ultrasound Instrumentation physics


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ultrasound Instrumentation physics

  1. 1. Instrumentation & Knobology<br />MODERATORS<br />DR SURESH MASIMADEDR SHIVANAND MELKUNDI<br />1<br />vaseemali@gmail.com<br />
  2. 2. The battle!<br />vaseemali@gmail.com<br />2<br />
  3. 3. Why study ultrasound<br />vaseemali@gmail.com<br />3<br />Bread and butter!<br />
  4. 4. comparision<br />vaseemali@gmail.com<br />4<br />
  5. 5. Piezoelectric effect : history<br />1880 piezoelectric effect : Pierre Curie and Jacques Curie.<br />Curie temperature<br />1917, SONAR, Paul Langevin ultrasonic submarine detector.<br />Post World War II :<br />“AT cut” crystal barium titanate<br />lead zirconatetitanate<br />vaseemali@gmail.com<br />5<br />
  6. 6. vaseemali@gmail.com<br />6<br />
  7. 7. vaseemali@gmail.com<br />7<br />
  8. 8. Machine externally<br />vaseemali@gmail.com<br />8<br />Monitor<br />Speaker<br />Keyboard <br />Probes <br />CPU<br />
  9. 9. Internal components<br />vaseemali@gmail.com<br />9<br />
  10. 10. Ultrasound gel<br />Contents<br />Carbomer<br />EDTA<br />Propylene glycol<br />Trolamine<br />Don’t adjust gain till gel is applied<br />Apply gel on both sides of plastic<br />When nothing is available : use water<br />vaseemali@gmail.com<br />10<br />
  11. 11. Transducer orientaion<br />vaseemali@gmail.com<br />11<br />
  12. 12. Transducer : piezoelectric effect<br />Direct<br />mechanical force applied<br />Internal generation of electrical charge<br />Reverse<br />Electrical field applied<br />internal generation of a mechanical force<br />vaseemali@gmail.com<br />12<br />
  13. 13. Construction <br />vaseemali@gmail.com<br />13<br /><ul><li>Matching layers
  14. 14. Transducer crystal
  15. 15. Damping material
  16. 16. Casing
  17. 17. Cables </li></li></ul><li>Matching layers<br />In front of PZT<br />Acoustic connection b/n skin & PZT<br />Decreases difference in acoustic impedance<br />Less reflection<br />More transmission<br />vaseemali@gmail.com<br />14<br />
  18. 18. Transducer crystal<br />Lead zirconatetitanate<br />vaseemali@gmail.com<br />15<br />
  19. 19. Damping materials<br />Rubber<br />Back of PZT<br />Decreases Secondary vibrations<br />vaseemali@gmail.com<br />16<br />
  20. 20. Casing & Cables <br />Casing<br />Housing for crystal<br />Insulation from electrical noise<br />Cables<br />Excite <br />Receive<br />1 wire for 1 element<br />vaseemali@gmail.com<br />17<br />
  21. 21. Thickness<br />to change f we change transducer .why?<br />any f by applying AC of that f<br />Concept of resonant frequency<br />vaseemali@gmail.com<br />18<br />
  22. 22. Resonant frequency<br />vaseemali@gmail.com<br />19<br />frequency at which transmits sound most efficiently<br />depends on disc thickness<br />wavelength 2x disc thickness<br />
  23. 23. Pulsed mode<br />DC applied<br />Disc expands<br />A layer is compressed<br />Subsequently adjacent layer compressed<br />Compression wave of v velocity<br />vaseemali@gmail.com<br />20<br />
  24. 24. Continuous mode<br />AC voltage applied<br />Crystal pulsed like piston<br />Compressions and rarefactions<br />Wavelength <br />Frequency <br />vaseemali@gmail.com<br />21<br />
  25. 25. Near field(Fresnel zone) & far field(Fraunhofer zone)<br />Near field : inhomogeneous interference<br />Far field : diverges <br />Focal zone<br />Between near and far field<br />Best resolution <br />vaseemali@gmail.com<br />22<br />
  26. 26. Mechanical transducers<br />Obsolete<br />Physically moved for beam steering<br />Used in 3D 4D<br />Types <br />Rotary wheel<br />Oscillating transducer<br />Oscillating mirror<br />vaseemali@gmail.com<br />23<br />Diagnostic Ultrasound: Physics and Equipment<br /> edited by Peter R. Hoskins, Kevin Martin, Abigail Thrush<br />
  27. 27. Rotary wheel<br />One or more elements<br />Wheel like housing<br />Small transducer face<br />Intercostal access <br />vaseemali@gmail.com<br />24<br />
