Digital processing of film radiographs

Initial clinical experience with a system for the digitization, processing, and display of film radiographs is described. Film is digitized using a high-intensity laser scanner; the recorded image data may then be subjected to a wide variety of processing options, with display of processed images on television monitors. The possibilities of clinical applications to processing and display of chest radiographs and film mammograms are described. A comparison of conventional analog subtraction and digitized film subtraction angiography indicated equivalent diagnostic capability, with the advantage of flexible, interactive image processing with the digital technique. A specially designed, energy-selective cassette permits dual-energy imaging from two films effectively exposed to different x-ray energy spectra. Dual-energy imaging may be capable of the characterization of body materials, including lung nodules, and useful for eliminating obscuring radiographic shadows overlying regions of interest.     

Microcomputer processing of film radiographs

An inexpensive image processing system, assembled from commercially available components and driven by "in-house" software, was tested as a means of processing radiographs obtained in a radiology department. In this preliminary study, the main interest was to investigate, through subjective appraisal, the ability of the system to recover the image quality of poorly exposed radiographs. Subsidiary objectives were to obtain some information regarding the specification limits of the system and its components, as well as some quantitative estimate of its advantages for clinical diagnosis. The system was used to process a set of film radiographs of an anthropomorphic chest phantom, produced under conditions that were designed to provide a wide range of image qualities. Following this, four sets of randomly ordered processed and unprocessed images were formally assessed by a group of experienced observers. Consensus opinion from the group indicated that significant improvement could be obtained through simple image processing. Some radiographs regarded as unacceptable became, after processing, acceptable to viewers.     

Evaluation of new film high-light system by comparison with conventional film.

The 3M "High Light System" has been used in a clinical environment for one and one-half years. The inherent advantages, as well as the disadvantages, of this system are discussed. An objective comparison of the blue based HL film and the conventional Type R film was made. This comparison indicates that image quality is similar with either film and, hence, radiographs produced with either system will be of diagnostic quality.     

Evaluation of a new computerized analysis system developed for the processing of CT follow-up scans after EVR of infrarenal aneurysm

Purpose

The aim of this retrospective study was to present a new computerized analysis system developed for the evaluation of follow-up CT scans after endovascular repair (EVR) of infrarenal aneurysm and to compare it to the conventional evaluation method as regards preciseness and ease of application. The system is based on the extraction of the surface of the stent-graft (SG) and that of the spinal canal and the overlay of surfaces obtained at different points in time.

Materials and methods

A total of 116 CT follow-up data sets obtained from 49 patients after EVR of infrarenal aneurysm were evaluated using both, the conventional method and the new computerized system. Two parameters were analyzed: SG length and the distance between the most ventral point of the SG and the vertebral column. The correlation between the results of the two methods and the correlation between the results obtained by two independent observers (radiologist and lay person) using the new system were assessed by statistical analysis.

Results

Comparison of the two methods yielded a very high correlation for both parameters, (correlation coefficients of around 0.9 and p < 0.001). Comparison of the results obtained by the two observers yielded an equally high correlation (correlation coefficients of around 0.9 and p < 0.001).

Conclusion

Our results show that the new computerized system is as precise and reliable as the conventional method, but allows better visualization and quantification of SG changes by surface overlay. Moreover, it is easier to apply and less time-consuming and can be easily integrated into existing systems.     

Evaluation of a new digital panoramic system: a comparison with film

OBJECTIVES: To evaluate the diagnostic efficacy of the Orthophos DS digital panoramic system (Sirona, Bensheim, Germany) for the detection of dento-alveolar disease in comparison with film. METHODS: Five patients selected for admission to the School of Dentistry had a panoramic radiograph obtained with the Orthophos Plus (Sirona, Bensheim, Germany) system, a digital panoramic image obtained with the Orthophos DS (Sirona, Bensheim, Germany) system and a full mouth series. The ground truth was determined from the full mouth series by a panel of board certified oral and maxillofacial radiologists using the Delphi method. Four observers scored both the film and digital panoramic images for the presence of caries and marginal periodontitis. Results were statistically analysed using ROC analysis and ANOVA. RESULTS: There was no significant difference (P=0.704) between the two modalities for the detection of caries but there was a significant difference (P=0.015) for the detection of periodontal disease where conventional panoramic film performed better than the digital image. CONCLUSIONS: Though the conventional film was better than the digital image for the detection of periodontal disease, further studies are needed to determine the clinical significance of this result in relation to the potential advantages of digital technology.     

Evaluation of different methods of control of film processing]

In addition to the official control method (DIN 6868), alternative test methods have been developed in the last few years: the "visuelle Methode" by Eder and the "Stuttgarter Modell." The aim of both methods is mainly to increase practicability and economy. The DIN method, however, demonstrates clear benefits, precision, practicability and economy, and it is the only method that allows a trend analysis at small intervals, which is the basis for possible preventive action.     

