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Diagnostic radiology Lec. 22 - Object localization - Localization techniques can be used to obtain the dimensional information , so we can use it to locate the following : 1.Foreign bodies . 2.Impaction teeth . 3.Unerupted teeth . 4.Salivary stones . 5.Retained roots . 6.Broken needles . Types of localization techniques : 1.Right angle technique . 2.Tube shift technique 3.Stereo radiography . 4.Radiopaque media technique . The first two techniques are the more used because of there simplicity and accuracy . Right angle technique . This technique involve the use of at least two films taken in at right angle to each other . A. One periapical film is exposed using the proper technique and angulations to show the position of the object in a superior inferior and anterior posterior relation . B .An occlusal film is exposed directing the central ray at right angle to the film . The occlusal film show the object in a bucco- lingual and anterior posterior relationships . After the two films have been exposed and processed , the radiographs are compared together to locate the object in three dimensions . This technique is mainly used to detect object in the mandible . On a maxillary occlusal projection the superimposition of features in the anterior part of the skull may frequently obscure the area of interest. The periapical radiograph shows impacted canine lying apical to roots of lateral incisor and first premolar . Occlusal view shows that the canine lies palatal to the roots of the lateral incisor and first premolar. Tube shift technique : This technique is also called Buccal object rule or Clarks rule .This rule governing the orientation of structure portrayed in two radiographs exposed at different angulations . One periapical or bite wing film is exposed using proper technique and angulations . A second periapical or bite- wing film is then exposed after changing the direction of the x ray beam , a different horizontal or vertical angulations is used . When the dental structure or object seen in the second radiograph appears to have moved in the same direction as the shift of the tubehead , the structure or object in question is positioned to the lingual . An object on the lingual surface of the mandible may appear apical to the second premolar . The object appears to have moved mesially with respect to the second premolar apex . When the dental structure or object seen in the second radiograph appears to have moved in the direction opposite the shift of the tube . the structure or object in question is positioned to the buccal . An object on the buccal surface of the mandible may appear apical to the second premolar .When another radiograph is made of this region angulated from the mesial . The object appears to have moved distally with respect to the second premolar apex . SLOB Same = Lingual Opposite = Buccal This document was created with Win2PDF available at http://www.win2pdf.com. The unregistered version of Win2PDF is for evaluation or non-commercial use only. This page will not be added after purchasing Win2PDF.