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J T Rhea

Publications and source records attributed to J T Rhea.

At least 19 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.

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Bronchial Diseases↗
PubMed1984

Vocal cord paralysis. A latent effect of perivascular thorium dioxide.

The late effects of thorium dioxide (Thorotrast) in the perivascular space of the neck are reviewed. The roentgenographic analysis of the problem consists of both plain films (to detect the residual density of extravasated thorium dioxide) and computed tomography (to help define any involvement of the carotid artery).

Calcinosis↗
PubMed1983

The effects of chemotherapy on bony metastases as measured by quantitative skeletal imaging.

The effect of chemotherapy on bony metastases from adenocarcinoma of the colon was investigated by quantitative skeletal imaging over a two-month interval. The quantitative skeletal imaging results correlated with conventional blood chemistry results over this time period. While chemical assay techniques furnish an average value of lesion response, the quantitative bone scan represents a method for individual lesion analysis. This methodology has the potential to provide a better understanding of metastatic bone disease therapy.

Adenocarcinoma↗
PubMed1983

Wilms' tumor.

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Child, Preschool↗
PubMed1983

Skull fractures.

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Humans↗
PubMed1983

Thorium dioxide.

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Extravasation of Diagnostic and Therapeutic Materi↗