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Biomedical subjects

F A Mettler

Publications and source records attributed to F A Mettler.

At least 19 recordsLinked to original sources
PubMed1992

Thyroid nodules in the population living around Chernobyl.

OBJECTIVE: To determine the baseline incidence, prevalence, and characteristics of thyroid nodules in the population living around the Chernobyl nuclear power plant and to compare the findings with unexposed populations. DESIGN: Prevalence study. Population samples from seven highly contaminated villages were compared with six nearby control villages of the same size and type. The data were obtained as part of the International Chernobyl Project conducted in 1990. SETTING: The study was conducted 4.5 years after the Chernobyl reactor accident that released large quantities of radionuclides, including radioiodine. PATIENTS OR OTHER PARTICIPANTS: Population samples of approximately 100 persons residing in both highly contaminated villages and control villages since the accident were compared. Individuals were selected on the basis of birth date as being 5, 10, 40, or 60 years old at the time of the study. All persons selected underwent a thyroid examination. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Two main outcome measures were used, both for thyroid nodularity: clinical palpation and high-resolution ultrasonography. RESULTS: There was no significant difference in thyroid nodularity between the study groups. Nodules were palpated in 0.7% of children and 2.9% of adults. Discrete nodules were found by ultrasonography in 0.5% of children and 14.9% of adults. Multinodular goiter was found in 3% of adults. Nodules were more common in females. CONCLUSIONS: Four and a half years after the Chernobyl accident, the incidence, prevalence, and characteristics of thyroid nodules were the same in population samples from both highly contaminated and control settlements and similar to results reported for unexposed populations in other countries.

Accidents↗
PubMed1992

The two-view radionuclide ventriculogram. Advantages of the LPO view.

This report is a prospective study of 33 male patients who underwent both contrast ventriculography (CVG) and radionuclide ventriculography (RVG) within a 24-hour period. Expert, blinded observers graded the left ventricle's regional wall motion (RWM) in the left anterior descending (LAD), left circumflex (LCx), and posterior descending arterial (PDA) distributions on right anterior oblique (RAO), and left anterior oblique (LAO) CVGs, and on anterior (ANT), LAO, 70 degrees left anterior oblique (LAO70), and left posterior oblique (LPO) RVGs. When statistically compared with CVG RWM standard data, RVG studies composed of LAO and LPO views were equal to the RVG studies composed of ANT, LAO, and LAO70 views in assessment of the LAD and LCx distributions. The RVG with LAO and LPO views was superior to the RVG with ANT, LAO, LAO70 in the detection of the posterior descending artery RWM. The authors conclude that accurate assessment of RWM is efficiently performed with the RVG composed of LAO and LPO views.

Coronary Artery Disease↗
PubMed1991

Comparison of CT, low-field-strength MR imaging, and high-field-strength MR imaging. Work in progress.

To assess objectively the sensitivity and specificity of low-field-strength (0.064 T) magnetic resonance (MR) imaging, a prospective blind study of 280 examinations was performed to compare low-field-strength MR imaging with computed tomography (CT) and with high-field-strength (1.5-T) MR imaging of the cranium. The sensitivity (defined as the true-positive rate) with high-field MR imaging was superior to that with low-field MR imaging and CT in helping detect overall abnormalities. Sensitivities were generally similar over a broad range of specific cranial central nervous system diseases. Low-field and high-field MR imaging were equivalent in the blind diagnoses of neoplasms and white matter disease, whereas low-field MR and CT were equivalent in the blind diagnoses of contusion, subdural and epidural hematoma, sinus disease, normality, and abnormality. The specificities with low-field MR imaging and CT were substantially better than those with high-field MR imaging.

Brain↗
PubMed1990

Radiographic microcalcification and parenchymal patterns as indicators of histologic "high-risk" benign breast disease.

Breast tissue from a forensic autopsy series of 486 women (15 to 98 years of age) was studied radiographically and by histologic sampling. Prevalence of Wolfe P2/Dy parenchymal patterns decreased with age. Radiographic nonvascular microcalcification and histologic presence of marked ductal epithelial hyperplasia and lobular microcalcification increased with age. Both of these histologic parameters of increased risk for breast cancer correlated with the presence of radiographic microcalcification and Wolfe P2/Dy parenchymal pattern. The predictive value of the radiographic parameters for presence of "high-risk" proliferative fibrocystic change increased with age.

