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J T Rhea

Publications and source records attributed to J T Rhea.

11 recordsLinked to original sources
PubMed1989

Impact of postprocessing on the detection of simulated pulmonary nodules with digital radiography.

The authors compared the impact of five postprocessing algorithms on diagnostic performance in the detection of simulated pulmonary nodules on storage phosphor-based digital chest radiographs. Tissue equivalent paraffin nodules (0.5-2.5 cm diameter) were randomly positioned over the chest of a normal volunteer. Receiver operating characteristics (ROC) analysis of a total of 2500 observations by five readers indicated that the default unenhanced image having the appearance of a conventional chest radiograph (ROC area = 0.87 +/- 0.05) was as good as an image with moderate enhancement of medium frequencies (ROC area = 0.85 +/- 0.03), an image with reversed gray scale polarity (ROC area = 0.84 +/- 0.02), an image with reversed gray scale and moderate enhancement of medium frequencies (ROC area = 0.87 +/- 0.03), and an image with a linear rather than a sigmoid gradation curve and incorporating moderate enhancement of medium frequencies (ROC area = 0.87 +/- 0.03). The authors conclude that the specific algorithms they tested had no effect on the detection of pulmonary nodules.

Algorithms↗
PubMed1989

"Single-exposure" dual energy digital radiography in the detection of pulmonary nodules and calcifications.

We studied the detectability of mineralized and non-mineralized simulated pulmonary nodules with dual energy digital radiography. "Soft tissue" and "bone" images (pixel size = 0.2 mm, 10 bits deep) were obtained with subtraction image processing after a single simultaneous exposure (100 kVp, 8 mAs, 17 mR skin exposure dose) of two storage phosphors with an interleaved 0.9 mm copper wafer. Three classes of paraffin-based nodules (0.5 to 3.0 cm) of varying mineral concentration (0, 120 and 190 mg/cm3 K2HPO4) were randomly positioned on the chest wall of two healthy volunteers to simulate calcified and non-calcified nodules. The average receiver operating characteristics (ROC) area of six readers (n = 2880 observations) showed that digital "bone" images (ROC area: 0.77 +/- 0.03) were significantly better (P less than 0.04) than conventional radiographs (OC Film, Lanex medium screens, 141 kVp, 19 mR skin exposure dose) (ROC area: 0.71 +/- 0.05) in detecting calcification in nodules. The unsubtracted digital images of lower kilovoltage were not superior to the 141 kVp conventional radiographs in a subgroup of two readers (ROC area: 0.73 +/- 0.02). Digital "soft tissue" images were equivalent to conventional chest radiographs in detecting soft tissue pulmonary nodules (ROC areas: 0.92 +/- 0.04 and 0.92 +/- 0.05, respectively.

Adult↗
PubMed1989

The frequency and significance of thoracic injuries detected on abdominal CT scans of multiple trauma patients.

Of 174 multiple trauma patients undergoing abdominal CT examination for suspected abdominal trauma, 65 patients had 109 chest injuries detected by abdominal CT, chest film, or both examinations. Forty-one patients had 55 chest injuries at the base of the thorax which were not detected on the initial chest film. The most frequent chest injuries detected only by CT were pneumothroax, fracture (rib, thoracic spine, and sternum), lung contusion, aspiration pneumonia, hemothorax, and post-traumatic atelectasis. Seven patients whose chest injury initially was seen only at abdominal CT required treatment of the injury, suggesting that a variety of chest injuries which may vitally affect patients can be detected early in multiple trauma patients by abdominal CT, and that all abdominal trauma CT scans should be scrutinized for signs of a chest injury.

False Positive Reactions↗
PubMed1989

Improved control of image optical density with low-dose digital and conventional radiography in bedside imaging.

The technical and diagnostic performance of simultaneously acquired low-dose (44% of standard dose) storage-phosphor digital radiographs (system resolution = 0.2 mm, 10 bits) were compared with those of standard-dose conventional bedside radiographs of the chest in 32 patients. The mean optical density (OD) of the lungs (800 measurements) was closer to the ideal density with digital radiography (1.45 OD +/- 0.20 [standard deviation] vs 1.75 OD +/- 0.53) and was less often outside the usable range (2.5% vs 42.5%). Receiver operating characteristic analysis for detection of simulated nodules and monitoring devices (nine readers, 4,608 observations) showed that digital radiography was superior to conventional radiography (P less than .05) for four of the nine readers and equivalent to conventional radiography for five readers. The authors concluded that digital radiography produces more consistent and ideal image density and performs at least as well as conventional radiography under phantom test conditions.

Absorptiometry, Photon↗
PubMed1986

Broncholithiasis.

Explore the source record for details and available documents.

Bronchial Diseases↗
PubMed1979

The relationship of patient waiting time to capacity and utilization in emergency room radiology.

The relationship between patient waiting time and capacity and utilization is quantified. By deciding upon the average acceptable and maximum allowable waiting times, the required capacity and resulting utilization rate are fixed. The data needed for analysis include waiting time, patient volume, time required for specific types of examinations, and technologist and equipment capacity. Cost reduction is achieved without adversely affecting waiting time if volume variability can be reduced. Steps to increase productivity should also be considered as a means of reducing cost per examination, given the cost structure in emergency room radiology and the personnel costs.

Appointments and Schedules↗
PubMed1979

Errors of interpretation as elicited by a quality audit of an emergency radiology facility.

A process-oriented quality care audit was performed in a large metropolitan hospital emergency radiology facility with an annual volume of over 50,000 examinations. One aspect of the audit dealt with errors found among interpretations by radiology residents, the initial interpreters of x-ray studies. Misinterpretations were identified by staff radiologists, who checked all examinations and countersigned the reports. Error rates were correlated with duration of training and were separated as to significance and whether the errors were false-negative (omission) or false-positive (commission). The false-positive to false-negative ratio was 27:73% which is in agreement with previous studies. For all cases of errors, the significance of change in interpretation was high in 20%, moderate in 29% and low in 51%. The effect of inadequate clinical history on the rate and significance of interpretation errors was also determined. When clinical information was inadequate, the significance was high in 27%, moderate in 40% and low in 33%.

Diagnostic Errors↗
PubMed1979

Basilar pneumothorax in the supine adult.

A pneumothorax in a supine patient may outline the anterior costophrenic sulcus, resulting in an abrupt curvilinear change in density projected over the right or left upper quadrant, which is normally convex inferiorly. The upper quadrant will also appear relatively lucent. In a small pneumothorax these may be the only radiographic findings when the patient is supine. This can be easily identified on mobile-unit radiographs of limited technical quality. Either finding should lead to a prompt cross-table lateral or decubitus study to confirm the diagnosis and allow estimation of the size of the pneumothorax.

Adult↗
PubMed1978

Quality assessment and assurance in diagnostic imaging. Theoretical and practical considerations and a quality audit of the excretory urogram.

Concepts necessary to an understanding of the basics of quality assurance audits are presented. Included are specific examples that bridged theory and practice by applying the protocol to a real-life diagnostic imaging situation. This method meets the present requirements of the Joint Commission of the Accrediation of Hospitals.

Costs and Cost Analysis↗