口腔颌面医学影像诊断学（中山大学）1.2口内投照技术.pptVIP

Chapter 3  Intraoral radiography techniquesand normal image Zeng Donglin PhD., Director Periapical radiology Bite-wing film I Periapical radiology Bisecting Angle Technique Paralleling Technique 一、 Bisecting Angle Technique 原理：等腰三角形两边相等 (head tipped back) MSP floor Full-mouth series, Bisecting Angle Technique (all # 2 films for adults) ADVANTAGES (compared to Paralleling technique) More comfortable No anatomical restrictions Film holder not essential DISADVANTAGES Images distorted Harder to position beam Film less stable (compared to Paralleling Angle technique) Perpendicular angle 垂直角度：X线中心线与被检查牙长轴与胶片之间夹角的分角线的角度。 X-ray beam perpendicular to line bisecting angle formed by film and long axis of tooth. Long axis of the tooth not parallel with long axis of the film. X-ray beam perpendicular to line bisecting angle formed by film and long axis of tooth. Bisecting line 90o = foreshortening 90o = elongation 水平角度：X线中心线向牙弓近远中向所倾斜的角度. The angle formed by Central X-ray line tips to the distal medial surface of teeth. 0 Overlap (incorrect) Imaging the third molar region when having difficulty placing film far enough posteriorly. 二 Paralleling Technique Film/tooth/ring all parallel X-ray beam perpendicular to tooth/film X-ray beam 原理：胶片平行牙体长轴，X线中心线垂直胶片投照 Best OK OK Paralleling Technique Head Position Paralleling Technique ADVANTAGES 1. Better dimensional accuracy 2. Beam alignment simplified 4. Head position not critical 3. Easier to standardize films (compared to Bisecting Angle technique) Paralleling Technique DISADVANTAGES 1. May be uncomfortable 2. Limited by anatomy (compared to Bisecting Angle technique) Paralleling Instruments ANTERIOR POSTERIOR Technique: Position: sit upright, tragal-ala line parallel to the floor Film placement: 3x4mm( a wing or a tab(标签） attached to the pebbled side（感光面） of the film) film held in a lingual position to the examined region, the patient bites down on the wing. Vertical angulation: +8 degrees Point of e