound, how ultrasound waves are transmitted and reflected at tissue interfaces depending on acoustic impedance, and how the reflected echoes are used to generate images. It also outlines different types of ultrasound scanners and transducers as well as imaging modes.
Ultrasound imaging uses high-frequency sound waves to visualize internal structures. The document discusses the history and physics of ultrasound, how ultrasound machines work, and applications of ultrasound imaging. It provides details on how ultrasound transducers produce and receive sound waves, and how echo signals are processed to form images. Common uses of ultrasound include obstetrics, cardiology, and abdominal imaging. The future of ultrasound includes higher resolution 3D and 4D imaging.
This document discusses the physical principles of ultrasound used in medical imaging. It defines key terms like frequency, wavelength, attenuation and resolution. It describes how piezoelectric transducers convert electrical pulses to ultrasound pulses and echoes. It explains how sector and linear array transducers work and the different display modes. It also discusses artifacts and the safety of diagnostic medical ultrasound.
This document summarizes the history and technology of multi-slice CT scanning. It describes the evolution from 4-slice to 16-slice machines beginning in 1999. The main components of CT scanners are identified as the generator, X-ray tube, and solid state detector. Multi-slice CT provides advantages over single-slice machines such as improved spatial resolution, reduced motion artifacts, and the ability to image larger volumes more quickly using less contrast medium and radiation dose. New detector technologies like the stellar detector provide ultra-thin slices with high resolution at low radiation doses.
Ultrasound uses high frequency sound waves to generate images of the inside of the body without using ionizing radiation. It works by transmitting sound wave pulses into the body from a probe, detecting the echoes returning from tissue boundaries, and processing and displaying the images on a screen. Ultrasound gel is used between the probe and skin to allow for tight contact and transmission of the waves. Doppler ultrasound can detect the speed and direction of moving structures like blood cells by measuring the change in frequency of returning echoes. The images can display flow information in color or measure concentration and velocity.
This document discusses different types of ultrasound transducers and systems. It describes linear array, sector, and vector array transducers. It also discusses mechanical transducers, electronically steered systems, and phased array transducers. Finally, it outlines several specialized ultrasound transducers including those used for small parts, endocavity, transesophageal, transluminal, and intracardiac applications.
This document provides an overview of ultrasound physics basics. It discusses how ultrasound uses sound waves between 10-20 MHz to generate images. Sound waves are longitudinal waves that travel through materials at different speeds depending on compressibility and density. Ultrasound imaging works by transmitting pulses into the body and receiving echoes, with transducers converting between electrical and sound signals. Factors like frequency, beam characteristics, and tissue interactions impact the resulting images and potential artifacts. Understanding ultrasound physics principles is important for optimizing scans and interpreting images.
The document discusses ultrasound technology including its history, basic principles, imaging modes, transducer types, and diagnostic applications. It provides details on how ultrasound works by sending sound waves into the body and analyzing the echoes. Key points covered include pulse echo imaging, Doppler imaging, resolution, propagation of ultrasound in tissue, and common ultrasound machines and transducer types.
Ultrasound imaging uses high-frequency sound waves to visualize internal structures. The document discusses the history and physics of ultrasound, how ultrasound machines work, and applications of ultrasound imaging. It provides details on how ultrasound transducers produce and receive sound waves, and how echo signals are processed to form images. Common uses of ultrasound include obstetrics, cardiology, and abdominal imaging. The future of ultrasound includes higher resolution 3D and 4D imaging.
This document discusses the physical principles of ultrasound used in medical imaging. It defines key terms like frequency, wavelength, attenuation and resolution. It describes how piezoelectric transducers convert electrical pulses to ultrasound pulses and echoes. It explains how sector and linear array transducers work and the different display modes. It also discusses artifacts and the safety of diagnostic medical ultrasound.
This document summarizes the history and technology of multi-slice CT scanning. It describes the evolution from 4-slice to 16-slice machines beginning in 1999. The main components of CT scanners are identified as the generator, X-ray tube, and solid state detector. Multi-slice CT provides advantages over single-slice machines such as improved spatial resolution, reduced motion artifacts, and the ability to image larger volumes more quickly using less contrast medium and radiation dose. New detector technologies like the stellar detector provide ultra-thin slices with high resolution at low radiation doses.
Ultrasound uses high frequency sound waves to generate images of the inside of the body without using ionizing radiation. It works by transmitting sound wave pulses into the body from a probe, detecting the echoes returning from tissue boundaries, and processing and displaying the images on a screen. Ultrasound gel is used between the probe and skin to allow for tight contact and transmission of the waves. Doppler ultrasound can detect the speed and direction of moving structures like blood cells by measuring the change in frequency of returning echoes. The images can display flow information in color or measure concentration and velocity.
This document discusses different types of ultrasound transducers and systems. It describes linear array, sector, and vector array transducers. It also discusses mechanical transducers, electronically steered systems, and phased array transducers. Finally, it outlines several specialized ultrasound transducers including those used for small parts, endocavity, transesophageal, transluminal, and intracardiac applications.
This document provides an overview of ultrasound physics basics. It discusses how ultrasound uses sound waves between 10-20 MHz to generate images. Sound waves are longitudinal waves that travel through materials at different speeds depending on compressibility and density. Ultrasound imaging works by transmitting pulses into the body and receiving echoes, with transducers converting between electrical and sound signals. Factors like frequency, beam characteristics, and tissue interactions impact the resulting images and potential artifacts. Understanding ultrasound physics principles is important for optimizing scans and interpreting images.
The document discusses ultrasound technology including its history, basic principles, imaging modes, transducer types, and diagnostic applications. It provides details on how ultrasound works by sending sound waves into the body and analyzing the echoes. Key points covered include pulse echo imaging, Doppler imaging, resolution, propagation of ultrasound in tissue, and common ultrasound machines and transducer types.
This document provides an overview of ultrasound imaging. It discusses how ultrasound is used in various medical specialties like internal medicine, radiology, surgery, and cardiology for diagnostic and therapeutic purposes. It explains the basic physics behind ultrasound including sound waves, transducers, interaction with tissues, and Doppler imaging. Modes of ultrasound like A-mode, B-mode, and M-mode are described. Clinical applications of ultrasound in areas like abdomen, superficial structures, gynecology, obstetrics, and neonatology are covered. Different types of ultrasound probes are also mentioned.
Usg transducer and basic principles of ultrasound Doppler, this slide describe the basic physics of ultrasound transducer and Doppler , must know thing is given in this presentaion. Good review for radiology resident. Thanks.
Fluoroscopy is a form of real-time radiographic imaging used to guide procedures. It was invented in 1896 by Thomas Edison. Modern fluoroscopy uses image intensifiers or flat panel detectors to convert x-rays into visible light images. Digital systems have replaced conventional film-based fluoroscopy. Fluoroscopy provides real-time imaging but also exposes patients and staff to radiation, so dose reduction techniques must be used such as automatic brightness control, collimating to the area of interest, and minimizing unnecessary images and magnification.
An ultrasound uses sound waves to examine organs and abnormalities inside the body. It has various clinical applications in areas like cardiology, obstetrics, and neurology. The document discusses the physical principles of ultrasound including how sound waves propagate as longitudinal waves, and how an ultrasound machine works using components like a transducer, receiver, and display to produce images. It explains techniques like Doppler effect and how ultrasounds are used in different medical specialties to diagnose conditions.
This document provides an overview of ultrasound diagnostics and various ultrasound imaging techniques. It begins with a brief history of ultrasound diagnostics and outlines common ultrasound modalities including ultrasonography (A, B, and M modes), Doppler flow measurement, tissue Doppler imaging, and ultrasound densitometry. The document then discusses physical properties of ultrasound, acoustic parameters of tissues, and interactions of ultrasound with tissues. It provides details on various ultrasound imaging modes and techniques such as B-mode, M-mode, harmonic imaging, and 3D imaging. The document also covers Doppler blood flow measurement principles and different Doppler methods including duplex, color Doppler, and triplex.
Ultrasound machines use high-frequency sound waves to safely produce images of internal organs and tissues without using harmful radiation. The machines emit ultrasound pulses that bounce off tissues and are detected to generate live images on a screen. While initially used mainly for obstetric imaging, ultrasound is now widely used by doctors to examine many organs and guide procedures, making it a highly cost-effective diagnostic tool. When operated by trained technicians, ultrasound is considered very safe due to its non-ionizing pulses and short exposure times.
The MRI machine contains a large bore that holds several important components, including a powerful magnet. The magnet, which is usually a superconducting magnet, generates a strong and uniform magnetic field around the patient. Gradient coils are also used to distort the field during imaging. RF coils transmit signals to and receive signals from the patient's tissues to produce images. MRI can be used to image both anatomy and physiology, and is particularly useful for visualizing soft tissues and internal organs in 3D without exposing the patient to radiation.
1. Single slice CT acquires one slice at a time requiring longer acquisition times, while multi-slice CT acquires multiple slices per rotation allowing a larger volume to be scanned more quickly with less motion artifacts.
2. Multi-slice CT uses a detector array segmented in the z-axis to acquire multiple slices simultaneously, while single slice CT uses a long narrow detector array. This allows multi-slice CT to reconstruct images at various thicknesses and intervals.
3. Applications of multi-slice CT include faster whole organ and cardiac imaging, virtual endoscopy, isotropic imaging, and CT angiography due to its ability to acquire multiple slices simultaneously in a shorter time period.
Computed tomography (CT) uses computer-processed X-rays to create cross-sectional images of the body. CT works by rotating an X-ray tube and detectors around the patient, acquiring multiple transmission measurements at different angles to reconstruct a 3D image. Image reconstruction involves algorithms like back projection and filtered back projection that use the transmission data to calculate the attenuation coefficients of different tissues and generate tomographic images representing slices of the body. CT numbers, measured in Hounsfield units, provide standardized values related to tissue density and visibility.
Quality Assurance Programme in Computed TomographyRamzee Small
Introduction to Computed Tomography
Basic description of the components of a CT System
Introduction to Quality Assurance
Quality Assurance and Quality Control Tests in Computed Tomography base on frequency
Objective of QA/QC Test
This document discusses ultrasound transducers and resolution. It begins by describing how ultrasound is produced and detected using a transducer composed of piezoelectric elements. Over time, transducers have evolved from single elements to arrays with hundreds of individual elements. The key components of a basic transducer are then outlined. The remainder of the document provides detailed explanations of piezoelectric materials, resonance transducers, damping blocks, matching layers, and the properties of transducer arrays including linear arrays and phased arrays. Beam properties such as the near field and far field are also defined.