  28. 28. Rotary wheel<br />vaseemali@gmail.com<br />25<br />Motor <br />Belt<br />transducers<br />
  29. 29. oscillating <br />Drive motor<br />Housed in container<br />Motor movement<br />Element rotates back & forth<br />vaseemali@gmail.com<br />26<br />
  30. 30. Oscillating mirror<br />Element is stationary<br />Mirror moves<br />Directs beam which moves<br />vaseemali@gmail.com<br />27<br />
  31. 31. electronicfocusing<br />Multiple elements used<br />Separate electrical supply<br />Sequential excitement of elements<br />Types <br />Linear<br />curved<br />2 dimensional<br />Annular<br />phased array<br />vaseemali@gmail.com<br />28<br />
  32. 32. Electronic focusing<br />Mounted on straight bar<br />Electronic pulsing<br />Focal depth<br />Focus at many FL<br />Greater time delay b/n elements=shorter focal length<br />vaseemali@gmail.com<br />29<br />
  33. 33. Multiple zone focusing<br />2 focal zones<br />Focused in 2 pulses<br />First one focused at f1<br />Second at f2<br />vaseemali@gmail.com<br />30<br />
  34. 34. Linear VS Curved array<br />Linear <br />curved<br />Larger area of pt contact<br />Wide field near the skin<br />Better quality image<br />Superficial structures<br />Small acoustic window<br />Narrow field near skin<br />Wide field at depth<br />Detailing is less<br />vaseemali@gmail.com<br />31<br />
  35. 35. Evolution of arrays<br />vaseemali@gmail.com<br />32<br />Medical imaging: principles, detectors, and electronics<br /> By Krzysztof Iniewski<br />
  36. 36. 1.5 D array<br />Multiple(5-7) linear arrays<br />Beam steering in Azimuthal plane<br />Phased : outer to inner<br />Frame rate reduction<br />vaseemali@gmail.com<br />33<br />The essential physics of medical imaging<br /> By Jerrold T. Bushberg<br />
  37. 37. 2D array<br />Multiple rows of elements<br />Voxel instead of pixel<br />Obstetrics<br />vaseemali@gmail.com<br />34<br />
  38. 38. 2d arrays<br />vaseemali@gmail.com<br />35<br />
  39. 39. Annular array<br />Elements in concentric rings<br />vaseemali@gmail.com<br />36<br />
  40. 40. Linear VS phased array<br />vaseemali@gmail.com<br />37<br />
  41. 41. Phased array<br />Elements pulsed as groups <br />Small time delays<br />Pulsed by processor<br />vaseemali@gmail.com<br />38<br />
  42. 42. Phased array<br />vaseemali@gmail.com<br />39<br />
  43. 43. Endorectal <br />vaseemali@gmail.com<br />40<br />360 degree radial rectal transducer.<br />Main SpecificationsArray Type: Mechanical RadialScan angle: 360ºFrequency range: 7.5/10 MHz<br />
  44. 44. endovaginal<br />vaseemali@gmail.com<br />41<br />Array type: Convex ArrayScan angle: 120°Radius: 14 mmFrequency range: 3-7.5 MHz<br />
  45. 45. “T" Style Intraoperative<br />vaseemali@gmail.com<br />42<br />Array Type: Linear ArrayScan angle/width: 42mmFrequency range: 5-10 MHz<br />
  46. 46. "I" Style Finger-Grip intraop<br />vaseemali@gmail.com<br />43<br />design fits comfortably between the index and middle finger which allows for palpating organs and scanning at the same time.<br />Array Type: Convex ArrayScan angle/width: 65°/20mmFrequency range: 3.75-10 MHz<br />
  47. 47. End Fire Laparoscopic<br />vaseemali@gmail.com<br />44<br />End-fire laparoscopic transducer that is perfect for CBD scanning and targeting lesions. <br />Array Type: Phased ArrayScan angle/width: 90°Frequency range: 3-7.5 MHz<br />
  48. 48. Micro Surgery<br />vaseemali@gmail.com<br />45<br />pediatric scanning <br />CBD scanning. <br />small vessels <br />Array Type: Linear ArrayInsertion diameter: 10mmScan angle/width: 10mmFrequency range: 5-13 MHz<br />
  49. 49. Motorized TEE<br />vaseemali@gmail.com<br />46<br />cardiac anesthesia, cardiac surgery, or intensive care work<br />Array type: Phased Array SectorScan angle: 90°Frequency range: 2-8 MHzInsertion Depth: 1000 mmDiameter: 12.5 mm<br />
  50. 50. 38mm for Regional Anesthesia<br />vaseemali@gmail.com<br />47<br /><ul><li>slightly larger footprint 38mm
  51. 51. visualization of deeper structures
  52. 52. nerves
  53. 53. Infraclavicular
  54. 54. popliteal regions.
