Advanced Imaging Test 3 continued
Terms
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- Unlike Diaggnostic Radiology, US uses _____ to visualize soft tissue structures in the body
- high frequency sound waves
- What four things can also be determined within a chamber or vessel by specific US techniques?
- Direction, flow resistance, turbulence, regurgitation
- what is the def. of US
- using a high frequency sound wave to create images of body structures
- What are the advantages of US over other modalities?
-
more mobile
accessible for small hospitals
more cost effective
minimal supplies - US is considered to be invasive or non invasive?
- invasive
- IN US, _____ now provide detailed prenatal images
- 3d and 4d techniques
- WHat is the contrast media for in US?
- to provide more detailed pictures than ever in tumor invasion in specific structures and details of the endometrial cavity and fallopian tubes
- Contrast media has been used and investigated by who?
-
cardiologists during ischemic heart disease
radiologist for enhanced tumor invasion of the liver, gallbladder and pancreas
gynecologists for endometrial cavity and fallopian tubes - what is the transducer for?
- generate ultrasonic energy
- what is the functional component of the transducer?
- piezoelectric element
- What do the elements in the transducer convert?
- electric energy, to ultrasonic energy and ultrasonic energy to electric signal
- what was the precursor in US
- sonar
- Sonar was developed for?
- equipment defense during WW1 to detect the presence of submarines
- who discovered the through transmission to technique
- Dussick
- Who all continued to use this techniqie along with computer to analyze brain lesions.
- Dussick Hueter Bolt adn Ballantyne
- Who and in when? developed the first ultrasound scanner?
- howry
-
____consisted of a cattle watering tank with a wooden rail anchored along the side. The transducer carriage and the object to be scanned were inside the water. The transducer carriage moved along the rail in a horizontal plane.
- 1948 scanner
-
____ (Sweden) developed Echocardiographic techniques
- 1954- Hertz & Edler
-
______(Scotland) built an early OB contact compound scanner
- 1957- Brown and Donald
-
Development of US lead to:
-
Real time instrumentation
High frequency transducers with improved resolutions
Several frames per second to a rate of up to 30 frames per second
-
Two groups of Biologic effects:
-
Heating
Mechanical (or non-thermal)
-
Ultrasound is absorbed by tissue producing a _____ . If the critical this values are exceeded, tissue damage will occur.
- temperature rise
- Heating increases as ______ is increased. The extent of temp rise depends on amount of intensity and frequency applied. Temp rises as ultrasound passes through tissues
- frequency or intensity;
-
why is bone heating is of major concern especially in a fetus.
- Absorption coefficients are higher in bone than soft tissue-
-
Examples of Hyperthermia consequences⬦
-
-fetal absorption or abortion
-Growth retardation
-
Production and behavior of bubbles in a liquid medium
- cavitation
-
Cavitation can occur in tissues containing _____ Damage can result from cavitational activity in tissue.
- gas bubbles with sufficient pressure amplitude and frequency conditions.
-
Stable cavitation vs. Transient cavitation
-
Stable: bubbles that occilate in diameter with the passing pressure variations of the sound wave. Streaming of surrounding liquid can occur.
This type has been reported in tissues under continuous wave, high intensity conditions.
Transient: bubbles so large that they collapse causing a shock wave effect because of the pressure that it causes, localized high temps, and light emission in clear liquids.
Has potential for significant destructive effects. Thresholds due to pressure and frequency have recently been determined.
- Safety Standards for US
-
Goal: To keep the patient risks minimal and to keep the diagnostic usefulness equal and standardized for all patients
Quality Assurance test of the instruments
FDA values for equipment operation
Exposure is determined non-harmful to at risk persons or a fetus (unlike radiation)
Medical diagnostic use only- ALARA
- An _____is a propagation of energy that moves back and forth or vibrates at a steady rate.
- acoustic wave
-
: mechanical oscillations that are transmitted by particles in a gas, liquid, or solid
- acoustic wave definition
-
Ultrasound refers to sound waves beyond the audible range (_____).
Diagnostic application uses _____cycles/sec (or 1 to 10 MHz).
-
16000 to 20000 cycles/sec
1 to 10 million -
creating sound waves
generated by an ____ _____ - external source
-
Ultrasound is the transmission of high frequency mechanical vibrations greater than ____ through a medium
- 20kHz
-
The velocity of sound in a medium is determined by the _____and ____properties of the medium.
- density and elastic
-
The velocity of sound differs in ___,___,___.
it varies slightly from tissue to another.
Slowed down _____
Attenuated through most bony structures
-
Differs greatly among air, bone, and soft tissue
by air filled structures (lungs)
-
The presentation of multiple image frames per second over selected areas of the body.
- real time imaging
-
_____ (which produce and capture waves) may be composed of several elements that can rapid fire sequences and can electronically focus to produce a real time image.
- Transducers
- Some other examples of real-time imaging uses are:
-
pulsative vascular and cardiac structures (arteries and veins, heart); diaphragm motion; and stomach peristalsis.
