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Biomedical subjects

S B Dove

Publications and source records attributed to S B Dove.

15 recordsLinked to original sources
PubMed1992

Preliminary evaluation of a digital system for rotational panoramic radiography.

A prototype system for direct digital panoramic radiography has been evaluated with respect to density, contrast, magnification, distortion, resolution, and overall image quality. Density and contrast depend on detector calibration and may be modified by the display system or by digital processing of the captured image. Variation of magnification in the horizontal and vertical dimensions gives rise to distortion phenomena that are identical to those encountered in film-based systems. Resolution in the vertical dimension is determined by the pitch of the detector elements. In the horizontal dimension, resolution is limited by the effective width of the detector elements. To evaluate the clinical acceptability of the images, radiologists and general practice residents were asked to assess the perceptibility of important radiographic landmarks in film-based and digital images of both a radiographic phantom and a patient. The digital system performed on a par with film in the representation of normal morphologic structures of the clinical human subject whereas more differences were apparent in the phantom images. The general practice residents consistently rated the digital images higher than their radiologist counterparts did. No consistent trends were found to indicate any inherent deficiencies of the digital system in the depiction of any one area. The results indicate the promise of direct digital acquisition as a method of panoramic imaging.

Evaluation Studies as Topic↗
PubMed1992

Magnetic resonance spectroscopy of inflammation associated with the temporomandibular joint.

Noninvasive early recognition and treatment of temporomandibular joint dysfunction remains a diagnostic challenge. This pilot study evaluated the use of phosphorus 31 magnetic resonance spectroscopy with magnetic resonance imaging to measure alterations in pH and high-energy phosphate metabolite ratios of muscle that is adjacent to an inflamed temporomandibular joint. Ten New Zealand white rabbits were used in this study. Two animals were used to develop signal acquisition protocols and to ensure that stable baseline data could be measured. In each of the eight animals used in the experiment, one temporomandibular joint was injected with a suspension of silica particles and the contralateral joint served as a control. Data were collected from control and experimental joints on days 0, 7, 14, 21, and 28, after the injection. At the end of the study, temporomandibular joints were block resected and histologically examined to confirm the presence of an inflammatory response. Results indicated that pH and metabolite ratios could be obtained by 31P-magnetic resonance spectroscopy. Changes in pH and some metabolite ratios in experimental joints showed statistical significance (p < 0.001). Differences were seen on day 2 and day 7 (p = 0.040 and p = 0.008, respectively) in the phosphocreatine/alpha-adenosine triphosphate ratios. This contrasts with phosphocreatine/beta adenosine triphosphate ratios that showed significance that began at day 7 (p = 0.022) and continued to day 14 (p = 0.025). Histologic examination indicated that the tissue response within the joint capsule was less than the granulomatous reaction expected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1992

Direct digital radiography for the detection of periodontal bone lesions.

In this study the diagnostic accuracy of D-speed and E-speed film in the detection of simulated periodontal bone lesions was compared with that of an electronic direct digital image receptor. Lesions of increasing depth were created in 11 human hemimandibles at the buccal cortical plate in the interproximal marginal bone area by means of 1.4 mm diameter round bursa. Specimens were imaged at each lesion stage with the use of all three receptors. Nine viewers used a 5-point rating scale to evaluate whether lesions were present or absent in the resulting images. Receiver operating characteristic curves were generated, and maximum-likelihood curve areas were calculated. The area under the curve was used as the index of diagnostic accuracy. The mean receiver operating characteristic areas for D-speed film, E-speed film, and the direct digital system were 0.745 +/- 0.038, 0.740 +/- 0.038, and 0.741 +/- 0.037, respectively. Critical ratio analysis was used to compare the means. No statistical difference was found between any of the three image receptors (p > 0.05) for the detection of simulated periodontal lesions 1.0 to 3.0 mm in depth, which suggested that the digital system performed comparably with conventional film systems.

Alveolar Bone Loss↗
PubMed1992

Direct digital extraoral radiography of the head and neck with a solid-state linear x-ray detector.

