Calibration of medium-resolution monochrome cathode ray tube displays for the purpose of board examinations.

This report discusses calibration and set-up procedures for medium-resolution monochrome cathode ray tubes (CRTs) taken in preparation of the oral portion of the board examination of the American Board of Radiology (ABR). The board examinations took place in more than 100 rooms of a hotel. There was one display-station (a computer and the associated CRT display) in each of the hotel rooms used for the examinations. The examinations covered the radiologic specialties cardiopulmonary, musculoskeletal, gastrointestinal, vascular, pediatric, and genitourinary. The software used for set-up and calibration was the VeriLUM 4.0 package from Image Smiths in Germantown, MD. The set-up included setting minimum luminance and maximum luminance, as well as positioning of the CRT in each examination room with respect to reflections of roomlights. The calibration for the grey scale rendition was done meeting the Digital Imaging and communication in Medicine (DICOM) 14 Standard Display Function. We describe these procedures, and present the calibration data in. tables and graphs, listing initial values of minimum luminance, maximum luminance, and grey scale rendition (DICOM 14 standard display function). Changes of these parameters over the duration of the examination were observed and recorded on 11 monitors in a particular room. These changes strongly suggest that all calibrated CRTs be monitored over the duration of the examination. In addition, other CRT performance data affecting image quality such as spatial resolution should be included in set-up and image quality-control procedures.

American Board of Radiology computer test center.

In 1997, the American Board of Radiology (ABR) determined to develop a computer-based examination and to create a test center for administration of computer-based examinations. In implementation of its plan, the Board has developed a flexible examination platform, well-adapted to the graphics needs of an image-based examination, and at the same time, compatible with test centers being developed by other medical specialty boards in terms of hardware, software, and candidate surroundings. A test center for secure proctored examination of up to 33 candidates has been created at the Board's headquarters in Tucson, AZ. The decision of the ABR to employ computer-based testing as a part of its recertification process represents an important step of significance to the entire field of radiology, embracing methods that are rapidly becoming integral to the practice of radiology in the acquisition, display, and management of diagnostic imaging information.

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

RATIONALE AND OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Standardization of network addressing in picture archiving and communications systems utilizing the ISO OSI protocols.

The establishment of a communications network requires the definition of addressing schemes to identify systems attached to the network. When it is anticipated that such a network will interconnect to, or communicate with, other similar networks it is beneficial to define standardized addressing schemes. This paper discusses the need for the standardization of network service access point (NSAP) addresses in picture archiving and communications systems (PACS) which use the open systems interconnect (OSI) communications protocols. Possible methods for establishing the necessary hierarchy of address registration authorities are discussed, along with the corresponding address formats.

Computed radiographic evaluation of simulated pulmonary nodules. Preliminary results.

We evaluated the capabilities of a computed radiography system (CRS) and a standard radiography system (SRS) in the detection of simulated solitary pulmonary lung nodules of various sizes and contrast. A phantom simulated the pulmonary anatomy, and specially shaped plexiglass disks were externally mounted to simulate solitary pulmonary nodules of different diameters and thicknesses. ROC curves were generated based on the performance of each of the radiologists observing each film set. In this preliminary study, the overall performance for both the CRS and the SRS were comparable in detecting simulated pulmonary nodules.

Evaluation of double aortic arch and aortic coarctation by intravenous digital subtraction angiography (IV DSA).

Eleven pediatric patients with congenital aortic anomalies were evaluated using intravenous digital subtraction angiography (IV DSA). Excellent correlation was found between IV DSA, other imaging studies, and operative findings. Ten of 11 patients studied (90.9%) were correctly diagnosed using this technique. Intravenous DSA may be the procedure of choice in assessing aortic arch anomalies in selected patients.

Total digital radiology department: spatial resolution requirements.

