Computed Radiography Film Research Articles

A comparative study for resolution and density of chest imaging using film/screen, CR and DR

The objective of this study was to compare the resolution and density appropriate to diagnosis in chest PA radiography. In comparing the resolution, we radiographed with conventional radiography, computed radiography(CR) and digital radiography(DR) using the linear resolution phantom(Nuclear Associates-Carle Place. N.Y.). 2 radiologists and 3 radiological technologists read the resolution value by the blind test. DR, conventional radiography and CR measured 3.95, 3.58, 3.48 resolution value respectively. In analysing the density, we chose the fifty normal chest CR and DR and conventional film. We estimated the density using by densitometer(X-rite company-Model 301) in seven regions(lung field, lung field margine, mediastinum I, mediastinum II, heart shadow I, heart shadow II, diaphragm) of chest film. We adapted to analysis the Japanese chest X-ray evaluating method and table. It was scored 0(farthest density value) to 2(nearest density value). DR scored 2 at mediastinum I, mediastinum II, heart shadow I, heart shadow II and diaphragm. On the contrary with, CR scored 2 at lung field and lung field margine. Consequently, DR superior than CR and conventional radiography film compairing density and resolution. It was due to small pixel size and post processing algorithm with digital radiography.

Validation of a Radiographic Model for the Assessment of Mesh Migration

The natural history of laparoscopically placed mesh remains uncharacterized. Mesh migration is not infrequently discovered at reoperation and implicated as a cause of hernia recurrence, and it has also been associated with more serious complications, such as enteric and bladder erosion and fistula formation. To date, there is no noninvasive method by which to reliably assess the in-vivo behavior of laparoscopically placed mesh. In this study, we devised and validated a safe and noninvasive model, utilizing computed radiography (CR), for measuring postoperative mesh migration that may be applied to the clinical setting. The anatomical structures of the inguinal region were recreated using a skeletal male pelvic model. A sheet of commercially available surgical mesh, marked with three 5mm surgical clips at its medial and superior corners, was moved along the inguinal ligament wire for various random distances. The mesh displacement was measured from the model, and a CR film was obtained. The corresponding mesh displacement was then measured on the CR using two different calibration methods (calibration disk and clip measurement). A total of 60 measurements were made and recorded. There were no statistically significant differences between the true (as measured from the model) and CR-measured distances of mesh migration. In comparing the two methods, only method 1 (calibration disk) showed a tendency towards a significant difference when lateral or superior displacement was measured, but correlation remained excellent (r(2) = 0.99). All other measurements showed no significant difference and excellent correlation (r(2) > 0.96). Pearson's correlation coefficients showed no significant inter-rater variability using either of these methods. Our CR model reliably provides a noninvasive means to characterize mesh movement in the postoperative clinical setting. This should provide an instrument to facilitate future clinical evaluation of mesh migration in human trials.

SU-FF-T-210: Electron Beam Dosimetry Using a Computed Radiography System

Purpose: To investigate the ability of the Kodak 2000RT computed radiography(CR) system to accurately measure electron beam isodoses. Method and Materials: The Kodak 2000RT CR reader and Agfa MD‐10 CR plate were used to measure electron beam dose distributions and the results were compared to EDR2 film. The film was scanned by a Vidar dosimetry Pro scanner. The CR plate or film was oriented either perpendicular or parallel to the electron beam. Electron energies of 6, 12, and 20 MeV were used, delivered by a Varian 2100C. Field sizes of 4×4, 10×10, and 25×25 cm square were used. Calibration of the CR plate or film was performed with perpendicular and parallel irradiation techniques for comparison. Calibration curves as a function of beam energy and field size were compared between CR and film. Results: The CR system was able to reproduce electron beam isodoses spatially within 2mm of those from film. CR is very sensitive and easily demonstrates the x‐ray contamination beyond the range of the electrons. CR dose response differences were found between parallel and perpendicular irradiation geometries but little difference as a function of energy or field size.Conclusion: The Kodak 2000RT CR system is capable of accurately measuring dose distributions from electron beamirradiation.Conflict of Interest: This work was supported by Eastman Kodak.

Computed radiography printing problems: a quantitative, observer-independent solution.

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.

Diagnostic usefulness of chest computed radiography--film versus cathode-ray tube images.

