Simultaneous multilayer arthrotomography of the temporomandibular joint using photostimulable phosphor computed radiography

OBJECTIVE: To compare the image quality of photostimulable phosphor computed radiography (CR) with that of a conventional screen-film system for simultaneous multilayer arthrotomography of the temporomandibular joint (TMJ). METHODS: X-ray attenuation, resolution and granularity was compared. Simultaneous multilayer tomography of TMJ was performed using a skull phantom and diagnostic quality of bone structures estimated. The clinical outcome is demonstrated in two typical cases. RESULTS: X-ray attenuation was larger with CR. Granularity was more prominent in edge-enhanced CR images and was associated with inferior diagnostic quality. However, it was improved by using a higher tube voltage. Clinical CR without edge enhancement showed a similar resolution to the conventional system but this decreased with enhancement. In an enhanced arthrotomogram, the boundary between contrast medium, bone and soft tissue were clearly defined and a fibrous adhesion also easily seen. CONCLUSION: Photostimulable phosphor CR is an acceptable alternative for simultaneous multilayer arthrotomography of the TMJ.     

Use of computed radiography in the study of an historic painting

The authors demonstrate the use of radiography in the investigation of an historic painting and describe the potential benefits of computed radiography compared with conventional screen-film radiography. The subject for the comparison was a 16 x 19-foot oil-on-canvas painting, Scipio Africanus Freeing Massiva, by Giovanni Battista Tiepolo. Radiographs of the painting were obtained by using a portable, industrial radiographic unit and both conventional screen-film and photostimulable phosphor plate cassettes. For this investigation, computed radiography had a number of advantages over screen-film radiography, largely due to its wider dynamic range and its capabilities for enhancing the digital images with image processing tools such as magnification, edge enhancement, colorization, and airbrushing. The ability to electronically combine images from the large painting into a single composite image file was extremely valuable, as this technique was much less cumbersome and resulted in much higher quality composite images than could be achieved with conventional radiography. An additional advantage of computed radiography includes the capability to easily archive and transmit these images in a digital format for subsequent review.     

Improvement of detectability of microcalcifications by magnification digital mammography

Our aim in this study was to evaluate the potential utility of magnification mammography with a CR system by investigating the basic imaging parameters and detectability of microcalcifications in comparison with those of conventional screen-film systems. The basic imaging parameters were evaluated by measuring scatter fraction, modulation transfer function (MTF), Wiener spectrum, and incident dose for the various magnification factors. The detection of simulated microcalcifications in radiographs of a mammographic phantom and breast specimens were evaluated subjectively and quantitatively for screen-film and CR techniques with various magnification factors. The scatter fraction of digital magnification mammography decreased with increasing magnification factor. MTF of magnification digital mammography improved with increasing magnification factor. The detectability of microcalcifications with the CR system was significantly improved by magnification technique. From the above results, it is expected that the use of magnification mammography with a CR system will improve the detectability of microcalcification.     

Automatic background recognition and removal (ABRR) in computed radiography images

A novel method to automatically recognize and remove background signals in computed radiography (CR) images caused by X-ray collimation during projection radiographic examinations is presented. There are three major steps in this method. In the first step, a statistical curve is derived based on many hierarchical CR sample images as a first approximation to loosely separate image and background pixels. Second, signal processing methods, including specific sampling, filtering, and angle recognition, are used to determine edges between image and background pixels. Third, adaptive parameter adjustments and consistent and reliable estimation rules are used to finalize the location of edges and remove the background. In addition, this step also evaluates the reliability of the complete background removal operation. With this novel method implemented in a clinical picture archiving and communication system (PACS) at the University of California at San Francisco, we achieved 99% correct recognition of CR image background, and 91% full background removal without removing any valid image information.     

