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Biomedical subjects

M W Herman

Publications and source records attributed to M W Herman.

35 records · Page 2Linked to original sources
PubMed1980

A comparative study of scattered radiation levels from 80-kVp and 240-kVp x rays in the surgical intensive care unit.

The levels of scattered radiation from 80-kVp and 240-kVp mobile x-ray units were measured in the surgical intensive care unit (ICU). The intensity of scatter of the 240-kVp x rays does not decrease with distance as rapidly as with the 80-kVp beam. In an ICU with four beds, the weekly radiation exposure at the nurses' station approximated 0.05 mR (0.13 X 10(-7) C/kg) for the 80-kVp beam and 0.2 mR (0.52 X 10(-7) C/kg) for the 240-kVp beam. Thus, the annual exposure from either unit would be well below the Maximum Permissible Exposure for nonoccupational workers.

Intensive Care Units↗
PubMed1980

Mobile 240 kVp phototimed chest radiography.

Chest radiographs obtained with mobile equipment for 240 kVp phototimed technique and conventional technique were compared in 161 patients. Features of interest were visualization of air space, interstitium, mediastinum, pleura and vessels, tracheobronchial tree, catheters and tubes. The 240 kVp system demonstrated consistently good visualization of central air passages, hilar contours, and pulmonary detail. It was superior to the conventional portable in eliminating respiratory motion, defining lung infiltrates, and localizing the endotracheal tube relation to the carina. The 240 kVp system had noticeable deficiencies in depicting calcifications, bone detail, and fat planes. These deficiencies were not of clinical significance. Although the equipment was compact, easily maneuverable, and simple to operate, the cassette holder was somewhat heavy--a detrimental but manageable factor. Another shortcoming was poor visualization of homogeneously opacified catheters within the mediastinum, although catheters with a dense radiopaque stripe alleviated this problem.

Angiography↗
PubMed1979

Relationships between performance in medical school and first postgraduate year.

Data from a longitudinal study of Jefferson Medical College graduates were analyzed to determine levels of clinical competence in the first postgraduate year and relationships between postgraduate ratings and performance during medical school. Ratings were obtained on knowledge, data-gathering skills, clinical judgement, and professional attitudes from the hospitals in which the graduates received their training. Significant relationships were found among three levels of performance in medical school and postgraduate ratings and in all four competence areas. Relationships were strongest at the highest and lowest performance levels. It is concluded that in a substantial number of cases good and poor performance in the first postgraduate year can be predicted on the basis of information already available to the medical school faculty.

Attitude of Health Personnel↗
PubMed1977

Family medicine and primary care: trends and student characteristics.

Using data from a longitudinal study of medical students at Jefferson Medical College, the authors analyzed trends in senior student interest in primary care specialties between 1971 and 1975 and selected background characteristics and performance levels of students choosing family medicine compared with those in other specialties. The proportion of students interested in family medicine residencies increased from 6 to 17 percent in the study period. The academic performance of students selecting family medicine was equal to or better than that of those in all other specialties except internal medicine. Smaller proportions were interested in teaching and research than those in other specialties, and larger proportions intended to work in communities of 100,000 population or less.

Achievement↗
PubMed1975

Value of gallbladder B-scan ultrasonography.

The gallbladder B-scans of 20 patients who had subsequent surgery were separated into three categories based upon certain sonographic criteria. Our data, in this limited series, revealed gallbladder pathology in each patient who had any one or combination of the following scan characteristics: (1) internal echos, (2) irregular wall, or (3) absence of recognizable gallbladder sonolucency. The category which demonstrated a normal sonographic gallbladder, namely a smooth wall and no internal echos, contained a number of false negatives which proved to have either small stone cholelithiasis or extraphepatic ductal obstruction. Within the described limitations, the B-scan can be a valuable test in confirming the significance of a radiographically nonvisualized gallbladder or in detecting a biliary tract lesion in a patient with a disease entity that precludes radiographic visualization by conventional techniques.

Adenocarcinoma↗
PubMedDate not supplied

Ultrasonic visualization of the non-opacified gallbladder: response of the normal and obstructed canine gallbladder to C8CCK.

In vitro studies of a simulated gallbladder show that B-scan ultrasonography is as reliable as radiography in measuring changes in volume of the organ. The width or planimetric area of the sonogram correlates with the change in balloon volume and with similar radiographic measurements. In vivo measurements of the normal canine gallbladder stimulated by a carefully prescribed infusion of C8CCK in the dose range of 2.2 to 5.5 ng/kg/min over an 8 to 10 minute interval, showed a clearly defined decrease in gallbladder width. In ligation and division of the common bile duct no change in gallbladder size was demonstrated. We conclude that sonography alone can be used to measure a change in gallbladder size to better differentiate complete obstruction of the common bile duct from medical causes in the jaundiced patient.

Animals↗
PubMedDate not supplied

Definition of source for head shielding requirements in linear accelerators may affect room shielding design.

Siemens Corporation defines the source of the Mevatron 20 linear accelerator as a line source approximately 2 m in length. Calculations for secondary barriers for leakage radiation are generally based on 0.1% of the useful beam 1 m from the target. The difference in source terms can lead to calculating thinner barriers than are required. The placement of a 30 X 10 X 10-cm block of lead behind the head was required to achieve acceptable radiation levels.

California↗