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牙科放射線學 (1) PowerPoint Presentation
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牙科放射線學 (1)

牙科放射線學 (1)

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牙科放射線學 (1)

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  1. 牙科放射線學(1) Dental Radiographic Facility (1) (2) 牙科放射線設備與設施 (1) (2) 陳玉昆副教授: 高雄醫學大學 口腔病理科 07-3121101~2755 yukkwa@kmu.edu.tw

  2. 學 習 目 標 Dental X-ray generating equipment Dental X-ray film/image plate Dental radiographic processing equipment

  3. References: 1. Harring JI & Jansen L: Dental radiography- principle & techniques 2nd edition, Chapters 2,3,5-9, 22, 23 p. 11-34, 35-46, 63-80, 81-90, 91-107, 108-122, 123-153, 342-362, 363-383 2. Eric Whaites: Essentials of dental radiography & radiology 3rd edition, Chapter 5, p. 33-49 3. 何復辰: 牙科放射線學 1st edition, p. 21, 23, 37 4. White & Pharoah: Oral radiology: principle & interpretation, 5th edition, Chapter 6, p. 94-109 5. Kaohsiung Medical University, Oral pathology department 6. Nickoloff ED. Radiology review – radiologic physics. Chapter 2, p. 7-16 7. http://www.ndt-ed.org/EducationResources/CommunityCollege/Radiography/TechCalibrations/definition.htm

  4. Dental Radiographic Facility X-ray generating equipment X-ray machine Image receptors Radiographic film/detector Processing facilities Dark room, machine Components of X-ray machine Ref . 1

  5. Transformer Transformer work only with AC voltage Turn ratio=Nr Nr = [Ns/Np] Nr = >1 Nr = <1 Step-down transformer Step-up transformer Adjusts input voltage to be constant Autotransformer Ref. 1

  6. X-ray tubehead Position indicating device Excess radiation Outline of size 2 intraoral film Colliamator Diaphragm Round collimator Excess radiation Rectangular Tubular Outline of size 2 intraoral film Rectangular collimator Lead collimator Ref . 1

  7. X-ray tubehead at most 7.6cm in diameter Position- indicating device Lead collimator Refs. 1, 2

  8. Length Material Shape Parallel X-ray beam Not recommended Correct focus Correct focus Parallel X-ray beam Parallel X-ray beam Position-indicating device (spacer cone) Correct focus Lead collimator Parallel X-ray beam 2.75” PID X-ray tubehead Short cone Pointed plastic PID Open-ended PID Long cone Refs. 1, 2

  9. Position-indicating device (spacer cone) 8-inch PID 16-inch PID Ref. 1

  10. Cooling (99% heat) Cooling X-ray tube 直徑-2mm 長度-1cm Absorb of unwanted x-ray from all other directions 60 - 90 kVp Molydenum cup (focal device) Tungsten filament 真空 Copper Target 3 - 5V (Tungsten) Anode (+) Cathode (-) Window (lead glass) Tungsten (鎢) 熔點:3410℃ Generators can be classified as a conventional, minifocus, and microfocus system Conventional units have focal-spots > ~0.5 mm, minifocus units have focal-spots ranging from 50 microns to 500 microns (.050 mm to .5 mm), and microfocus systems have focal-spots < 50 microns Refs. 2, 3

  11. Anode Cathode Anode Cathode e - e - e - e - Anode Cathode X-ray tube Higher kVp – faster electron produced 1 X-ray release in all directions 2 Higher (5-20) mA – more electron produced Effective X-ray beam (1%) 3 X-rays Refs. 1, 2, 3

  12. Two types of anodes STATIONARY – FLUORO PORT DENTAL & RADIOTHERAPY ROTATING – MOST DIAGNOSTIC Ref. 7

  13. Stationary Anode TypeX-ray Tube GLASS ENVELOPE FILAMENT CATHODE ANODE TUNGSTEN TARGET Ref. 6

  14. Rotating Anode TypeX-ray Tube GLASS ENVELOPE ROTOR ANODE BEARINGS FILAMENT Ref. 6

  15. Rotating Anode TypeX-ray Tube HOUSING: stator VACCUM Lead & steel cathode anode rotor OIL filter mirror bulb X-ray collimator Ref. 6

  16. Exchangeable cathode Target Lateral view Anode (+) e e e e e e e e e e e e e e e e Focal spot Front view Rotating X-ray machine>90kVp Rotatory Target Cathode 1 Anode (+) X-ray beam Cathode (-) X-ray beam Stronger X-ray beam Cathode 2 X-ray beam Ref. 3

  17. Anode Angle ANODE SHAFT ANODE BOMBARDING ELECTRONS ANODE ANGLE Ref. 6

  18. Anode Angle anode cathode ELECTRONS Focal spot EFFECTIVE FOCAL SPOT EYE Ref. 6

  19. Anode Angle HEAT HEAT ANODE ANODE 450 ELECTRONS 300 Most usual anode angle-12.50 ELECTRONS EFFECTIVE FOCAL SPOT SIZE EFFECTIVE FOCAL SPOT SIZE For the same effective focal spot size, the heat capacity increases as the anode angle decreases Ref. 6

  20. EFFECTIVE FOCAL SPOT SIZE Increases as mA increases Decreases as kVp increases Depends upon intensity distribution Depends upon anode angle

  21. Sharp image 20 degree Blurred image e - e e - e - e - Penumbra effect Focal spot – penumbra effect Anode (+) Cathode (-) Target Actual focal spot Focal spot 10mm X-ray beam Apparent focal spot X-ray beam 4mm Ref. 2

  22. Focal spot – penumbra effect Point Source Focal Spot Anode Film Penumbra Image (no penumbra) Image Image Anode Penumbra Film Image Ref. 1