Mottle on computed radiographs of the chest in pediatric patients

PURPOSE: To investigate the relationship between radiation exposure and perceived mottle at bedside pediatric chest examinations performed with screen-film and computed radiographic techniques. MATERIALS AND METHODS: In a pediatric intensive care unit, chest radiographs were obtained with both computed radiography (60 radiographs) and a 600-speed screen-film system (14 radiographs). The relative radiation exposure was estimated by using the sensitivity value obtained in the processing of each computed radiograph. Five radiologists assessed the mottle present in the computed radiographs and screen-film images. RESULTS: For computed radiographs, the perceived level of mottle was inversely related to radiation exposure. For the same radiation exposure, the perceived mottle on computed radiographs was significantly higher than that on screen-film images (P < .001 for small cassettes; P < .01 for large cassettes). CONCLUSION: Pediatric computed radiography of the chest requires approximately twice the exposure of a 600-speed screen-film system to attain the same level of mottle.     

Digital radiography in paediatrics: radiation dose considerations and magnitude of possible dose reduction

The purpose of this study was to evaluate the radiation doses received by paediatric patients examined using a digital radiography unit, and to compare these doses with those received from conventional screen-film systems. In this way, guidelines could be drawn up concerning the magnitude of possible dose reductions achievable using digital radiography. The study was undertaken on approximately 900 patients undergoing abdomen, chest, pelvis and skull examinations. Patients were categorized into the following age groups: 0-1 month, 1-12 months, 1-5 years, 5-10 years and 10-15 years. Approximately half were X-rayed using a Fuji computed radiography system and half using a conventional screen-film system. Entrance surface dose was calculated from the recorded exposure parameters and measured X-ray tube outputs. Dose-area product was recorded directly. Image quality was assessed clinically using criteria recommended by a working group of the Commission of the European Communities. Apart from chest examinations, it was found possible to reduce doses by about 40% on average, by using a computed radiography system instead of a 600 speed screen-film combination. There was no significant difference in the dose for chest examinations. Satisfactory image quality can therefore be achieved by using computed radiography as a 1000 speed system for abdomen, pelvis and skull examinations, and as a 600 speed system for chests. Since very few departments appear to use screen-film systems of speeds greater than 400, then, for most departments, the use of computed radiography would result in dose reductions of at least 60%, or 33% for chests.     

Three-dimensional CT measurement of adult acetabular dysplasia: technique, preliminary results in normal subjects, and potential applications

OBJECTIVE: To assess a three-dimensional computed tomography (3DCT) technique for measurement of acetabular coverage in adults. DESIGN: We used 3DCT to define the geometric centre of the femoral head and to measure centre-edge angles (CEAs) at 10 degrees rotational increments around the acetabular rim. The means, ranges, standard deviations and 95% confidence intervals for the CEAs at the various rotational increments were determined. Inter- and intra-observer variability was measured. The normal values are compared with two example cases of acetabular dysplasia. PATIENTS: The normal hips of 15 subjects aged 1949 years (mean 34.2 years) were measured. RESULTS: The 3DCT measurements are reproducible (mean difference interobserver, 1.7 degrees - 7.9 degrees; mean difference intra-observer, 0.6 degrees-6.9 degrees). Mean normal CEA at the lateral rim was 33 degrees with a 95% confidence interval of 23 degrees - 43 degrees. Mean normal CEAs at 10 rotational increments from anterior to posterior rim were determined, and graphed as a 'normal curve'. CONCLUSION: This new 3DCT method of assessing acetabular dysplasia is simple, reproducible, and applicable to diagnosis, quantification and surgical planning for adult acetabular dysplasia patients.     

