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Biomedical subjects

R H Gold

Publications and source records attributed to R H Gold.

151 records · Page 9Linked to original sources
PubMedDate not supplied

Film-screen mammography x-ray tube anodes: molybdenum versus tungsten.

Gridless screen-film mammography at 23 kVp with a W anode (inherent filtration: 0.1 mm A1, added filtration: 0.025 mm Mo) can achieve contrast identical to that achieved with gridless film-screen mammography at 27 kVp with a Mo anode (inherent filtration: 1.0 mm Be, added filtration: 0.025-mm Mo). However, W-anode film-screen mammograms obtained at 23 kVp require more radiation than Mo-anode film-screen mammograms obtained at 27 kVp. The lack of contrast of W-anode film-screen images produced at the same kVp as Mo-anode images was verified clinically and with a low contrast test object imaged over a range of densities. A step wedge test object was then used to match contrast between Mo- and W-anode gridless film-screen images at various kVp. The low contrast test object images verified the contrast equivalence of images obtained at 23 kVp for a W anode and 27 kVp for a Mo anode. A comparison of the two kVp for different anode materials was tested clinically on ten patients. The clinical and low contrast test object experiments were reviewed by three radiologists specializing in mammography.

Electrodes↗
PubMedDate not supplied

Mammography screen-film selection: individual facility testing technique.

Variations in tube output, film processing, and radiologist's preferences affect the screen-film combination that is appropriate for any particular mammographic facility. A technique to test a variety of screen-film combinations for screening mammography is described. Films are selected for testing because of their densitometric characteristics. Dose and clinical reliability are established with phantoms before the screen-film combinations are used to image consecutive patients having bilateral examinations. The mammograms selected for evaluation are those with similar optical density ranges, and which also may be compared to available previous mammograms or which have unusual mammographic findings. All radiologists reading mammograms at a facility independently score the selected cases. Scores of "unacceptable," "acceptable," or "outstanding" are assigned to four basic imaging characteristics: sharpness, contrast, visibility of skin line, and noise. Interobserver variations by this method require normalization, unlike ROC analysis which is not applicable for this data because of the absence of proved pathologic diagnoses. The testing of 5 films and two screens using 42 patient examinations required 2 h of time from each radiologist. It took 7 h of the physicist's time to pretest the 5 films, select the 42 acceptable examinations for testing by the radiologists, and summarize the data.

Female↗
PubMedDate not supplied

Testing mammography equipment: evolution over a 4-year period.

The results of quality control (QC) tests on 70 mammography units in Southern California from 1986 to 1990 are reported. Thirteen facilities, selected because they housed all of the mammography units in three communities involved in a National Institutes of Health research project, had their units tested twice at an interval of 1 year. Fourteen self-selected units were also tested twice at intervals ranging from 1-3 years. Forty-three self-selected units in 31 additional facilities had testing only once. All 70 units underwent measurement of focal spot size or resolution, tube output, half-value layer (HVL), automatic exposure control (AEC) accuracy, relative kVp accuracy, mean glandular dose, and imaging of several test objects. The test results for the units tested once showed no significant differences compared to those tested twice. For the latter, once the units were tested and determined to be acceptable, retesting showed differences only in overall film optical density, dose, and AEC performance.

Ambulatory Care Facilities↗
PubMedDate not supplied

Magnetic resonance imaging as a tool for evaluation of traumatic knee injuries. Anatomical and pathoanatomical correlations.

Traumatic injury to the knee remains a diagnostic and therapeutic challenge. Magnetic resonance imaging (MRI) has been applied to musculoskeletal pathoanatomy and has been shown to be an effective tool for definition and characterization of knee pathology. A systematic approach is taken to establish anatomical and pathoanatomical correlations, as well as the role of MRI in the management of knee injuries. Imaging was performed at the UCLA Medical Center using a permanent magnet system and a combination of solenoidal surface coils and thin-section, high-resolution scanning techniques. Images depict structural anatomical and spatial details of the knee that correlate well with corresponding cadaveric cryosections. To determine pathoanatomical correlations and the efficacy of MRI, 105 patients with preoperative diagnoses of meniscal tears, anterior and posterior cruciate ligament tears, tibial plateau fracture, and patella and quadriceps injuries were imaged. Results indicated that for the medial meniscus MRI demonstrated a 95.7% sensitivity, 81.8% specificity, 90% accuracy, 88.2% positive predictive value (PPV), and 93.1% negative predictive value (NPV). Imaging of the lateral meniscus demonstrated a 75% sensitivity, 95% specificity, 91% accuracy, 80% PPV, and 94% NPV. MRI of the ACL revealed 100% sensitivity, specificity, accuracy, positive and negative predictive values. MRI is a noninvasive tool which uses no ionizing radiation and can accurately define and characterize anatomy and pathoanatomy. This study indicates that MRI in conjunction with clinical evaluation can contribute to treatment decision-making processes and assist in preoperative planning. An algorithm demonstrating the potential clinical use of MRI is presented.

Humans↗
PubMedDate not supplied

Spinal neuroarthropathy after traumatic paraplegia.

Spinal neuroarthropathy is a little-known complication of traumatic paraplegia. Four cases of this syndrome are described, with emphasis on the characteristic radiographic findings of severe juxta-articular bone destruction, dense appositional new bone formation, large osteophytosis, and soft-tissue bony debris. The factors predisposing patients to develop a neuropathic joint are diminished pain and proprioceptive sensations with maintained mobility. When a paraplegic patient transfers in or out of a wheelchair or moves his upper torso, he exerts force on an insensate spine. Repeated trauma increases joint mobility beyond the normal limits, and this leads to further damage, with the process culminating in severe instability and bone destruction. The other causes of neuropathic joints in the spine--tertiary syphilis, syringomyelia, and diabetes--must be ruled out on clinical grounds. Neuropathic changes in the spine are often silent, delaying treatment, or may be mistaken for infection or degenerative disease. Their true prevalence is difficult to determine, but the possibility should be considered in paraplegic patients with the characteristic radiographic findings.

Adult↗