A narrow fan beam of x-rays intercepted by a linear array detector was used to acquire transmission data for a radiographic phantom moved across the beam. The digital data were displayed as images representing a variety of extraoral views of the head and neck. Projections investigated include the straight lateral view, two frontal projections, and a half-axial projection. The digital images appear to provide adequate contrast and resolution for common diagnostic tasks. In addition, the use of a scanning linear detector reduces the amount of scatter, which increases contrast relative to images made with an area detector. The system appears to provide a versatile and convenient means for the acquisition of extraoral views relevant to dental practice while it eliminates the logistical difficulties and errors associated with film processing.

Analog-Digital Conversion↗
PubMed1992

Assessment of external root resorption using digital subtraction radiography.

Digital subtraction radiography was investigated for its capability to detect and quantify experimentally produced external root resorptive defects in teeth. Using a long source to object X-ray technique and E-speed film, serial radiographs of teeth with artificial lesions in a dry human skull (soft tissue simulated) were obtained. Receiver operating characteristic analysis was used to evaluate the diagnostic performance for each imaging system (conventional versus subtraction). To explore the quantitative assessment potential of digital subtraction radiography, images were produced after sequential demineralization by HCl. The acid solution was analyzed for calcium concentration by atomic absorption spectrophotometry. Three-dimensional histogram quantification for each subtracted image was performed. In overall performance for detecting experimentally produced external root resorption, digital subtraction radiography was found to be significantly superior to conventional radiography. In addition, digital subtraction radiography can provide quantification of experimentally produced external root resorptive defects.

Humans↗
PubMed1992

CT reconstruction algorithm for a dental panoramic x-ray unit.

A variable Jacobian and weighted backprojection algorithm, used for medical CT, was adapted to perform CT reconstructions on data obtained with a dental panoramic x-ray unit. A detector array, fitted to the unit for the purpose of acquiring digital panoramic radiographs, was used to collect the data. Compensations were made for the incomplete (230 degrees) rotation of the panoramic x-ray unit, the non-fixed centre of rotation, the irregular rotation of the x-ray target and detector, and the resulting variances in magnification. The algorithm was tested on mathematically simulated phantoms and on acquired data. Reconstruction of simulated data proved the success of the algorithm. Real data reconstructions showed some defects as a result of inaccuracies in quantifying the experimental panoramic device.

Algorithms↗
PubMed1992

Morphometric analysis of the dental pulp chamber as a method of age determination in humans.

Eighty bite-wing radiographs from 40 female and 40 male patients were selected from the patient record system at the University of Texas Dental School at San Antonio, Texas. All samples were equally divided into four age groups, with a range from 15 to 55 years of age. The lower right first permanent molar tooth was chosen as the representative tooth for measuring the maximum height and width of the pulp chamber. The reproducibility of the method was checked by repeating all measurements on two different occasions. Regression analysis indicates that the height and width of the pulp chamber were negatively correlated with age (height r = -0.376 and width r = -0.125). The coefficient of determination (r2) for pulp chamber height and width were 0.123 and 0.058, respectively. This indicates that although there appears to be a definite relationship between the age of an individual and the height and width of the dental pulp chamber, these measures cannot be used as a reliable method of age determination.

Adolescent↗
PubMed1992

Digital subtraction radiography in artificial recurrent caries detection.

The diagnostic accuracy of digital subtraction radiography in detection of artificial recurrent caries lesions was assessed in this project. The use of digital subtraction radiography has been shown to markedly increase the accuracy of the detection of destruction in the periodontal bone, but the method has not been evaluated in secondary caries detection. Defects of three different sizes, simulating recurrent caries, were sequentially prepared in the interproximal cavity preparation margins of 28 teeth. Two composite restorative materials with different radiographic densities were used as posterior restorations, and a radiograph was obtained of each defect size and restorative material. The radiographs were digitized and subtracted from the reference images, and the conventional radiographs and the subtraction images were evaluated by seven observers. The data were analysed with ROC statistics. Subtraction radiography was found to be superior to conventional radiography in recurrent caries detection, mainly by reducing the false-positive diagnoses. The radiopacity of the restorative material had a significant effect on accuracy with conventional but not with subtraction radiography.

Analysis of Variance↗
PubMed1992

A comparison of conventional intra-oral radiography and computer imaging techniques for the detection of proximal surface dental caries.

