Cultural physics

448 views

Published on

Published in: Business, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
448
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
10
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Cultural physics

  1. 1. Titan I date and venueUltrasound Physics AndObtaining an Image Sandra Thomas Clinical Marketing & Education Manager SonoSite Ltd – Middle East,India & Africa 1
  2. 2. Titan I date and venueAgenda•What is ultrasound?•How is it generated?•What happens to it?•What do things look like?•Other stuff – Doppler etc2
  3. 3. Titan I date and venueWhat is Ultrasound? •Infrasound 0-20 Hz •Audible Sound 20 Hz to 20,000 Hz •Ultrasound >20,000 Hz (or 20 KHz) •Medical Ultrasound 2 MHz to 15 MHz3
  4. 4. Titan I date and venueGeneration of Ultrasound•Transducer convertsenergy from one form toanother •Piezoelectric effect •Electrical energy applied to crystal(s) causes dimensional change (mechanical energy) •Dimensional change produces sound wave •Reception of reflected beam is reverse of generation4
  5. 5. Titan I date and venue Image Generation Initiate sound wave by system Transmission through medium Reflection from structures Signal returns to systemll of the above occur simultaneously real time scanning so we can see otion 5
  6. 6. Titan I date and venue2D Real-time ultrasound2D images of tissue traversed by ultrasound scan. Displaysmotion by showing images of tissue under the transducer as it isbeing scanned6
  7. 7. Titan I date and venueUltrasound Resolution Resolution is the ability to identify closely separated interfaces • Resolution has two components • Axial resolution – ability to distinguish 2 reflectors along the path of the beam • Depends on pulse length/frequency • In practice axial resolution is 0.5mm for high frequency transducers • Lateral resolution • Ability to distinguish 2 reflectors as individual elements which are perpendicular to the US beam 7 • Depends on beam profile/scan line density
  8. 8. Titan I date and venue Axial Resolution Lateral ResolutionDepends on pulse length (frequency) 8 Depends on beam profile/line density
  9. 9. Titan I date and venueInteraction of Ultrasound with TissuesPositives:Reflection- occurs at 07.39.12 hrs __[0000007].mp4boundaries betweentissues of differingacoustic impedances.Best reflection whenbeam is perpendicularto boundary9
  10. 10. Titan I date and venueInteraction of Ultrasound with TissuesPositives:Reflection- occurs atboundaries betweentissues of differingacoustic impedances.Best reflection whenbeam is perpendicularto boundary10
  11. 11. Titan I date and venue Multibeam technology…• Real time acquisition software• Improves image quality : more detail, more tissue signature• Artifact reduction• Improves contrast resolution 11 Standard Multibeam
  12. 12. Titan I date and venueMultibeam technology… Standard acquisition Multibea m12
  13. 13. Titan I date and venue Benefits…Improves contrast resolutionIncreases tissue information 13 Standard Multibeam
  14. 14. Titan I date and venueWhat is the effect of frequency ? Frequency = Resolution Frequency = Resolution 1 Frequency = Penetration Frequency = 14 Penetration
  15. 15. Titan I date and venue15
  16. 16. Titan I date and venueEffect of frequency shift10MHz16
  17. 17. Titan I date and venue7.5MHz17
  18. 18. Titan I date and venue5MHz18
  19. 19. Titan I date and venue10MHz19
  20. 20. Titan I date and venueTransducers •Transmits and receives the ultrasound beam •Contacts the patient’s skin •Takes thin slices of object being imaged •Rotate or angle to change views 38 mm 1 mm20
  21. 21. Titan I date and venueTransducer Orientation Markings Markings are located on one side of transducer only and correspond to orientation marke on screen groove vertical protrusion horizontal protrusion 21
  22. 22. Titan I date and venueTransverse Transducer Orientation 22
  23. 23. Titan I date and venueTransverse Transducer Orientation Orientation marker Groove towards patient’s right Skin surface Blood vessel 23 Right Left
  24. 24. Titan I date and venueLongitudinal Transducer Orientation 24
  25. 25. Titan I date and venueLongitudinal Transducer Orientation Groove towards patient’s head Orientation marker Skin surface Blood vessel Head Feet 25
  26. 26. Titan I date and venue26
  27. 27. Titan I date and venue Image Appearance N E Tissue = Grey A R Blood = Black F A R27
  28. 28. Titan I date and venue Ultrasound appearancesArtery Anechoic - black PulsatileVein Anechoic - black CompressibleMuscle Hyperechoic fascia Hypoechoic muscle Hyperechoic Tubular (fibrillar)Tendon Discontinuous hypoechoic lines separated byNerves – LS hyperechoic lines(fasicular) 28 TS Multiple round hypoechoic areas(fasicles) surrounded by hyperechoic halo (connective tissue,
  29. 29. Titan I date and venueAppearance of nerves TS LS29
  30. 30. Titan I date and venueFemoral Nerve Artery Vein Nerve30
  31. 31. Titan I date and venueBrachial Plexus - interscalene31
  32. 32. Titan I date and venueImage Optimisation - Gain Amplification of returning echoes One of the commonest mistakes in ultrasound imaging is the use of incorrect gain settings. Insufficient gain can result in missed structures of low reflectivity. Excessive gain can result in false echoes or over saturation, which may obscure important diagnostic image characteristics such as shadowing or enhancement32
  33. 33. Titan I date and venue GainNearFarOverall 33
  34. 34. Titan I date and venueNear Gain34
  35. 35. Titan I date and venue Image OptimizationDepth adjustment N EThe choice of correct depth setting is a trade- Aoff between achieving adequate field of view Rto resolve all relevant structures andmaximising detail resolution F A R35
  36. 36. Titan I date and venue Image Optimization-DepthIncreasing the depth allows you to visualize deeper structures N E Tissue = GreyAdjust the depth so that the target is centered in the image A R Blood = Black F A R Too close Too far Just right 36
  37. 37. Titan I date and venue37
  38. 38. Titan I date and venue Doppler UltrasoundDoppler Effect based on work by Austrian physicist JohannChristian Doppler N E Tissue = Grey AApparent change in received frequency due to relative Rmotion between a sound source and sound receiverSource moving TOWARD receiver = HIGHER frequency Blood = Black F ASource moving R AWAY from receiver = LOWER frequency 38
  39. 39. Titan I date and venue39
  40. 40. Titan I date and venue Doppler Ultrasound N E Tissue = Grey A R Blood = Black F A R40 Color Power Doppler-venous & arterial flow
  41. 41. Titan I date and venueDCPD41
  42. 42. Titan I date and venue Acoustic Couplants• Air/tissue interface allows Nlittle ultrasound Tissue = Grey E transmissionso gel is A needed on skin toexclude R air•Best quality image= requires F Blood Blackan air free coupling between A RALL surfaces 42
  43. 43. Titan I date and venue Acoustic Couplants N E Tissue = Grey A R Blood = Black F A R43
  44. 44. Titan I date and venueAnd finally……..Aoccdrnig to rscheearch at CmabrigdeUinevrtisy, it deosn’t mtlaer in what oredr theltteers in a wrod are, the olny iprmoatnt tihng istaht the frist and lsat ltteer be in the rghit pclae.The huamn mnid deos not raed ervey lteter butthe word as a wlohe44
  45. 45. Titan I date and venueMedian Nerve Common extensor Tendon 45
  46. 46. Titan I date and venueAnd finally………really! What happens when you……………. 1. Have nothing to do 2. Own a sharp knife 3. Have a large lime 4. Own a patient cat……………………46
  47. 47. Titan I date and venue Thanks for listening!47

×