Digital fluoroscopy is most commonly configured as a conventional fluoroscopy system where the analog video signal is converted to digital format via an analog-to-digital converter. Alternatively, digitization can be done with a digital video camera or direct capture of x-rays with a flat panel detector. Digital fluoroscopy systems allow for digital image recording and processing using techniques like frame averaging and edge enhancement. Radiation protection for patients and staff is important for digital fluoroscopy and techniques like collimation, minimum source-to-skin distance, and lead shielding help reduce exposure.
This document discusses CT image acquisition. It describes how CT scanners work, including the components of a CT scanner like the x-ray tube and detector array. It explains the image acquisition process, from x-ray generation to data collection and processing, and image reconstruction. Key steps include positioning the patient, rotating the x-ray tube, acquiring data projections from different angles, converting analog signals to digital, reconstructing images from the data using algorithms. The document provides an overview of the CT imaging process.
The gantry assembly contains the x-ray tube and detectors that generate and detect x-rays, as well as the patient support and positioning equipment. There are two main types of detectors: scintillation detectors that use materials like sodium iodide and gas filled detectors that use gases like xenon and krypton. The data acquisition system converts the detected x-ray signals into digital images that are processed and reconstructed into scans by computer software. The operating console is used by the technician and physician to control the scan settings and movement of the patient.
Ultrasound Physics Made easy - By Dr Chandni WadhwaniChandni Wadhwani
History of ultrasound, Principle of Ultrasound.
Ultrasound wave and its interactions
Ultrasound machine and its parts, Image display, Artifacts and their clinical importance
what is Doppler ultrasound, Elastography and Recent advances in field of ultrasound.
Safety issues in ultrasound.
1. Ultrasound uses high frequency sound waves and their echoes to produce medical images of the inside of the body. 2. The ultrasound machine transmits sound pulses into the body using a probe, which detects the echoes reflected back from tissues and organs. 3. By measuring the time it takes for the echoes to return, the machine can calculate distances to internal structures and display a 2D image on the screen based on the intensities of the echoes.
This document discusses the interaction of ultrasound with matter. It explains that ultrasound reflections, refractions, absorptions, and scatterings are determined by the acoustic properties of tissues. Reflection is the most important interaction for generating ultrasound images. Reflection depends on the acoustic impedance at tissue interfaces, which is determined by density and sound velocity. Differences in acoustic impedance between tissues result in more reflection. Absorption converts ultrasound to heat as it passes through tissues. Scattering results in weaker, diffuse reflections that degrade image quality. Refraction bends ultrasound beams at tissue boundaries based on changes in sound speed. The effects of these interactions are important for ultrasound imaging.
This document discusses various applications of 4D technology including 4D cinema, games, buildings, ultrasound, and a virtual human caveman project. 4D cinema combines 3D movies with physical effects like movement and smells. 4D ultrasound provides 4D images of a fetus over time. The caveman project aims to create virtual maps integrating medical data about diseases with a digital human body atlas.
Basic physics of multidetector computed tomography ( CT Scan) - how ct scan works, different generations of ct, how image is generated and displayed and image artifacts related to CT Scan.
Learn from our Slideshare about the differences between ultrasound transducers. We also cover tips on how to treat your probes and how to select the right one.
A short description of the brain scanning method: electroencephalogram. In addition o the basic method, the slideshow also briefly describes the techniques strengths and weaknesses compared to other brain scanning techniques.
The document provides an overview of basic echocardiography techniques and measurements. It discusses how ultrasound is used to create 2D and Doppler images of the heart. Key metrics for assessing the left ventricle, valves, and other structures are defined. Case studies demonstrate how echocardiography is used to diagnose various conditions like mitral stenosis and evaluate their severity.
This document provides an overview of ultrasound imaging. It discusses how ultrasound is used in various medical specialties like internal medicine, radiology, surgery, and cardiology for diagnostic and therapeutic purposes. It explains the basic physics behind ultrasound including sound waves, transducers, interaction with tissues, and Doppler imaging. Modes of ultrasound like A-mode, B-mode, and M-mode are described. Clinical applications of ultrasound in areas like abdomen, superficial structures, gynecology, obstetrics, and neonatology are covered. Different types of ultrasound probes are also mentioned.
Usg transducer and basic principles of ultrasound Doppler, this slide describe the basic physics of ultrasound transducer and Doppler , must know thing is given in this presentaion. Good review for radiology resident. Thanks.
Fluoroscopy is a form of real-time radiographic imaging used to guide procedures. It was invented in 1896 by Thomas Edison. Modern fluoroscopy uses image intensifiers or flat panel detectors to convert x-rays into visible light images. Digital systems have replaced conventional film-based fluoroscopy. Fluoroscopy provides real-time imaging but also exposes patients and staff to radiation, so dose reduction techniques must be used such as automatic brightness control, collimating to the area of interest, and minimizing unnecessary images and magnification.
An ultrasound uses sound waves to examine organs and abnormalities inside the body. It has various clinical applications in areas like cardiology, obstetrics, and neurology. The document discusses the physical principles of ultrasound including how sound waves propagate as longitudinal waves, and how an ultrasound machine works using components like a transducer, receiver, and display to produce images. It explains techniques like Doppler effect and how ultrasounds are used in different medical specialties to diagnose conditions.
This document provides an overview of ultrasound diagnostics and various ultrasound imaging techniques. It begins with a brief history of ultrasound diagnostics and outlines common ultrasound modalities including ultrasonography (A, B, and M modes), Doppler flow measurement, tissue Doppler imaging, and ultrasound densitometry. The document then discusses physical properties of ultrasound, acoustic parameters of tissues, and interactions of ultrasound with tissues. It provides details on various ultrasound imaging modes and techniques such as B-mode, M-mode, harmonic imaging, and 3D imaging. The document also covers Doppler blood flow measurement principles and different Doppler methods including duplex, color Doppler, and triplex.
Ultrasound machines use high-frequency sound waves to safely produce images of internal organs and tissues without using harmful radiation. The machines emit ultrasound pulses that bounce off tissues and are detected to generate live images on a screen. While initially used mainly for obstetric imaging, ultrasound is now widely used by doctors to examine many organs and guide procedures, making it a highly cost-effective diagnostic tool. When operated by trained technicians, ultrasound is considered very safe due to its non-ionizing pulses and short exposure times.
The MRI machine contains a large bore that holds several important components, including a powerful magnet. The magnet, which is usually a superconducting magnet, generates a strong and uniform magnetic field around the patient. Gradient coils are also used to distort the field during imaging. RF coils transmit signals to and receive signals from the patient's tissues to produce images. MRI can be used to image both anatomy and physiology, and is particularly useful for visualizing soft tissues and internal organs in 3D without exposing the patient to radiation.
1. Single slice CT acquires one slice at a time requiring longer acquisition times, while multi-slice CT acquires multiple slices per rotation allowing a larger volume to be scanned more quickly with less motion artifacts.
2. Multi-slice CT uses a detector array segmented in the z-axis to acquire multiple slices simultaneously, while single slice CT uses a long narrow detector array. This allows multi-slice CT to reconstruct images at various thicknesses and intervals.
3. Applications of multi-slice CT include faster whole organ and cardiac imaging, virtual endoscopy, isotropic imaging, and CT angiography due to its ability to acquire multiple slices simultaneously in a shorter time period.
Computed tomography (CT) uses computer-processed X-rays to create cross-sectional images of the body. CT works by rotating an X-ray tube and detectors around the patient, acquiring multiple transmission measurements at different angles to reconstruct a 3D image. Image reconstruction involves algorithms like back projection and filtered back projection that use the transmission data to calculate the attenuation coefficients of different tissues and generate tomographic images representing slices of the body. CT numbers, measured in Hounsfield units, provide standardized values related to tissue density and visibility.
Quality Assurance Programme in Computed TomographyRamzee Small
Introduction to Computed Tomography
Basic description of the components of a CT System
Introduction to Quality Assurance
Quality Assurance and Quality Control Tests in Computed Tomography base on frequency
Objective of QA/QC Test
This document discusses ultrasound transducers and resolution. It begins by describing how ultrasound is produced and detected using a transducer composed of piezoelectric elements. Over time, transducers have evolved from single elements to arrays with hundreds of individual elements. The key components of a basic transducer are then outlined. The remainder of the document provides detailed explanations of piezoelectric materials, resonance transducers, damping blocks, matching layers, and the properties of transducer arrays including linear arrays and phased arrays. Beam properties such as the near field and far field are also defined.
Digital fluoroscopy is most commonly configured as a conventional fluoroscopy system where the analog video signal is converted to digital format via an analog-to-digital converter. Alternatively, digitization can be done with a digital video camera or direct capture of x-rays with a flat panel detector. Digital fluoroscopy systems allow for digital image recording and processing using techniques like frame averaging and edge enhancement. Radiation protection for patients and staff is important for digital fluoroscopy and techniques like collimation, minimum source-to-skin distance, and lead shielding help reduce exposure.
This document discusses CT image acquisition. It describes how CT scanners work, including the components of a CT scanner like the x-ray tube and detector array. It explains the image acquisition process, from x-ray generation to data collection and processing, and image reconstruction. Key steps include positioning the patient, rotating the x-ray tube, acquiring data projections from different angles, converting analog signals to digital, reconstructing images from the data using algorithms. The document provides an overview of the CT imaging process.
The gantry assembly contains the x-ray tube and detectors that generate and detect x-rays, as well as the patient support and positioning equipment. There are two main types of detectors: scintillation detectors that use materials like sodium iodide and gas filled detectors that use gases like xenon and krypton. The data acquisition system converts the detected x-ray signals into digital images that are processed and reconstructed into scans by computer software. The operating console is used by the technician and physician to control the scan settings and movement of the patient.
Ultrasound Physics Made easy - By Dr Chandni WadhwaniChandni Wadhwani
History of ultrasound, Principle of Ultrasound.