Feasibility of cardiac cryoablation using a transvenous steerable electrode catheter

BACKGROUND AND PURPOSE: Accurate contouring of the clinical target volume (CTV) is a fundamental prerequisite for successful conformal radiotherapy of prostate cancer. The purpose of this study was to investigate intra- and inter-observer variability in contouring prostate (P) and seminal vesicles (SV) and its impact on conformal treatment planning in our working conditions. MATERIALS AND METHODS: Inter-observer variability was investigated by asking five well-trained radiotherapists of contouring on CT images the P and the SV of six supine-positioned patients previously treated with conformal techniques. Short-term intra-observer variability was assessed by asking the radiotherapists to contour the P and SV of one patient for a second time, just after the first contouring. The differences among the inserted volumes were considered for both intra- and inter-observer variability. Regarding intra-observer variability, the differences between the two inserted contours were estimated by taking the relative differences in correspondence to the CT slices on BEV plots (antero-posterior and left-right beams). Concerning inter-observer variability, the distances between the internal and external envelopes of the inserted contours (named projected diagnostic uncertainties or PDUs) and the distances from the mean inserted contours (named mean contour distances or MCDs) were measured from BEV plots (i.e. parallel to the CT slices). RESULTS: Intra-observer variability was relatively small (the average percentage variation of the volume was approximately 5%; SD of the differences measured on BEV plots within 1.8 mm). Concerning inter-observer variability, the percentage SD of the inserted volumes ranged from 10 to 18%. Differences equal to 1 cm in the cranio-caudal extension of P + SV were found in four out of six patients. The largest inter-observer variability was found when considering the anterior margin in the left-right beam of P top (MCD = 7.1 mm, 1 SD). Relatively high values for MCDs were also found for P bottom, for the posterior and lateral margins of P top (2.6 and 3.1 mm, respectively, I SD) and for the anterior margin of SV (2.8 mm, 1 SD). Relatively small values were found for P central (from 1.4 to 2.0 mm, 1 SD) and the posterior margin of SV (1.5 mm, 1 SD). CONCLUSIONS: The application of larger margins taking inter-observer variability into account should be taken into consideration for the anterior and the lateral margins of SV and P top and for the lateral margin of P. The impact of short-term intra-observer variability does not seem to be relevant.     

Acute theophylline intoxication as differential diagnosis of pneumothorax in an asthma patient

In Germany, three-dimensional non-invasive measurement techniques are not in routine use for medical purposes. Completely integrated applications of photogrammetric technology are lacking. The results of clinical examination, X-rays and pre- and postoperative photographs from different angles have been used for medical analysis. In an interdisciplinary research project we tested the general applicability of photogrammetric measurement systems. We examined patients with malformations of the mandible-maxilla complex by taking pictures of the face. In order to assess the surface structure we projected regular patterns onto the surface. We calculated about 500 points on the surface with accuracy better than 0.2 mm. Graphical analyses of measurement results are presented in clinically relevant form. We produce representations of the faces in auto-CAD by means of regular meshes which allow views from any perspective, longitudinal and lateral sections. In addition to calculating angles, distances, surfaces and volumes, visualisation of shape is a useful aid in documentation and quantification of changes of soft tissue of the human face under surgery treatment.     

Interpretation time of serial chest CT examinations with stacked-metaphor workstation versus film alternator

PURPOSE: Interpretation time of serial staging chest CT cases, which each contained current and previous examinations, with a simple prototype workstation called filmstack was experimentally compared with interpretation time with a film alternator. MATERIALS AND METHODS: The filmstack displayed a "stack" of sections for each examination; user controls allowed rapid selection of preset attenuation windows and both synchronized and unsynchronized scrolling. Eight radiologists were timed as they used the filmstack and the film alternator to interpret four ergonomically complex serial CT cases. RESULTS: All reports dictated on the basis of findings with filmstack and film were of acceptable clinical accuracy. The time to examine a case with filmstack was significantly faster than the time with film, including the time to load and unload the alternator (99% confidence [P = .01]). There was no statistically significant difference in interpretation time between filmstack and prehung film. CONCLUSION: Use of a low-cost stacked CT workstation with a single 1,024 x 1,024 monitor is an effective means of interpreting cases that require comparison of multiple CT examinations.     

