Stationary intraoral digital tomosynthesis using a carbon nanotube X-ray source array.

OBJECTIVES: Intraoral dental tomosynthesis and closely related tuned-aperture CT (TACT) are low-dose three-dimensional (3D) imaging modalities that have shown improved detection of multiple dental diseases. Clinical interest in implementing these technologies waned owing to their time-consuming nature. Recently developed carbon nanotube (CNT) X-ray sources allow rapid multi-image acquisition without mechanical motion, making tomosynthesis a clinically viable technique. The objective of this investigation was to evaluate the feasibility of and produce high-quality images from a digital tomosynthesis system employing CNT X-ray technology. METHODS: A test-bed stationary intraoral tomosynthesis unit was constructed using a CNT X-ray source array and a digital intraoral sensor. The source-to-image distance was modified to make the system comparable in image resolution to current two-dimensional intraoral radiography imaging systems. Anthropomorphic phantoms containing teeth with simulated and real caries lesions were imaged using a dose comparable to D-speed film dose with a rectangular collimation. Images were reconstructed and analysed. RESULTS: Tomosynthesis images of the phantom and teeth specimen demonstrated perceived image quality equivalent or superior to standard digital images with the added benefit of 3D information. The ability to "scroll" through slices in a buccal-lingual direction significantly improved visualization of anatomical details. In addition, the subjective visibility of dental caries was increased. CONCLUSIONS: Feasibility of the stationary intraoral tomosynthesis is demonstrated. The results show clinical promise and suitability for more robust observer and clinical studies.

Effect of data compression on proximal caries detection: observer performance with DenOptix photostimulable phosphor images.

OBJECTIVES: To study the effect of lossy image compression on caries detection. Null hypothesis states no difference in caries detection efficacy among observers using original digital images versus images compressed at various rates of compression. METHODS: Digital images of 41 extracted posterior teeth were obtained with a storage phosphor DenOptix (Gendex DenOptix Imaging system) system. Images were exported in Tagged Image File Format (TIFF) and compressed with Joint Photographic Experts Group File Interchange Format (JFIF), as provided by the software of the imaging system. The compressions options JFIF100%, JFIF75% and JFIF50% resulted in reducing the image size to 1:2, 1:11 and 1:16, respectively. Eight observers evaluated the presence or absence of caries on a 5-point confidence scale. The actual caries status of each proximal surface was determined by ground section histology. Responses were evaluated by receiver operating characteristic (ROC) analysis. Areas under the curves (Az) were assessed using analysis of variance (ANOVA). RESULTS: The mean Az scores were 0.85 for original/uncompressed images, and 0.89 for JFIF100%, 0.88 for JFIF75% and 0.88 for JFIF50% images. These differences were not statistically significant (P = 0.26). Differences between observers were also not statistically significant (P = 0.12). CONCLUSIONS: JFIF compression at the level of 1:16 can be used without significant deterioration in diagnostic accuracy for proximal caries detection.

Characteristics of Kodak Insight, an F-speed intraoral film.

OBJECTIVES: This study reports film speed, contrast, exposure latitude, resolution, and response to processing solution depletion of Kodak Insight intraoral film. METHODS: Densitometric curves were generated by using International Standards Organization protocol. Additional curves were generated for Ultra-speed, Ektaspeed Plus, and Insight films developed in progressively depleted processing solutions. Eight observers viewed images of a resolution test tool for maximum resolution assessment. Images of an aluminum step-wedge were reviewed to determine useful exposure latitude. RESULTS: Insight's sensitivity in fresh automatic processor solutions places it in the F-speed group. An average gradient of 1.8 was found with all film types. Insight provided 93% of the useful exposure latitude of Ektaspeed Plus film. Insight maintained contrast in progressively depleted processing solutions. Like Ektaspeed Plus, Insight was able to resolve at least 20 line-pairs per millimeter. CONCLUSIONS: Under International Standards Organization conditions, Insight required only 77% of the exposure of Ektaspeed Plus film. Insight film provided stable contrast in depleted processing solutions.

Dental digital radiographic imaging.

