Biomedical subjects

P F Van der Stelt

Publications and source records attributed to P F Van der Stelt.

8 recordsLinked to original sources

PubMed2003

Does digital radiography increase the number of intraoral radiographs? A questionnaire study of Dutch dental practices.

OBJECTIVES: To compare the number of radiographs taken in general dental practices equipped with digital radiography vs conventional film-based radiography and to determine the reasons for any difference in numbers. METHODS: In a mail survey, 473 questionnaires were sent to Dutch General Dental Practitioners (GDPs) using digital radiography and 105 questionnaires were sent to GDPs using film. The questionnaire concerned the number of intraoral radiographs taken in the dental practice, as well as possible reasons to take more or fewer radiographs after conversion to digital radiography. RESULTS: The response rate was 73%. Users of a phosphor plate system on average take 42.8 radiographs per week and solid-state system users take 48.4 radiographs, whereas film users take on average only 32.5 radiographs per week. The need for more certainty about the planned or ongoing treatment as well as better diagnostics were the most important reasons for taking more radiographs. CONCLUSIONS: It seems that GDPs using a system for digital radiography are more inclined to take radiographs than dentists taking conventional radiographs. Although digital intraoral radiography requires 50-80% less radiation per exposure than film, it is likely that the effective dose reduction after converting from conventional to digital radiography is less than 25% owing to the greater numbers of radiographs taken.

Attitude of Health Personnel↗

PubMed2002

A comparison of digital and film radiography in Dutch dental practices assessed by questionnaire.

OBJECTIVES: The purpose of this study was to assess the experiences of general dental practitioners (GDPs) with solid-state and storage phosphor digital sensors compared to film. METHODS: In a mail survey 578 questionnaires were sent to Dutch GDPs who were users of digital X-ray detectors and film. The questionnaire requested demographic data, information about the digital system used and the user-friendliness of the X-ray detector system. In the analysis of the data these variables were related to the type of system used and also to the demographic data. The data were analysed using descriptive statistics, variance-analysis (One-Way ANOVA) and nonparametric tests (Kruskal-Wallis, Mann-Whitney and Wilcoxon) (SPSS 9.0). RESULTS: Four hundred and twenty-four questionnaires were returned (overall response rate 73%). The user-friendliness of the handling of the different systems before exposing the radiograph is better for conventional film, whereas the handling after exposing the radiograph favoured the digital X-ray detector systems. CONCLUSIONS: The user-friendliness was best for film pre-exposure and digital sensors post-exposure.

Adult↗

PubMed1998

The radiographic trabecular pattern of hips in patients with hip fractures and in elderly control subjects.

Due to the increasing number of osteoporotic fractures of hip, spine, and wrist there is a growing need for methods to track down the subjects with inferior bone structure and to monitor the effects of therapeutic measures. This study aims at a noninvasive diagnostic tool, deriving architectural properties of trabecular bone from in vivo measurements on plane radiographic films. Pelvic radiographs of the nonfractured hips of 81 patients with hip fractures and of the right hips of 74 controls were studied. The regions of interest, 2 x 2 cm2, located in the femoral neck, were sampled and digitized with a video camera connected to an image analysis system. Several geometrical and directional measurements were made. The measurements were evaluated by statistical comparison with fracture risk, gender, and Singh index. By discriminant analysis, type of fracture, as well as gender and Singh index could be predicted correctly for 58% of the subjects, whereas guessing would be correct in only 8%. It was found that the geometrical parameters discriminate between hips of controls and patients. With respect to the directional measurements associations were found with gender and Singh index. Although the new parameters assess fracture risk less accurately than bone density measurements, some parameters suggest by their behavior that they are relevant with respect to femoral bone architecture and its mechanical behavior. Although interpretation of the measurements in histological concepts requires methods that have been reported in literature only recently, it is concluded that digital analysis of the radiographic trabecular pattern is an interesting option to increase the diagnostic yield of plane film radiographs and to study the structure of bone in vivo.

Age Factors↗

PubMed1997

Orientation of the trabecular pattern of the distal radius around the menopause.