Improved methods for quantitative radiographic evaluation with particular reference to total-hip arthroplasty

The range of magnification factors in 40' and 72' radiographs were calibrated using three simple mathods. The relationship between X-ray source to cassette distance, object to cassette distance and magnification factors was determined experimentally for both 40' and 72' radiographs. The resulting nomogram showed that: (1) there was no significant magnification difference between centered (AP-hip) and offset (AP-pelvis) radiographs; (2) magnification factors of 40' films were twice those of 72' films for the same object to cassette distances; and (3) due to the smaller magnification range of 72' films (1 to 13%) compared to 40' films (1 to 26%) there was less chance of error in determining magnification factors for the larger film distances. The skin radiation dosage for the patient was similar in both procedures. Magnification factors were also calculated from 414 A-P radiogrphs of total-hip prosthesis, using the femoral ball as a calibration standard. This provided magnifications of 20 per cent +/- 6(2SD) for 40' films and by extrapolation on the nomogram gave corresponding values of 10 per cent +/- 3 for the 72' films. The associated hip to cassette distances (L), also obtained from the nomogram, varied from 125 to 205 mm, average 165 mm. In subsequent clinical trials using 72' films, it was possible to represent the patients as either small (L less than 145 mm) medium (145 less than or equal to L less than or equal to 185 mm) or large (L greater than 185 mm) with corresponding magnification factors of 8, 10 and 12 per cent, respectively. The error with this simplification was still within +/-21/2 per cent. For 40' films the corresponding magnification factors for small, medium or large patient categories were 16, 20 and 24 per cent respectively with likely errors within +/-5 per cent. Magnification factors were also calculated from the radiographic image of a 100 mm long rod which had been attached to the patien's thigh. The overall accuracy with this method was comparable to the techniques described above and had the advantage that every radiograph featured its own scale, a particularly important feature for preoperative films which have no implant for calibration purposes. As a result of such simple calibration procedures, it was possible to identify the overall magnification variations and specify particular magnification factors within +/-21/2 per cent (72' films) or +/-5 per cent (40' films).     

A method for measuring the presampled MTF of digital radiographic systems using an edge test device

The modulation transfer function (MTF) of radiographic systems is frequently evaluated by measuring the system's line spread function (LSF) using narrow slits. The slit method requires precise fabrication and alignment of a slit and high radiation exposure. An alternative method for determining the MTF uses a sharp, attenuating edge device. We have constructed an edge device from a 250-microm-thick lead foil laminated between two thin slabs of acrylic. The device is placed near the detector and aligned with the aid of a laser beam and a holder such that a polished edge is parallel to the x-ray beam. A digital image of the edge is processed to obtain the presampled MTF. The image processing includes automated determination of the edge angle, reprojection, sub-binning, smoothing of the edge spread function (ESF), and spectral estimation. This edge method has been compared to the slit method using measurements on standard and high-resolution imaging plates of a digital storage phosphor (DSP) radiography system. The experimental results for both methods agree with a mean MTF difference of 0.008. The edge method provides a convenient measurement of the presampled MTF for digital radiographic systems with good response at low frequencies.     

Rapid detection of traumatic effusion using surgeon-performed ultrasonography

BACKGROUND: In the injured patient, rapid assessment of the thorax can yield critical information for patient management and triage. OBJECTIVES: The objectives of this prospective study were (1) to determine if experienced surgeon sonographers could successfully use a focused thoracic ultrasonographic examination to detect traumatic effusion, and (2) to compare the accuracy and efficiency of ultrasonography with supine portable chest radiography. METHODS: Surgeon-sonographers performed thoracic ultrasonographic examinations on patients with blunt and penetrating torso injuries during the Advanced Trauma Life Support secondary survey. All patients also underwent portable chest radiography. Performance times for ultrasonography and chest radiography were recorded. Comparisons were made of the performance times and accuracy of both tests in detecting traumatic effusion. RESULTS: In 360 patients, there were 40 effusions, 39 of which were detected by ultrasonography and 37 of which were detected by chest radiography. The 97.5% sensitivity and 99.7% specificity observed for thoracic ultrasonography were similar to the 92.5% sensitivity and 99.7% specificity for portable chest radiography. Performance time for ultrasonography was significantly faster than that for chest radiography (1.30 +/- 0.08 vs. 14.18 +/- 0.91 minutes, p < 0.0001). CONCLUSION: Surgeons can accurately perform and interpret a focused thoracic ultrasonographic examination to detect traumatic effusion. Surgeon-performed thoracic ultrasonography is as accurate but is significantly faster than supine portable chest radiography for the detection of traumatic effusion.     

