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Biomedical subjects

D B Washburn

Publications and source records attributed to D B Washburn.

8 recordsLinked to original sources
PubMed2000

Human breast cancer specimens: diffraction-enhanced imaging with histologic correlation--improved conspicuity of lesion detail compared with digital radiography.

Seven breast cancer specimens were examined with diffraction-enhanced imaging at 18 keV with a silicon crystal with use of the silicon 333 reflection in Bragg mode. Images were compared with digital radiographs of the specimen, and regions of increased detail were identified. Six of the seven cases (86%) showed enhanced visibility of surface spiculation that correlated with histopathologic information, including extension of tumor into surrounding tissue.

Biopsy, Needle↗
PubMed1999

Effects of processing conditions on mammographic image quality.

RATIONALE AND OBJECTIVES: Any given mammographic film will exhibit changes in sensitometric response and image resolution as processing variables are altered. Developer type, immersion time, and temperature have been shown to affect the contrast of the mammographic image and thus lesion visibility. The authors evaluated the effect of altering processing variables, including film type, developer type, and immersion time, on the visibility of masses, fibrils, and speaks in a standard mammographic phantom. MATERIALS AND METHODS: Images of a phantom obtained with two screen types (Kodak Min-R and Fuji) and five film types (Kodak Min-R M, Min-R E, Min-R H; Fuji UM-MA HC, and DuPont Microvision-C) were processed with five different developer chemicals (Autex SE, DuPont HSD, Kodak RP, Picker 3-7-90, and White Mountain) at four different immersion times (24, 30, 36, and 46 seconds). Processor chemical activity was monitored with sensitometric strips, and developer temperatures were continuously measured. The film images were reviewed by two board-certified radiologists and two physicists with expertise in mammography quality control and were scored based on the visibility of calcifications, masses, and fibrils. RESULTS: Although the differences in the absolute scores were not large, the Kodak Min-R M and Fuji films exhibited the highest scores, and images developed in White Mountain and Autex chemicals exhibited the highest scores. CONCLUSION: For any film, several processing chemicals may be used to produce images of similar quality. Extended processing may no longer be necessary.

Absorptiometry, Photon↗
PubMed1993

Effects of delayed processing on mammographic phantom object detection.

OBJECTIVES: Delayed processing of films is a common occurrence in mobile mammography screening programs. The effects of such delayed processing on radiologists' detection of phantom test objects are investigated. METHODS: Twelve screen-film combinations were exposed using a phantom and developed after delays of 0, 1, 2, 3, 5, and 7 days. Films were scored by three board-certified radiologists specializing in mammography, based on visibility of calcifications, masses, fibrils, and line pairs. RESULTS: Variance analyses of mean scores indicate that, across screen-film combinations, there are no statistically significant decreases in object detection associated with delayed processing. The analyses do indicate, however, a statistically significant difference in scores unrelated to delay, attributable to the screen-film combination used. CONCLUSIONS: Delayed processing of mammography film does not lead to a decrease in the visibility of phantom test objects, despite large decreases in overall image optical density.

Analysis of Variance↗
PubMed1991

Parameter optimization and calibration of 19F magnetic resonance imaging at 1.5 Tesla.

Fluorine-19 magnetic resonance imaging is limited by the fact that acquisition times are long and that high concentrations must be used in order to obtain good signal to noise. A significant improvement in signal to noise ratio may be brought about by the addition of Gd-DTPA, a paramagnetic agent which shortens T1. Images of phantoms containing trifluoroacetic acid (TFA) doped with Gd-DTPA were obtained using a standard spin echo sequence in a 1.5 T field. Interpulse times (TR and TE) and Gd-DTPA concentrations were optimized to yield maximum signal to noise ratios. The use of fast-field-echo scans to image fluorine is also demonstrated. Signal averaging successive FFE scans yields good signal to noise and resolution and may find clinical applicability in imaging areas subject to motion.

Calibration↗
PubMed1987

The effect of rare earth filtration on patient exposure, dose reduction, and image quality in oral panoramic radiology.

Rare earth intensifying screen material (Gd2O2S:Tb) was added to the standard Al filtration of an oral panoramic x-ray unit, resulting in a beam capable of achieving reductions in patient dose without a loss of image quality. The added rare earth filtration technique resulted in patient dose reductions of 21-56%, depending on anatomic sites, when compared to the conventional Al filtration technique. Films generated from both techniques were measured densitometrically and evaluated by a panel of practicing clinicians. Diagnostically significant differences were minimal. The results indicate that use of rare earth filters in oral panoramic radiography is an effective means of reducing exposures of dental patients to ionizing radiation.

Film Dosimetry↗
PubMed1987

Effects of rare-earth filters on patient exposure and image contrast.

Minimizing patient exposure while maintaining a diagnostically acceptable radiograph is a major goal in diagnostic radiography. Rare-earth filters may be the means to achieve this goal due to their "band-pass effect". The purpose of this study was to examine the image contrast effects and exposure reductions for various thicknesses of aluminum, samarium, gadolinium, gadolinium oxysulfide, and gadolinium oxysulfide added to 2.5 mm of aluminum. Trials were conducted on an intra-oral dental x-ray unit (range, 65 to 90 kVp). When compared with conventional aluminum, all of the rare-earth filters provided lower radiation exposures, with gadolinium in the metallic or oxysulfide form providing the lowest exposures. Samarium, at a thickness of 0.127 mm, yielded the highest image contrast. Gadolinium or gadolinium oxysulfide added to 2.5 mm of aluminum resulted in a slight loss of contrast when compared with conventional aluminum filtration. This loss may not be clinically significant, and when coupled with the reduced exposure afforded by these filters, they become viable as acceptable alternatives to aluminum filtration.

Aluminum↗
PubMed1984

Prenatal diagnosis of a severe deforming type of osteogenesis imperfecta.

A pregnancy at risk for a severe deforming type of osteogenesis imperfecta (OI) was monitored by ultrasonography and radiography. Long bone measurements were normal at 15 1/2 weeks gestation, but ultrasound detected an abnormality of one femur that appeared to be a fracture. The ultrasound study at 19 weeks revealed severe shortness of the femora, and radiographs showed only vertebral bodies with no other fetal skeletal parts clearly visible. These studies indicate the feasibility of prenatal diagnosis before 20 weeks for the more severe handicapping types of OI that are compatible with survival past the newborn period and that can result in death during later infancy.

Female↗