Temporomandibular joint pantomography using charge-coupled device, photostimulable phosphor, and film receptors: a comparison. (1/90)

Our objective was to compare the accuracy and practicality in use of three available imaging receptors for temporomandibular joint (TMJ) imaging; namely, two computer-assisted and one traditional analog x-ray film system. A standardized tissue-equivalent encased human skull specimen was imaged using lateral and posteroanterior (PA) pantomographic projections with the Orthopantomograph OP 100 (Instrumentarium Imaging, Tuusula, Finland) and three different receptor modalities: (1) Ektavision film with Ektavision screens (Eastman Kodak, Rochester, NY); (2) DenOptix photostimulable phosphor screens (Dentsply/Gendex, Chicago, IL); and (3) the charge-coupled device (CCD) receptor, DigiPan (TREX/Trophy Radiology, Marne-la-Vallee, France). The effective focal trough was found for each receptor using lead resolution grids placed at fractional millimeter distances along empirically determined beam projection angulations. The time to acquire and process images was also established. We found that the CCD system permitted real-time display, whereas the use of traditional film took 2 minutes to load the cassette in a darkroom and perform the exposure, and then a further 2 minutes to unload and process. The storage phosphor took 3 minutes to unload the cassette and process the image and a further 20 seconds to clear the plate following laser scanning. Film produced the greatest maximum resolution followed by the storage phosphor and the CCD. In conclusion, CCD-based TMJ pantomography provided an instant image. The photostimulable phosphor system used was the least satisfactory in terms of the time expended to obtain an image, but provided better spatial resolution than the CCD. Ektavision film/screens provided the best spatial resolution in this investigation.  (+info)

Impact of electronic imaging on clinician behavior in the urgent care setting. (2/90)

Although it is intuitively valuable that more expedient delivery of radiographic images and reports to clinicians would improve patient care, it is important to document these outcomes to validate further advances in these areas. We evaluated the care of 215 patients seen at a walk-in clinic to determine what benefit digital imaging is to the patient. Cohorts consisted of all patients for whom specified radiology examinations were ordered during a 7-day period. The first cohort was recruited when analog films were used. The second cohort received examinations performed with computed radiography (CR) acquisition and computer display, which had been in use for 2 years. Patients were categorized as to the type of study they received, as well as whether a staff radiologist was immediately available to read the study. Clinical behavior was characterized by outcome measures of time to final diagnosis, time to final treatment, and need for follow-up. Our analysis demonstrated a reduction in time to final diagnosis that was better appreciated during the times when a staff radiologist was not immediately available. It also suggested that greater time reductions were seen for patients who received extremity examinations than those who received chest, sinus, or rib films. These data suggest that digital imaging is a useful tool to improve clinical outcome of patients seen in the acute care setting.  (+info)

Computed radiography printing problems: a quantitative, observer-independent solution. (3/90)

Even though facilities using computed radiography (CR) operate in an electronic environment, the production of hard-copy films is still necessary during the transition period, as well as for particular needs following complete implementation. We have implemented a quantitative technique to match the response of printed CR film with that of previous screen/film combinations. A stepwedge is radiographed using the conventional system. The same stepwedge is then radiographed (same geometry and technique) using the CR system. Following processing and printing, the plot of optical density versus step for the CR system is compared with that of the screen/film system. Adjustments are made to the printing parameters until the response curves are identical. All other translation tables in the system are set to be linear. This has proven to be a valuable technique for us and provides CR printed image quality that is equivalent to that of our previous screen/film combinations.  (+info)

Modality interfacing: the impact of a relay station. (4/90)

We evaluated the effect of a deploying a relay station on demographic discrepancies, image segmentation for routing, quality control (QC), and technologist workflow in a distributed architecture type picture archiving and communication system (PACS) environment. A currently existing PACS environment for computed tomography (CT) was evaluated before and after the implementation of a relay station for demographic error-rate and correct study routing to the workstations. Assessment of the technologists' perceptions with respect to numerous workflow factors was performed with a questionnaire. Statistical analysis was performed using a chi-square test. The demographic error rate for CT examinations was nearly abolished with relay station deployment (14.0% pre-Relay v 0.55% post-Relay, P < .001, chi2). The technologists' perception was favorable, with a substantial majority indicating that a positive impact is made on correcting demographic errors (90%), facilitating QC (67%), and ensuring proper routing (77%). A majority also felt the user interface was intuitive (93.3%) and preferred relay (90%) over film handling but that training should be provided both by didactic sessions and "hands on" time with a trainer. The times to perform tasks were favorable for the relay station (1 to 5 minutes) versus film production and handling (2 to 15 minutes). In conclusion, the relay station prospectively eliminates demographic errors, effectively segments images from the same study routing them to different workstations, and can be seamlessly integrated into the technologists' current workflow. This can be scalable and a lower cost solution as opposed to deploying dedicated PACS QC workstations.  (+info)