Radiographs are an important adjunct to providing oral health care for the total patient. Historically, radiographic images have been produced using film-based systems. However, in recent years, with the arrival of new technologies, many practitioners have begun to incorporate digital radiographic imaging into their practices. Since dental hygienists are primarily responsible for exposing and processing radiographs in the provision of dental hygiene care, it is imperative that they become knowledgeable on the use and application of digital imaging in patient care and record keeping. The purpose of this course is to provide a comprehensive overview of digital radiography in dentistry. Specific components addressed are technological features, diagnostic software, advantages and disadvantages, technique procedures, and legal implications.

A comparison of Web page and slide/tape for instruction in periapical and panoramic radiographic anatomy.

Self-guided slide/tape (ST) and web page (WP) instruction in normal radiographic anatomy of periapical and panoramic images is compared using objective test performance and subjective preference of freshman dental students. A class of seventy-four students was divided into a group studying anatomy in periapical images using WP and a group studying similar ST material. In a modified cross-over design the groups switched presentation technologies to learn anatomy in panoramic images. Students completed self-administered on-line quizzes covering WP materials and conventional quizzes for ST material. Students also completed a voluntary survey. Mean quiz performance identifying matched anatomic features in PA (n = 26) and panoramic images (n = 35) was excellent (96.9%) and not different between image types (p = 0.12) or presentation technologies (p = 0.81). Students preferred WP for accessibility, ease of use, freedom of navigation, and image quality (p < .01). Student comfort level with the quiz formats of the two technologies was not different (p = 0.11). Students experienced a higher rate of mechanical and logistical problems with ST than with WP technology. While 71 percent of the students preferred WP technology, this preference appears to be related to ease of use and facilitation of flexible learning styles rather than improved didactic performance.

Updated quality assurance self-assessment exercise in intraoral and panoramic radiography. American Academy of Oral and Maxillofacial Radiology, Radiology Practice Committee.

This updated self-assessment exercise for the dental team by the Radiology Practice Committee of the American Academy of Oral and Maxillofacial Radiology is intended to produce the highest quality diagnostic radiographs while keeping patient exposure as low as is reasonably achievable. To continue to provide the best radiographic services to patients, those involved in dental radiography need to be aware of the latest changes and advances in dental radiography and need to use them in their practice.

Clinical and in vitro film quality comparison of manual and automatic exposure control in panoramic radiography.

OBJECTIVE: Automatic exposure control has been used successfully in medicine to improve image quality and reduce the number of retakes necessitated by inadequate operator selection of exposure factors. The purpose of this study was to assess the influence of automatic exposure control on panoramic image quality. STUDY DESIGN: A total of 352 patients were imaged with either the OP 100 or the Orthophos Plus panoramic machine. An expert consensus panel judged film quality using a 5-point scale. Differences in quality that would have resulted from the use of operator-determined exposures were calculated through use of an algorithm validated with test images of a human phantom. RESULTS: McNemar's test demonstrated significant improvements in quality with automatic exposure control (P = .001) in comparison with manual exposure control. No quality difference was found between the 2 machines (P = .9661). Manual exposure selection by oral and maxillofacial radiology residents was better than selection by technologists and assistants (P = .006). CONCLUSIONS: This study confirms the utility of automatic exposure control for panoramic radiography.

The influence of storage conditions on film characteristics of Ektaspeed plus and Ultra-speed films.

BACKGROUND: Dental professionals were reluctant to accept Ektaspeed (Eastman Kodak Co.) intraoral film despite its X-radiation dose-sparing advantages for patients. One reason may have been Ektaspeed film's known sensitivity to long-term storage as compared with that of Ultra-speed film (Eastman Kodak Co.). In 1995, Kodak replaced Ektaspeed with Ektaspeed Plus, claiming it had better resolution and higher stability than Ektaspeed, as well as equal exposure radiation. The authors compared film response to storage condition and time for Ultra-speed and Ektaspeed Plus films. METHODS: The authors stored 10 boxes of newly produced Ultra-speed and Ektaspeed Plus film in five locations. They conducted 23 image trials over a 26-month period, exposing each film with an aluminum step-wedge under controlled conditions. After processing the film, they measured density to calculate the film's base + fog and contrast index values. RESULTS: The authors found significant differences in film type (P = .0002), processing status (P < .0001), storage location (P < .0001) and month of storage (P < .0001). They also found a film-type-by-location interaction (P < .0001) but did not find a film-type-by-processing interaction (P = .3271). Regression lines suggested that the optical density of base + fog levels rose more steeply for Ultra-speed film than they did for Ektaspeed Plus film. A significant association of decreasing contrast with increasing months of storage was seen with Ultra-speed film (P < .0001). There was a small increase in base + fog levels resulting from the use of used solutions over the course of the study. CONCLUSIONS: Ektaspeed Plus film compared favorably with Ultra-speed film under all conditions. CLINICAL IMPLICATIONS: The authors recommend the use of Ektaspeed Plus film for intraoral imaging, as its performance is comparable to that of Ultra-speed film while requiring half the X-radiation exposure to patients. Clinicians must ensure that the correct safelights and processing solutions are used before switching to the new film.