The impact of routine chest radiography on ICU management decisions: an observational study

Inter-observer and intra-observer reliability for classifying radial head fractures by the system of Mason was analyzed. Twenty-three cases of isolated radial head fractures and twenty-five sets of corresponding AP and lateral radiographs representing these fractures were assembled. The cases were reviewed and assessed independently according to the system of Mason by twenty practicing orthopedic surgeons. On two occasions, the inter-observer and intra-observer variation was analyzed by standard unweighted Kappa statistics. In both observations, complete agreement was seen in only 16% of the cases. Kappa statistic values indicated that 69% of the cases at first observation and 45% of the cases at second observation suggest moderate to poor agreement. Intra-observer agreement between the first and second observation was graded fair to poor in 60% of the cases. Individual observer consistency was, on average, only 78% (range 60% to 92%). The demonstrated wide degree of variation suggests that the Mason classification is unreliable.     

In vivo accuracy of two radiographic systems in the detection of Bj?rk-Shiley convexo-concave heart valve outlet strut single leg separations

OBJECTIVE: Modified cineradiographic systems have been used clinically to detect partially broken outlet struts in normally functioning Bj?rk-Shiley convexo-concave heart valves. Almost all such valves were explanted, presuming that full failure would likely follow. Inasmuch as the clinical setting only rarely permits examination of normally rated valves, the accuracy of radiographic detection cannot be clinically defined. This study uses the clinical radiographic technique in sheep implanted with known-status convexo-concave valves, comparing its accuracy and that of a newly developed, geometric image magnification radiography system. METHODS: Twenty-one sheep with mitral convexo-concave valves were studied on both systems. Five were used for extensive training. When operators were expert with both systems, images of four intact valves and 12 valves with outlet strut single leg separations, along with a seventeenth single leg separation valve used for calibration, were integrated into 112 image sets organized into a balanced incomplete block design for evaluation by eight trained, blinded reviewers. RESULTS: Cineradiography sensitivity was 24% versus 31% for direct image magnification. The odds ratio for detection of single leg separation by direct image magnification versus cineradiography was 2.0 (95% confidence interval, 0.76 to 5.9; p = 0.13). Cineradiography specificity was 93% versus 90% for direct image magnification. Sensitivity and specificity varied markedly by reviewer, with sensitivity ranging from 8% to 55% and specificity from 51% to 100% for the combined technologies. CONCLUSIONS: The data support the need for more intensive training for convexo-concave valve imaging and further investigation of unconventional radiographic technologies. Clinical cineradiography of convexo-concave valves may detect as little as 25% of valves having a single leg separation, underestimating the prevalence of single leg separations and thereby implying more rapid progression to full fracture than is actually the case.     

An orphan nuclear receptor lacking a zinc-finger DNA-binding domain: interaction with several nuclear receptors

BACKGROUND: Affections of the lacrimal drainage system are often seen by ophthalmologists. Inspection, palpation, diagnostic rinsing and sounding can distinguish anatomical stops before or after tear sac. For final diagnostics however more apparative examinations are necessary. The ultrasonic examination with contrast media is a simple method for diagnostics of affections of the lacrimal drainage system besides the dacryocystography, the scintigraphy and other ones. PATIENTS AND METHODS: On 12 patients with a dysfunctional lacrimal drainage system and 12 normal controls the ultrasonic examination with instillation of contrast media: silicon oil, glycerine, dispersions of almond oil and viscoelastic substances was performed. All examinations were performed with the 13 B-scan. RESULTS: The lacrimal drainage way was detectable from the canaliculus to the middle nasolacrimal duc CONCLUSION: An additional advantage of the ultrasonic examination with contrast-media is the neglect of radiation, the simple and often repeatable examination method, especially the enhancement of the contrast of different valves and stenoses and mucinous deposits in stationary anatomical variations and dynamic defects.     