Seventy-one plain chest images obtained by computed radiography (CR) with an imaging plate were interpreted on film and two kinds of cathode-ray tube (CRT) monitors installed separately at two facilities (1,024 x 1,536 pixels, 8 bits, and 1,024 x 1,280 pixels, 10 bits) by 20 radiologists and four chest internists. The clinical categories of these 71 cases included pulmonary nodules and interstitial abnormalities. Image reading sessions were held over a total of 4 days, ie, 2 days and then another 2 days, 3 weeks later. Twenty-four observers formed four groups with six members each. Two groups read either films or CRT images at one of the two facilities. In the second experiment, 26 of 71 images were compressed at 10:1, 19 of 71 were compressed at 20:1, and 26 were not compressed. Analyses of the areas under the receiver-operating characteristic curves showed no significant differences in detection of pulmonary abnormalities between film and CRT. In detecting interstitial pulmonary abnormalities, film was more sensitive than CRT monitor. There were no significant differences in observers' performances between the two different kinds of CRT workstation. Subjective evaluation of image quality showed that images irreversibly compressed to the ratios of 10:1 and 20:1 were inferior to original images. Although further considerations are needed with regard to spatial resolution requirements, image processing, and image compression, the utilization of CR CRT image as a substitute for CR film image will be possible.

Evaluation of the image quality of ink-jet printed paper copies of digital chest radiographs as compared with film: A receiver operating characteristic study

Paper copies of digital radiographs printed with the continuous ink-jet technique have proved to be of a high enough quality for demonstration purposes. We present a study on the image quality of ink-jet printed paper copies of digital chest radiographs, based on receiver operating characteristic (ROC) analysis. Eighty-three digital radiographs of a chest phantom with simulated tumors in the mediastinum and right lung, derived from a computed radiography (CR) system were presented in two series of hard copies as ink-jet printed paper copies and as laser recorded film. The images, with a matrix of 1,760 x 2,140 pixels, were printed with a spatial resolution of 10 pixels/mm in the CR film recorder as well as in the ink-jet printer. On film, every image was recorded in two versions, one optimized for the mediastinum and one for the lungs. On paper, only one image was printed; this constituted an effort to optimize both the mediastinum and the lungs. The ink-jet printed images, printed on a matt coated paper, were viewed as on-sight images with reflected light. The examinations were reviewed by six radiologists, and ROC curves were constructed. No significant difference was found between the performance of film and that of ink-jet paper prints. Because the cost for a paper copy is only a tenth of that of film, remarkable cost reductions can be achieved by using the ink jet technique instead. Our results show that further quality studies of ink-jet printed images are worthwhile.

Receiver operating characteristic evaluation of computer display of adult portable chest radiographs.

The suitability of using an image console monitor for interpretation of adult portable chest radiographs was evaluated with receiver operating characteristic (ROC) analysis and subjective techniques. Radiologists read 80 chest images, once on a display monitor and once on computed radiography film, for the presence or absence of pneumothorax or atelectasis. Judgments of correct or incorrect positions of tubes and lines were reported, and total viewing time was recorded. A statistically significant difference was found in favor of monitor reading for detection of pneumothoraces. Atelectasis detection also was higher with monitor reading, but the difference did not reach statistical significance. Tube/line judgments were equivalent for both modes. Total viewing time was approximately 1 minute longer per image with the monitor. Viewing computed radiography images on a workstation monitor does not seem to affect diagnostic accuracy compared with film viewing. Preset image defaults tailored to the individual radiologist could decrease total viewing time to acceptable levels.

Film density calibration for computed radiography systems: is the standard three-point procedure accurate?

With computed radiography (CR) systems, laser printer-film processor combinations are normally checked daily by using test film three-point density measurements. In this study, the authors show that the recommended three-point quality assurance procedure can show satisfactory results even though the CR film output behaves in an anomalous manner. This problem can be corrected by using a 16-point calibration procedure. Regular 16-point calibrations should be performed to ensure satisfactory CR system performance.

Picture archiving and communication system in Hokkaido University Hospital: Advantage and disadvantage of HU-PACS chest roentgenogram images in the outpatient clinic

A new Hokkaido University picture archiving and communication system (HU-PACS) has been in clinical use in the outpatient clinic at HU Hospital. To evaluate the quality of the cathode-ray tube (CRT) monitor images, we compared the detectability of line shadows in the chest roentgenogram images on the CRT monitor with those on the computed radiography (CR) film. We randomized chest roentgenograms from 20 patients who were admitted to the outpatient clinic with pulmonary disease. Two physicians, whose speciality is chest roentgenogram diagnosis, checked whether they could recognize a horizontal fissure line (hairline) on the posteroanterior view and a minor fissure line and major fissure lines on the lateral view. Only 30% of hairlines were recognized on CRT monitor as compared with 65% on CR film. On the lateral view, only 68% of major fissures and 53% of minor fissures on CRT monitor were recognized as compared with 89% and 79%, respective on CR film. Furthermore, it was somewhat difficult to follow entire lines on some of the CRT monitor images. Clinically, the greatest advantage of the PACS is immediate availability of images, including chest roentgenogram, chest computed tomography (CT) and magnetic resonance imaging (MRI). PACS is also convenient for consulting colleagues in other departments. Unfortunately, the quality of the image on the CRT monitor is not yet good enough to visualize line shadows and small solitary lesions on the chest roentgenogram image. Recent advances in high technology have been so rapid, however, that higher resolution CRT monitors will be available soon.