Two- and three-dimensional imaging modalities for the detection of caries. A comparison between film, digital radiography and tuned aperture computed tomography (TACT).

OBJECTIVES: To compare the diagnostic performance provided by two- (film and digital radiography) and three-dimensional imaging modalities (TACT slices and TACT pseudoholograms) in the detection of primary caries. METHODS: Forty-two extracted human posterior teeth were mounted and imaged with conventional film and direct digital radiography. Free-hand positioning of a dental X-ray source was used for all exposures. From the digital images, iteratively restored TACT slices and TACT pseudoholograms were generated. Film images were viewed on a viewbox. Digital format images were viewed on a high-resolution monitor. Eight observers used a five-point scale to score the presence or absence of occlusal and proximal caries using the four image modalities. Observers' assessments were compared with the histological examination of tooth sections. Possible differences in ROC curve areas among image modalities, observers, and surfaces were assessed by ANOVA. Intra- and interobserver reliability as indicated by intraclass correlation was also calculated. RESULTS: There were no statistically significant differences between the diagnostic performances of film, digital radiography, TACT slices and TACT pseudoholograms in the detection of caries (P = 0.310). Intraclass correlation indicated the highest concordance both within and between observers when film was used for the evaluation. CONCLUSIONS: Under the experimental conditions of this study, three-dimensional TACT images did not improve caries detection over film or digital radiography. Further research should investigate the effects of imaging variables on TACT's diagnostic efficacy.

A quantitative analysis of dental radiography quality assurance practices among North Carolina dentists.

OBJECTIVE: The purpose of this study was to assess the level of compliance with dental radiography quality assurance recommendations on the part of dental practitioners in the state of North Carolina and to determine whether the age of the practice was an influential factor affecting compliance. STUDY DESIGN: On-site survey inspections by state officials using measurement devices and questionnaires were used to assess x-ray machine parameters and gather information about quality assurance practices in private offices in the state of North Carolina. RESULTS: There were approximately three intraoral units per facility, with an average entrance skin exposure of 267 mR per bitewing radiograph. There were no significant differences associated with the age of the practice in quality assurance practices except with respect to the type of processor used: dentists who had been in practice for more than 20 years used manual processing more frequently than those who had been in practice for less than 20 years (p = 0.001). CONCLUSIONS: Most practices showed a high level of compliance with equipment function requirements. North Carolina dentists are making an effort to comply with the American Academy of Oral and Maxillofacial Radiology recommendations. However, the use of faster film and rectangular collimation was much less than expected. Only 9% of the participants reported using E-speed film exclusively, and only 7.33% reported using rectangular collimation.

Periodontitis detection efficacy of film and digital images.