  23. Focal spot – penumbra effect Ref. 7

  24. Particulate radiations X-ray beam characteristics Particle Mass Units Charge Origin Ref. 1

  25. X-ray beam properties Ref. 1

  26. X-ray beam properties Ref. 1

  27. X-raytubehead Patient’s head Film X-ray beam properties Primary Radiation (1) Secondary Radiation (2) Scatter Radiation (3) Ref. 1

  28. X-ray beam properties X-RAY TUBE LEAKAGE RADIATION SECONDARY RADIATION PRIMARY RADIATION -LEAKAGE -SCATTERED SCATTERED X-RAY Ref. 6

  29. Thickness of aluminium filter (absorblow level x-ray) =70kVp -- at least 1.5mm >70kVp -- more than 2.5mm Aluminum filter Aluminum filter Aluminum filter Long & short wavelengths Short wavelengths low energy high energy Enlargement of detail Long wavelength Low frequency Short wavelength High frequency Refs. 2, 3

  30. DC current (+) Voltage Time AC current X-ray production X-ray production Constant-potential rectification Time Single phase, full wave rectification DC current X-ray production DC current 3 phase, full wave rectification X-ray production DC current Half wave rectification Ratification Refs. 2

  31. Arm X-ray tube X-ray tube Tube head Extraoral/ intraoral film Extraoral film Conventional Arm X-ray tube X-ray tube Tube head Extraoral film Conventional/ digital Intraoral film X-ray machine Ref. 5

  32. kV mA Control Panel 固定 kVP 調整 時間 Upper anterior Lower molar Upper premolar Lower premolar Upper molar Lower anterior Control Panel X-ray machine – control panel X-ray tube Extraoral film Conventional Intraoral film Arm X-ray tube Tube head Ref. 5

  33. 關 門 警告標誌 X-光使用中 操作步驟 鉛玻璃 X-ray room 鉛片 Ref. 5

  34. Dental Radiographic Facility X-ray generating equipment X-ray machine Image receptors Radiographic film/detector Processing facilities Dark room, machine Double film Direct-action, non-screen, wrapped/packet film Periapical film (2#) (31x41mm) Front (smooth surface) dot Front (white color) dot Back Occlusal film (57x76mm) largest intraoral film (pebbled surface) Back Back Front Periapical film (0#) (22x35mm) Intraoral film dot Bitewing film Ref. 5

  35. Placed towards X-ray beam Placed towards occlusal surface of tooth 鉛 片 底 片 Dot Film orientation 黑 紙 塑膠封套 塑膠封套 底 片 鉛 片 0.007吋 0.2mm 黑 紙 從此處拉開封套 紋路 Intraoral radiographic film 黑 紙 黑 紙 底 片 鉛 片 塑膠封套 Protective layer Film emulsion (silver halide) Adhesive layer Film base cellulose (flexible) Protective layer Film emulsion (silver halide) Refs. 1, 3, 5 Adhesive layer

  36. Film orientation Film orientation 塑膠封套 黑 紙 正面 背面 底 片 鉛 片 Left Posterior Intraoral radiographic film 上 下 顛 倒 鉛 片 底 片 背面 正面 黑 紙 塑膠封套 Refs. 3, 5

  37. 粒子 最大 感光 最快 Detail 最差 粒子 最小 感光 最慢 Detail 最好 Intraoral radiographic film Kodak film packet color codes Kodak film packet color codes 淡綠色 green gray Mint Gray blue mauve Raspberry Tan 淡紫色 褐色 Speed of Film 大 小 Refs. 1, 5

  38. Panoramic Cassette Front Intensifying Screen Back Back Cephalometric Panoramic Cassette Back Intensifying Screen Front Front Front Intensifying Screen Back Intensifying Screen Unexposed film Indirect-action, screen film Extraoral radiographic film Refs. 1, 5

  39. Cross-section Protective coating Phosphor layer Calcium tungstate (CaWO4) Rare earth phosphors (gadolinium, lanthanum) Non-rare earth phosphorus (yttrium) Reflective layer (Titanium dioxide) Screen support layer (polyester/ plastic) Ultraviolet system No cross-over – better resolution Intensifying Screen(增感屏) Photoelastic effect Absorb low energy photons 螢 光 Cross over 底 片 Absorb high energy photons CaWO4 System (Blue light) Ref. 2

  40. Periapical Size 1 X-ray beam Size 2 Front screen Phosphorus Size 0 Screen Film Fluorescent light from screens Back screen Bite-wing Size 2 Size 3 Size 1 Size 0 Occlusal Size 4 Radiographic film - Summaries Labeled film packet Ref. 1

  41. Radiographic film - Summaries Sizes, Measurements, and Uses for Intraoral Film Film Type Size Measurements Adult Child Anterior Posterior Periapical Bite-wing Occlusal Ref. 1

  42. Cassette carrier orbits around the front of the face Shifting centers Start Finish Shifting centers Continuous mode The film also starts to move The entire film has been exposed Split mode R L Refs. 2, 4

  43. Ref. 1

  44. Two centers Three centers Continual centers Ref. 1

  45. Rigid cassette (curved) Rigid cassette (flat) Flexible cassette Pouch Ref. 1

  46. Orbit before patient Orbit Cassette carrier X-ray source cassette Orbit behind patient Cassette carrier Cassette with film inside Ref. 5; manufacturer’s catalogue

  47. 3D focal trough (image layer) Control panel X-ray source F-H plane Anterior Bite block Ref. 4; manufacturer’s catalogue

  48. True cephalometric lateral skull 1.5-1.8 m Cephalometric Radiography Refs. 1, 2

  49. Cephalometric postero- anterior of the jaws (PA jaws) Refs. 1, 2

  50. Extraoral Radiography Refs. 2, 5