-
refers to a change in frequency when the motion of laminar or turbulent flow is detected within a vascular structure.
- The Doppler effect
-
is a technique that assigns a color scale to the change in frequency or Doppler shift.
____ signifies a shift toward the transducer
___signifies a shift away from the transducer
- Color-flow Doppler; Red; BLue
-
The ability of the Sonographer to understand anatomy as it relates to the ______ is critical to the performance of a high-quality sonogram.
- sectional, coronal, and oblique planes
-
Sonographers must be able to analyze a mass to determine if its borders are:
- smooth, irregular, poorly defined, thin, or thick to further define its characteristics.
- After a mass is suspected, the acoustic properties of the structure must be determined. These characteristics can be defined as:
- heterogeneous, homogeneous, hypoechoic, hyperechoic, isoechoic, or anechoic
-
having a mixed composition
- Heterogeneous:
-
having a uniform composition
- Homogeneous:
-
Producing fewer echoes than normal
- Hypoechoic:
-
Producing more echoes than normal
- Hyperechoic:
-
Having a texture nearly the same as the surrounding parenchyma
- Isoechoic:
-
Property of being free of echoes or without echoes
- Anechoic:
-
____lesion is characterized by low-level echoes with a good posterior border
- Hypoechoic
-
: Bright echo reflectors and possibly shadows beyond it; usually representing a tumor, thrombus, or calcification
- Hyperechoic lesion
-
shows nearly the same texture pattern as the surrounding tissue with no significant change in the through transmission (ex. If a liver and a kidney are of the same texture then that could indicate kidney failure)
- Isoechoic mass:
-
shows no internal echoes, has smooth walls, and displays increased through transmission (ex. Cyst)
- Anechoic:
-
A mass that exhibits more than one characteristic/pattern is considered -____Ex. Absecess, nectrotic tumor with hemmorhage, a decomposing thrombus, or a cyst with separation.
- complex.
-
A ________ can be performed with the assistance of an ultrasound image.
- biopsy or aspiration
-
Sonographer is responsible for :
-
Locating the site of the lesion
Calculate it’s depth
Determine the direction of angulation for needle placement
- Parts of the US
-
Transducer Probe
Central Processing Unit (CPU)
Transducer pulse controls
Display
Keyboard/cursor
Disk Storage Device
Printer
-
One of the most important functional parts to the entire machine.
Basically the “mouth and ears of the unitâ€.
It functions by producing/sending the ultrasound waves and receives the wave echoes.
- trandsducer probe
- The transducer Usually contain one or more crystals, usually ___ Come in many different shapes and sizes; shapes determines the ______
-
quartz
; field of view
-
Transducer
Frequency of emitted sound waves determines the _____ and of the image
- depth ; resolution
-
is capable of converting one form of energy to another
- Piezoelectric element
-
Transducer
An electric current is applied to the crystals which causes them to change ______(vibrations)
- shape rapidly
- How does a transducer work?
-
Piezoelectric element is capable of converting one form of energy to another
An electric current is applied to the crystals which causes them to change shape rapidly (vibrations)
These vibrations produce sound waves that travel away
And when the pressure of the sound waves bounces back to the crystals, the crystals emit electrical currents
Therefore transducers have the ability to not only produce a sound wave from an electric current ( but it also has the ability to receive a sound wave to produce another electrical current (toward).
A sound absorbing substance eliminates back scatter from the probe itself
Acoustic lens helps focus emitted waves in a particular direction
- What are the components of teh the CPU
- microprocessor, memory, amplifiers, and power supply)
-
What is the function of the CPU
-
Sends electrical current to transducer to create sound wave
Receives electrical pulses from probe
Processes the date sent back from the electrical pulses
Forms the image on the monitor or display
Stores the images and data on an internal or external storage device (disk).
-
Allows the Sonographer to set and change the frequency and the duration of the wave pulses
Also allows the operator to change the scanning mode of the machine
- transducer pulse controls
- simply a monitor or computer screen that displays the images created by the CPU
- display
- is a form of a “mouse†or rolling sphere and keyboard that allows you to select different areas on the screen and label specific views or anatomy demonstrated. It is also used for the measurement taking properties of the system.
- keyboard/
- can be various forms of storage media (hard disk, CD, portable drive) for the CPU to store the data and images created so that they can be read.
- disk storage device
- some sort of printing device (laser, film, paper) that provides a hard copy of the images seen on the display screen for patient use or for radiologists/physicians to read
- printer
- Difference bw radiographer and US
-
Differences include:
Sonographer’s detailed knowledge of anatomy and pathophysiology
Understanding of three-dimensional anatomy
Reproducing the reconstruction of a sonographer’s image is necessary to produce an adequate image
- organizations important to US
-
American Society of Echocardiography (ASE)
Society of Diagnostic Medical Sonography (SDMS)
American Institute of Ultrasound in Medicine (AIUM)
Society of Radiologist in Ultrasound (SRU)
Society of Vascular Technology (SVT)