OBJECTIVE: The objective of this study was to evaluate the accuracy of alveolar crestal bone detection in a comparison of unenhanced and enhanced Sidexis (Siemens Medical Systems, Inc., Bensheim, Germany) digital images with Ektaspeed Plus (Eastman Kodak, Rochester, N.Y.) films by means of receiver operating characteristic analysis. STUDY DESIGN: More than 100 proximal and furcal areas in the anterior and posterior areas of the mandible and maxilla of each of three tissue-equivalent human skull phantoms were imaged with film, direct digital images, and contrast- and brightness-enhanced digital images. Alveolar crest status was assessed by a consensus panel of three experts who used the Delphi method and evaluated information from all of the imaging modalities concurrently. Five observers assessed all images for the presence or absence of crestal bone loss using a five-point confidence scale. Receiver operating characteristic curves were generated, and calculated areas (Az) were analyzed by means of analysis of variance. RESULTS: The expert panel determined that of 106 crestal areas, 48 were disease free and 58 exhibited bone loss greater than 2 mm apical to the cemento-enamel junction. Analysis of variance of observer Az scores showed significant differences among readers (p < 0.001) and among readings (p = 0.027), but not among modalities (p = 0.435). Mean Az values for the different modalities were as follows: Sidexis, 0.70; enhanced Sidexis, 0.71; Ektaspeed Plus films, 0.735. CONCLUSION: The Sidexis digital imaging system was not significantly different from Ektaspeed Plus film for crestal bone evaluation in this in vitro study.

A comparison of Kodak Ektaspeed Plus film and the Siemens Sidexis digital imaging system for caries detection using receiver operating characteristic analysis.

OBJECTIVE: To evaluate the accuracy of proximal caries detection comparing enhanced and unenhanced Siemens Sidexis CCD-based digital images with Ektaspeed Plus films utilizing receiver operating characteristic analysis. STUDY DESIGN: Sixty extracted teeth (24 posterior and 36 anterior) were imaged under identical standardized geometric and exposure conditions. Six observers, using a 5-point confidence scale, rated 120 proximal surfaces for the presence or absence of carious lesions by means of three image modalities: (1) observer enhanced and (2) unenhanced Sidexis displays, and (3) Ektaspeed Plus films. The ground truth was determined by microscopic analysis of ground sections. Receiver operating characteristic curves were generated with calculated areas (AZ) analyzed with analysis of variance for effect of reader, reading, and modality. RESULTS: Analysis of variance demonstrated significant differences among readers, readings and modalities (mean square values of 0.012, 0.005, 0.004, F ratios of 13.604, 5.329, 5.100; p = values of 0.001, 0.043, and 0.030, respectively). Post-hoc paired comparisons of modalities using Tukey's statistic demonstrated that only film and enhanced Sidexis images were different from each other (p = 0.024). AZ scores were 0.7650, 0.7499, and 0.8008 respectively, for unenhanced Sidexis, enhanced Sidexis, and Ektaspeed Plus film. CONCLUSION: Unenhanced digital Sidexis images were equivalent to film for the detection of proximal caries in this in vitro study. Observer enhanced Sidexis images exhibited a statistically significant lower diagnostic accuracy than the unenhanced digital and film images.

The efficacy of caries detection using three intraoral films under different processing conditions.

This study compares the diagnostic accuracy of caries detection using Ultra-speed (Eastman Kodak), Ektaspeed (Eastman Kodak) and Ektaspeed Plus (Eastman Kodak) films after they were developed in both new and used processing solutions. Ektaspeed Plus film provided significantly better diagnostic accuracy for small proximal-surface caries limited to the outer third of the dentin than did Ektaspeed film. Ektaspeed Plus film did not differ significantly from Ultra-speed film in aiding in the diagnosis of small carious lesions, and it maintained diagnostic accuracy in used processing solutions. Dentists can offer the X-ray dose-reducing technology of Ektaspeed Plus film to their patients and maintain consistently high diagnostic quality.

Effects of beam collimation on image quality.

PURPOSE: The purpose of this study was to determine the effect of three film-speed/collimator combinations on image quality, based on reviewer preference and diagnostic quality, based on caries detection. METHOD: Two hundred sixteen proximal surfaces were evaluated for the presence and severity of carious lesions on bitewing-simulated projections using D-speed film/circular, E-speed film/rectangular, and E-speed film/circular collimation. Matched films by model type were ranked, based on reviewer preference. Preference data were analyzed using Friedman's test, while the caries detection data were analyzed using a 3 x 3 x 3 x 6 ANOVA model and the kappa statistic. Variability components of the ANOVA were used to determine inter- and intra-rater reliability. RESULTS: Inter- and intra-rater reliability were 90.9 and 98.7%, respectively. Each of the film-speed/collimator combinations had average preference rankings that were significantly different from one another for each criteria (p < 0.001), with E-speed film/rectangular collimation consistently ranking highest and E-speed film/circular collimation consistently ranking lowest. There was excellent agreement in caries detection among the three film-speed/collimator combinations (kw = 0.92, kw = 0.94). CONCLUSION: Results from the subjective comparison indicated that E-speed film with rectangular collimation ranked highest for film resolution, overall appearance, and choice for caries diagnosis, while E-speed film with circular collimation ranked lowest. Caries diagnosis was comparable among the three film-speed/collimator combinations.

