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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) X-Ray Film Processing & Artifact 牙科傳統X光片沖洗與失誤 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. 傳統牙科X光片洗 片的 過 程 傳統牙科X光片洗 片失誤的 原因與辨識 學 習 目 標 Understand: References 1. White & Pharoah: Oral radiology: principle & interpretation, 5th edition, Chapter 6, p. 94-109 2. 何復辰: 牙科放射線學 1st edition, p. 33, 74-79 3. Eric Whaites: Essentials of dental radiography & radiology 3rd edition, p. 47 4. Kaohsiung Medical University, Oral Pathology Department 5. Harring JI & Jansen L: Dental radiography- principle & techniques 3rd edition, Chapter 9, p. 101-127 6. www.ndt-ed.org/EducationResources/CommunityCollege/Radiography/TechCalibrations.htm

  3. X-ray photon Iodide ion Bromide ion Bromide atom Silver ion Interstitial silver ion + Silver atom Latent image site electron Formation of latent image 文字解說 卡通解說 • Collision of X-ray photon with Br- • Br- Br atom,release of e- • Attraction of e- to latent image site • +ve interstitial Ag ion attracted to -ve latent image site 5. Ag ion Ag atom as latent image 底 片 Latent image Latent image site - charge Silver atom (Br-) Bromide ion 底片 結構 atom + charge + charge Latent image是指底片已被X光照射之處, 但仍未產成肉眼可見之影像 Ref. 1

  4. Before exposure After development Emulsion Emulsion Base Base After exposure Emulsion Emulsion After fixing Latent image Base Base 底 片 AgBr Ag 洗片 AgBr被洗掉 Ref. 1

  5. Ref. 6

  6. 底片佈滿未受感光 的溴化銀離子 底片浸到顯影液中 未受照射的區域,溴化銀無改變 已受照射的區域,溴被顯影液除去 留下黑色的金屬銀沉澱 底片浸到定影液中 未受照射的區域,溴化銀 被定影液除去,留下透明 的賽洛路片 Latent image Latent image 底片受到X光 照射 底片受到 X光照射 已受照射區域,還留 下黑色的金屬銀沉澱 未受照射的區域,溴化銀 無改變 已受照射的區域,溴化銀 中的銀分離出來 Ref. 2

  7. Chemical fog Temperature Development time 6 min 650F Full development Film density 680F 5 min 700F 4.5 min 720F 4 min 760F 3 min Development time Q1.顯影液內何成份可解決chemical fog的問題? Ref. 1

  8. 成 分 功 用 顯 影 液 Phenidone(低溫作用) Helps bring out the image Hydroquinone(高溫作用) Build contrast Sodium sulphite Preservative- reduces oxidation Potassium carbonate Activator- governs the activity (Soften the emulsion) of the developing agents Benzotriazole Restrainer- prevents fog and controls the activity of the developing agents Glutaraldehyde Softens the emulsion Fungicide Prevents bacterial growth Buffer Maintains pH (7+) Water Solvent Ref. 3

  9. 定 影 液 成 分 功 用 Ammonium thiosulphate Removes unsensitized silver (hyposulfite) halide Sodium sulphite Preservative- prevents deterioration of the fixing agent Aluminum chloride Hardener Acetic acid Acidifier – maintains pH Water Solvent Ref. 3

  10. Ref. 6

  11. * * * Radiographic definition is the abruptness of change in going from one area of a given radiographic density to another Ref. 6

  12. Ref. 6

  13. source source Well defined feature Distorted and less defined feature Ref. 6

  14. Ref. 6

  15. * Radiographic contrast is the degree of density difference between two areas on a radiograph Ref. 6

  16. High keV Low keV 4 to 1 2 to 1 Ref. 6

  17. Ref. 6

  18. Changing the log of the relative exposure from 0.75 to 1.4, only changes the film density from 0.20 to about 0.30. Therefore, the sensitivity of the film is relatively low. At film densities above 2.0, the slope of the characteristic curve for most films is at its maximum. Changing the log of relative exposure from 2.4 to 2.6 would change the film density from 1.75 to 2.75. Therefore, the sensitivity of the film is high in this region of the curve. In general, the highest overall film density that can be conveniently viewed or digitized will have the highest level of contrast and contain the most useful information. Ref. 6

  19. Since radiographic contrast & definition are not dependent upon the same set of factors, it is possible to produce radiographs with the following qualities: • Low contrast and poor definition • High contrast and poor definition • Low contrast and good definition • High contrast and good definition Ref. 6