Adolescent↗
PubMed1990

The 1986 and 1988 UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) reports: findings and implications.

The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has published a substantive series of reports concerning sources, effects, and risks of ionizing radiation. This article summarizes the highlights and conclusions from the most recent 1986 and 1988 reports. The present annual per person effective dose equivalent for the world's population is about 3 mSv. The majority of this (2.4 mSv) comes from natural background, and 0.4 to 1 mSv is from medical exposures. Other sources contribute less than 0.02 mSv annually. The worldwide collective effective dose equivalent annually is between 13 and 16 million person-Sv. The Committee assessed the collective effective dose equivalent to the population of the northern hemisphere from the reactor accident at Chernobyl and concluded that this is about 600,000 person-Sv. The Committee also reviewed risk estimates for radiation carcinogenesis which included the new Japanese dosimetry at Hiroshima and Nagasaki. These data indicate that risk coefficient estimates for high doses and high dose rate low-LET radiation in the Japanese population are approximately 3-10% Sv-1, depending on the projection model utilized. The Committee also indicated that, in calculation of such risks at low doses and low dose rates, a risk-reduction factor in the range of 2-10 may be considered.

Accidents↗
PubMed1990

Flexible protective gloves: the emperor's new clothes?

The risk of developing skin cancer is estimated for interventional radiologists who do and do not wear thin, flexible protective leaded gloves. The use of these gloves is extremely expensive in terms of dollars per potential cancer prevented. Good radiographic practice without the use of flexible protective gloves provides adequate protection.

Cost-Benefit Analysis↗
PubMed1990

Diagnostic radiology around the world.

The frequency and type of radiographic examinations performed, as well as the type and quantity of radiographic equipment currently available, vary from country to country, depending on the type of screening programs used and on the level of health care available. These factors are a reflection of the country's overall wealth and stage of development. In past years, the annual number of radiologic examinations performed has increased worldwide, and this trend is expected to continue. If less developed countries are unable to increase their radiologic capacity at least as quickly as their population increases, they will fall further behind in their ability to care for their citizens.

Canada↗
PubMed1989

Age and race related changes in mammographic parenchymal patterns.

The relationship between breast parenchymal patterns and age was examined in a nonselected, nonreferred group. The three major racial-ethnic subgroups represented have markedly different incidences of breast cancer, with Anglos (nonHispanic caucasians), Hispanics, and American Indians having higher to lower incidence rates of breast cancer, respectively. Mammograms were performed in 519 victims of nonhospital, nonnatural or unexplained deaths in New Mexico. The percentage of dense breast patterns (DY + P2) decreased with age for all groups. American Indian women showed a much earlier shift to a lower density parenchymal pattern than Anglo or Hispanic women. At older ages Indian women continued to have a slightly lower percentage of dense breast patterns than the other groups. The changes in breast parenchymal pattern with age and ethnic groups may reflect factors related to risk of breast cancer.

Adolescent↗
PubMed1989

Radon: is it a problem?

Radon gas is a major source of radiation exposure to the general public. Radon-222 is a product of uranium-238, present in varying concentrations in all soils. Radon enters buildings from soil, water, natural gas, and building materials. Its short-lived breakdown products, termed "radon daughters," include alpha-emitting solids that can deposit in the lungs. Firm evidence links lung cancer risk in miners with high exposure to radon daughters. The amount of risk associated with the much lower but chronic doses received in buildings is difficult to establish. By some extrapolations, radon daughters may be responsible for a significant number of lung cancer deaths. The existence or extent of synergism with smoking is unresolved. Local conditions can cause high levels of radon in some buildings, and measures that reduce indoor radon are of potential value.

Bismuth↗
PubMed1988

Structural comparison of 1-bromo- and 1-fluoroestradiol with D-estradiol.