A new needle-crystalline computed radiography detector. (5/90)

The most successful digital radiography detectors to date have been storage phosphor plates used in computed radiography (CR). The detector is cheap, has good producibility, and is robust. Direct radiography (DR) systems are being developed based on flat-panel technology. Better image quality is claimed for some DR systems. On the other hand, DR detectors have low producibility and robustness, and a high price. A new CR detector is being developed at Agfa that combines the advantages of CR and DR. It is a storage phosphor plate made up of needle-shaped crystals. The phosphor efficiently converts absorbed x-ray quanta into photostimulable centers for efficient read out. It has a large dynamic range and its emission is efficiently detected with both photomultiplier tube (PMT) and charge coupled device (CCD). It is shown that CR systems based on the new detector offer image quality that matches that of the best DR systems.  (+info)

Starting to think digitally: evaluation of web browser-based presentation of images at a Rad Path conference in a traditional film-based environment. (6/90)

Images have traditionally been projected from film to a large-screen television at the weekly Rad Path conference at University of Medicine and Dentistry of New Jersey-New Jersey Medical School. An alternative system was developed to digitally transfer computed tomography (CT) scans and magnetic resonance images (MRI) into a standard PC format, and present them at the conference in a hypertext markup language (HTML) document via a laptop computer and liquid crystal display (LCD) projector. Resident and attending physicians were given a questionnaire about the differences between the two modes of presentation. Their responses are presented here.  (+info)

Interpretation accuracy of a CCD film digitizer. (7/90)

There are no significant differences between the interpretations of radiographic images resulting from digitizing films using a recently developed CCD unit and the readings of the original films as measured by accuracy, sensitivity, specificity and ROC analysis. Digital imaging is rapidly becoming the basis of radiology practice resulting in the gradual elimination of conventional film examinations. Related to this trend is the ability of radiologists to provide reliable interpretations of imaging examinations using film digitization and soft copy display. An acceptable system must provide high-quality digital images to achieve the levels of diagnostic accuracy that are comparable to the interpretation of film. This study is an effort to contribute to the acceptance of digital imaging by testing the hypothesis.- The authors selected 120 radiographic examinations from the departmental film files which included chest, abdominal, extremity and other common procedures. Half of the cases contained specified abnormalities and half did not have such findings. All of the examinations had a high degree of diagnostic difficulty. The films were digitized on the CCD equipment and each of the four board certified radiologists who participated in the study interpreted each of the 120 cases, half on original film and half in the digitized format on a high resolution workstation. No radiologist read the same examination more than once. Data collection included variables such as perceived image quality, diagnostic difficulty and interpretation confidence. Accuracy measures were calculated and an ROC analysis was performed. As of this date, the preliminary results indicate acceptance of the hypothesis that there is no significant difference between the accuracy of film readings and the interpretations of the digitized images on a soft copy display. Differences noted in perceived image quality among readers were also not significant. The final results, including an ROC analysis, will be available in March 2002 when a paper is submitted for publication in the Journal of Digital Imaging. During the transition from conventional film practice to digital radiology there is a need to convert previous films to a digital format for comparison with new digital examinations and to facilitate expert reading and consultation on film procedures performed at distant sites. Diagnostic quality and cost effectiveness are key factors in the acceptability of film digitizers to meet these requirements. The preliminary results of this study are encouraging in that another option may be available to radiologists and administrators responsible for choosing equipment for the changing pratice of medical imaging.  (+info)

The use of radiation dose-reduction techniques in the practices of dental faculty members. (8/90)

X-ray exposure to dental patients has been significantly reduced by the introduction of speed group E intraoral film, rectangular beam limitation, long position indicating devices (PIDs), and rare-earth intensifying screens for extraoral radiography. Research indicates that many dentists do not use these techniques. However, schools of dentistry have implemented them to varying degrees for many years, so this investigation was conducted to determine the extent to which dental school faculty members use these materials and techniques in their own practices. Comparisons were made between full- and part-time instructors, those in practice for fifteen years or less and those in practice for more than fifteen years, and those with postgraduate education versus those with no formal education beyond dental school. The significance of differences was measured with chi-square analysis. The results indicate that dentists with faculty appointments utilize dose-reducing techniques to degrees that are comparable to or greater than reported usage by non-dental faculty practitioners. Faculty dentists in practice fifteen years or less are more likely than their older colleagues to use E-speed film (p = 0.001), whereas those in practice more than fifteen years are more likely to use longer PIDs (p = 0.049). Greater acceptance of these practices by faculty may lead to reinforcement of their use in the clinical education of dental students.  (+info)