The trabecular pattern depicted on radiographs of the distal radius of women around the menopause is analysed by a new method to measure orientation. It is shown that the trabecular pattern on radiographs of the distal radius is aligned preferentially along the axial direction and to a lesser extent along the transverse direction. Two minima of orientation are found at 60 degrees off the axial direction. A significant correlation is found between the average value of the orientation in the radius and the average lumbar bone mineral density. It is known that the bone mineral content decreases around the menopause. Previous reports on the present images describe several features that were found to be related to bone mineral content and to time. The orientation of the trabecular pattern, however, is found to be independent of time, at least during the two years of the investigation. Therefore, it is concluded that the orientation of the radiographic trabecular pattern tends to remain stable even if some features of the pattern evolve. Previous studies on radiographs of the radius of children and elderly women and men provide evidence for the tendency of orientation to remain stable not only in women around the menopause, but also in men and women during the entire adult life.

Analysis of Variance↗

PubMed1997

Processor quality assurance using digital imaging.

The purpose of this study was to develop and test a computer imaging method for assessing longitudinal processor variability. A technique called adaptive histogram equalization was used to test deviation in automatic processing when a test film is compared with a time-temperature processed standard at two different kVp's and film speeds. In a 14-day study we found that the density ranges for the standard film did not change, while the density range of the automatically processed films changed by a factor of two. These results suggest that if automatic processing is to be used for films taken as part of a longitudinal study-for example, subtraction-then processor variation can potentially lead to incorrect inference of bone gain or loss.

Absorptiometry, Photon↗

PubMed1993

Modern radiographic methods in the diagnosis of periodontal disease.

For many years, radiographs have been a valuable aid in the diagnosis of periodontal disease and the evaluation of treatment effects. Computer-based image acquisition and processing techniques will now further increase the importance of radiography in periodontal diagnosis. Temporal changes of lesions can be made easily visible by means of subtraction radiography based on digital images. This process requires a pair of images with identical gray-level distributions and projection geometry. The gray-level distribution and perspective projection of images can be corrected by means of digital image processing. A pair of identical images can thus be obtained without mechanical alignment of patient, film, and x-ray source. Algorithms have been developed for automatical determination of the borders of lesions and can subsequently produce quantitative information ranging from simple distance measurements to advanced multidimensional quantitation of image parameters. Accurate volume measurements can be carried out by the utilization of calibration wedges in the image. Image reconstruction procedures, such as tomosynthesis, provide information about the third dimension, which is normally lost in conventional radiographic projections. The buccal and lingual sites of the alveolar crest can be inspected separately. The progress of computer-aided procedures as discussed in this paper appears to have great potential for the improvement of the radiographic diagnosis of periodontal lesions. Especially, the benefits of reproducibility and quantitative evaluation of treatment effects will greatly improve the role of radiography in periodontics.

Humans↗

PubMed1990

A new method for automatic recognition of the radiographic trabecular pattern.

This study reports a method to describe and analyze the structure of the trabecular pattern seen on radiographs of the distal radius. The structure is measured and related to the bone mineral density (BMD) of the lumbar spine measured by dual-photon absorptiometry. Radiographs of hand and wrist combined with additional information of the bone mineral density of the vertebrae serve as testing material. With a computer-aided imaging system, a part of the depicted radius is scanned. The image is filtered and segmented into a bilevel picture consisting of a light network with dark meshes. Seven features of the bilevel picture are measured and analyzed. It is shown that six features correlate significantly with the bone mineral density measured at the lumbar spine, although the correlations between the trabecular pattern and the BMD are too weak to allow precise predictions of BMD values for individuals. Nevertheless, the correlations confirm the existence of a relationship between the radiographic trabecular pattern and the bone mineral density of the lumbar spine. The method is worth being further developed for use on individual patients. It provides a noninvasive tool to make an objective and quantitative assessment of the trabecular pattern.

Absorptiometry, Photon↗

PubMedDate not supplied

The radiographic trabecular bone pattern during menopause.

The purpose of this study is to increase the diagnostic value of radiographs by observing the radiographic trabecular pattern during occasions of changing three-dimensional bone structure. We explored how the shape of the radiographic trabecular pattern of the distal radius relates to bone mineral density, time, and menopausal status. We found that the trabecular pattern correlates with bone mineral density and time, especially in the early years of the climacterium.

Bone Density↗