Ultrasound wave and its interactions
Ultrasound machine and its parts, Image display, Artifacts and their clinical importance
what is Doppler ultrasound, Elastography and Recent advances in field of ultrasound.
Safety issues in ultrasound.
1. Ultrasound uses high frequency sound waves and their echoes to produce medical images of the inside of the body. 2. The ultrasound machine transmits sound pulses into the body using a probe, which detects the echoes reflected back from tissues and organs. 3. By measuring the time it takes for the echoes to return, the machine can calculate distances to internal structures and display a 2D image on the screen based on the intensities of the echoes.
This document discusses the interaction of ultrasound with matter. It explains that ultrasound reflections, refractions, absorptions, and scatterings are determined by the acoustic properties of tissues. Reflection is the most important interaction for generating ultrasound images. Reflection depends on the acoustic impedance at tissue interfaces, which is determined by density and sound velocity. Differences in acoustic impedance between tissues result in more reflection. Absorption converts ultrasound to heat as it passes through tissues. Scattering results in weaker, diffuse reflections that degrade image quality. Refraction bends ultrasound beams at tissue boundaries based on changes in sound speed. The effects of these interactions are important for ultrasound imaging.
This document discusses various applications of 4D technology including 4D cinema, games, buildings, ultrasound, and a virtual human caveman project. 4D cinema combines 3D movies with physical effects like movement and smells. 4D ultrasound provides 4D images of a fetus over time. The caveman project aims to create virtual maps integrating medical data about diseases with a digital human body atlas.
Basic physics of multidetector computed tomography ( CT Scan) - how ct scan works, different generations of ct, how image is generated and displayed and image artifacts related to CT Scan.
Learn from our Slideshare about the differences between ultrasound transducers. We also cover tips on how to treat your probes and how to select the right one.
A short description of the brain scanning method: electroencephalogram. In addition o the basic method, the slideshow also briefly describes the techniques strengths and weaknesses compared to other brain scanning techniques.
The document provides an overview of basic echocardiography techniques and measurements. It discusses how ultrasound is used to create 2D and Doppler images of the heart. Key metrics for assessing the left ventricle, valves, and other structures are defined. Case studies demonstrate how echocardiography is used to diagnose various conditions like mitral stenosis and evaluate their severity.
This document discusses arrhythmias, which are abnormalities in the heart's rhythm. Arrhythmias can be too fast (tachycardia) or too slow (bradycardia) and can occur in the heart's upper chambers (atria) or lower chambers (ventricles). While some arrhythmias are not life-threatening, others can cause cardiac arrest or sudden death. The causes of arrhythmias include physical conditions, heart disease, other systemic diseases, electrolyte imbalances, and toxins. Diagnosis involves tests such as EKGs, Holter monitors, and stress tests. Treatment includes anti-arrhythmic drugs that block sodium, potassium, calcium, or beta channels, as well
The document discusses electroencephalography (EEG), which is a medical imaging technique that reads electrical activity in the brain using electrodes placed on the scalp. An EEG machine consists of electrodes, amplifiers, filters, and a recording unit. EEGs are used to diagnose epilepsy, monitor brain activity during anesthesia, and investigate sleep disorders. The document describes the components of an EEG machine and preparation of patients for EEG recording. It also explains the different types of brain waves - beta, alpha, theta, and delta - that are analyzed during EEG interpretation.
This document provides a high-level overview of cardiac electrophysiology and EKG interpretation. It discusses the different types of cardiac cells, the cardiac action potential, and the phases of the cardiac cycle. It describes how electrical signals travel through the heart via specialized conduction pathways, and explains common EKG complexes and intervals like the P wave, QRS complex, and ST segment. Key concepts covered include the roles of the sinoatrial node, atrioventricular node, and Purkinje fibers in cardiac conduction.
Ultrasonography uses high frequency sound waves to non-invasively image soft tissues. It is used for both diagnostic purposes like organ imaging and measurement as well as therapeutic purposes like HIFU and lithotripsy. Ultrasound has a range above human hearing and most diagnostic instruments use 1-10 MHz. It provides greyscale images based on tissue density and is useful for visualizing soft tissue structures and blood flow.
Biomedical Image Processing
Topics covered: Biomedical imaging, Need of image processing in medicine, Principles of image processing, Components of image processing, Application of image processing in different medical imaging systems
On the occasion of National Epilepsy Day 2014, Dr. V Natarajan gave a talk titled "New Trends in Epilepsy Management" at the Epilepsy Knowledge Forum in Chennai organised by Neurokrish & Trimed and Sponsored Medall.
Hans Berger, a German psychiatrist, published the first paper on the human electroencephalogram (EEG) in 1924 after placing electrodes on the scalps of patients who had undergone brain surgery. An EEG detects and records the brain's electrical activity through electrodes attached to the scalp. It can help diagnose conditions like epilepsy, brain tumors, strokes, and sleep disorders. An EEG is a painless and safe test, but may cause minor scalp irritation in some cases. Proper preparation is important to get accurate results.
The document summarizes various techniques for measuring respiratory rate that were presented in a seminar. It discusses methods using piezoelectric sensors, laser Doppler vibrometry, pyroelectric sensors, impedance pneumography, capnometry, and photoplethysmography. Piezoelectric sensors directly measure electric potential changes from respiratory airflow. Laser Doppler vibrometry allows non-contact measurement of vibrations on the chest from respiration. Pyroelectric films can also detect temperature differences from breathing. The document provides examples of systems using these techniques and concludes that respiratory monitoring using pyroelectric films is cost-effective.
The cardiac conduction system is made up of four main structures that stimulate contraction of the heart muscle in a coordinated way. The sinoatrial node acts as the pacemaker and initiates electrical impulses throughout the heart. The atrioventricular node receives impulses from the atria and slows conduction to allow for proper atrial contraction before ventricular contraction. Impulses then travel through the atrioventricular bundle and Purkinje fibers to coordinate simultaneous contraction of the ventricles. An electrocardiogram is used to measure the electrical activity of the heart and detect any abnormalities.
The document discusses the physics of ultrasound imaging, including an overview of acoustic waves, wave propagation equations, reflection and refraction of waves, Doppler effect, and the functioning of ultrasound transducers using piezoelectric crystals to generate and receive acoustic waves for medical imaging applications.
This document provides an overview of various types of arrhythmias including their typical presentation, underlying causes, characteristic ECG patterns, and treatment approaches. Key types are discussed such as sinus tachycardia, atrial fibrillation, various degrees of heart block, premature ventricular contractions, ventricular tachycardia, ventricular fibrillation, and asystole. For each, the rate, P wave, QRS complex, conduction, and rhythm are defined and potential causes and management strategies are outlined. The document serves as a guide for clinicians in identifying and treating different cardiac arrhythmias.
Cardiac arrhythmias are abnormalities in the heart's rhythm that can cause symptoms ranging from palpitations to sudden death. The two main types are bradycardias, which are slow heart rates below 60 bpm, and tachycardias, which are fast heart rates over 100 bpm. Arrhythmias can arise from problems in the sinus node, atria, AV junction, or ventricles due to issues with automaticity or re-entry of electrical impulses. Common arrhythmias include sinus tachycardia/bradycardia, premature beats, atrial fibrillation, and heart blocks. Treatment depends on the specific arrhythmia and symptoms but may include lifestyle changes, medications
Ultrasound uses high frequency sound waves to visualize internal structures. It works by transmitting sound waves into the body using a transducer probe, which detects the echoes as they bounce off tissues and organs. The echoes are processed to form images on the ultrasound machine screen in real-time. Common applications include obstetrics, cardiology, and urology. The Philips HD11 is an ultrasound system with curvilinear, linear, and phased array probes for different exams. It provides grey scale, Doppler, and color imaging modes. Ultrasound has benefits of being non-invasive, portable, and having no radiation, but has limitations of being operator dependent and unable to penetrate bone.
Vector cardiography analyzes the electrical activity of the heart along three axes by obtaining an ECG, displaying the results as a vector cardiogram which produces loop patterns representing the distribution of electrical potential generated by the heart. It examines ECG potentials along three-dimensional x, y, and z axes of the body to determine the direction of atrial and ventricular depolarization and repolarization, detecting each electric heart vector component with equal sensitivity.
Ultrasound uses sound waves to produce images of internal organs and tissues. Sound waves are transmitted into the body and the echoes produced by reflections from structures and tissues are detected. Three key points:
1) Ultrasound transducers convert electrical pulses into sound waves which penetrate the body and receive the echoes. Piezoelectric crystals in the transducer perform this function.
2) Reflected sound waves are displayed as images on screen to visualize internal structures. The brightness of each pixel depends on the strength of reflection.
3) Different transducer designs like linear arrays and curved arrays allow imaging of different body regions. Imaging modes like B-mode show anatomical structures while M-mode depicts motion.
Electromyography (EMG) measures the electrical activity produced by muscle contractions. Surface EMG (sEMG) uses electrodes on the skin to detect muscle activation, while fine wire EMG inserts electrodes directly into muscles. EMG data provides information about muscle timing and activity during movements like gait, but does not indicate strength or type of movement. Proper electrode placement, skin preparation, and signal processing are needed to obtain accurate, repeatable EMG measurements.
The document provides an overview of electromyography (EMG). It begins by defining EMG as a technique for evaluating and recording muscle activation signals using an electromyograph. The electromyograph detects the electrical potentials generated by muscle cells during contraction and relaxation. It then discusses the history of EMG and describes the EMG signal and factors that can influence it. The document outlines the electrical characteristics of EMG signals and the procedures for EMG. It also discusses applications of EMG, different electrode types used, and general concerns regarding EMG signals.
Dynamic shoulder ultrasonography is a noninvasive and accurate method for evaluating the rotator cuff tendons that is less expensive and safer than other imaging options like MRI and arthrography. Advancements in ultrasound technology have made high resolution dynamic sonography a practical method for assessing conditions like rotator cuff tears, bursitis, and tendonitis. While ultrasound has limitations in evaluating some shoulder issues, it is over 90% sensitive and specific for diagnosing rotator cuff tears when used by skilled radiologists following dedicated protocols. The newsletter advocates for increased use of musculoskeletal sonography in diagnosing and treating painful shoulder conditions.
