Ultrasound Flashcards
Diagnostic ultrasound also called ?
Diagnostic Medical Sonography , Sonography
and Ultrasonography
Diagnostic uses ?
Cardiology , GIT , Gynecology , Obstetrics
Ophthalmology , Urology
What are Obstetric ultrasound used for ?
Date the pregnancy (gestational age)
Confirm fetal viability
Determine location of fetus, intrauterine or ectopic
Check for the number of fetuses (multiple pregnancy)
Check for major physical abnormalities
Assess fetal growth
Sound ?
Sound energy is mechanical which exist from physical movement of molecules and particle in medium
Sound waves cannot travel propagate on vacuum
What is physical movement of molecules and particle in medium is called ?
Sound
What is Diagnostic ultrasound ?
Imaging using non-ionizing, high frequency sound to generate images of tissues in the body
what is procedure of diagnostic ultrasound ?
Sound waves are transmitted into body
structures as a small transducer is passed over the patient’s skin
Difference between sound and ultrasound ?
Is a mechanical wave that travels in a straight line (which can be heard by humans is 20 -20,000 Hz )
Ultrasound: Is a wave with a frequency greater than the upper limit of human hearing
(2 – 20 MHz)
What sound is ?
Is mechanical wave , Is longitudinal wave , Is type of pressure and form of energy
Is NOT ionizing radiation , Is NOT transverse wave and Is NOT an electromagnetic wave
Doppler and color doppler introduce ?
In 1980s
Real time scanner used ?
In late 1970s
Uses of 2D US made in ?
In early mid of 1970s
Properties of sound waves ?
Velocity , Frequency , Wavelength
and Amplitude
Velocity ?
The speed of a sound wave through a medium
Units of measure are distance/time
cm/sec
Speed of sound is determined by what ?
Density and stiffness of the medium in which it travels (slowest in air/gasses)
What velocity depends on ?
On the medium it’s traveling through
speed of sound in ?
air = 300 meters/second
water = 1,480 meters/second
bone = 4,080 meters/second
Frequency ?
The number of cycles occurring in one sec of times
( cycles per sec)
Units to describe frequency ?
Hertz = 1 cycle in one second
Kilohertz (kHz) = 1,000 cycles per second (or 1,000 Hertz)
Megahertz (MHz) = 1,000,000 cycles per second (or 1,000,000 Hertz)
Ultrasound imaging frequency range is 2-13 MHz
Wavelength ?
Length OR space over one cycle (distance)
Amplitude ?
The strength/intensity of the sound wave at any given point in time
Represented by the height point in the wave
Ultrasound machine consist of what ?
An important part which is Probe OR transducer OR Scan head probe which produces “pulses” of ultrasound waves
The reflected waves return to the probe and processed by ?
ultrasound machine – image processing
An image which represents these reflections is formed ?
Monitor
Reflection ?
occurs at interface between two adjacent tissues
The difference in acoustic impedance (z) between the two tissues causes reflection of the sound wave
The greater the difference in acoustic impedance between two adjacent tissues, the greater the reflection
What ultrasound image is formed from ?
Reflected echoes
Scattering ?
Redirection of the sound wave in several directions
Caused by interaction with a very small reflector or a very rough interface
Transmission ?
Not all of the sound wave is reflected, therefore some of the wave continues deeper into the body
These waves will reflect from deeper tissue structure
What is Attenuation ?
The deeper the wave travels in the body, the weaker it becomes
The amplitude/strength of the wave decreases with increasing depth
What are basic US instrument ?
Beam generation
Reception of the retaining echo
Image processing
Image display
Transducer ?
It is (probe) which made of Piezoelectric crystal
Emit sound after electric charge applied
Sound reflected from patient
Is a device that can convert one form of energy into another form Electrical energy to US (vice versa)
Depth of penetration ?
The HIGHER the frequency, the LESS it can penetrate into the body
The LOWER the frequency, the DEEPER the penetration
Image display ?
Four different modes of ultrasound are used in medical imaging. These are:
A-mode (amplitude)
M-mode (time-motion)
B-mode (real time)
Doppler ( measure blood flow)
Allows assessment of dynamics ?
Real time imaging
Used in 1950s , and considered one of the safest modalities ?
Non - ionizing radiation
Coupling Gel ?
A gel is used on the skin
Has low acoustic impedance and high reflectivity is ?
Air
If there is air between the transducer and the skin then the U/S is reflected
