Choksi S K, Rao M S
Department of Oral Diagnosis and Radiology, Howard University of Dentistry, Washington, DC 20059, USA.
MSDA J. 1996 Spring;39(1):23-6.
A clinical study was done at Howard University, College of Dentistry, to compare the difference in the incidence of radiographic technique faults between two similar intraoral film-holding, beam-aligning, devices in a series of 1,248 radiographs. The primary difference between a conventional Extension Cone Paralleling (XCP-I) film holder and a modified, all-metal, Extension Cone Paralleling (XCP-II) film holder is the incorporation of a collimated rectangular x-ray-beam-restricting plate. This latter film holder possessed an indicator rod attached to the bite block and a metal shield to reduce primary and back-scattered radiation behind the film. In the oral diagnosis clinic, 78 dentulous patients were randomly selected and randomly divided into two groups of 39 patients. One of the two film holders was used separately for the two groups of patients, and a full mouth series of 16 periapical radiographs were made for each patient. The difference in the occurrence of total errors between the two instruments was not statistically significant. However, the conventional instrument was associated with significantly more errors in improper film positioning, while the modified device had significantly more errors in cone cutting (p < 0.01).
霍华德大学牙科学院进行了一项临床研究，旨在比较在一系列1248张口腔X光片中，两种类似的口腔内胶片固定、射线束对准装置的放射技术失误发生率的差异。传统的扩展锥平行投照（XCP-I）胶片夹与改良的全金属扩展锥平行投照（XCP-II）胶片夹之间的主要区别在于，后者并入了一个准直的矩形X射线束限制板。后一种胶片夹在咬块上附有一根指示杆和一个金属屏蔽，以减少胶片后方的原发射线和反向散射辐射。在口腔诊断诊所，随机挑选了78名有牙患者，并随机分为两组，每组39名患者。两种胶片夹分别用于两组患者，为每位患者拍摄了全口系列的16张根尖片。两种仪器的总误差发生率差异无统计学意义。然而，传统仪器在胶片放置不当方面的误差明显更多，而改良装置在锥束切割方面的误差明显更多（p < 0.01）。