How high frequency ultrasound imaging is supporting preclinical research appl...Scintica Instrumentation
This free webinar hosted by Scintica Instrumentation introduced participants to some of the basics of high frequency ultrasound imaging and reviewed the most common preclinical research applications for this exciting technology. Our presenter, Ms. Tonya Coulthard, discussed the basic principles of ultrasound imaging, presented sample images from various organs and tissues as a way of surveying common research applications, and introduced a few novel techniques that will be of interest to many researchers. Throughout the webinar, technical information, product specifications and sample images where shown from the Prospect T1 compact, high-frequency, preclinical ultrasound imaging system.
This document lists various categories and types of medical equipment. The categories include electrocardiographics, laryngoscopes, patient monitors, vital signs devices, colposcopes, and more. Specific equipment listed includes electrocardiography devices, fiber optic laryngoscope blades and handles, pulse oximeters, vital signs monitors, video colposcopes, thermometers, blood pressure cuffs, and anesthetic gas monitors. The document provides brief descriptions and specifications for several pieces of medical equipment.
This document summarizes a new portable ultrasound device called the Signos RT. In 3 sentences:
The Signos RT is a low-cost ($5,500), portable ultrasound system that weighs just 300 grams and boots up in under 1 second, providing high quality imaging comparable to cart-based systems costing over $100,000. It is designed for point-of-care use by physicians in specialties like emergency medicine, obstetrics, and family practice to obtain rapid ultrasound scans. Feedback from medical professionals was very positive about the image quality and clinical utility of the Signos RT for a wide range of applications from trauma to obstetrics.
The Signos Personal Diagnostic Assistant is a palm-sized, affordable ultrasound device that allows for point-of-care diagnosis. It provides high-resolution imaging of acute pathology in multiple applications. The touchscreen device stores up to 10,000 images, has long battery life, and includes training and support. The Signos improves diagnostic accuracy and patient care through accessible ultrasound technology.
Ultrasound uses sound waves to create images of the inside of the body. It has several medical applications and advantages over other imaging methods. Ultrasound imaging can be used to examine many organs and tissues in the body, as well as to guide procedures. The appearance of structures in ultrasound images depends on how they reflect or transmit sound waves. While ultrasound has advantages like being noninvasive, painless, and avoiding radiation, it also has some limitations like not being able to image certain tissues well. Breast ultrasound is commonly used along with mammography to evaluate breast abnormalities.
Medical imaging is the technique and process of creating visual representations of the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology).
This document discusses various types of medical imaging technologies. It describes radiologic/x-ray technology, ultrasound technology, CT scans, MRI scans, and nuclear imaging including PET and SPECT. The goal of medical imaging is to non-invasively examine the inside of the body to diagnose health problems and guide treatment. Each technology has advantages for certain applications based on the type of information and depth of imaging it provides. Together these modalities provide physicians a variety of tools to accurately diagnose and monitor patient health issues.
This document discusses innovations in clinical security and mobility at hospitals in the Valencia region of Spain. It describes a solution using identification bracelets, mobile beacons, and a central server to locate and track patients and assets in real time. The system provides secure identification, effective tracking and analytics, and mobility of information. It has been implemented at the new Hospital La Fe in Valencia to guarantee clinical security for over 1,500 patients and 1,000 assets across its 260,000 square meter facility.
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Eigen strives to improve healthcare and quality of life through innovations in image-guided diagnosis and treatment of diseases.
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Ultrasound uses high-frequency sound waves to produce images of the inside of the body in real-time without using radiation. It is widely used due to its availability, low cost, speed, and ability to show internal structures and blood flow. Common uses include examining organs like the heart, liver, and kidneys, as well as guiding procedures, imaging breasts and blood vessels, and assessing fetal development in pregnancies. The procedure works by a transducer sending sound waves into the body and receiving echoes to create images based on the return signal.
Ultrasound imaging uses high-frequency sound waves to produce real-time images of the inside of the body without exposing the patient to radiation. It is a widely used and low-cost imaging method applied in areas like obstetrics, cardiology, and internal medicine. The document discusses how ultrasound works, describing how sound waves bounce off tissues and organs to create images, and Doppler ultrasound's use of the Doppler effect to evaluate blood flow. It outlines the procedure, equipment, advantages like safety and availability, and limitations like difficulty imaging air or bone.
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1. BME 5040 - MedicalInstrumentation in the Hospital
General-Purpose
Ultrasound Scanners
Mariana Hu
Linc Health
April 23, 2012
2. Outline
1. Introduction
2. System components
3. Imaging principles
4. Types of transducers
5. Imaging modes
6. Conclusion
3. Outline
1. Introduction
2. System components
3. Imaging principles
4. Types of transducers
5. Imaging modes
6. Conclusion
4. Introduction
• Ultrasound imaging utilizes the interaction of
high frequency sound waves with living tissue
to obtain an image of the tissue or to
determine the velocity of a moving tissue
• The dynamic, real-time images provide
quantitative structural and functional
information
5. Introduction
• General-Purpose
• abdominal
• obstetric/gynecologic
• small parts
• vascular
Types of Ultrasound
• Dedicated Cardiac
Scanners
•real-time, non-invasive imaging of
heart structures andfunctionality
• Dedicated Intravascular
• 360o cross sectional images of blood vessels
for diagnostic and therapeutic purposes
• Portable
• Compact and light weight to be
carried by hand between exams
6. Introduction
• General-Purpose
• abdominal
• obstetric/gynecologic
• small parts
• vascular
Types of Ultrasound
• Dedicated Cardiac
Scanners
•real-time, non-invasive imaging of
heart structures andfunctionality
• Dedicated Intravascular
• 360o cross sectional images of blood vessels
for diagnostic and therapeutic purposes
• Portable
• Compact and light weight to be
carried by hand between exams
7. Introduction
• General-Purpose
• abdominal
• obstetric/gynecologic
• small parts
• vascular
Types of Ultrasound
• Dedicated Cardiac
Scanners
•real-time, non-invasive imaging of
heart structures andfunctionality
• Dedicated Intravascular
• 360o cross sectional images of blood vessels
for diagnostic and therapeutic purposes
• Portable
• Compact and light weight to be
carried by hand between exams
8. Introduction
• General-Purpose
• abdominal
• obstetric/gynecologic
• small parts
• vascular
Types of Ultrasound
• Dedicated Cardiac
Scanners
•real-time, non-invasive imaging of
heart structures andfunctionality
• Dedicated Intravascular
• 360o cross sectional images of blood vessels
for diagnostic and therapeutic purposes
• Portable
• Compact and light weight to be
carried by hand between exams
9. Introduction
• General-Purpose
• abdominal
• obstetric/gynecologic
• small parts
• vascular
Types of Ultrasound
• Dedicated Cardiac
Scanners
•real-time, non-invasive imaging of
heart structures andfunctionality
• Dedicated Intravascular
• 360o cross sectional images of blood vessels
for diagnostic and therapeutic purposes
• Portable
• Compact and light weight to be
carried by hand between exams
10. Outline
1. Introduction
2. System components
3. Imaging principles
4. Types of transducers
5. Imaging modes
6. Conclusion
18. Outline
1. Introduction
2. System components
3. Imaging principles
4. Types of transducers
5. Imaging modes
6. Conclusion
19. Imaging Principles
• Ultrasound waves generated by a transducer are
transmitted through soft tissue relative to their
acoustic impedance
• Acoustic impedance:
Z = vxd
20. Imaging Principles
• Ultrasound waves generated by a transducer are
transmitted through soft tissue relative to their
acoustic impedance
• Acoustic impedance:
Z = vxd
Velocity of sound Tissue density
transmission
21. Imaging Principles
• Ultrasound waves generated by a transducer are
transmitted through soft tissue relative to their
acoustic impedance
• Acoustic impedance:
Z is primarily
a function of
the tissue
Z = vxd density
Velocity of sound Tissue density
transmission
Constant: 1540 m/s
22. Imaging Principles
• When two tissues with different densities are
located next to each other, the acoustic impedance
mismatch causes the sound waves to be reflected
• The transducer receives the reflections and converts
them into an electronic signal
• The image is created based on the signal amplitude
and frequency, and the time delay between the
transmitted pulse and its echo
23. Imaging Principles
• When two tissues with different densities are
located next to each other, the acoustic impedance
mismatch causes the sound waves to be reflected
• The transducer receives the reflections and converts
them into an electronic signal
• The image is created based on the signal
amplitudeand frequency, and the time delay
between the transmitted pulse and its echo a
The time delay is
measure of the
depth of the tissue
interface
24. Imaging Principles
The transducer continuously switches between transmit and receive modes
Probe Probe
Ultrasound Echo
Pulse Pulse
Interface
Penetrating
Ultrasound
Pulse
Transmit Mode Receive Mode
30. Types of Transducers
The transducer’s physical design and the technique of beam
generation determine the direction of the ultrasound beams
This, in turn, determines the shape of the image
31. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
32. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
33. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
34. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
35. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
36. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
37. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
38. Types of transducers
Types of
• Individual beams travel at the same
Images
angle, perpendicular to the transducer’s
scanning surface
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
39. Types of transducers
•Externally similar to linear array
transducers
Types of
• Electronic steering directs beams
Images
at an angle slanted relative to the
scanning surface.
