basics of ultrasound machine
DESCRIPTION
Ultrasound is a one of the most used imaging method in field of medicine & healthcareTRANSCRIPT
Welcome you all
BY:lokendra yadav
ULTRA SOUNDA
REVOLUTIONIN
MEDICAL IMAGING
WHAT IS MEDICAL IMAGING?
?
MEDICAL IMAGING: The techniques and processes used to create image of the internal as well as external human body parts for clinical purpose .
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 and treat
TYPES OF MEDICAL IMAGING WIDELY USED
X-RAYMAMOGRAPHYCONTRAST RADIOGRAPHYULTRA SOUNDCT SCANMRISPECT(SINGLE PHOTON EMMISION TOMOGRAPHY)PET(POSITRON EMISSION TOMOGRAPHY)
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 application in use since late 1950’s
WHAT IS ULTRA SOUND
?
ULTRA SOUND : PHYSICAL DEFINATION !!!!!!!!!
• Sound waves greater than 20,000 Hertz orcycles per
secondInfrasound
<20 Hz (ACOUSTIC) >20 KHZ Ultrasound
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
Piezoelectric Effect Definition: The principle of
converting energy by applying pressure to a crystal.
The reverse of the piezoelectric effect converts the energy back to its original form
piezoelectric effect Ultrasound Transducers
•A transducer converts one type of energy into another
• Based upon the
:pulse-echo principleoccurring with ultrasound piezoelectriccrystals, ultrasound transducers convert:
– Electricity into sound = pulse– Sound into electricity = echo
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
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
ECHOECHO IS PRODUCED BY SOFT TISSUESTISSUE INTRACTION WITH SOUND = ACOUSTIC PROPAGATION PROPERTIESECHOES ARE RECEIVED BY THE TRANSDUCER CRYSTALECHOES ARE INTRPRETED AND PROCESSED BY ULTRA SOUND MACHINE
Incident
reflective
refraction
Angle of incidence = angle of reflection
Scattered
echoes
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
FACTORS AFFECTING ULTRASOUNDFREQUENCYWAVELENGTHBANDWIDTHATTENUATIONTIME GAIN COMPENSATION
The thickness of the crystal determines the frequency of the scan head
Low Frequenc
y3 MHz
High Frequency
10 MHz
FREQUENCY AND RESOLUTION
HIGH FREQUENCY = HIGH RESOLUTION 3.5
MHz(sector)
7.5 MHz(linear)
DYNAMIC RANGE
Decreased DR Increased DR
B-MODE M-MODE
Color Doppler Power Doppler
MACHINE COMPONENTTransducer probe
CPU(central processing unit)Transducer pulse
controlDisplay Keyboard /cursor
Disk storage device Printer
Size, design and frequencydepend upon theexamination
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
‘B’ mode
•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• works both ways (send and receive directions)
Medium 1 Medium 2 Medium 3
Tra
nsd
ucer
Interactions of Ultrasound with Tissue
Sound is attenuated by tissueMore tissue to penetrate = more
attenuation of signalCompensate by adjusting gain
based on depthnear field / far field
AKA: TGC
Gain controlsreceiver gain only
does NOT change power output
think: stereo volumeIncrease gain = brighterDecrease gain = darker
Gain settings are important to obtaining adequate images.
balancedbalanced
bad near fieldbad near field bad far fieldbad far field
Strong Reflections = White dotsDiaphragm, tendons, bone
‘Hyperechoic’
Weaker Reflections =
Grey dots
Most solid organs,
thick fluid – ‘isoechoic’
No Reflections = Black dotsFluid within a cyst, urine, blood
‘Hypoechoic’ or echofree
Beam comes out as a sliceBeam Profile
Approx. 1 mm thickDepth displayed – user controlled
Image produced is “2D”tomographic slice
assumes no thicknessYou control the aim
1mm
The ultimate goal of any ultrasound system is to make like tissues look the same and unlike tissues look
different
Resolving capability of the systemaxial/lateral resolution
spatial resolutioncontrast resolutiontemporal resolution
Processing Powerability to capture, preserve and display
the information
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
Imaging
Know your anatomy – Skin, muscle, tendons, nerves and vessels
Recognise normal appearances – compare sides!
Epidermis
Loose connective tissue and subcutaneous fat is hypoechoic
Muscle interface
Muscle fibres interface
Bone
Skin, subcutaneous tissue
Summary
• Frequency & wavelength are inversely proportional
• Attenuation & frequency are inversely related
• Resolution determines image clarity
• Electronic Arrays may be sector or linear
• Display mode chosen determines how image is registered
• Diagnostic Medical Ultrasound is safe!
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.