  55. 55. guide needle placement </li></ul>Main SpecificationsArray Type: Convex ArrayScan angle/width: 38mmFrequency range: 5-10MHz<br />
  56. 56. Cardiac Phased Array<br />vaseemali@gmail.com<br />48<br />Cardiac transducer <br />Array type: Phased ArrayScan angle: 90°Frequency range: 2.5-5 MHz<br />
  57. 57. intravascular<br />vaseemali@gmail.com<br />49<br />Atheromatous plaque<br />After stenting<br />
  58. 58. image display<br />vaseemali@gmail.com<br />50<br />
  59. 59. image display<br />vaseemali@gmail.com<br />51<br />Manufacturer <br />
  60. 60. image display<br />vaseemali@gmail.com<br />52<br />Date/time<br />
  61. 61. image display<br />vaseemali@gmail.com<br />53<br />Clinic info<br />
  62. 62. image display<br />vaseemali@gmail.com<br />54<br />Patient info<br />
  63. 63. image display<br />vaseemali@gmail.com<br />55<br />Profile / Preset<br />
  64. 64. image display<br />vaseemali@gmail.com<br />56<br />Transducer in use<br />
  65. 65. gain<br />Degree of echo amplification<br />Bightness of display<br />Measured in db<br />More : artifactual echoes<br />Less : negates real echo info<br />vaseemali@gmail.com<br />57<br />Gain <br />
  66. 66. image display<br />vaseemali@gmail.com<br />58<br />Map/smooth/persist <br />
  67. 67. image display<br />vaseemali@gmail.com<br />59<br />depth<br />
  68. 68. Annotation <br />vaseemali@gmail.com<br />60<br />Annotation <br />
  69. 69. Image tinting<br />vaseemali@gmail.com<br />61<br /><ul><li>Golden hue is aesthetically pleasing to the eye
  70. 70. Shows excellent shadows and highlights. </li></li></ul><li>Left right invert<br />vaseemali@gmail.com<br />62<br />
  71. 71. Up down invert<br />vaseemali@gmail.com<br />63<br />
  72. 72. Split frame<br />vaseemali@gmail.com<br />64<br />Display 2 images side by side<br />Comparison of echotexture<br />
  73. 73. Modes of image display<br />65<br />vaseemali@gmail.com<br />
  74. 74. A mode<br />Ophthalmic exam<br />Precise length & depth measurements<br />Transducer : line of sight<br />Position of structure : X<br />Strength of backscatter <br />vaseemali@gmail.com<br />66<br />Amplitude of<br /> backscatter<br />Time/distance<br />
  75. 75. B mode<br />vaseemali@gmail.com<br />67<br />Brightnessα intensity of echo<br />Position in tissue α position on screen<br />
  76. 76. M mode<br />Brightness α intensity of reflected signal<br />Position of moving reflectors<br />Rapid motion : cardiac valves<br />vaseemali@gmail.com<br />68<br />Essentials of medical ultrasound: a practical introduction to the principles<br /> By Michael H. Repacholi, Dierdre A. Benwell<br />
  77. 77. M mode<br />vaseemali@gmail.com<br />69<br />The essential physics of medical imaging<br /> By Jerrold T. Bushberg<br />
  78. 78. M mode<br />ECG concurrent<br />Line of sight<br />vaseemali@gmail.com<br />70<br />
  79. 79. Real time USG<br />Succession of frames<br />Motion of tissues<br />Line density<br />at least 100 per frame<br />Frame rate<br />Depth of view<br />vaseemali@gmail.com<br />71<br />
  80. 80. Frame rate<br />Movie FR 25-30fps<br />Temporal resolution<br />Now >100 fps, TR 10ms<br />Real time 20-30fps<br />M mode : very high fps<br />Hence LOS ,TR 0.1ms<br />Better frame rate<br />Less depth<br />Less field of view<br />Depth X scan lines X frame rate =constant<br />vaseemali@gmail.com<br />72<br />