  20. Processing Errors Artifacts

  21. 放置口外片常犯之錯誤 Intensifyingscreen 增感屏 正 確 錯 誤 片子完全置於片夾內 片子沒完全置於片夾內 Ref. 4

  22. 放置口外片常犯之錯誤 錯 誤 正 確 片夾完全扣上 片夾沒完全扣上 微量 曝光 Ref. 4

  23. 拍攝口外片常犯之錯誤 錯 誤 鉛衣領子過高 正 確 Collar 鉛依 Lead apron Ref. 4

  24. 拍攝口外片常犯之錯誤 Pano之拍攝條件 錯誤常發生於 某人拍攝TMJ 後,別人於拍 攝pano時沒有調整回正確 pano之條件 TMJ 之拍攝條件 Ref. 4

  25. 沖洗口外片常犯之錯誤 錯 誤 正 確 片子正放於洗片機內 片子歪放於洗片機內 先接觸定影液 Ref. 4

  26. 沖洗口外片常犯之錯誤 正 確 錯 誤 洗片時黑布套往下垂,以免曝光。 洗片時黑布套過高, 造成曝光。 曝光 Ref. 4

  27. 沖洗口外片常犯之錯誤 根尖片 疊片 Pano片 根尖片 錯誤常發生於有人先洗片 (如pano片), 別人沒有注意間隔至少30秒, 即再洗另外一張片子 (如根尖片), 因此發生疊片之情形。 Ref. 4

  28. 沖洗咬合片常犯之錯誤 根尖片 疊片 錯誤常發生於洗片時,覆蓋的黑紙 沒有拿掉,連同底片一起洗片 (P.S.)覆蓋的黑紙前後分開各自一張,往往只拿掉一張,留下一張連同底片一起洗片 Ref. 4

  29. 片子太白 原因: • 顯影時間不夠 • 顯影溫度不夠 • 顯影液濃度不夠 • 曝光不夠 Artifact 片子太黑 原因: • 顯影時間太長 • 顯影溫度太高 • 顯影液濃度太濃 • 曝光太多 霧狀的片子 原因: • 受到其他光線的曝光,如紅燈不安全, 暗室漏光 • 顯影液太舊 • 底片過期,或因潮溼、太熱等失效 Ref. 2

  30. 關 門 X光門沒關緊 X光機按鈕沒按到底 空白片 原因: • 沒有受到X光曝光 • 錯把定影當顯影 黑片 原因: • 片子完全受到可見光的曝光 片子上有白點或白線 原因:表示那個地方顯影不夠 • 因氣泡而引起 • 因灰塵或其他物体附著在片子上而引起 • 因片子先接觸到定影液而引起 Refs. 2, 4

  31. 片子上有黑點或黑線 原因: • 因片子先接觸到顯影液而引起 黑褐色不透明的片子 原因: • 定影不夠 片子保存不久後便有黃褐色的染色 原因: • 片子定影後清水沖洗不夠,片子上有定影液殘留 Ref. 2

  32. 抓痕 原因: • 片子遭到刮傷 摺痕 原因: • 因用力折彎片子而引起 影像變形 原因: • 因照射時片子彎曲得太利害而引起 Ref. 2

  33. 片子放反,太白,上面有車輪輾過 之痕跡 原因: • 片子放反。車輪狀痕跡是片子背面鉛片的投影 口水流入片子 原因: • 因口水流入片子裡。黑紙黏住片子而引起 靜電引起 原因: • 因拿出片子時用力過猛。引起靜電而產生 Ref. 2

  34. 兩個影像重疊 原因: • 同一底片曝光兩次而引起 對比不夠 原因: • 有散射 • 曝光過度而顯影不足 Cone cut 錐切 原因: • 錐體spacer cone無對準底片 影像模糊生毛 原因:照射時 • 病人移動 • 底片移動 • X光機移動 Ref. 2

  35. An underdeveloped film appears light An overderdeveloped film appears dark A film with a damaged emulsion appears crack Developer spots appear dark or black Ref. 5

  36. Fixer spots appear light or white Developer cutoff appears as a straight white border on a film A number of processing errors result in a yellow-brown film Fixer cutoff appears as a straight black border on a film Ref. 5

  37. A black fingerprint artifact appears on the film Scratches appear as thin white lines Static electricity appears as black branching lines Ref. 5

  38. Portion of the film exposed to light appears black A fogged film appears gray & lacks detail & contrast Ref. 5

  39. Summaries Knowing: 傳統 牙科X光片洗 片的 過 程 傳統牙科X光片洗 片失誤的原因 與辨識