The detection of proximal surface caries by the visual interpretation of bitewing radiographs is known to be relatively inaccurate. The present study was designed to examine whether computer image processing could improve the diagnostic accuracy. A computer-aided, software-driven, TV-based system was used to digitize conventional radiographs and digitally process the images using histogram equalization and grey-scale inversion to enhance the images. The computer-enhanced images were compared with conventional intra-oral radiographs for the detection of proximal surface caries using receiver operating characteristic analysis. The results indicate that the digital image processing techniques used did not improve the diagnostic accuracy of dental radiographs. No significant difference in diagnostic accuracy could be detected between the non-enhanced digital images and conventional film-based images for the detection of proximal surface caries.

Dental Caries↗
PubMed1992

Design and implementation of an image management and communications system (IMACS) for dentomaxillofacial radiology.

An Image Management and Communications System for digital dentomaxillofacial radiology is under development at the Department of Dental Diagnostic Science at the University of Texas Health Science Center at San Antonio, Texas, USA. In its final stage, the system will provide a method of integrating different direct digital image acquisition modalities such as intraoral, panoramic and extraoral radiography. A review of the design criteria necessary for establishing such a system for clinical dentistry is discussed and the first phase of its implementation described.

Computer Communication Networks↗
PubMed1991

Electronic system for digital acquisition of rotational panoramic radiographs.

A prototype system for digital panoramic imaging of the maxillofacial complex has been developed. In this system x-ray film is replaced by an electronic sensor that delivers the image information to a computer for storage in digital format. The images, which are similar to conventional panoramic radiographs, are displayed on a high-resolution video monitor and may be stored on optical disk for future use. Hard-copy output is also available. The present prototype system has been installed on an Orthopantomograph model OP10 panoramic x-ray machine is programmed for operation with this machine, but in principle the system can be installed on any such device. The system may be incorporated into the design of future panoramic x-ray systems or may be used to retrofit panoramic x-ray systems now using photographic film to record the radiographic image. Greater sensitivity of electronic sensors should make possible a reduction of x-ray dose to the patient, compared with film-based systems.

Analog-Digital Conversion↗
PubMed1990

Knowledge and attitudes of Texas dentists concerning AIDS.

A total of 1,200 practicing Texas dentists were surveyed concerning AIDS knowledge, attitudes and behaviors. The results were analyzed and an analysis of variance indicated an inverse relationship between city population and avoidance behavior towards AIDS by dentists. Additionally, dentists in practice over 10 years manifested higher avoidance characteristics towards AIDS. Increased knowledge did not correlate with less avoidance behavior. The results of this study indicate that additional methods of educating dentists concerning HIV infection and AIDS, infection control, and the role of health care professionals concerning patients with infectious diseases are needed.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Spatial resolution requirements for digitizing dental radiographs.

A study was performed to determine the appropriate spatial resolution for digitizing and transmitting dental radiographs with the KODAK EKTASCAN, a computer-based digital enhancement and transmission system. Periapical, bitewing, and panoramic radiographs were digitized in three formats representing varying spatial resolution parameters. Eight viewers used a 5-point rating scale to evaluate the detectability of periapical pathosis on the periapical images, of proximal surface caries on the bitewing images, and of various bony abnormalities on the panoramic images. Receiver operating characteristic curves were generated, and the results of the periapical, bitewing and panoramic experiments were presented as trapezoidal and maximum likelihood receiver operating characteristic curve areas. The results of this study indicate that digital images of dental radiographs provide adequate diagnostic accuracy for evaluating the presence of periapical pathosis, proximal surface caries, and specified bony abnormalities. The digitization parameters established for the KODAK EKTASCAN provide a guide for digitizing dental radiographs on other commercially available digital image-processing systems.

Computers↗
PubMed1988

Failure of use of cemental annulations in teeth to determine the age of humans.

The reliability of cemental annulation counts in teeth was examined to determine its value as an age indicator for humans. One hundred extracted human teeth were embedded in polyester casting resin and sectioned using a diamond wafering saw. Thin sections were photomicrographed, projected, and counted in a double blind random method of presentation. The age of the specimen was determined by adding the number of cemental annulations counted by the observers and the eruption age of the specific tooth that was used. The data analyzed by simple regression indicated that determining chronologic age in humans from cemental annulations is not possible.

Adolescent↗