ULTRASOUND IMAGING - RADIOLOGY MACHINES

Monday, February 24, 2014

ultrasound
Why Ultrasound?
  • Because it is Non-Ionizing
  • Portable and flexible
  • Easy to Operate
  • Does not require special room or building
  • Cost effective
  • Safe-even pregnats

Ultrasound Imaging vs. Radiography
  • They complement each other
  • Both have strengths a weaknesses
  • Cost concerns - correct selection
  • All patients should receives abdominal radiographs before ultrasonography to get all the information and eliminate need for ultrasound

Strength of Ultrasound
  • Determining origin of an abdominal mass
  • Evaluation of organ parenchyma like: Liver, speen, kidney, adrenal, pancreas, intestines, prostate, bladder, heart.
  • Fetal visibily
  • Real time scanning - see movement / motion
  • Performing fine needle aspiration / biopsy
  • Cells or tissue NOT images ultimately give us the definition diagnosis for neoplasm, etc.
  • Ultasound does not provide a histopathologic diagnosis

Disadvantage of Ultrasonography
  • Ultrasound cant penetrate gas or bone
  • Can't assess intestinal gas patterns
  • Can't evaluate some extra abdominal structures like spine
  • Equipment can be expensive
  • Diagnosis success is user dependent
  • Must know anatomy very well

Earliest Ultrasound

History of Ultrasound
Preparation Period
  • 1842 - Doppler ultrasound: Principle of frequency shift.
  • 1880 - Brother Curie: Discovery of Piezoelectric Phenomenon
  • 1916 - Langevin and Chilowski : Construction of the First Ultrasound Generator (SONAR)
  • 1929 - SOKOLOV : Basis of Non-Destructive Ultrasound Material Testing.

History of Diagnostic Ultrasound
FIRST ATTEMP
  • 1942 - DUSSIK : Hyperphonograpie (Tranmission Method)
  • 1949 - KEIDEL : Heart Volume Measurement
  • 1949 - UCHIDA : A model Encephalography
  • 1950 - WILD : Tissue Differentiation
  • 1951 - WAGAI : Bile Stone Detection
  • 1942 - FIRST ATTEMP : UNSUCCESSFUL

3d ultrasound
Sample 3d Ultrasound
Clinical Applications of Ultrasound
  • 1950 - 1D imaging (A - Mode)
  • 1954 - Echocardiography (M - Mode)
  • 1955 - 2D Image of the abdomen (B - Mode)
  • 1958 - 2D Imaging in Obstretrics
  • 1958 - 2D Imaging of Opthalmology
  • 1968 - Transrectal Examination
  • 1968 - First Contrast Imaging (SALINE)
  • 1978 - Transesophageal Examination
  • 1990 - Broad Band Transducers
  • 1992 - 3D Ultrasound imaging in OB/GYNE
  • 1992 - Transpulmonary Echocontrast Agents
  • 1996 - Native Harmonic Imaging
  • 1998 - 4D Ultrasound (3D Ultrasound in real time)

What is Ultrasound?
  • An acoustic vibrations of frequency higher than 20 kHz, it is non audible by human ear
  • According to the type of interaction with cells and tissues

Active Ultrasound
  • High intensity (Application in physical therapy and surgery)

Passive Ultrasound
  • Low intensity ( Application in medical diagnostics )

Ultrasounds Principle
  • When you shout into a well, the sound of your shout travels down the well and is reflected (echoes) off the surface of the water at the buttom of the well. If you measure the time it takes for the echo to return and if you know the speed of sound, you can calculate the depth of the well fairly and accurately.
  • Ultrasound is sound having a frequency greater than 20,000 cycles per second, that is sound above the audible range.
  • Medical Ultrasound is sound having frequency greater 2 - 100 Mhz and is a sound that converted to an image.
Diagnostic Ultrasound
  • Physical Principle Ultrasonic waves passing through the body are partially reflected on tissue interfaces, reflection (echoes) are received, processed and display.

Instrumentation

Ultrasound Scanners
  • All ultrasound scanners consist of similar componets that perform the same key functions. One of these is a transmitter that sends pulses to the transducer, a receiver and a processor that detects and amplifies the backscattered energy.

The Transmitter
  • Although the tranducer is itself the transmitter of the ultrasound pulses into the body, it must be energized initially by the transmitter, which applies precisely timed, high amplitude voltage to the transducer.
  • The length of an ultrasound pulse is determined by the number of alternating voltage changes applied to the transducers. Transducers have a range of frequencies which they are able to produce. This is known as the bandwith.

Components of Ultrasound
  • Transducer
  • Ultrasonic Beam
  • Display unit

Pressure Generation
Piezoelectric Crystal

"piezo" means pressure, so piezoelectric means:
  • Pressure generated when electric field if applied
  • electric energy generated when pressure is applied.

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