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Ultrasound - Coggle Diagram

- - - - shorter wavelength
  - - - Longer wavelength
- - - - a voltage (alternating potential difference) is applied to the crystal, causing it to vibrate
        
        Crystal is polarised and electrodes placed on either side: contraction and relaxation of crystal = vibration
        
        A vibrating crystal produces sound waves
        
        We choose the frequency at which the crystal vibrates
        
        Reflected sound waves re-enter the probe
        
        crystal vibrates
        
        EMF induced across crystal sides
        
        EMF measured (in proprtion to the amount of reflection, producing a specific vibration and thus EMF)
        
        Reflects many echoes: Hyperechoic => WHITE
        
        Air
        
        Lungs
        
        Bone (hypoechoic with hypoechoic shadow due to lack of penetration)
        
        Muscle (mix of hypo and hyper)
        
        Because sound waves cant penetrate gas and bone as well as deep structures.
        
        Gas in lungs and bowel.
        
        Therefore not good for these
        
        1 more item...
        
        Reflects some echoes: Hypoechoic => GREY
        
        Fat (hyperechoic with hyperechoic lines)
        
        Muscle (mix of hyper and hypo)
        
        Reflects no echoes: Anechoic => BLACK
        
        Veins (and compressible)
        
        Arteries (and pulsatile)
        
        Cysts
        
        Fluid in bladder
        
        Overall image: :warning:
        
        Tissue = Grey
        
        fat = bright border
        
        Fluid = Black
        
        Calculation of the depth of reflected tissue: Based on:
        
        Beam travel time
        
        Sound velocity in tissue
        
        Ultrasound gives you an image based on reflection and refraction
        
        some light is reflected
        
        Some light is transmitted and refracted into next layer
        
        1 more item...
        
        Time: time between the first and second voltage pulse received back to the transducer
        
        Higher frequency probes: superficial structures
        
        SUPERFICIAL structures:
        Frequency = 7-18MHz
        
        Provides better linear (axial) and horizontral (lateral) resolution
        
        Neonatal brain, breast, Thyroid, Parathryoid, Muscle, Tendon, Testis
        
        Lower frequency probes: Penetrate deeper structures
        
        **DEEPER structures**
        Frequency = 1-6MHz
        
        Lower axial and lateral resolution due to deeper tissue penetration
        
        liver, kidney
      - Piezoelectric effect:
        -Mechanical -electrical energy conversion