Ultrasound is a one of the most used imaging method in field of medicine & healthcare

1. Welcome you all
BY:lokendra yadav

2. ULTRA SOUND
A
REVOLUTION
IN
MEDICAL IMAGING

3. WHAT IS MEDICAL
IMAGING?
?

4. MEDICAL IMAGING: The techniques
and processes used to create image of
the internal as well as external human
body parts for clinical purpose .

5. why medical imaging is required?
Medical imaging provides a pictorial status
of particular organ which is to be treated
It makes a surgical targets more clear and
precise
It provides a pictorial status of fetus
development right from 4th weak to 36th- 38th
week
It make therapeutic targets easy to detect

6. TYPES OF MEDICAL IMAGING WIDELY
USED
X-RAY
MAMOGRAPHY
CONTRAST RADIOGRAPHY
ULTRA SOUND
CT SCAN
MRI
SPECT(SINGLE PHOTON EMMISION
TOMOGRAPHY)
PET(POSITRON EMISSION
TOMOGRAPHY)

7. HISTORY OF
ULTRASOUND……………..
PIZOELECTRIC IS DEVELOPED BY THE
CURIES IN 1880 USING NATURAL
QUARTZ
SONAR was first time used in
war time 1940
Diagnosis medical

8. WHAT IS
ULTRA SOUND
?

9. ULTRA SOUND : PHYSICAL
DEFINATION !!!!!!!!!
• Sound waves greater
than 20,000 Hertz or
cycles per
second
Infrasoun <20 Hz (ACOUSTIC) >20 KHZ Ultrasoun
d

10. ULTRA SOUND : MEDICAL
DEFINATION!!!
DIGNOSTIC MEDICAL
ULTRASOUND IS THE USE OF HIGH
FREQUENCY SOUND TO AID IN
DIGNOSIS AND TREATMENT OF
PATIENT.
FREQUENCY RANGES USED IN
MEDICAL ULTRASOUND ARE 2-
15 MHZ

11. Piezoelectric
Effect The principle
 Definition: of
converting energy by applying
pressure to a crystal
.
The reverse of the piezoelectric
effect converts the energy back to its
original form

12. piezoelectric effect Ultrasound
Transducers
•A transducer converts one type
of energy into another
• Based upon :pulse-echo principle
occurring with ultrasound
the
crystals, ultrasound transducers
piezoelectric
convert:
– Electricity into sound = pulse
– Sound into electricity = echo

13.  Transducer contains piezoelectric
elements/crystals which produce the
ultrasound pulses (transmit 1% of the
time)
 These elements convert electrical
energy into a mechanical ultrasound
wave

14. PULSE
• Pulse of sounds is send to soft
tissues
•Sound interaction with soft tissues=
bio effect
•Pulsing is determined by transducer
or probe crystal and ins not operated
or control

15. ECHO
ECHO IS PRODUCED BY SOFT TISSUES
TISSUE INTRACTION WITH SOUND =
ACOUSTIC PROPAGATION PROPERTIES
ECHOES ARE RECEIVED BY THE
TRANSDUCER CRYSTAL
ECHOES ARE INTRPRETED AND PROCESSED
BY ULTRA SOUND MACHINE

16. reflective
refraction
Scattered
echoes
Incident
Angle of incidence = angle of reflection

17.  Reflected echoes return to the
scan head where the piezoelectric
elements convert the ultrasound
wave back into an electrical signal
 The electrical signal is then
processed by the ultrasound
system

18. FACTORS AFFECTING
ULTRASOUND
FREQUENCY
WAVELENGTH
BANDWIDTH
ATTENUATION
TIME GAIN COMPENSATION

19.  The thickness of the crystal
determines the frequency of the scan
head
Low High
Frequency Frequency
3 MHz 10 MHz

20. FREQUENCY AND
RESOLUTION
HIGH FREQUENCY = HIGH RESOLUTION
3.5 MHz(sector) 7.5 MHz(linear)

21. DYNAMIC RANGE
Decreased DR Increased DR

22. B-MODE M-MODE

23. Color Doppler Power Doppler

24. MACHINE COMPONENT
Transducer probe
CPU(central processing
unit)
Transducer pulse
control
Display
Keyboard /cursor
Disk storage device
Printer

27. Size, design and
frequency
depend upon the
examination

28. Electrical signal produces ‘dots’ on the
screen
Brightness of the dots is proportional to
the strength of the returning echoes
Location of the dots is determined by
travel time. The velocity in tissue is assumed
constant at 1540m/sec
 Distance = Velocity
Time

29. „B‟ mode

30. Interactions of Ultrasound with
Tissue
• Acoustic impedance (AI) is dependent on the
density of the material in which sound is
propagated
- the greater the impedance the denser the
material.
• Reflections comes from the interface of
different AI‟s
• greater  of the AI = more signal reflected
Transducer
• works both ways (send and receive directions)
Medium 1 Medium 2 Medium 3

31. Sound is attenuated by tissue
More tissue to penetrate = more
attenuation of signal
Compensate by adjusting gain based on
depth
near field / far field
AKA: TGC

32. Gain controls
receiver gain only
does NOT change power
output
think: stereo volume
Increase gain = brighter
Decrease gain = darker

33. Gain settings are important to
obtaining adequate images.
bad far
bad near field
field
balanced

34. Strong Reflections = White dots
Diaphragm, tendons, bone
„Hyperechoic‟

35. Weaker Reflections =
Grey dots
Most solid organs,
thick fluid – „isoechoic‟

36. No Reflections = Black dots
Fluid within a cyst, urine, blood
„Hypoechoic‟ or echofree

37. Beam comes out as a slice
Beam Profile
Approx. 1 mm thick
Depth displayed – user controlled
Image produced is “ 2D ”
tomographic slice
assumes no thickness
You control the aim
1mm

38. The ultimate goal of any ultrasound
system is to make like tissues look the
same and unlike tissues look different

39. Resolving capability of the system
axial/lateral resolution
spatial resolution
contrast resolution
temporal resolution
Processing Power
ability to capture, preserve and display the
information

40. Ultrasound Applications
Visualisation Tool:
Nerves, soft tissue masses
Vessels - assessment of position, size,
patency
Ultrasound Guided Procedures in real
time – dynamic imaging; central venous
access, nerve blocks

41. Imaging
Know your anatomy – Skin, muscle,
tendons, nerves and vessels
Recognise normal appearances –
compare sides!

42. Skin, subcutaneous
tissue Epidermis
Loose connective tissue and subcutaneous
fat is hypoechoic
Muscle interface
Muscle fibres interface
Bone

45. Summary
• Resolution determines image clarity
• Electronic Arrays may be sector or linear
• Frequency & wavelength are inversely proportional
• Attenuation & frequency are inversely related
• Display mode chosen determines how image is
registered
• Diagnostic Medical Ultrasound is safe!

46. conclusion
•Imaging tool – Must have the knowledge to
understand how the image is formed
•Dynamic technique
•Acquisition and interpretation dependant
upon the skills of the operator.