Doss McDavid - Academia.edu (original) (raw)
Papers by Doss McDavid
Dental Clinics of North America
Intraoral, panoramic, and extraoral radiographs are the primary means of diagnosing hard-tissue d... more Intraoral, panoramic, and extraoral radiographs are the primary means of diagnosing hard-tissue disorders of the dentomaxillofacial region. These imaging methods require the use of x-ray film and subsequent chemical processing to produce diagnostic images. A goal of recent research has been the replacement of this film-based technology with computer-based devices that use electronic or storage phosphor receptors to record the x-ray image in a digital format. This article discusses some of these emerging technologies and their potential effect on the future of panoramic and extraoral radiology.
Oral Surgery, Oral Medicine, Oral Pathology, 1990
In rotational panoramic radiography, the image layer is generally positioned between the rotation... more In rotational panoramic radiography, the image layer is generally positioned between the rotation center of the beam and the film. It is also possible to create a layer that is positioned between the rotation center and the x-ray source. The reversed layer position is useful clinically and gives rise to image properties that are somewhat different from the conventional geometry.
Oral Surgery, Oral Medicine, Oral Pathology, 1990
Dentomaxillofacial Radiology, 1983
Dentomaxillofacial Radiology, 1983
Dentomaxillofacial Radiology, 1988
Age- and sex-specific risks for adult female patients from rotational panoramic radiography have ... more Age- and sex-specific risks for adult female patients from rotational panoramic radiography have been estimated by means of a modification of the ICRP effective dose equivalent and computer simulation of radiation transport in human anatomy using Monte Carlo techniques. Risks are expressed as the equivalent whole-body radiation doses of 6.6 to 28 μSv, and the probability of stochastic effect (fatal cancer or mutation expressed in the first two postirradiation generations) of 0.07 to 0.4 per million examinations.
Dentomaxillofacial Radiology, 1992
An Image Management and Communications System for digital dentomaxillofacial radiology is under d... more 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.
Oral Surgery, Oral Medicine, Oral Pathology, 1988
Oral Surgery, Oral Medicine, Oral Pathology, 1994
The purpose of this study was to compare the diagnostic performance of a digital radiography syst... more The purpose of this study was to compare the diagnostic performance of a digital radiography system that uses 6 and 8-bit displays with conventional D-speed film for the detection of simulated periodontal bone lesions, Eleven human hemimandibles were used as specimens. Simulated lesions were created at the buccal cortical plate in the marginal bone area with the use of a round bur 1.4 mm in diameter. Lesions were created in a defined sequence to preclude visual cues as to the depth of the lesions. Lesion size progressed in 0.5 mm increments. At each stage the mandibles were imaged with a Sens-A-Ray system (REGAM Medical Systems AB, Sundsvall, Sweden) and D-speed film. Exposure parameters tor each specimen/receptor combination were standardized by either the mean optical densrty or mean gray value at the approximal crestal bone area. Film images and digital images displayed with 64 and 256 gray levels were presented to six observers for evaluation. Observers were ask to rate their confidence as to the presence or absence of a lesion using a S-point confidence scale. A total of 96 lesion sites and 96 control sites were presented to the observers. Receiver operating characteristic curves were generated for each system. The area under the curve was used as the index of diagnostic accuracy The mean receiver operating characteristic areas for 6-bit and 8-bit displays and D-speed film were 0.746 f 0.043, 0.717-+ 0.056 and 0.742 I 0,059, respectively. Analysis of variance was used to compare the means. No statistical difference was found between any of the three image displays @ > 0.05). These findings are consistent with an analytic analysis of the viewing conditions and indicate that h-bit (64 gray levels) are sufficient for the diagnosis of these simulated periodontal lesions. (ORAL SURG ORAL MED ORAL PATHOL 1994;77:40&11) Far from representing a definitive study of the relationship between image bit depth and diagnostic capacity, this article attempts to raise the main issues that complicate this relationship. As computer monitors replace video monitors because of lower costs for the former, the question of bit-depth (number of gray levels) necessary for good
Dentomaxillofacial Radiology, 1989
The Zonarc (Palomex Oy, Helsinki, Finland) uses the principles of rotational panoramic radiograph... more The Zonarc (Palomex Oy, Helsinki, Finland) uses the principles of rotational panoramic radiography to image various structures of the head and neck. System parameters obtained from the manufacturer have been used to derive data on the imaging characteristics of the Zonarc when using each of the following programmes: MT, DENT, TMJ, EAR, CV and LAT. The beam path along with the shape, position and relative thickness of the layer has been calculated for each programme, together with the resolution and magnification associated with the different layers.