1-Bromoestra-1,3,5(10)-trien-3,17 beta-diol, C18H23BrO2, Mr = 351.3, orthorhombic, P2(1)2(1)2(1), a = 9.3864 (12), b = 12.927 (2), c = 12.948 (2) A, V = 1571.1 (4) A3, Z = 4, Dx = 1.484 Mg m-3, lambda(Mo K alpha) = 0.71069 A, mu = 259 mm-1, F(000) = 728, T = 298 K, R = 0.0514 for 2083 observed reflections. 1-Fluoroestra-1,3,5(10)-trien-3,17 beta-diol.0.5H2O, C18-H23FO2.0.5H2O, Mr = 299.4, orthorhombic, P2(1)2(1)2, a = 12.046 (4), b = 19.358 (5), c = 6.656 (2) A, V = 1552.1 (7) A3, Z = 4, Dx = 1.28 Mg m-3, lambda(Mo K alpha) = 0.71069 A, mu = 86 mm-1, F(000) = 644, T = 293 K, R = 0.0776 for 2781 observed reflections. Except for the carbon-halogen bond, bond angles and bond lengths of 1-bromoestradiol are within 7 e.s.d.'s of estradiol. Bond angles and bond lengths of 1-fluoroestradiol are within 11 and 7 e.s.d.'s of estradiol, respectively. The molecular conformations are nearly identical to that of estradiol. Like estradiol, 1-fluoroestradiol is present as a hemihydrate and extensive hydrogen bonding is observed. 1-Bromoestradiol is not hydrated and hydrogen bonding is limited to hydroxyl groups along the c axis.

Estradiol↗
PubMed1987

Three-phase radionuclide bone scanning in evaluation of local radiation injury. A case report.

The management of local radiation injuries is influenced by the degree of vascular compromise within the skin and underlying tissues. Other authors have used thermography and angiography in assessing the blood flow to radiation damaged tissues. This report describes the use of radionuclide imaging in the evaluation of a patient who developed necrosis of his distal digits following a radiation accident. In addition to determining the vascular status of the hands, imaging helped indicate an appropriate level for amputation.

Accidents, Occupational↗
PubMed1987

Analytical modeling of worldwide medical radiation use.

An analytical model was developed to estimate the availability and frequency of medical radiation use on a worldwide basis. This model includes medical and dental x-ray, nuclear medicine, and radiation therapy. The development of an analytical model is necessary as the first step in estimating the radiation dose to the world's population from this source. Since there is no data about the frequency of medical radiation use in more than half the countries in the world and only fragmentary data in an additional one-fourth of the world's countries, such a model can be used to predict the uses of medical radiation in these countries. The model indicates that there are approximately 400,000 medical x-ray machines worldwide and that approximately 1.2 billion diagnostic medical x-ray examinations are performed annually. Dental x-ray examinations are estimated at 315 million annually and approximately 22 million in-vivo diagnostic nuclear medicine examinations. Approximately 4 million radiation therapy procedures or courses of treatment are undertaken annually.

Africa↗
PubMed1987

The radiologist and angiographic procedures. Absorbed radiation dose.

The radiation dose absorbed by the angiographer during angiographic procedures is of vital importance to the radiologist. Nevertheless, most articles on the subject are incomplete, and few measure gonadal dose. In this study, three TLDs were used for each of the following sites: radiologist's eyes, thyroid, gonads with and without shielding apron, and hands. The average dose during carotid angiograms was 2.6, 4.1, 0.4, 4.7, and 7.1 mrads to the eyes, thyroid, gonads with and without .5 mm of lead shielding, and hands, respectively. Average dose during abdominal and peripheral vascular angiographic procedures was 5.2, 7.5, 1.2, 8.5, and 39.9 mrads to the eyes, thyroid, gonads with and without shielding, and hands, respectively. A literature review demonstrates a significant reduction in radiation dose to the angiographer after the advent of automated injectors. Our measured doses for carotid angiography are compatible with contemporary reported values. There was poor correlation with fluoroscopy time and measured dose to the angiographer.

Angiography↗
PubMed1987

Diagnostic radiology: usage and trends in the United States, 1964-1980.

From recent surveys and other sources, an estimate has been made of the utilization and trends in medical and dental diagnostic radiology as practiced in the United States from 1964 through 1980. Trends in estimated number of diagnostic x-ray examinations, age distribution of patients, and number of diagnostic x-ray machines are presented. In the decade 1970-1980, x-ray film sales increased 57%, while the number of all types of hospital-based x-ray examinations increased by over 60%. Increases have occurred not only in hospital-based examinations but in private office examinations as well. In 1980 there were estimated to be 180 million medical x-ray examinations and 101 million dental x-ray examinations.

Age Factors↗