ROC comparison of visualization of hand fractures using digital and conventional techniques

PURPOSE: To compare the accuracy of digital luminescence radiography (DLR) and conventional film-screen radiography (FSR) in diagnosing fractures. MATERIAL AND METHOD: Both conventional and digital radiographs were acquired from a consecutive series of 57 patients with suspected wrist or hand fractures. The digital images were obtained with a 30% dose reduction. A ROC-analysis (receiver-operating characteristics) was performed. RESULTS: The area under the curve was 0.89 for conventional FSR, 0.93 for DLR, "gray scale" and 0.94 for DLR, "edge enhanced". CONCLUSIONS: Although its spatial resolution is lower, DLR provided better results than conventional FSR, when contrast processing algorithms were optimised for the specific clinical question. The edge-enhanced version was superior to the non-edge enhanced version. The reason for this seems to be the higher contrast resolution of DLR compared to FSR.     

Clinical evaluation of single-exposure dual-energy subtraction chest radiography: with FCR 9501 ES]

Using the one-shot energy subtraction method, we took chest radiography of 1,031 outpatients of Kanazawa University Hospital. Chest radiographs were taken with the FCR 9501 ES system, with patients upright. We studied the clinical efficacy of this diagnostic method. The method and usage procedures involved have been sufficiently technologically refined to permit handling of an adequate number of patients in a reasonable time at a permissible exposure dose. However, the system can be further improved technologically in order to obtain fully consistent high-quality images, regardless of the patient's physique. For well-rounded image reading, three kinds of images must be generated simultaneously: an original image; soft tissue (bone subtracted image) and bone (soft tissue subtracted image) Some soft tissue image were helpful for detecting non-calcified parenchymal nodules that overlapped the rib shadow, and some bone image served to precisely diagnose the existence of abnormal ribs, calcified lymph nodes, and calcified nodules. Furthermore, the bone images were helpful for revealing that the fine infiltrative shadows in the lung fields in original images were actually pleural calcifications and that the poorly defined nodular opacities were, in reality, abnormal rib calcifications. In light of the above, we wish to stress the importance of clinical efficacy of not only soft tissue images but bone images derived using the energy subtraction method. The clinical usefulness of this method was confirmed in 66 of 1,031 patients (6.4%) who had initially been scheduled for routine chest radiography. This result indicates how frequently the method encounters applicable cases when applied non-selectively to general patients who require radiographic chest examination. The advantages of this method will become much more evident with an examination protocol that minimizes unnecessary special examinations or optimizes the balance between screening and special examinations.     

Digital radiology in dentistry: experience with direct intraoral techniques (radiovideography)

The aim of this paper was to discuss the techniques for intraoral digital radiography (radiovisiography) and to compare their accuracy in dental radiographical diagnosis. Emphasis was given to their potential applications in oral radiology. Radiovisiography was compared with intraoral films and electronic magnifications from digital panoramic radiographs in 38 patients, for a total amount of 36 caries, 27 periapical conditions and 58 metal implants. Moreover, the accuracy of the measurements made with the three techniques was assessed on a specimen of mandibular and maxillary arches containing 28 extracted teeth with endodontic files of known length. Radiovisiography was as effective as intraoral films and more effective than digital panoramic radiographs in the diagnosis of caries and periapical lesions. Nevertheless, it produced a significant magnification and yielded unreliable measurements of root canals and metal implants. Radiovisiography is very easy to use and does not require dark room procedures nor chemicals of any kind. In addition, it reduces patient's X-ray exposure by over 50% with respect to film studies. For these reasons, this technique seems to be worthy of widespread use in dental radiography, with the exception of the conditions requiring an exact measurement of working length.