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
40. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
41. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
42. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
43. Types of transducers
Types of
Images • Curved surface
• Emission of beams at different angles
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
44. Types of transducers
Types of
Images • Smaller footprint
• Imaging in tight areas or behind
obstructions
Rectangular Sector
Steered Micro
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
45. Types of transducers
• Flat and small
• Even narrower in the near field
Types of
Images
• Electronic steering directs beams at
different angles
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
46. Types of transducers
• Electronic steering directs beams at
different angles
Types of
ImagesLarger scanning surface
•
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
47. Types of transducers
Types of
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
48. Types of transducers
Types of Endocavity transducers
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
49. Types of transducers
Endovaginal
Types of Endocavity transducers
Images
Rectangular Sector
Steered
Linear Array Convex Array Phased Array Vector Array
Linear Array
Transducer Transducer Transducer Transducer
Transducer
50. Outline
1. Introduction
2. System components
3. Imaging principles
4. Types of transducers
5. Imaging modes
6. Conclusion
51. Imaging modes
• B-Mode
• M-Mode
• Harmonic
• Doppler
– Spectral
– Color Flow Mapping
– Color Power
52. Imaging modes
• B-Mode
• M-Mode
• Harmonic
• Doppler
– Spectral
– Color Flow Mapping
– Color Power
54. Imaging modes
• B-Mode Brightness Mode
– Shows the signal amplitude as the brightness of a point
– An array of transducers scan a plane through the body
simultaneously
55. Imaging modes
• B-Mode Brightness Mode
– Shows the signal amplitude as the brightness of a point
– An array of transducers scan a plane through the body
simultaneously
– Real-time, 2-D image representing cross-sectional slice
56. Imaging modes
• B-Mode Brightness Mode
– Shows the signal amplitude as the brightness of a point
– An array of transducers scan a plane through the body
simultaneously
– Real-time, 2-D image representing cross-sectional slice
57. Imaging modes
• B-Mode Brightness Mode
– Shows the signal amplitude as the brightness of a point
– An array of transducers scan a plane through the body
simultaneously
– Real-time, 2-D image representing cross-sectional slice
B-Mode
image of the
liver
58. Imaging modes
• B-Mode
• M-Mode
• Harmonic
• Doppler
– Spectral
– Color Flow Mapping
– Color Power
60. Imaging modes
• M-Mode Motion Mode
– Captures returning echoes in only one line of the B-mode
image but displays them over a time axis
– Pulses are emitted in quick succession
61. Imaging modes
• M-Mode Motion Mode
– Captures returning echoes in only one line of the B-mode
image but displays them over a time axis
– Pulses are emitted in quick succession
– Produces a moving display of a structure over time
62. Imaging modes
• M-Mode Motion Mode
– Captures returning echoes in only one line of the B-mode
image but displays them over a time axis
– Pulses are emitted in quick succession
– Produces a moving display of a structure over time
63. Imaging modes
• M-Mode Motion Mode
– Captures returning echoes in only one line of the B-mode
image but displays them over a time axis
– Pulses are emitted in quick succession
– Produces a moving display of a structure over time
M-Mode
image of left
ventricle
64. Imaging modes
• B-Mode
• M-Mode
• Harmonic
• Doppler
– Spectral
– Color Flow Mapping
– Color Power
65. Imaging modes
Harmonics are
frequencies that
occur at
multiple times of
the transmitted
• Harmonic
66. Imaging modes
Harmonics are
frequencies that
occur at
multiple times of
the transmitted
• Harmonic
– Ultrasound is transmitted at one frequency and received at twice
the transmitted frequency
– The returning high-frequency signal is isolated from the
fundamental signal by using a filter
67. Imaging modes
Harmonics are
frequencies that
occur at
multiple times of
the transmitted
• Harmonic
– Ultrasound is transmitted at one frequency and received at twice
the transmitted frequency
– The returning high-frequency signal is isolated from the
fundamental signal by using a filter
– Image is produced by high frequency signal
68. Imaging modes
Harmonics are
frequencies that
occur at
multiple times of
the transmitted
• Harmonic
– Ultrasound is transmitted at one frequency and received at twice
the transmitted frequency
– The returning high-frequency signal is isolated from the
fundamental signal by using a filter
– Image is produced by high frequency signal
vs
69. Imaging modes
Harmonics are
frequencies that
occur at
multiple times of
the transmitted
• Harmonic
– Ultrasound is transmitted at one frequency and received at twice
the transmitted frequency
– The returning high-frequency signal is isolated from the
fundamental signal by using a filter
– Image is produced by high frequency signal
vs
70. Imaging modes
• B-Mode
• M-Mode
• Harmonic
• Doppler
Spectral
Color Flow Mapping
Color Power
72. Imaging modes
• Doppler
– Utilizes “Doppler shift” principle to determine blood flow velocity and
direction
73. Imaging modes
• Doppler
– Utilizes “Doppler shift” principle to determine blood flow velocity and
direction
Blood cells
flowing
toward
transducer
74. Imaging modes
• Doppler
– Utilizes “Doppler shift” principle to determine blood flow velocity and
direction
Blood cells
flowing
toward
transducer
75. Imaging modes
• Doppler
– Utilizes “Doppler shift” principle to determine blood flow velocity and
direction
Blood cells
flowing
toward
transducer
Blood cells
flowing away
from
transducer
76. Imaging modes
• Doppler
– Utilizes “Doppler shift” principle to determine blood flow velocity and
direction
Blood cells
flowing
toward
transducer
Blood cells
flowing away
from
transducer
77. Imaging modes
• Doppler
– Utilizes “Doppler shift” principle to determine blood flow velocity and
direction
Blood cells Doppler shift: the
flowing difference in
toward transmitted and
transducer reflected wave
frequency
Blood cells
flowing away
from
transducer
78. Imaging modes
• Doppler
– Utilizes “Doppler shift” principle to determine blood flow velocity and
direction
Blood cells Doppler shift: the
flowing difference in
toward transmitted and
transducer reflected wave
frequency
Blood cells
flowing away Doppler shift
from
transducer Velocity of flow
79. Imaging modes
• B-Mode
• M-Mode
• Harmonic
• Doppler
Spectral
Color Flow Mapping
Color Power
81. Imaging modes
• Spectral Doppler
– Pulsed Wave (PW): the same transducer is used both for
transmitting and receiving
• User can select a specific depth
• Limited maximum velocity that can be measured
82. Imaging modes
• Spectral Doppler
– Pulsed Wave (PW): the same transducer is used both for
transmitting and receiving
• User can select a specific depth
• Limited maximum velocity that can be measured
– Continuous Wave (CW): one transducer transmits and another
transducer detects signal
• No information about depth of received signal
• Can measure very high velocities
83. CW Doppler Image across the left
PW Doppler Image of left ventricular outflow tract and aortic
ventricular outflow tract valve in subject with aortic stenosis
84. Imaging modes
• B-Mode
• M-Mode
• Harmonic
• Doppler
Spectral
Color Flow Mapping
Color Power
86. Imaging modes
• Color Flow Mapping (CFM)
– Color-encoded map of flow velocity and direction
superimposed on a real-time 2-D image
– Preset color flow map assigns one color to a flow velocity and
direction
87. Imaging modes
• Color Flow Mapping (CFM)
– Color-encoded map of flow velocity and direction
superimposed on a real-time 2-D image
– Preset color flow map assigns one color to a flow velocity and
direction
88. Imaging modes
• Color Flow Mapping (CFM)
– Color-encoded map of flow velocity and direction
superimposed on a real-time 2-D image
– Preset color flow map assigned one color to a flow velocity and
direction
CFM image
of the kidney
89. Imaging modes
• B-Mode
• M-Mode
• Harmonic
• Doppler
Spectral
ColorFlow Mapping
Color Power
91. Imaging modes
• Color Power Doppler
– Images blood flow by displaying the density of RBC rather than
their velocity
– Does not display flow direction or different velocities
– Increased flow sensitivity
– Very poor temporal resolution
– Susceptible to noise
92. Imaging modes
• Color Power Doppler
– Images blood flow by displaying the density of RBC rather than
their velocity
– Does not display flow direction or different velocities
– Increased flow sensitivity
– Very poor temporal resolution
– Susceptible to noise
93. Imaging modes
• Color Power Doppler
– Images blood flow by displaying the density of RBC rather than
their velocity
– Does not display flow direction or different velocities
– Increased flow sensitivity
– Very poor temporal resolution
– Susceptible to noise
Power Doppler
image of
the liver
94. Outline
1. Introduction
2. System components
3. Imaging principles
4. Types of transducers
5. Imaging modes
6. Conclusion
The CPU controls and processes the majority of the functions of the ultrasound system. Itis responsible for the input to the other components, such as the transducer and monitor. It alsoreceives and analyzes electronic input from the transducer to ultimately construct the image.Nowadays, they have full digital image processing capabilities and the computing speed neededfor high resolution imaging at high frame rates. The CPU can also serve as a temporary storagesystem for images. Rather than requiring purchase of an entirely new system, CPUs can beupgraded easily by installing software as technology advances
The CPU controls and processes the majority of the functions of the ultrasound system. Itis responsible for the input to the other components, such as the transducer and monitor. It alsoreceives and analyzes electronic input from the transducer to ultimately construct the image.Nowadays, they have full digital image processing capabilities and the computing speed neededfor high resolution imaging at high frame rates. The CPU can also serve as a temporary storagesystem for images. Rather than requiring purchase of an entirely new system, CPUs can beupgraded easily by installing software as technology advances
The CPU controls and processes the majority of the functions of the ultrasound system.It is responsible for the input to the other components, such as the transducer and monitor.It also receives and analyzes electronic input from the transducer to ultimately construct the image.Nowadays, they have full digital image processing capabilities and the computing speed neededfor high resolution imaging at high frame rates. The CPU can also serve as a temporary storagesystem for images. Rather than requiring purchase of an entirely new system, CPUs can beupgraded easily by installing software as technology advances
The CPU controls and processes the majority of the functions of the ultrasound system. Itis responsible for the input to the other components, such as the transducer and monitor. It alsoreceives and analyzes electronic input from the transducer to ultimately construct the image.Nowadays, they have full digital image processing capabilities and the computing speed neededfor high resolution imaging at high frame rates. The CPU can also serve as a temporary storagesystem for images. Rather than requiring purchase of an entirely new system, CPUs can beupgraded easily by installing software as technology advances
The CPU controls and processes the majority of the functions of the ultrasound system. Itis responsible for the input to the other components, such as the transducer and monitor. It alsoreceives and analyzes electronic input from the transducer to ultimately construct the image.Nowadays, they have full digital image processing capabilities and the computing speed neededfor high resolution imaging at high frame rates. The CPU can also serve as a temporary storagesystem for images. Rather than requiring purchase of an entirely new system, CPUs can beupgraded easily by installing software as technology advancesDICOM stands for "Digital imaging & Communications in Medicine" and is a format for passing information between various pieces of digital medical equipment. It is the industry standard format for transferring images and movies from an ultrasound machine to a PACS network, storage device or computer.
