The role of xeroradiography in cephalometric radiology

Xeroradiography and its application to dentistry

Xeroradiography is a highly accurate electrostatic imaging technique. In this technique a conventional single-phase dental x-ray unit is used as an x-ray source, but instead of a silver-halide film image, a uniformly charged selenium alloy plate housed in a light-proof cassette is used. In this article the equipment, procedure, properties and artifacts related to the xeroradiographic technique are described. An evaluation of the xeroradiographic images is also presented. Xeroradiography, which requires only about one-third of the dose required for conventional radiographs, is a valuable alternative to conventional radiography for detecting carious lesions, calculus deposits and periodontal disease. It is also of value in interpreting periapical structures.

Exposure reduction in cephalometric radiology: a comprehensive approach

Various methods have been proposed and investigated for the purpose of reducing radiation exposures in cephalometric radiography. The purpose of this investigation was to use various dose-reducing methods from four major categories--(1) rare-earth intensifying screens, (2) rare-earth filtration, (3) prepatient soft-tissue enhancement methods, and (4) films varying in speed and latitude--to determine optimal combinations on the basis of exposure reduction and image quality achieved. In laboratory tests and clinical trials, radiation doses were compared along with various tests of image quality for the standard system currently used at this institution and for experimental systems. Image quality was assessed by standard panel-of-expert methods and more quantitative methods involving optical densitometry, contrast indices, and landmark envelopes of error. Results demonstrated that significant exposure reductions were achievable, often with improved image quality. The degree of exposure reduction was dependent largely upon the type of intensifying screen and to a lesser extent on beam filtration or film types. The greatest reduction in exposures were achieved with techniques using rare-earth beam filtration. Image quality was highest with a new wide-latitude type film. Because such significant reduction in radiation exposure for cephalometrics is possible with new techniques, we conclude that a change from the previous standard should occur. In establishing a new technique, orthodontists should consider adopting rare-earth screens and beam filters, flat-grained films, prepatient soft-tissue enhancement methods, and the elimination of grids.

A critical evaluation of xerocephalometry: absorbed dose and diagnostic information

The present study showed that the thyroid (60X) and active bone marrow (100X) doses are increased when xeroradiography is used in cephalometrics, as compared to a rare earth screen/film system. These results are compared to previously published articles. The rationale for advocating a kVp setting of approximately 100 and a negative development mode is presented. It is recommended that xeroradiographic cephalometric examinations be reserved for special cases in which image quality is a top-priority requirement.

Radiologic exposure conditions and resultant skin doses in application of xeroradiography to the orthodontic diagnosis

Xeroradiography is the recording of radiologic images by a photoelectric process rather than the photochemical one used in conventional radiography. In order to investigate the advantages and disadvantages of xeroradiography in the orthodontic field, minimum xeroradiologic exposure conditions for skull projections, Schüller's and oblique temporomandibular joint projections, and hand projections were established by thirteen examiners and the relationship between the image production and x-ray radiation was discussed in comparison with related findings obtained with conventional film techniques. The advantages of xeroradiograph were finer and clear images caused by the "edge effect" and wide latitude of xeroradiography; the main hazard was the unavoidable larger skin dose required by the projection procedures. The skin doses with xeroradiography were 2.4 to 16.2 times larger than those with conventional film techniques.

A cephalometric appraisal of xeroradiography

The literature on the physics, the radiation hazard, and the current medicodental applications of xeroradiography is reviewed. A study is presented on estimating the effect of a xeroradiographic technique on the degree of inter- and intraobserver error in cephalometric landmark identification, as compared to a radiographic technique. This study involved identification by four observers of sixteen cephalometric landmarks on twelve xeroradiographs and twelve radiographs, on two separate occasions. The conclusions are that neither technique provided a significant reduction in interobserver differences. However, for eight of the thirty-two variables (nasion's Y axis, portion's X and Y axes, basion's X axis, Bolton point's X axis, anterior nasal spine's X axis, menton's Y axis, and the tip of the nose's X axis), as opposed to two (basion's Y axis and gonion's Y axis), xeroradiography produced a significant reduction in intraobserver error in comparison to radiography.

Dental xeroradiography as an adjunct in the evaluation of oral cancer: a preliminary report

This pilot study of an experimental dental xeroradiography imaging system involved twelve oral cancer clinic patients. Xeroradiographs were compared with conventional intraoral film radiographs, taken with similar x-ray projections. The new dental xeroradiographic system was judged superior for the imaging of both osseous and soft-tissue structures. Especially significant was the new imaging system's ability to portray early bone erosion not detectable with the conventional intraoral film technique. These results point to the need for controlled clinical evaluations of dental xeroradiography, in order to assess the full potential of this rapid, low-radiation imaging system in the evaluation of oral cancer.

Clinical trials of intraoral dental xeroradiography

A new dental xeroradiographic processor was clinically tested. In comparison with conventional radiographs, xeroradiographs often showed more anatomic detail of teeth and bone and required approximately half the exposure time. These characteristics, the speed of operation and the added features for convenience, suggest that xeroradiography may be important to dental radiography in the future.

Patient radiation dose in conventional and xerographic cephalography

A comparison of the radiation doses for xeroradiographic and conventional film screen cephalography was made. Alderson tissue-equivalent phantoms were used for patient stimulation. An optimum technique in terms of patient dose and imaqe quality was established for the xeroradhe data indicated that the dose for the Xerox process ranged from five to eleven times greater than that for the conventional process for entrance and exit exposures, respectively. The most commonly reported dose, the entrance dose, was found to be 206 mrad, which is five Imes that for the conventional cephalogram. This dose, however, falls within an acceptable range for other dental and medical radiation doses. It is recommended that conventional cephalography be used for routine purposes and that xeroradiography be reserved for situations requiring the increased image quality that the process affords.

Landmark identification accuracy in xeroradiographic cephalometry

Identification accuracy of fourteen cephalometric landmarks was compared between xeroradiographic cephalograms and conventional cephalograms. Four landmarks--point A, upper incisor tip, infradentale, and menton--were more accurately determined on the xeroradiograph, while two landmarks--point B and condylion--were more accurately determined on the conventional cephalogram. Although not conclusively demonstrated in this study, the xeroradiograph does appear to offer more clarity and detail than the conventional cephalogram. Further investigation of this new diagnostic medium will be necessary before its true significance to dentistry can be evaluated.