The minimum spatial resolution required for a total digital radiology department has yet to be defined. A pilot study designed to provide this information was performed. Abnormal and normal radiographic images of children were digitized and redisplayed on film at spatial resolutions of 5.0, 2.5, 1.25, and 0.625 lp/mm. These resolutions are comparable to a digital display of a 14 X 14 in. chest image having pixel elements of 4096 X 4096, 2048 X 2048, 1024 X 1024, and 512 X 512, respectively. Contrast resolution was maintained at 12 bits or 4096 gray levels. The three phases of data acquisition were (1) the standard analysis of receiver operating characteristics, (2) a checklist evaluation of the "seeability" of important structures, and (3) a comparison of all resolutions and a discernment of usability. Fifteen radiologists participated in the study. On the basis of the pediatric cases used, the results showed that the needed spatial resolution for a total digital radiology department may be around 2.5 lp/mm (2048 X 2048). Checklist data on seeability of structures and comparisons of all resolutions give information on specific changes that are occurring as the resolution is decreased, and, when included with the receiver-operating-characteristic data, they become a major component in developing a resolution standard. The finding that 2.5 lp/mm is the required spatial resolution makes construction of a total digital radiology department possible with present state-of-the-art technology.

The digital radiology department of the future.

The boom in microelectronics, including cost-effectiveness, has now allowed us to consider the use of these objects to store digital images. There remains much research, development, and clinical evaluation to be done in receptor technology. Further improvements in image processing, optical laser disk storage, and optical transmission and further commercial development of display technology must take place. All of these developments are occurring simultaneously. Within 5 to 10 years, radiology departments will most likely be totally electronic, probably cost-effective, and, it is hoped, more diagnostically accurate.

Rolls Royces and compacts. Selection of radiological instrumentation.

The technological revolution that has occurred in radiology since World War II has greatly improved patient care, and some initially expensive high-technology innovations are now becoming cost effective. Some of these innovations are reviewed, and the importance of not judging new technology prematurely is emphasized.

Comparison of conventional pulmonary angiography with intravenous digital subtraction angiography for pulmonary embolic disease.

Intravenous digital subtraction pulmonary angiography was performed in 33 patients with suspected pulmonary embolism. It was performed as the initial examination, followed immediately by conventional film-screen pulmonary angiography performed with selective right or left main pulmonary injections. Intravenous studies of diagnostic quality were obtained in 31 of 33 patients (93.9%). Of the satisfactory intravenous studies, pulmonary embolism was correctly diagnosed in 12 cases and excluded in 18 cases. Emboli were detected in major and second-order branches, and occasionally in third-order branches as well. There was one false-positive intravenous pulmonary study, but the overall accuracy was 90.9% considering all studies and 96.8% excluding the two inadequate intravenous examinations. It is concluded that intravenous pulmonary angiography is an acceptable substitute for routine pulmonary angiography in most patients with suspected major pulmonary embolism. The technique is less expensive, and is safer, faster, and easier to perform than conventional pulmonary angiography.

Intracranial applications of digital intravenous subtraction angiography.

The intracranial vessels of 175 patients were examined with digital intravenous subtraction angiography. The equipment and the technique of the examination are briefly described. Of these patients, 129 underwent intravenous cerebral angiography in conjunction with examination of the extracranial carotid arteries for suspected arteriosclerotic disease. Postoperative and occasionally preoperative studies of intracranial aneurysms and arteriovenous malformations were performed in 16 patients, patency and flow patterns of extracranial-to-intracranial bypass grafts were evaluated in 11 instances, and selected vascular cranial and intracranial neoplasms were studied in 16 cases. Venous sinus occlusion has also been diagnosed by this technique. In many instances, digital intravenous subtraction angiography can replace conventional cerebral angiography.

Subjective vs. objective evaluation of gallbladder opacification during oral cholecystography in comparative clinical trials: implications for studies involving visual assessment.

Radiographs and CT images taken during oral cholecystography in dogs were interpreted in an independent, blind fashion by three radiologists on two occasions and visual assessment of gallbladder density compared to the actual CT values. While there was significant intra- and inter-observer variation, the mean scores for the observers' interpretations of both radiographs and prints correlated well with the actual CT values (p less than 0.05). In five out of six comparisons between first and second readings, the observers gave a lower score on the second reading. The considerable variation reflects the problems inherent in subjective evaluation of agents that produce small but measurable differences in radiographic density. Studies involving such subjective data have to be carefully designed in order to obtain meaningful results.