The CPU controls and processes the majority of the functions of the ultrasound system. Itis responsible for the input to the other components, such as the transducer and monitor. It alsoreceives and analyzes electronic input from the transducer to ultimately construct the image.Nowadays, they have full digital image processing capabilities and the computing speed neededfor high resolution imaging at high frame rates. The CPU can also serve as a temporary storagesystem for images. Rather than requiring purchase of an entirely new system, CPUs can beupgraded easily by installing software as technology advancesOn current systems, the operator can store images or transfer them via networks forstorage on picture archiving and communication systems (PACS). Many ultrasound scannersuppliers incorporate the Digital Imaging and Communications in Medicine (DICOM) Standard.Its purpose is to allow digital images produced by any medical device to be stored andtransferred through PACS) regardless of the device supplier 3.
The CPU controls and processes the majority of the functions of the ultrasound system. Itis responsible for the input to the other components, such as the transducer and monitor. It alsoreceives and analyzes electronic input from the transducer to ultimately construct the image.Nowadays, they have full digital image processing capabilities and the computing speed neededfor high resolution imaging at high frame rates. The CPU can also serve as a temporary storagesystem for images. Rather than requiring purchase of an entirely new system, CPUs can beupgraded easily by installing software as technology advances
Ultrasound waves travel through the tissue until they reach a boundary between substances (organ and fluid, or muscle and bone) where they are reflected back to the transducer. Using the strength of the signal and the length of time it took the echoes to return, the transducer uses them to turn them into an image
One limitation of using higher frequencies is that as the frequency increases, the soundwave penetration decreases. Lower sound frequencies provide greater tissue penetration butdecreased resolution. The latter is desirable, for example, in pediatric applications or whenviewing small body parts because the targets are generally within the depth penetration. Thereexist multifrequency (broadband) transducers that have larger frequency ranges than traditionaltransducers. These allow the user to easily select transducer resolution and tissue penetration indifferent imaging procedures
Ultraosund transducers work on the basis of the piezoelectric effect, which consists of the conversion of electrical into mechanical energy and viceversa. The transducers are made of a piezoelecctric material between 2 electrodes that apply AC voltage and make it vibrate and generate the ultrasound wave. When the sound wave is reflected back and hits the piezoelectric material, this mechanical energy causes it to generate an electric signal. Ultrasound transducers work on the basis of the piezoelectric effect in which an alternating voltage applied to piezoelectric crystal material causes the crystals to become electrically polarized and hence vibrate to produce ultrasound. Such crystals also become electrically polarized when any incident sound wave and hence the generation of an alternating voltage.Thus, an ultrasound transducer consists of a suitable piezoelectric material sandwiched between electrodes that are used to provide a fluctuating electric field when the transducer is required to generate ultrasound. When the transducer is required to detect ultrasound, the electrodes may be used to detect any fluctuating voltages produced as a result of the polarization of the crystals of the piezoelectric material in response to incident sound which generates fluctuating mechanical stresses on the material. Piezoelectric materials include quartz, ferroelectric crystals such as tourmaline and Rochelle salt as well as the group of materials known as the piezoelectric ceramics, which include lead titanate (PbTiO3) and lead zirconate (PbZrO3).To produce an ultrasound, alternating current is applied across a piezoelectric crystal. The piezoelectric crystal grows and shrinks depending on the voltage run through it. Running an alternating current through it causes it to vibrate at a high speed and to produce an ultrasound. This conversion of electrical energy to mechanical energy is known as the piezoelectric effect. The sound then bounces back off the object under investigation. The sound hits the piezoelectric crystal and then has the reverse effect - causing the mechanical energy produced from the sound vibrating the crystal to be converted into electrical energy. By measuring the time between when the sound was sent and received, the amplitude of the sound and the pitch of the sound, a computer can produce images, calculate depths and calculate speeds.
The transducer’s physical design and the technique of beam generation determine the shape of the image
Rectangular images are produced by linear array transducers. They are the same width in the near field as they are in the far field. This makes a linear array system ideal for obstetric examinations in which the placenta or fetal skull might be positioned close to the transducer
Rectangular images are produced by linear array transducers. They are the same width in the near field as they are in the far field. This makes a linear array system ideal for obstetric examinations in which the placenta or fetal skull might be positioned close to the transducer
AbdominalOb/gynSmall partsvascular
Peripheral vascular imaging
Some convex-array, phased-array, vectorarray,and mechanically steered transducers are configuredfor endocavity applications
Ideally, endocavity transducers arespecially designed for either endovaginal or endorectal studies,but some vendors compromise by offering a single transducerfor both studies. Left: Endovaginal transducers are intended forgynecologic and early-trimester obstetric studies
Endovaginal: gynecologic and early-trimester obstetric studies
A B-mode image of the liver. It is the most basic imaging mode. Itproduces a real-time, 2-D image that represents a cross-sectional slice of the area under study.The image is created as the transducer sweeps the pulsed ultrasound beam through the imageplane either mechanically or electronically. The image is updated multiple times to produce amoving image, and the sweep (or frame) rate determines how often the image updating occurs
A B-mode image of the liver. It is the most basic imaging mode. Itproduces a real-time, 2-D image that represents a cross-sectional slice of the area under study.The image is created as the transducer sweeps the pulsed ultrasound beam through the imageplane either mechanically or electronically. The image is updated multiple times to produce amoving image, and the sweep (or frame) rate determines how often the image updating occurs
A B-mode image of the liver. It is the most basic imaging mode. Itproduces a real-time, 2-D image that represents a cross-sectional slice of the area under study.The image is created as the transducer sweeps the pulsed ultrasound beam through the imageplane either mechanically or electronically. The image is updated multiple times to produce amoving image, and the sweep (or frame) rate determines how often the image updating occurs
A B-mode image of the liver. It is the most basic imaging mode. Itproduces a real-time, 2-D image that represents a cross-sectional slice of the area under study.The image is created as the transducer sweeps the pulsed ultrasound beam through the imageplane either mechanically or electronically. The image is updated multiple times to produce amoving image, and the sweep (or frame) rate determines how often the image updating occurs
A B-mode image of the liver. It is the most basic imaging mode. Itproduces a real-time, 2-D image that represents a cross-sectional slice of the area under study.The image is created as the transducer sweeps the pulsed ultrasound beam through the imageplane either mechanically or electronically. The image is updated multiple times to produce amoving image, and the sweep (or frame) rate determines how often the image updating occurs
A B-mode image of the liver. It is the most basic imaging mode. Itproduces a real-time, 2-D image that represents a cross-sectional slice of the area under study.The image is created as the transducer sweeps the pulsed ultrasound beam through the imageplane either mechanically or electronically. The image is updated multiple times to produce amoving image, and the sweep (or frame) rate determines how often the image updating occurs
A B-mode image of the liver. It is the most basic imaging mode. Itproduces a real-time, 2-D image that represents a cross-sectional slice of the area under study.The image is created as the transducer sweeps the pulsed ultrasound beam through the imageplane either mechanically or electronically. The image is updated multiple times to produce amoving image, and the sweep (or frame) rate determines how often the image updating occurs
A B-mode image of the liver. It is the most basic imaging mode. Itproduces a real-time, 2-D image that represents a cross-sectional slice of the area under study.The image is created as the transducer sweeps the pulsed ultrasound beam through the imageplane either mechanically or electronically. The image is updated multiple times to produce amoving image, and the sweep (or frame) rate determines how often the image updating occurs
A B-mode image of the liver. It is the most basic imaging mode. Itproduces a real-time, 2-D image that represents a cross-sectional slice of the area under study.The image is created as the transducer sweeps the pulsed ultrasound beam through the imageplane either mechanically or electronically. The image is updated multiple times to produce amoving image, and the sweep (or frame) rate determines how often the image updating occurs
In contrast harmonics, the harmonic frequency energy is generated on reflection from the microbubble contrast agent. In tissue harmonics, the harmonic frequency energy is generated gradually as the ultrasonic wave propagates through the tissue. Critical to the utility of tissue-generated harmonic frequencies is their origin beyond the chest wall and their nonlinear relation to the fundamental frequency energy strength. These two characteristics of tissue-generated harmonics ensure that the echoes most likely to produce artifact are least likely to produce harmonic waves
Left: breast cyst undetermined, taken with conventional UsRight: breast cyst image taken with HI
It utilizes the Doppler shift principle to determine blood flow velocity and direction. Withrespect to ultrasound imaging, the Doppler effect is the apparent shift in sound wave frequencythat occurs when a sound wave is reflected by a moving target, primarily blood cells. If the bloodcells are flowing toward the transducer, the frequency of the reflected waves is higher than theoriginal transmitted waves. If the blood is flowing away from the transducer, the frequency ofthe reflected waves is lower than that of the original transmitted waves. This difference intransmitted and reflected wave frequency is the “Doppler shift”. The greater the Doppler shift,the greater the velocity of blood flow. The Doppler shift is affected by the alignment of theultrasound beam and the flowing blood. As this alignment diverges from parallel, the detectedDoppler shift is attenuated. Therefore, it is important to orient the ultrasound beam as parallel aspossible to the direction of flow or movement. In most situations, completely parallel alignmentis not possible, so it has been recommended that the alignment be no greater than 20 to 30° fromparallel.
It utilizes the Doppler shift principle to determine blood flow velocity and direction. Withrespect to ultrasound imaging, the Doppler effect is the apparent shift in sound wave frequencythat occurs when a sound wave is reflected by a moving target, primarily blood cells. If the bloodcells are flowing toward the transducer, the frequency of the reflected waves is higher than theoriginal transmitted waves. If the blood is flowing away from the transducer, the frequency ofthe reflected waves is lower than that of the original transmitted waves. This difference intransmitted and reflected wave frequency is the “Doppler shift”. The greater the Doppler shift,the greater the velocity of blood flow. The Doppler shift is affected by the alignment of theultrasound beam and the flowing blood. As this alignment diverges from parallel, the detectedDoppler shift is attenuated. Therefore, it is important to orient the ultrasound beam as parallel aspossible to the direction of flow or movement. In most situations, completely parallel alignmentis not possible, so it has been recommended that the alignment be no greater than 20 to 30° fromparallel.
