10. This effect ws named "piezoelectricity" after
tge Greek piezein which means to squeeze or
press.
The principle of converting energy by
applying pressure to a crystal. When an
electric voltage is applied to a transducer
crystal, the crystal gets excited and is
deformed.
Piezoelectric effect explain how ultrasound
is generated from ceramic crystals in the
transducer. An electric current passes
through a cable to the transducer and is
applied to the crystal, causing them deform
and vibrate. This vibration produces the
ultrasound beam.
11. It explain how the image is generated.
Ultrasound waves are produced in pulses , not
continuously beacuse the same crystals are
used to generate and receive sound waves ,
they cannot do both at the same time.
In the time between the pulses , the
ultrasound beam enter the patient and is
reflected back to the transducer.
These reflected sound waves cause the crystals
in the transducer to deform again and
produced an electrical signal ,that is converted
into an image displayed on the monitor.
The transducer generally emits ultrsound only
1% of the time , the rest of the time is spent
receiving the returning echoes.
17. Piezeolectric crystal arrangement is linear.
The shape of the beam is rectangular.
Near field resolution us good.
The frequency , application depend on
wheather the product is for 2D And 3D
imaging .
Linear transducer for 2D imaging:- frequency
2.5-12MHz. Application: blood vessels
visualization, breast , thyroid, tendon,
laproscopy.
18. Tendon is a connective tissue which attaches
muscle to bone.
Laproscopy is a type surgery that uses
smaller cut.(minimally invasive technque). A
slender tool that has a tinny video camera
and light on the end. When a surgeon insert
it through a small cut and into the patient
body , they can look at monitor.
19. Linear transducer 3D Igmaing:- frequency
7.5-11MHz.
Application- breast, thyroid.
20. Also called curved transducer. Because the
piezeoelectric crystal arrangement is
curvillinear.
The beam shape is convex and the
transducer is good for depth examination.
Convex 2D imaging:- frequency-2.5 MHz-
7.5 MHz. Can be used for abdominal ,
transvaginal, transrectal examination.
Convex 3D imaging:- 3.5- 6.5 MHz. used for
abdominal examination.
**micro convex transducer is used for
pediatric***
21. Frequency- 2-7.5 MHz.
Can be used for cardiac examination ,
including transoesophageal examination ,
abdominal and brain examination.
22. Also called CW doppler probe.
Measure blood flow and Speed of sound in
blood.
Uses low frequency- 2-8 MHz.
23. Used for internal examination.
Endovaginal, endo rectal and endocavity.
Frequency- 3.5-11.5MHz.
24. used in cardiology to obatin better image
of the heart .
Frequency 3-10MHz.
25. Produce electrical pulses that are applied
to the transducer.
A rate if approximately 1000 pulses per
second.
26. Amplification is used to increase the
size of electrical pulses coming from the
transducer after an echo is received.
31. Contrast is the difference in density.
Density is the amount of overall blackenning
ptoduced on the image after processing.
Digital image is the numerical representation
of an image(a set of pixel)
A matrix is a square arrangement of number
in column and rows.