title: Studies of the angular reproducibility of positioning patients adjacent to an x-ray tube: 1. Stent-rod based and extra-oral systems.
abstract: The usefulness of subtraction radiography for detecting small changes in crestal bone is dependent upon achieving reproducible geometry between x-ray beam and patient structures when serial radiographs are taken. This study evaluates 2 methods currently employed to maintain geometric correspondence: 1) a stent-based system which rigidly fixes a custom-made stent to the x-ray tube by the use of a rod and 2) an extra-oral system which positions a patient in the x-ray unit by means of ear rods. The projection of a light beam from a fixed subject reference was used to measure the change of the orientation of the reference at 2 different measurement times. The rod-stent system was able to maintain a discrepancy of less than 2 degrees 75% of the time over a time period of 6 months. For the extra-oral system this ranged from 72% to 92% during a 1-month period.
authors.affiliation: Department of Oral Biology, State University of New York at Buffalo 14214-3008.
authors.forename: K M
authors.initials: KM
authors.lastname: Allen
authors.forename: E
authors.initials: E
authors.lastname: Hausmann
authors.forename: M E
authors.initials: ME
authors.lastname: Kutlubay
authors.forename: J
authors.initials: J
authors.lastname: Loza
authors.forename: L C
authors.initials: LC
authors.lastname: Carpio
authors.forename: L
authors.initials: L
authors.lastname: Ortman
authors.forename: D
authors.initials: D
authors.lastname: Wobschall
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging*; D000539:Alveolar Process / Q000000981:diagnostic imaging*; D006801:Humans; D007834:Lasers; D010518:Periodontitis / Q000000981:diagnostic imaging; D011187:Posture; D011861:Radiography, Dental / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D015607:Stents; D013382:Subtraction Technique / Q000295:instrumentation