Dentomaxillofacial Radiology, 1992
The diagnostic accuracy of digital subtraction radiography in detection of artificial recurrent c... more 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 sequential1y 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.
Acta Radiologica, 1983
The use of the modulation transfer function in rotational panoramic radiography is described. The... more The use of the modulation transfer function in rotational panoramic radiography is described. The separate and combined effects of the various system components are discussed.
Oral Surgery, Oral Medicine, Oral Pathology, 1994
Oral Surgery, Oral Medicine, Oral Pathology, 1994
Line spread functions for four commercially available systems for direct digital intraoral radiog... more Line spread functions for four commercially available systems for direct digital intraoral radiography were determined from1 images of a slit of negligible width. From the fitted line spread functions presampling modulation transfer functions were calculated. The four systems were the Sens-A-Ray (Regam Medical System AB, Sundsvall, Sweden), the VIXA/Visualix (Cendex, Chicago Ill.), the RVC (Trophy Radiologic, Paris, France), and the Flash Dent (Villa Sistemi Medicale srd, Buccinasco, Italy). Digital intraoral radiography is in a state of rapid development, and detectors as well as computer hardware and software are continually modified and improved resulting in successively changing system parameters. As this occurs the present work provides a method that may be used to determine comparable data on future systems. (ORAL SURG ORAL Mm ORAL
Oral Surgery, Oral Medicine, Oral Pathology, 1988
Oral Surgery, Oral Medicine, Oral Pathology, 1986
The use of aluminum, gadolinium, and yttrium filters in conjunction with E-speed film was studied... more The use of aluminum, gadolinium, and yttrium filters in conjunction with E-speed film was studied. The resulting radiographs were judged to be acceptable for diagnostic purposes, although clinicians showed a preference for E-speed radiographs made at reduced exposure times and for D-speed radiographs. There was no detectable difference between the radiographs produced with the various filter materials.
Dental Clinics of North America
Intraoral, panoramic, and extraoral radiographs are the primary means of diagnosing hard-tissue d... more Intraoral, panoramic, and extraoral radiographs are the primary means of diagnosing hard-tissue disorders of the dentomaxillofacial region. These imaging methods require the use of x-ray film and subsequent chemical processing to produce diagnostic images. A goal of recent research has been the replacement of this film-based technology with computer-based devices that use electronic or storage phosphor receptors to record the x-ray image in a digital format. This article discusses some of these emerging technologies and their potential effect on the future of panoramic and extraoral radiology.
Oral Surgery, Oral Medicine, Oral Pathology, 1990
In rotational panoramic radiography, the image layer is generally positioned between the rotation... more In rotational panoramic radiography, the image layer is generally positioned between the rotation center of the beam and the film. It is also possible to create a layer that is positioned between the rotation center and the x-ray source. The reversed layer position is useful clinically and gives rise to image properties that are somewhat different from the conventional geometry.
Oral Surgery, Oral Medicine, Oral Pathology, 1990
Dentomaxillofacial Radiology, 1983
Dentomaxillofacial Radiology, 1983
Dentomaxillofacial Radiology, 1988
Age- and sex-specific risks for adult female patients from rotational panoramic radiography have ... more Age- and sex-specific risks for adult female patients from rotational panoramic radiography have been estimated by means of a modification of the ICRP effective dose equivalent and computer simulation of radiation transport in human anatomy using Monte Carlo techniques. Risks are expressed as the equivalent whole-body radiation doses of 6.6 to 28 μSv, and the probability of stochastic effect (fatal cancer or mutation expressed in the first two postirradiation generations) of 0.07 to 0.4 per million examinations.
Dentomaxillofacial Radiology, 1992
An Image Management and Communications System for digital dentomaxillofacial radiology is under d... more 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.
