lesson 2 Flashcards
Piezoelectric effect noted by who in 1880
Pierre and Jacques Curie
In the 1950s they published their work on direct contact scanners showing images of
muscles of the forearm and later of breast tissue and reported percent accuracy in differentiating benign from malignant lesions.
Wild and Reid
in 1970s he developed an ophthalmic scanner. He subsequently repeated the
sonographic visualization of intraocular and orbital tumors, foreign bodies, and retinal detachments.
Baun
- they laid the foundation of
midline echoencephalography. This field of investigation was further developed in Europe by Gordon - This technique
was widely used in accidents and emergencies and in the neurology department until the advent of CT scanner in the late 1970s
Luksell and Turner
The BLANK was introduced in the mid-1970s to early 1980s, and a high-resolution conventional real-time imaging scanner was linked to a pulsed Doppler device. These systems were popular for the evaluation of carotid circulation
duplex system
- Sound waves beyond the ordinary limits of hearing
- A form of mechanical energy which can be characterized as a wave phenomenon. (Ultrasound wave is similar to X-ray, both are waves transmitting energy)
- Requires a medium for propagation as it travels poorly through air thus requiring an airless
contact with the body during examination (mineral oil/jelly as coupling
agent) - Important method for imaging interventions in
the body - Used for real-time imaging of the location of the tip of a catheter as it is inserted into a blood vessel and guided along the length of the vessel
- Used for minimally invasive surgery to guide
the surgeon with real-time images of the inside of the body
ULTRASOUND
The alternate compression and rarefaction created by the motion of the speaker cone produce alternate to and fro motion that is passed from molecule to molecule
longitudinal waves
is primarily along the direction of particle movement (longitudinal
waves). Longitudinal waves are important in conventional ultrasound imaging and Doppler, while transverse waves are measured in shear wave elastography.
Sound propagation
is dependent on medium of propagation whereas frequency is independent of the medium and does not
change significantly.
SPEED OF SOUND
the distance traveled per
unit of time
Propagation speed
- Are mechanical disturbances that propagate through a medium.
- used to form medical images are longitudinal waves, which propagate (travel) through a physical
medium (tissue or liquid).
SOUND WAVES
Audible sound
20 to 20,000 Hz
Ultrasound frequencies are higher than the audible sound which is?
> 20 KHz
Diagnostic ultrasound uses transducers w/frequencies
ranging from
1 to 20 MHz
- the number of oscillations or wave crests passing a stationary observer per second. It is the number of waves that pass a given point in one second
- units of Hertz (1 Hz = 1 cycle per second).
- Symbol: f
FREQUENCY
- It is the distance between identical points in the
adjacent cycles of a waveform signal
propagated in space or along a wire - units of meters or millimeters.
- Symbol: λ (lambda)
WAVELENGTH
Measure of the height of the wave. It is the size
of the wave displacement or the intensity. Measurement of the amount of energy
transferred by a wave
AMPLITUDE
a medical test that utilizes
high-frequency sound waves to capture live images from the inside of your body
Ultrasound or Sonography
3 Interaction
- Reflection
- Refraction
- Absorption.
the return of incident ultrasound energy as an echo directly back to the transducer when interacting at a boundary with normal
incidence.
REFLECTION
When an ultrasound wave is incident on such a target, the wave is scattered over a large range of angles
SCATTERING
the characteristics of a material related to density and elastic properties. The product of density and velocity of propagation is called
ACOUSTIC IMPEDANCE
Occurs when the ultrasound signal is deflected from a straight path and the angle of deflection is away from the transducer.
REFRACTION
This law shows that the angles of the incident and transmitted waves are the same when the speeds of sound in the two media are the same. Used to describe the relationship between the angles of incidence and refraction
SNELL’S LAW