  81. 81. Calipers/measure<br />Length<br />Area <br />Volume <br />vaseemali@gmail.com<br />73<br />Calipers <br />
  82. 82. Trackball <br />Cursor motion<br />GUI control<br />vaseemali@gmail.com<br />74<br />Track ball<br />
  83. 83. Zoom<br />Magnifies selected area<br />Read zoom<br />Digital zoom<br />No changes in line density<br />Write zoom<br />Optical zoom<br />Increases scan line density<br />Improved resolution<br />vaseemali@gmail.com<br />75<br />
  84. 84. image display<br />vaseemali@gmail.com<br />76<br />Dynamic range Compress<br />
  85. 85. Dynamic range/compress<br />Ratio of largest/smallest echo<br />Measured in dB<br />From tissues 100-150dB<br />Decreases as signals into USG<br />Rejection filter : rejects very small & very large echoes<br />TGC<br />60 dB at ADC level <br />vaseemali@gmail.com<br />77<br />
  86. 86. Compress <br />60dB of interest<br />Display : only 20dB brightness levels<br />Non linear amplifier<br />More gain for smaller signals<br />Liver texture: wide <br />Obstetric: less <br />Dark : amniotic fluid<br />Bright : bones <br />vaseemali@gmail.com<br />78<br />
  87. 87. Power <br />vaseemali@gmail.com<br />79<br />
  88. 88. Power <br />Not the same as gain<br />Energy transferred to tissues<br />More power : more tissue damage<br />Measured in watts/cm2<br />ALARA : as low as reasonably allowable<br />More than 8 W/cm2 : therapeutic<br />AIUM guidelines(SATA,SPTP)<br />Doppler : excessive power levels<br />Use less power<br />Quick examination<br />vaseemali@gmail.com<br />80<br />
  89. 89. Gain <br />vaseemali@gmail.com<br />81<br />Overall “brightness”<br />Changes echo strength over entire image<br />
  90. 90. Time gain compensation<br />Each slider for a range of depth<br />Top : superficial<br />Bottom : deep<br />Buttons at Center : average gain<br />vaseemali@gmail.com<br />82<br />
  91. 91. Time gain compensation<br />vaseemali@gmail.com<br />83<br />
  92. 92. Time gain compensation<br />vaseemali@gmail.com<br />84<br />Springer handbook of acoustics<br /> By Thomas D. Rossing<br />
  93. 93. Freeze and cine loop<br />Stops further image acquisition<br />Displays current image <br />vaseemali@gmail.com<br />85<br />
  94. 94. Cine loop<br />Track ball<br />Not USG specific<br />Used in CT MRI PET<br />Still images in succession<br />Played back <br />Dynamic movement :<br />Cardiac motion<br />Doppler studies<br />Recorded as movie<br />Physician/cardiologist can view later<br />vaseemali@gmail.com<br />86<br />
  95. 95. Image processor<br />Interpolation between scan lines<br />Log compress<br />Post processing<br />Spatial filtering<br />Reduce noise<br />Enhance edges<br />Temporal filtering : frame avg/persist<br />Reduces image noise<br />Image demonstrates a lag<br />Reduction in temporal resolution<br />vaseemali@gmail.com<br />87<br />
  96. 96. Scan converter (ADC)<br />Echo : Analog wave<br />Analogue<br />Storage CRT<br />Unstable<br />“drift” in settings<br />Analog-Digital convertor<br />Digital <br />Stable<br />Processing<br />vaseemali@gmail.com<br />88<br />
  97. 97. Image display<br />Displays : analogue input<br />Modern machines: digital architecture<br />DAC <br />Input : digital<br />Output : analogue<br />Brightness <br />Contrast <br />vaseemali@gmail.com<br />89<br />