Oral Surgery, Oral Medicine, Oral Pathology, 1988
Oral Surgery, Oral Medicine, Oral Pathology, 1994
The purpose of this study was to compare the diagnostic performance of a digital radiography syst... more The purpose of this study was to compare the diagnostic performance of a digital radiography system that uses 6 and 8-bit displays with conventional D-speed film for the detection of simulated periodontal bone lesions, Eleven human hemimandibles were used as specimens. Simulated lesions were created at the buccal cortical plate in the marginal bone area with the use of a round bur 1.4 mm in diameter. Lesions were created in a defined sequence to preclude visual cues as to the depth of the lesions. Lesion size progressed in 0.5 mm increments. At each stage the mandibles were imaged with a Sens-A-Ray system (REGAM Medical Systems AB, Sundsvall, Sweden) and D-speed film. Exposure parameters tor each specimen/receptor combination were standardized by either the mean optical densrty or mean gray value at the approximal crestal bone area. Film images and digital images displayed with 64 and 256 gray levels were presented to six observers for evaluation. Observers were ask to rate their confidence as to the presence or absence of a lesion using a S-point confidence scale. A total of 96 lesion sites and 96 control sites were presented to the observers. Receiver operating characteristic curves were generated for each system. The area under the curve was used as the index of diagnostic accuracy The mean receiver operating characteristic areas for 6-bit and 8-bit displays and D-speed film were 0.746 f 0.043, 0.717-+ 0.056 and 0.742 I 0,059, respectively. Analysis of variance was used to compare the means. No statistical difference was found between any of the three image displays @ > 0.05). These findings are consistent with an analytic analysis of the viewing conditions and indicate that h-bit (64 gray levels) are sufficient for the diagnosis of these simulated periodontal lesions. (ORAL SURG ORAL MED ORAL PATHOL 1994;77:40&11) Far from representing a definitive study of the relationship between image bit depth and diagnostic capacity, this article attempts to raise the main issues that complicate this relationship. As computer monitors replace video monitors because of lower costs for the former, the question of bit-depth (number of gray levels) necessary for good
Dentomaxillofacial Radiology, 1989
The Zonarc (Palomex Oy, Helsinki, Finland) uses the principles of rotational panoramic radiograph... more The Zonarc (Palomex Oy, Helsinki, Finland) uses the principles of rotational panoramic radiography to image various structures of the head and neck. System parameters obtained from the manufacturer have been used to derive data on the imaging characteristics of the Zonarc when using each of the following programmes: MT, DENT, TMJ, EAR, CV and LAT. The beam path along with the shape, position and relative thickness of the layer has been calculated for each programme, together with the resolution and magnification associated with the different layers.
Dentomaxillofacial Radiology, 1992
The diagnostic accuracy of digital subtraction radiography in detection of artificial recurrent c... more 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 sequential1y 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.
Acta Radiologica, 1983
The use of the modulation transfer function in rotational panoramic radiography is described. The... more The use of the modulation transfer function in rotational panoramic radiography is described. The separate and combined effects of the various system components are discussed.
Oral Surgery, Oral Medicine, Oral Pathology, 1994
Oral Surgery, Oral Medicine, Oral Pathology, 1994
Line spread functions for four commercially available systems for direct digital intraoral radiog... more Line spread functions for four commercially available systems for direct digital intraoral radiography were determined from1 images of a slit of negligible width. From the fitted line spread functions presampling modulation transfer functions were calculated. The four systems were the Sens-A-Ray (Regam Medical System AB, Sundsvall, Sweden), the VIXA/Visualix (Cendex, Chicago Ill.), the RVC (Trophy Radiologic, Paris, France), and the Flash Dent (Villa Sistemi Medicale srd, Buccinasco, Italy). Digital intraoral radiography is in a state of rapid development, and detectors as well as computer hardware and software are continually modified and improved resulting in successively changing system parameters. As this occurs the present work provides a method that may be used to determine comparable data on future systems. (ORAL SURG ORAL Mm ORAL
Oral Surgery, Oral Medicine, Oral Pathology, 1988
Oral Surgery, Oral Medicine, Oral Pathology, 1986
The use of aluminum, gadolinium, and yttrium filters in conjunction with E-speed film was studied... more The use of aluminum, gadolinium, and yttrium filters in conjunction with E-speed film was studied. The resulting radiographs were judged to be acceptable for diagnostic purposes, although clinicians showed a preference for E-speed radiographs made at reduced exposure times and for D-speed radiographs. There was no detectable difference between the radiographs produced with the various filter materials.