Douglas K. Benn

Comparison of a photostimulable phosphor system with film for dental radiology

This study compared the imaging performance of a photostimulable phosphor system with E speed film for dental radiography. The response of each imaging system was measured as a function of radiation exposure. Measurements were also made of imaging performance in terms of the limiting spatial resolution and low contrast detectability. Photostimulable phosphors had a wider dynamic range in comparison with film. The limiting spatial resolution of the photostimulable phosphor was approximately 6.5 lp/mm and independent of image magnification. For film, the limiting spatial resolution was in the range 11 to 20 lp/mm depending on image magnification. At the same radiation exposure, low contrast detectability of the photostimulable phosphor was superior to that of film. Major benefits of photostimulable phosphor systems include the elimination of chemical processing and an improved low contrast detectability performance.

Validity of radiographic measurement of interproximal bone loss

The aim of the present study was to compare radiographic assessment of interproximal bone loss using a loupe with a 0.1 mm calibrated grid and a computer-assisted analysis system (LMSRT). In 35 patients suffering from untreated advanced periodontal disease, 62 standardized radiographs were taken presurgically. The horizontal and vertical angulation difference of the central beam from the orthoradial projection was calculated for each radiograph. At the time of surgery, for 115 interproximal defects, the distances from the cementoenamel junction (CEJ) to alveolar crest (AC), and CEJ to bottom of the bony defect (BD) were measured. In all radiographs, the linear distances CEJ to AC, and CEJ to BD were assessed using a loupe and LMSRT. Comparison between radiographic and intrasurgical assessments was performed using paired t-tests. A stepwise multiple linear regression analysis was used to evaluate factors that influence the discrepancy between radiographic and intrasurgical measurements. Both analyzing techniques underestimated interproximal bone loss as compared with intrasurgical measurements (CEJ-AC: loupe: 0.86 +/- 1.84 mm [p < 0.001]; LMSRT: 0.58 +/- 1.86 mm [p < 0.005]; CEJ-BD: loupe: 1.22 +/- 2.33 mm [p < 0.001]; LMSRT: 0.80 +/- 2.09 mm [p < 0.001]). LMSRT underestimated interproximal bone loss significantly less than the loupe (p < 0.001). The difference between LMSRT and intrasurgical assessments was modulated by the factors of vertical and horizontal angulation difference and defect depth (p < 0.1). Orthoradial projection reduced underestimation of radiographic assessment of bone loss. LMSRT underestimated interproximal bone loss to a lesser extent than conventional evaluation by loupe.

An imaging standard for dentistry. Extension of the radiology DICOM standard

No standard exists for electronic communication of dental images. However, maxillofacial radiology, being part of general radiology, does have the advantage of having an applicable standard: The American College of Radiology-National Electrical Manufacturers Association Standard for Digital Imaging and Communications in Medicine (Version 3.0). This standard encourages open systems interconnection of imaging equipment over standard networks while maintaining compatibility with earlier point-to-point connection standards. This standard, to be voted on in 1993, moves the American College of Radiology-National Electrical Manufacturers Association into full conformance with the International Standards Organization reference model for network communications. An object-oriented information model lays the groundwork for harmonization with other medical communications standards. This article outlines the American College of Radiology-National Electrical Manufacturers Association components and discusses the rationale of object-oriented design. The relevance of the standard to dentistry is discussed.

Centralized automated quality assurance for large scale health care systems: A pilot method for some aspects of dental radiography

President Clintons Health Security Act proposes the formation of large scale health plans with improved quality assurance. Dental radiography consumes 4% (

Characteristics of an oral and maxillofacial radiology department. Report of the ad hoc Department Characteristics Committee of the American Academy of Oral and Maxillofacial Radiology.

1.2 billion in 1990) of total dental expenditure yet regular systematic office quality assurance is not performed. A pilot automated method is described for assessing density of exposed film and fogging of unexposed processed film. A workstation and camera were used to input intraoral radiographs. Test images were produced from a phantom jaw with increasing exposure times. Two radiologists subjectively classified the images as too light, acceptable, or too dark. A computer program automatically classified global grey level histograms from the test images as too light, acceptable, or too dark. The program correctly classified 95% of 88 clinical films. Optical density of unexposed film in the range 0.15 to 0.52 measured by computer was reliable to better than 0.01. Further work is needed to see if comprehensive centralized automated radiographic quality assurance systems with feedback to dentists are feasible, are able to improve quality, and are significantly cheaper than conventional clerical methods.

A computer-assisted learning programme to reduce caries detection variability

Oral and maxillofacial radiology is a dynamic and multifaceted discipline that plays a critical role in patient care, the education of general dentists and dental specialists, and the academic health of the dental school. Diagnostic and treatment advances in temporomandibular joint disorders (TMD), implants trauma and orthognathic surgery, and craniofacial abnormalities depend heavily on conventional and advanced imaging techniques. Oral and maxillofacial radiology contributes to the education of pre- and post-doctoral dental students with respect to biomedical and clinical knowledge, cognitive and psychomotor skills, and the professional and ethical values necessary to properly prescribe, obtain, and interpret radiographs. The development of an active and successful oral and maxillofacial radiology department, division, or section requires the committment of institutional resources. This document may serve as a guide to dental schools committed to excellence in oral and maxillofacial radiology.

Radiographic Evaluation of Bone Regeneration Following Periodontal Surgery With or Without Expanded Polytetrafluoroethylene Barriers

Design A randomised controlled trial using block design was devised.Intervention A computer-assisted learning (CAL) programme, with feedback, was tested.Outcome measure Sensitivity and specificity of caries diagnosis, and the summary receiver operating characteristic (SROC) method for summarising true-positive ratio (sensitivity) and false-positive ratio (1 — specificity), were used to analyse the dichotomous data.Results The mean sensitivity for dentine caries detection was 76.3% (standard deviation (SD), 13.0%) for the experimental group and 66.9% (SD, 14.8%) for the control group (P=0.005). Mean false-positive ratios were similar (experimental 28.1% and control 28.7%; P=0.5). The area under the SROC curve was 0.832 for the experimental group and 0.773 for the control group (P=0.002).Conclusions The CAL programme does improve diagnostic performance. Improving the cognitive feedback provided by the programme should be considered before implementation.