  98. 98. Image memory<br />640 X 480 pixels<br />256 gray shade levels<br />¼ MB per image<br />Color images : Doppler imaging<br />Freeze function<br />Temporary image store<br />Archiving : MLC <br />Latest systems : internal storage<br />Hold many GB data<br />vaseemali@gmail.com<br />90<br />
  99. 99. Image resolution<br />Spatial : 2 close objects as distinct<br />Axial : along beam axis<br />Lateral : perpendicular to beam axis<br />Azimuthal : perpendicular to beam & transducer<br />Contrast : two regions of different avg brightness<br />Temporal : distinguish events in time<br />Real time cant in cardiac valve motion<br />Freedom from artifacts<br />vaseemali@gmail.com<br />91<br />
  100. 100. Spatial resolution<br />vaseemali@gmail.com<br />92<br />elevation<br />lateral<br />axial<br />Medical imaging: principles, detectors, and electronics<br /> By Krzysztof Iniewski<br />
  101. 101. Tickle UR brain!<br />Why does the high frequency superficial probe have a high resolution<br />vaseemali@gmail.com<br />93<br />
  102. 102. Axial resolution<br />vaseemali@gmail.com<br />94<br />SPL=no of cycles X wavelength<br />The essential physics of medical imaging<br /> By Jerrold T. Bushberg<br />
  103. 103. Axial resolution<br />95<br />Ultrasound in cardiology<br /> By Kurt J. G. Schmailzl, Oliver Ormerod<br />vaseemali@gmail.com<br />
  104. 104. Lateral resolution<br />Depends on Beam width<br />User controlled<br />Depends on focusing<br />vaseemali@gmail.com<br />96<br />The essential physics of medical imaging<br /> By Jerrold T. Bushberg<br />
  105. 105. Azimuthal/elevation resolution<br />Resolution in plane<br />Perpendicular to beam axis<br />Perpendicular to transducer<br />Thickness of beam<br />No user control<br />Fixed due to transducer thickness<br />vaseemali@gmail.com<br />97<br />
  106. 106. image display<br />vaseemali@gmail.com<br />98<br />Mechanical index<br />
  107. 107. image display<br />vaseemali@gmail.com<br />99<br />Thermal index<br />
  108. 108. safety<br />Thermal index<br />Mechanical index<br />vaseemali@gmail.com<br />100<br />
  109. 109. Thank you<br />vaseemali@gmail.com<br />101<br />
  110. 110. vaseemali@gmail.com<br />102<br />
  111. 111. vaseemali@gmail.com<br />103<br />
  112. 112. vaseemali@gmail.com<br />104<br />
  113. 113. References <br />Principles and Practice of Ultrasonography<br />By Bhargava<br />Doppler Ultrasound in Gynecology and Obstetrics<br />By ChristofSohn, Hans-Joachim Voigt, Klaus Vetter, Klaus Vetter (M.D.)<br />Small animal diagnostic ultrasound<br /> By Thomas G. Nyland, John S. Matto<br />Clinical sonography: a practical guide<br />  By Roger C. Sanders, Thomas Charles Winter on<br />Clinical diagnostic ultrasound<br /> By Grant M. Baxter, Paul L. P. Allan, Patricia Morley<br />PACS and Imaging Informatics: Basic Principles and Applications<br />By H. K. Huang<br />Medical imaging physics<br /> By William R. Hendee, E. Russell Ritenour<br />The essential physics of medical imaging<br /> By Jerrold T. Bushberg<br />Appleton & Lange's review for the ultrasonography examination<br />By Carol Krebs, Charles S. Odwin, Arthur C. Fleischer<br />Advances in mass data analysis of images and signals in medicine ...<br />By Petra Perner<br />The practice of ultrasound: a step-by-step guide to abdominal scanning<br />By Berthold Block<br />Diagnostic ultrasound imaging: inside out<br />By Thomas L. Szabo<br />vaseemali@gmail.com<br />105<br />