Test report on the system components for film processing by the middle-format technology

Industrially developed accessories for use with medium-format equipment, which have been tested in a-clinical settery, were evaluated separately. The automatic mounting system (Delcadro) with the plastic mount (Cadrix) was accepted by all of our colleagues, and was rated as an advantage, with hardly any reservations. A slight modification is needed in the design of the mounts. This equipment would be a desirable addition to our own equipment for routine work. The daylight system (camera magazine and feeder) is, in principle, certainly a step in the right direction. Handling of the magazine proved to be too complicated and it was prone to malfunctions. Simplification, especially of the loading mechanism, would be desirable. The film feeder is designed for use with conventional roll processing machines. In our opinion, a feeder will always be put to full use if the films processed in this machine are mainly or exclusively of middle format; the darkroom is not permanently staffed and/or adaptation to an existing daylight system (large formats) has already been effected and/or depending on availability, both large and medium size-formats can be processed fully automatically as quickly as possible. However, if films of various formats are processed by an assistant in a darkroom, it is possible to deal with the total quantity of films faster than with a feeder by inserting 3 or 4 medium-format films (or 2 or 3 large-format films) simultaneously. The Heliomat film viewer offers impressive reproductions of 100 mm film on a glare-free glass screen.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of a new type of high sharpness film for skull radiography

A new type of high sharpness, high speed film was evaluated in combination with rare-earth screens for modulation transfer function, root-mean-square granularity and characteristic curve, and compared with currently available film-screen combinations. The clinical applicability of the new system was also compared on the basis of resolution and the discrimination of anatomical features on radiographs of a skull phantom. The results indicated that the new type film provided a radiograph of higher image quality while at the same time reducing patient dose by about 20% compared with the present rare-earth screen systems, or with no loss of image quality while reducing patient dose by about 50% compared with the present calcium tungstate system.     

Digital film processing: Applications to the musculoskeletal system

A prototype digital film processing system was systematically evaluated for specific applications to the musculoskeletal system. Test objects included a line pair resolution phantom and specimens designed to simulate lytic cortical and both lytic and sclerotic cancellous bone lesions. Clinical radiographs from a wide variety of osseous and soft tissue disorders were studied. Although digitization cannot improve the inherent resolution and information content of film, it is capable of enhancing contrast and visualization of detail. As a result, digital processing carries significant potential for improved diagnosis in musculoskeletal radiology.     

Evaluation of a new F speed dental X-ray film. The effect of processing solutions and a comparison with D and E speed films

OBJECTIVE: To compare the properties of a new speed group F intra-oral X-ray film with those of three well established types both from groups D and E, and evaluate the impact of six commercially available processing solutions. METHODS: Four types of dental X-ray film, Flow (Flow X-ray, West Hempstead, NY, USA), speed group F, Ektaspeed Plus (Eastman Kodak, Rochester NY, USA) and M2 Comfort (AgfaGevaert, Morstel, Belgium), both speed group E, and Ultra-speed (Eastman Kodak), speed group D, were exposed under standardised conditions and processed in six different processing solutions. Base plus fog density, characteristic curves, film density, speed, average gradient, contrast and latitude and spatial resolution were calculated. RESULTS: The choice of processing chemistry affected radiographic characteristics including speed grouping. The new F film was consistently the fastest. M2 Comfort could achieve F speed and Ultra-speed achieved E speed using Automat XR chemicals. The speed of Ektaspeed Plus was independent of the automatic processing solution used. Ultra-Speed film had the lowest base plus fog density and the widest latitude. Film contrast was similar irrespective of the film and solution combination. CONCLUSIONS: The choice of processing chemistry can affect radiographic characteristics. The new F film reduces patient exposure by one-half compared with E speed film with no detriment to image quality.     

Technical note. Evaluation of a new screen/film combination.

The Trimax system offers film/screen combinations which reduce the X-ray exposure by factors of about 4. This is achieved without deterioration in image quality.     

Evaluation of endodontic files in digital radiographs before and after employing three image processing algorithms

OBJECTIVES: Two digital image processing algorithms, one aimed at correction for exponential attenuation and one at correction for visual response, have been developed. The aims of the present study were to test whether digital radiographs processed with these algorithms improve determination of the length of endodontic files and whether such processed radiographs are comparable with the radiographs processed with a default image processing method employed by one commercially available digital intraoral system. METHODS: A dried human skull embedded in an acrylic compound was used for exposing radiographs of the upper and lower premolars and molars with endodontic files (Kerr files size 10 and size 15) positioned to the full length of the roots or 1.5 mm short of it. Radiographs were then processed in three sets. In one set, the radiographs were processed to compensate for exponential attenuation and the response of the human visual system. In the second, the radiographs were processed with the same compensation but with an additional shift in grey levels so that the output luminance in dentin at root tips corresponds to the mean of the luminance range of a computer monitor. In the third, the radiographs were processed with the default processing method in the Sidexis program. Ten viewers evaluated all radiographs. Receiver operating characteristic (ROC) curves were obtained and areas under the curves were calculated. RESULTS: For file size 10, ROC curves for processed radiographs were higher than that for originals, while for file size 15, ROC curves for processed and original radiographs were close to each other. Significant differences were found between processed and original radiographs regarding areas under ROC curves for file size 10 but not between the differently processed radiographs. For file size 15, no significant differences were found. CONCLUSION: Radiographs processed to correct for attenuation and visual response may improve determination of the length of thin endodontic files. Such processed radiographs are comparable with the radiographs processed with the default processing method in the Sidexis program.