It utilizes the Doppler shift principle to determine blood flow velocity and direction. Withrespect to ultrasound imaging, the Doppler effect is the apparent shift in sound wave frequencythat occurs when a sound wave is reflected by a moving target, primarily blood cells. If the bloodcells are flowing toward the transducer, the frequency of the reflected waves is higher than theoriginal transmitted waves. If the blood is flowing away from the transducer, the frequency ofthe reflected waves is lower than that of the original transmitted waves. This difference intransmitted and reflected wave frequency is the “Doppler shift”. The greater the Doppler shift,the greater the velocity of blood flow. The Doppler shift is affected by the alignment of theultrasound beam and the flowing blood. As this alignment diverges from parallel, the detectedDoppler shift is attenuated. Therefore, it is important to orient the ultrasound beam as parallel aspossible to the direction of flow or movement. In most situations, completely parallel alignmentis not possible, so it has been recommended that the alignment be no greater than 20 to 30° fromparallel.
It utilizes the Doppler shift principle to determine blood flow velocity and direction. Withrespect to ultrasound imaging, the Doppler effect is the apparent shift in sound wave frequencythat occurs when a sound wave is reflected by a moving target, primarily blood cells. If the bloodcells are flowing toward the transducer, the frequency of the reflected waves is higher than theoriginal transmitted waves. If the blood is flowing away from the transducer, the frequency ofthe reflected waves is lower than that of the original transmitted waves. This difference intransmitted and reflected wave frequency is the “Doppler shift”. The greater the Doppler shift,the greater the velocity of blood flow. The Doppler shift is affected by the alignment of theultrasound beam and the flowing blood. As this alignment diverges from parallel, the detectedDoppler shift is attenuated. Therefore, it is important to orient the ultrasound beam as parallel aspossible to the direction of flow or movement. In most situations, completely parallel alignmentis not possible, so it has been recommended that the alignment be no greater than 20 to 30° fromparallel.
It utilizes the Doppler shift principle to determine blood flow velocity and direction. Withrespect to ultrasound imaging, the Doppler effect is the apparent shift in sound wave frequencythat occurs when a sound wave is reflected by a moving target, primarily blood cells. If the bloodcells are flowing toward the transducer, the frequency of the reflected waves is higher than theoriginal transmitted waves. If the blood is flowing away from the transducer, the frequency ofthe reflected waves is lower than that of the original transmitted waves. This difference intransmitted and reflected wave frequency is the “Doppler shift”. The greater the Doppler shift,the greater the velocity of blood flow. The Doppler shift is affected by the alignment of theultrasound beam and the flowing blood. As this alignment diverges from parallel, the detectedDoppler shift is attenuated. Therefore, it is important to orient the ultrasound beam as parallel aspossible to the direction of flow or movement. In most situations, completely parallel alignmentis not possible, so it has been recommended that the alignment be no greater than 20 to 30° fromparallel.
It utilizes the Doppler shift principle to determine blood flow velocity and direction. Withrespect to ultrasound imaging, the Doppler effect is the apparent shift in sound wave frequencythat occurs when a sound wave is reflected by a moving target, primarily blood cells. If the bloodcells are flowing toward the transducer, the frequency of the reflected waves is higher than theoriginal transmitted waves. If the blood is flowing away from the transducer, the frequency ofthe reflected waves is lower than that of the original transmitted waves. This difference intransmitted and reflected wave frequency is the “Doppler shift”. The greater the Doppler shift,the greater the velocity of blood flow. The Doppler shift is affected by the alignment of theultrasound beam and the flowing blood. As this alignment diverges from parallel, the detectedDoppler shift is attenuated. Therefore, it is important to orient the ultrasound beam as parallel aspossible to the direction of flow or movement. In most situations, completely parallel alignmentis not possible, so it has been recommended that the alignment be no greater than 20 to 30° fromparallel.
It utilizes the Doppler shift principle to determine blood flow velocity and direction. Withrespect to ultrasound imaging, the Doppler effect is the apparent shift in sound wave frequencythat occurs when a sound wave is reflected by a moving target, primarily blood cells. If the bloodcells are flowing toward the transducer, the frequency of the reflected waves is higher than theoriginal transmitted waves. If the blood is flowing away from the transducer, the frequency ofthe reflected waves is lower than that of the original transmitted waves. This difference intransmitted and reflected wave frequency is the “Doppler shift”. The greater the Doppler shift,the greater the velocity of blood flow. The Doppler shift is affected by the alignment of theultrasound beam and the flowing blood. As this alignment diverges from parallel, the detectedDoppler shift is attenuated. Therefore, it is important to orient the ultrasound beam as parallel aspossible to the direction of flow or movement. In most situations, completely parallel alignmentis not possible, so it has been recommended that the alignment be no greater than 20 to 30° fromparallel.
It utilizes the Doppler shift principle to determine blood flow velocity and direction. Withrespect to ultrasound imaging, the Doppler effect is the apparent shift in sound wave frequencythat occurs when a sound wave is reflected by a moving target, primarily blood cells. If the bloodcells are flowing toward the transducer, the frequency of the reflected waves is higher than theoriginal transmitted waves. If the blood is flowing away from the transducer, the frequency ofthe reflected waves is lower than that of the original transmitted waves. This difference intransmitted and reflected wave frequency is the “Doppler shift”. The greater the Doppler shift,the greater the velocity of blood flow. The Doppler shift is affected by the alignment of theultrasound beam and the flowing blood. As this alignment diverges from parallel, the detectedDoppler shift is attenuated. Therefore, it is important to orient the ultrasound beam as parallel aspossible to the direction of flow or movement. In most situations, completely parallel alignmentis not possible, so it has been recommended that the alignment be no greater than 20 to 30° fromparallel.
Spectral Doppler displays the velocity within a specific region within a vessel over time.The result is a velocity profile. Spectral Doppler can be either pulsed wave (PW) or continuouswave (CW). In PW Doppler (Figure 8), a single transducer produces and transmits the soundwaves and then receives the reflected sound waves, whereas in CW Doppler (Figure 9), onetransducer produces and transmits the sound waves and a second transducer detects the reflectedsound waves. One advantage of PW Doppler is that it allows the operator to select the area ofinterest for flow analysis using cursors superimposed on the 2D image, therefore allowing thedetermination of the velocity profile from a precise location (range resolution). However, themaximum flow velocity that can be accurately detected by PW Doppler is limited. In contrast,CW Doppler can detect higher flow velocities than PW Doppler but is not capable of rangeresolution.A problem in pulsed Doppler is that the Doppler shift is very small compared to the ultrasound frequency. In order to measure velocity at a certain depth, the next pulse cannot be sent out before the signal is returned. The Doppler shift is thus sampled once for every pulse that is transmitted, and the sampling frequency is thus equal to the pulse repetition frequency (PRF).Pulsed wave Doppler is used to provide analysis of the flow at specific sites in the vessel under investigation. PW produces a series of pulses used to study the motion of blood flow at a small region along a desired scan line. The x-axis of the graph represents time while the Y axis represent Doppler frequency shift. The shift can be converted into velocity and flow if an appropriate angle between the beam and blood flow is known Pulsed wave systems suffer from a fundamental limitation.The time interval between sampling pulses must be sufficient for a pulse to make the return journey from the transducer to the reflector and back. If a second pulse is sent before the first is received, the receiver cannot discriminate between the reflected signal from both pulses and ambiguity in the range of the sample volume ensues. As the depth of investigation increases, the journey time of the pulse to and from the reflector is increased, reducing the pulse repetition frequency for unambiguous ranging. The result is that the maximum fd measurable decreases with depth.When pulses are transmitted at a given sampling frequency (known as the pulse repetition frequency), the maximum Doppler frequency fd that can be measured unambiguously is half the pulse repetition frequency. If the blood velocity and beam/flow angle being measured combine to give a fd value greater than half of the pulse repetition frequency, ambiguity in the Doppler signal occurs. This ambiguity is known as aliasing. A similar effect is seen in films where wagon wheels can appear to be going backwards due to the low frame rate of the film causing misinterpretation of the movement of the wheel spokes.Continuous wave systems use continuous transmission and reception of ultrasound. Doppler signals are obtained from all vessels in the path of the ultrasound beam (until the ultrasound beam becomes sufficiently attenuated due to depth). Continuous wave Doppler ultrasound is unable to determine the specific location of velocities within the beam and cannot be used to produce color flow images. CW allows the operator to measure extremely high velocities. CW is not limited like PW with respect to the ability to measure high velocities as it is always sending and receiving signals, it does not have to wait for a signal to return before sending out another.: Doppler information is sampled along a line through the body, and all velocities detected at each time point is presented (on a time line)CW: high velocities, but no depth resolutionPW: depth resolution, but limited max velocity
Spectral Doppler displays the velocity within a specific region within a vessel over time.The result is a velocity profile. Spectral Doppler can be either pulsed wave (PW) or continuouswave (CW). In PW Doppler (Figure 8), a single transducer produces and transmits the soundwaves and then receives the reflected sound waves, whereas in CW Doppler (Figure 9), onetransducer produces and transmits the sound waves and a second transducer detects the reflectedsound waves. One advantage of PW Doppler is that it allows the operator to select the area ofinterest for flow analysis using cursors superimposed on the 2D image, therefore allowing thedetermination of the velocity profile from a precise location (range resolution). However, themaximum flow velocity that can be accurately detected by PW Doppler is limited. In contrast,CW Doppler can detect higher flow velocities than PW Doppler but is not capable of rangeresolution.A problem in pulsed Doppler is that the Doppler shift is very small compared to the ultrasound frequency. In order to measure velocity at a certain depth, the next pulse cannot be sent out before the signal is returned. The Doppler shift is thus sampled once for every pulse that is transmitted, and the sampling frequency is thus equal to the pulse repetition frequency (PRF).Pulsed wave Doppler is used to provide analysis of the flow at specific sites in the vessel under investigation. PW produces a series of pulses used to study the motion of blood flow at a small region along a desired scan line. The x-axis of the graph represents time while the Y axis represent Doppler frequency shift. The shift can be converted into velocity and flow if an appropriate angle between the beam and blood flow is known Pulsed wave systems suffer from a fundamental limitation.The time interval between sampling pulses must be sufficient for a pulse to make the return journey from the transducer to the reflector and back. If a second pulse is sent before the first is received, the receiver cannot discriminate between the reflected signal from both pulses and ambiguity in the range of the sample volume ensues. As the depth of investigation increases, the journey time of the pulse to and from the reflector is increased, reducing the pulse repetition frequency for unambiguous ranging. The result is that the maximum fd measurable decreases with depth.When pulses are transmitted at a given sampling frequency (known as the pulse repetition frequency), the maximum Doppler frequency fd that can be measured unambiguously is half the pulse repetition frequency. If the blood velocity and beam/flow angle being measured combine to give a fd value greater than half of the pulse repetition frequency, ambiguity in the Doppler signal occurs. This ambiguity is known as aliasing. A similar effect is seen in films where wagon wheels can appear to be going backwards due to the low frame rate of the film causing misinterpretation of the movement of the wheel spokes.Continuous wave systems use continuous transmission and reception of ultrasound. Doppler signals are obtained from all vessels in the path of the ultrasound beam (until the ultrasound beam becomes sufficiently attenuated due to depth). Continuous wave Doppler ultrasound is unable to determine the specific location of velocities within the beam and cannot be used to produce color flow images. CW allows the operator to measure extremely high velocities. CW is not limited like PW with respect to the ability to measure high velocities as it is always sending and receiving signals, it does not have to wait for a signal to return before sending out another.: Doppler information is sampled along a line through the body, and all velocities detected at each time point is presented (on a time line)CW: high velocities, but no depth resolutionPW: depth resolution, but limited max velocity
