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Techniek

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Techniek

  1. 1. Techniek BVT
  2. 2. Focus film afstand• FF van 50 naar 75 cm• dosis 50x50 naar 75x75 = factor 2,25
  3. 3. CT• Filtered back• views to voxels
  4. 4. Hiel effect• Minder straling productie aan anode kant
  5. 5. Penumbra• Kleine focal spot - weinig penumbra
  6. 6. T1-lattice-thermal
  7. 7. AAPM / Radiographics
  8. 8. MRI safety• Metal object• Wire• T top hoger op ECG• No nerve stimulation (itch)• Hearing protection• Training• SAR warmte (veel schakelen) – 4W/kg (neo 2W/kg)
  9. 9. MRI safety• New implants safe• 5 gauss line / 0.0005 T• Tissue heating• RF burns – loop by touching hands• Switching rate• pregnant: better than Xray
  10. 10. Fluoro - General• 45 mGy/min
  11. 11. Buis / techniek• 3 fase generator• Continu hoge spanning• Korter belichting• Fototimer: ionisatiekamer voor cassette• Grid ratio hoger: – meer contrast, meer straling, meer loodstrips, minder scatter
  12. 12. Buis / techniek• Bucky is moving grid – Meer dosis • Lateral decentering • Exposure spread out • Longer exposure – Higher cost• K (performance) hoger is meer contrast
  13. 13. Buis / techniek• Bucky factor (straling ontvangen / straling verzonden) – hogere BF bij hogere grid ratio – hogere BF bij dikke pat. – Hoge BF is hogere dosis• Air gap ook minder scatter
  14. 14. Screen• Xray naar licht (beter waargenomen door film• La / Ga• Speed 100-400• Thin more detail• Thick more signal, more blur
  15. 15. Fluoro• fosfor: X naar fotonen. CsI• kathode: fotonen -> electronen CsAn• anode: versnelt electronen• fosfor 2: electronen ->fotonen. CsI• Video camera of digitaal
  16. 16. Fluoro• Brightness gain = minfication gain x flux gain• min.gain = oppervlak input / oppervlak output• 4 lines / mm (CsI)• Distortion – perifeer, lage brightness (vignet), electron beam inhomogeen
  17. 17. Mammo• Mo anode, energie 17.5 en 19 keV, beter contrast• focal spot .3 mm (.1 voor vergroting)• 24 KVp (soft tissue contrast)• 65 cm tube-object (high res)• short time, high mA (motion, dose)
  18. 18. Mammo• Compression and grid to reduce scatter• Compression: – dose, short exposure, less overlap• automatic exposure• Screen / film
  19. 19. CT• Decrease noise – high mA – thick slice – decrease matrix – decrease FOV• Artifact – move (streak), alias (streak), cupping (black) – Calibration (ring)
  20. 20. DR• Plate – fosfor/ Eu stores info Eu 2+->3+ – releases after laser pulse – Blue light• particle 5-10 um – small grain sharp – large grain sensitive
  21. 21. CT processing• Reformat = ax->cor• NB reconstruct is raw->ax• VR / SR / perfusie / MIP / MinIP• Thickness, interval, pitch (zebra)• pitch = slab/step
  22. 22. CT processing• MPR (curved) – artifact detection – anatomy plane – involvement of structures – MIP/ MinIp – vessels / nodes• 3D voor presentatie / anatomie
  23. 23. Digital Fluoroscopy• Tube• Table• Image intensifier• Video system• Analog-Digital converter
  24. 24. Digital Fluoroscopy• Binair• Pixel• DSA• Frame averaging• Edge enhance• Road map• Mask• Vessel size
  25. 25. Digital Fluoroscopy• Processing: – image hold – grayscale / WL adjust – temporal average, less noise – edge (subtract blurred, add this to image)
  26. 26. Digital Fluoroscopy – DSA (shift the mask after movement) – Fade roadmap (meer/ minder in beeld) – Automatic table move / benen – Summation (MIP) – Size (calibrate)
  27. 27. US - adenomyomatosis• ring down• reverberation• comet tail• gas/metal/stone
  28. 28. US f• 2.5 MHz : deep abdomen,• 3.5 MHz : general abdomen,• 5.0 MHz : vascular, breast, pelvic• 7.5 MHz : breast, thyroid• 10.0 MHz : superficial
  29. 29. India ink / out of phase• T1
  30. 30. Chem shift
  31. 31. water: long T1
  32. 32. water: long T2
  33. 33. Fat: short T1, short T2