Effects of focal spot size on caries diagnosis with D and E speed images.

Annual measurement of the x-ray unit focal spot size has been recommended by the American Academy of Oral and Maxillofacial radiology as part of the dental radiographic quality control program. This study compares the effects of focal spot size on caries diagnosis. Three x-ray units with small, medium, and large focal spot sizes were used to produce bite-wing images on extracted teeth mounted in acrylic bases. Randomized films were scored for lesion presence and depth by two general dentists. Weighted kappa statistics were used to evaluate the agreement of reviewer caries diagnosis by film speed and focal spot size. Comparisons of caries cells with small versus medium and small versus large focal spot size produced weighted kappa statistics = 0.72 and 0.70, respectively. Differences in caries calls were greater because of film speed rather than focal spot size. The results of this study suggest that the clinical significance of varied focal spot size is negligible. The value of annual measurement of focal spot size is questionable, and its recommendation should be revisited.

Comparing E- and D-speed film: the effects of various storage conditions on fogging.

Despite the reduced radiation exposure documented with E-speed film use, many clinicians still prefer D-speed radiographic film. The authors tested various storage factors and found that E-speed film is more sensitive to these variables than D-speed film.

Densitometric comparisons of Ultra-speed, Ektaspeed, and Ektaspeed Plus intraoral films for two processing conditions.

This study compared film speed, contrast, exposure latitude, and resolution of Ultra-speed, Ektaspeed, and Ektaspeed Plus films (Eastman Kodak Co., Rochester, N.Y.). Densitometric curves were generated for each film type under processing conditions of fresh and used chemistry to observe their effect on factors associated with diagnostic quality. Ektaspeed Plus film displayed the least variability due to processing condition of any film; it also demonstrated the fastest speed and was twice as fast as Ultra-speed film. Ektaspeed exhibited the greatest relative exposure latitude followed by Ektaspeed Plus and Ultra-speed. Average gradient over a clinically useful range of densities was greatest for Ultra-speed in fresh processing solutions, but greatest for Ektaspeed Plus in used processing solutions. All film types were able to resolve more than 16.6 line pairs per millimeter regardless of processing conditions. The results of this study suggest that dental practitioners who have refrained from using E-speed film because of the sensitivity of this film to variations in processing may now consider providing this dose-reducing technology for their patients with the expectation of obtaining consistent image quality.

Knowledge and adoption of radiographic quality assurance guidelines by general dentists in North Carolina.

OBJECTIVES/STUDY DESIGN: A random survey of equal proportions of urban and rural North Carolina general dentists was conducted to assess their knowledge and adoption of radiographic quality assurance guidelines of the American Dental Association. RESULTS: A total of 159 surveys were returned representing a response rate of 51%. A majority of respondents answered "don't know" to questions dealing with intraoral and panoramic radiography units and darkroom monitoring. Higher levels of knowledge (58% to 77%) and adoption (63% to 86%) of guidelines were seen with film-processing activities. Linear regression demonstrated substantial positive association between knowledge and adoption of guidelines (R = 0.50). Stepwise multiple regression revealed positive associations of the demographic variables of years in practice, urban location, and age with greater knowledge of guidelines (R2 = 0.33, p < 0.05). Urban location was associated with increased likelihood of adoption of guidelines (R2 = 0.09, p < 0.05).

Exposure reduction in panoramic radiography.

Increased receptor speed in panoramic radiography is useful in reducing patient exposure if it doesn't substantially decrease the diagnostic quality of the resultant image. In a laboratory investigation four rare earth screen/film combinations were evaluated ranging in relative speed from 400 to 1200. The results indicated that an exposure reduction of approximately 15 percent can be achieved by substituting a 1200 speed system for a 400 speed system without significantly affecting the diagnostic quality of the image.