Spectral Doppler displays the velocity within a specific region within a vessel over time.The result is a velocity profile. Spectral Doppler can be either pulsed wave (PW) or continuouswave (CW). In PW Doppler (Figure 8), a single transducer produces and transmits the soundwaves and then receives the reflected sound waves, whereas in CW Doppler (Figure 9), onetransducer produces and transmits the sound waves and a second transducer detects the reflectedsound waves. One advantage of PW Doppler is that it allows the operator to select the area ofinterest for flow analysis using cursors superimposed on the 2D image, therefore allowing thedetermination of the velocity profile from a precise location (range resolution). However, themaximum flow velocity that can be accurately detected by PW Doppler is limited. In contrast,CW Doppler can detect higher flow velocities than PW Doppler but is not capable of rangeresolution.Pulsed wave (PW) Doppler systems use a transducer that alternates transmission and reception of ultrasound in a way similar to the M-mode transducer (Fig. 1.18). One main advantage of pulsed Doppler is its ability to provide Doppler shift data selectively from a small segment along the ultrasound beam, referred to as the "sample volume". The location of the sample volume is operator controlled. An ultrasound pulse is transmitted into the tissues travels for a given time (time X) until it is reflected back by a moving red cell. It then returns to the transducer over the same time interval but at a shifted frequency. The total transit time to and from the area is 2X. Since the speed of ultrasound in the tissues is constant, there is a simple relationship between roundtrip travel time and the location of the sample volume relative to the transducer face (i.e., distance to sample volume equals ultrasound speed divided by round trip travel time). This process is alternately repeated through many transmit-receive cycles each second.A problem in pulsed Doppler is that the Doppler shift is very small compared to the ultrasound frequency. In order to measure velocity at a certain depth, the next pulse cannot be sent out before the signal is returned. The Doppler shift is thus sampled once for every pulse that is transmitted, and the sampling frequency is thus equal to the pulse repetition frequency (PRF).Pulsed wave Doppler is used to provide analysis of the flow at specific sites in the vessel under investigation. PW produces a series of pulses used to study the motion of blood flow at a small region along a desired scan line. The x-axis of the graph represents time while the Y axis represent Doppler frequency shift. The shift can be converted into velocity and flow if an appropriate angle between the beam and blood flow is known Pulsed wave systems suffer from a fundamental limitation.The time interval between sampling pulses must be sufficient for a pulse to make the return journey from the transducer to the reflector and back. If a second pulse is sent before the first is received, the receiver cannot discriminate between the reflected signal from both pulses and ambiguity in the range of the sample volume ensues. As the depth of investigation increases, the journey time of the pulse to and from the reflector is increased, reducing the pulse repetition frequency for unambiguous ranging. The result is that the maximum fd measurable decreases with depth.When pulses are transmitted at a given sampling frequency (known as the pulse repetition frequency), the maximum Doppler frequency fd that can be measured unambiguously is half the pulse repetition frequency. If the blood velocity and beam/flow angle being measured combine to give a fd value greater than half of the pulse repetition frequency, ambiguity in the Doppler signal occurs. This ambiguity is known as aliasing. A similar effect is seen in films where wagon wheels can appear to be going backwards due to the low frame rate of the film causing misinterpretation of the movement of the wheel spokes.Continuous wave systems use continuous transmission and reception of ultrasound. Doppler signals are obtained from all vessels in the path of the ultrasound beam (until the ultrasound beam becomes sufficiently attenuated due to depth). Continuous wave Doppler ultrasound is unable to determine the specific location of velocities within the beam and cannot be used to produce color flow images. CW allows the operator to measure extremely high velocities. CW is not limited like PW with respect to the ability to measure high velocities as it is always sending and receiving signals, it does not have to wait for a signal to return before sending out another.: Doppler information is sampled along a line through the body, and all velocities detected at each time point is presented (on a time line)CW: high velocities, but no depth resolutionPW: depth resolution, but limited max velocity
Spectral Doppler displays the velocity within a specific region within a vessel over time.The result is a velocity profile. Spectral Doppler can be either pulsed wave (PW) or continuous7wave (CW). In PW Doppler (Figure 8), a single transducer produces and transmits the soundwaves and then receives the reflected sound waves, whereas in CW Doppler (Figure 9), onetransducer produces and transmits the sound waves and a second transducer detects the reflectedsound waves. One advantage of PW Doppler is that it allows the operator to select the area ofinterest for flow analysis using cursors superimposed on the 2D image, therefore allowing thedetermination of the velocity profile from a precise location (range resolution). However, themaximum flow velocity that can be accurately detected by PW Doppler is limited. In contrast,CW Doppler can detect higher flow velocities than PW Doppler but is not capable of rangeresolution.
Color flow mapping (CFM) Doppler represents a color-encoded map of flow velocity anddirection superimposed on a 2-D image. One color from a preset color flow map is assigned to aflow velocity and direction. These images display the velocity and direction of the blood flow inthe specific target structure in real time
Color flow mapping (CFM) Doppler represents a color-encoded map of flow velocity anddirection superimposed on a 2-D image. One color from a preset color flow map is assigned to aflow velocity and direction. These images display the velocity and direction of the blood flow inthe specific target structure in real time
Color flow mapping (CFM) Doppler represents a color-encoded map of flow velocity anddirection superimposed on a 2-D image. One color from a preset color flow map is assigned to aflow velocity and direction. These images display the velocity and direction of the blood flow inthe specific target structure in real time
Color flow mapping (CFM) Doppler represents a color-encoded map of flow velocity anddirection superimposed on a 2-D image. One color from a preset color flow map is assigned to aflow velocity and direction. These images display the velocity and direction of the blood flow inthe specific target structure in real time
Color power Doppler (Figure 11) can be used as an adjunct to CFM. It displays theintegrated power of the reflected signal in the conventional color-flow Doppler technique. Itincreases the flow sensitivity of color Doppler imaging and provides good results even at anglesperpendicular to the direction of flow, which cannot be visualized at all with standard Doppler.However, power Doppler provides no quantitative data, such as flow rate or direction 1.Power Doppler does not display flow direction or different velocities. Power mode is used to image blood flow by displaying the density of red blood cells, as opposed to their velocity. Power increases the sensitivity range of the soundwaves allowing even small flows of blood through organs to be tracked rather than the faster, more substantial flow in arteries and veins detected by Color Doppler. Power Doppler is:sensitive to low flows,No directional information in some modes,Very poor temporal resolution,Susceptible to noise
Color power Doppler (Figure 11) can be used as an adjunct to CFM. It displays theintegrated power of the reflected signal in the conventional color-flow Doppler technique. Itincreases the flow sensitivity of color Doppler imaging and provides good results even at anglesperpendicular to the direction of flow, which cannot be visualized at all with standard Doppler.However, power Doppler provides no quantitative data, such as flow rate or direction 1.power Doppler sonography is valuable in low-flow states and when optimal Doppler angles cannot be obtainedPower Doppler does not display flow direction or different velocities. Power mode is used to image blood flow by displaying the density of red blood cells, as opposed to their velocity. Power increases the sensitivity range of the soundwaves allowing even small flows of blood through organs to be tracked rather than the faster, more substantial flow in arteries and veins detected by Color Doppler. Power Doppler is:sensitive to low flows,No directional information in some modes,Very poor temporal resolution,Susceptible to noise
Color power Doppler (Figure 11) can be used as an adjunct to CFM. It displays theintegrated power of the reflected signal in the conventional color-flow Doppler technique. Itincreases the flow sensitivity of color Doppler imaging and provides good results even at anglesperpendicular to the direction of flow, which cannot be visualized at all with standard Doppler.However, power Doppler provides no quantitative data, such as flow rate or direction 1.Power Doppler does not display flow direction or different velocities. Power mode is used to image blood flow by displaying the density of red blood cells, as opposed to their velocity. Power increases the sensitivity range of the soundwaves allowing even small flows of blood through organs to be tracked rather than the faster, more substantial flow in arteries and veins detected by Color Doppler. Power Doppler is:sensitive to low flows,No directional information in some modes,Very poor temporal resolution,Susceptible to noise
Color power Doppler (Figure 11) can be used as an adjunct to CFM. It displays theintegrated power of the reflected signal in the conventional color-flow Doppler technique. Itincreases the flow sensitivity of color Doppler imaging and provides good results even at anglesperpendicular to the direction of flow, which cannot be visualized at all with standard Doppler.However, power Doppler provides no quantitative data, such as flow rate or direction 1.Power Doppler does not display flow direction or different velocities. Power mode is used to image blood flow by displaying the density of red blood cells, as opposed to their velocity. Power increases the sensitivity range of the soundwaves allowing even small flows of blood through organs to be tracked rather than the faster, more substantial flow in arteries and veins detected by Color Doppler. Power Doppler is:sensitive to low flows,No directional information in some modes,Very poor temporal resolution,Susceptible to noise