  34. 34. HU• Substance HU• Air -1000• Fat -120• Water 0• Muscle +40• Contrast +130• Bone +400 or more
  35. 35. Doppler• shift tussen uitgezonden en ontvangen f• aanname geluid veel sneller dan bloed• New – stitch, contrast, 3D, elasto
  36. 36. Doppler• PI= vmax-vmin /vmean – high in stenosis• RI = vmax-vmin /vmax – ...• systolic - max• diastolic - min
  37. 37. Doppler Poiseulle law• deltaP = 8L d Q / r4• L lengte cm• L viscositeit• Q flow (ml/s)• r diameter
  38. 38. Doppler / Type flow
  39. 39. Doppler
  40. 40. MRI• spoel in helium• 1x aanzetten, dan eindeloos veld• iedere maand / jaar helium bijvullen
  41. 41. MRI - spin
  42. 42. MRI veld
  43. 43. MRI
  44. 44. MRI
  45. 45. Precession
  46. 46. MRI - Larmor
  47. 47. RF pulse - rotates vector(flip angle)
  48. 48. Receiver coil
  49. 49. T1 - herstel na 90 pulsLongitudinal
  50. 50. WM short T1CSF long T1
  51. 51. T2 - transverse relaxationT2*, 3 effects (static)compensated
  52. 52. T2 in phase to out of phase
  53. 53. T2
  54. 54. T2
  55. 55. SE 90-180-180 (T2)• 90° pulse – 180° rephasing pulse at TE/2 – signal reading at TE.
  56. 56. T1 up - T2 down
  57. 57. RF
  58. 58. Coil
  59. 59. FID
  60. 60. 180 pulse
  61. 61. T2 / T2*
  62. 62. TE/TR
  63. 63. T2 only spin-spin
  64. 64. Sequence puls echo meting plak lezen fase echo
  65. 65. T1/T2
  66. 66. T1: TE small TR medium
  67. 67. T2: TE M. TR large
  68. 68. PD: TE S. TR L.
  69. 69. SE T1 of T2 of PD
  70. 70. ME T1 en T2
  71. 71. TSE / FSE (ETL = 3)• number of echoes in the same repetition (TR) is Turbo Factor / Echo Train Length (ETL).
  72. 72. IR STIR (fat) FLAIR (csf)
  73. 73. STIR geen gado
  74. 74. STIR
  75. 75. GRE fast, T1, T2*(metal sensitive)
  76. 76. Artifact / DC offset
  77. 77. Noise / deur
  78. 78. Homogeneous
  79. 79. Gradient
  80. 80. Susceptibility
  81. 81. Motion (fase richting X of Y) Rx: Fixation, trigger,
  82. 82. Flow BB / WB
  83. 83. Chemical shift (freqrichting)
  84. 84. Wraparound / Alias
  85. 85. Handout
  86. 86. Gradient Feet low B0 and f
  87. 87. Gradient• Steile gradient - dunne plak• voxels flippen in plak met lokale veldsterkte is B0 indien RF puls hoort bij B0
  88. 88. Frequentie codering
  89. 89. Gd
  90. 90. Angio
  91. 91. MRA• Gd: bolus timing - centrum K• TOF:plaksaturatie vers bloed• PC: verschil fase / statisch weefsel
  92. 92. Dynamic CE• Perfusie• T1: GE• T2: GE EPI
  93. 93. Diffusie• Hoge gradient• Afname van signaal door vrij water• T2 correctie in ADC
  94. 94. Cardio• ECG trigger• White blood: GE• Black blood: SE
  95. 95. Artefacten• View-to-view: plaats/vorm verand.• Withing view: fase fout tijdens gradient• Rx – fixatie, GMN nulling, snel, avg, fatsat
  96. 96. Flow• GMN - within view artefact• Gd/saturatieplak/flip<90 – minder ghost (view to view)
  97. 97. Motion
  98. 98. Wraparound / alias• Alleen in fase (std dubbele freq sampling)• Rx: – saturatie – meer k-lines• Kan ook 3D
  99. 99. Artefact• Chem shift: freq richting (verschil vet/water)• Susceptibility: magnetisering – Rx: SE, sterke gradient • GE met korte TE
  100. 100. Advanced 3d• 2Ri fase cod. – isotroop, lage snr, lange duur
  101. 101. Sneller• Half fourier 60-70%• SNR lager• rFOV - minder fase lijnen• FSE=TSE 180 - echos meten - centrum is eff. TE• T2 TSE fat high: J-koppeling, dipool, onvold. tijd voor signaalverlies vet
  102. 102. Contrast
  103. 103. USPIO, T2 korter, zwart
  104. 104. MR signal
  105. 105. Spin Excitatie Detectie Fliphoek Rotatietijd
  106. 106. T1 - longitudinal• TR bepaalt hoeveel tijd voor relaxatie• Korte T1 - hoog op T1- hoge Ernst <
  107. 107. T2 - transverse• TE bepaalt T2/T2* weging – 180 puls na TE• SE - T2. GE - T2*
  108. 108. SE
  109. 109. SI• Abs. dosis: 1Gy = 1 J/kg = 100 rad• Equivalente dosis = abs. dosis x stralingstype Sv.• Effectieve dosis E = Eq x weefseltype• DLP mGy/cm x factor (.015) = Eff dosis

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