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Biomedical subjects

C A Kelsey

Publications and source records attributed to C A Kelsey.

At least 19 recordsLinked to original sources
PubMed1991

Ocular hazard of metallic fragments during MR imaging at 0.06 T.

The hazard of magnetic resonance (MR) imaging at low field strength (0.06 T) was examined by using both in vitro and in vivo animal experiments. Ferromagnetic fragments, 0.25-2.2 mm in diameter, were placed in vitreous humor obtained from excised cow eyes and in rabbit eyes. The magnetic field strength at which motion occurred was measured for each fragment size. Two types of motion, rotation and translation, were observed. The authors found that fragments that could not be seen on plain radiographs did not appear to move enough to be a significant ocular hazard during MR imaging at a field strength of 0.06 T.

Animals↗
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↗
PubMed1988

Miniature radiation dosimeter for in vivo radiation measurements.

We have made initial characterization measurements on a miniature radiation dosimeter which can be used for in vivo radiation measurements. It consists of a radiation sensing field effect transistor (RADFET) mounted in a 0.8 mm OD plastic catheter. The RADFET acts as a dosimeter by storing trapped charge proportional to absorbed dose. The stored charge signal can be differentiated to give dose rate. We report on the techniques for mounting, a circuit for dose readout, drift of the readings, linearity of response, temperature and angular dependence, and unpowered operation of the device.

Radiometry↗
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↗
PubMed1986

Population characteristics and absorbed dose to the population from nuclear medicine: United States--1982.

Those in the U.S. population who receive nuclear medicine examinations have been characterized by age and sex. Males received 42% of examinations while females received 58%. More than one-third of the examinations were done on persons older than 64 y of age and more than two-thirds on patients older than 45 y of age. The per caput effective dose equivalent from nuclear medicine procedures in 1982 was 140 muSv (14 mrem); whereas, the per caput age-specific effective dose equivalent to the U.S. population was 50 muSv (5.9 mrem). These can be compared with 2 mSv (200 mrem) from natural background.

Adolescent↗
PubMed1986

Chest radiographs obtained with shaped filters: evaluation by observer performance tests.

The effectiveness of a shaped filter in improving nodule and infiltrate detection was measured by observer performance testing. Seven observers read 152 test radiographs of the chest obtained from human volunteers. Half the test radiographs had target images. Observer performance in detecting nodule or infiltrate images was compared with the shaped-filter system and with a conventional chest imaging system. The results were analyzed using receiver operating characteristic (ROC) techniques and indicate that the filter technique was not significantly different from the conventional technique in infiltrate depiction. Observer performance in detecting nodules was slightly worse on images obtained with the shaped-filter system.

Filtration↗
PubMed1986

Follow-up chest radiographs in Vietnam veterans: are they useful?

Agent Orange exposure and its long-term health consequences on Vietnam veterans have been widely discussed in the past few years. Myriad physical and mental disabilities have been studied with regard to exposure to various herbicides. The number of persons potentially exposed is large, since 2.4-2.8 million U.S. military personnel served in Vietnam. A case-control study was undertaken to determine if persons who served in the U.S. military in Vietnam have either cardiovascular or pulmonary effects that can be demonstrated on long-term follow-up chest radiographs. Information regarding military service in Vietnam was obtained from interviews and, in some cases, review of military records. Vietnam veterans did not have an increased prevalence of abnormalities on follow-up chest radiographs. A subset of Vietnam veterans who had greater estimated opportunities for Agent Orange exposure also did not appear to be at greater risk than the control population.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1985

ROC and contrast detail image evaluation tests compared.

Using both contrast detail and receiver operating characteristic (ROC) evaluation tests, we evaluated different quality images, produced with different film-screen combinations. ROC curves were obtained for six observers who were attempting to detect lung nodules and pulmonary infiltrates. The contrast detail curves were obtained from images of regular circular test patterns of differing contrast, which had been presented to the observers. Our results indicate that contrast detail tests can be used for relative ranking of image systems prior to detailed ROC testing.

Evaluation Studies as Topic↗
PubMed1985

Thyroid radiation absorbed dose from diagnostic procedures in U.S. population.

According to a 1981 survey of thyroid imaging methods in the United States, radionuclide thyroid scans and uptake studies increased 250%-300% between 1966 and 1981, while the U.S. population increased only 17%. Collective absorbed dose decreased from 18 X 10(6) rad (18 X 10(4) Gy) in 1966 to 13.9 X 10(6) rad (13.9 X 10(4) Gy) in 1981. The decrease was due to the use of iodine 123 and technetium 99m pertechnetate rather than iodine 131 (I-131 was used for 100% of scans and uptake studies in 1966 and 10% and 54%, respectively, in 1981) and also to fewer free-standing thyroid uptake studies (150,000 in 1966 and 33,000 in 1981). Even with reduced usage, I-131 still accounted for 93% of the collective absorbed dose in 1981. If I-131 were eliminated from diagnostic procedures, the annual absorbed dose would decrease to 1.4 X 10(6) rad (1.4 X 10(4) Gy). The number of radiation-induced cancer cases would also be reduced.

Humans↗
PubMed1985

Trends and utilization of nuclear medicine in the United States: 1972-1982.

In the decade 1972-1982, in vivo nuclear medicine procedures in the United States increased from 3.3 million to about 7.5 million per annum. This growth has been the result of a markedly increased frequency in some types of examinations; particularly bone, liver, lung, and cardiovascular imaging. The only type of imaging in which a decrease in frequency has been observed has been in radionuclide brain imaging. Examination of these trends illustrates the difficulty in forecasting, even over time periods as short as 5 years. Competing tests have largely replaced radionuclide imaging in some areas; although in other areas, such as cardiac nuclear medicine, competing technologies appear to have been additive in terms of the frequency of examinations. Comparison with recent data from other countries indicates that the frequency of nuclear medicine procedures in the United States is probably the highest in the world.

Biliary Tract Diseases↗
PubMed1984

Radiation exposure during fluoroscopically controlled percutaneous lithotripsy.

Radiation measurements in the vicinity of a standard urologic table modified for fluoroscopic-guided lithotripsy demonstrate radiation levels as high as 3000 mrem per hour at the edge of the table. Excessive radiation exposure to the physician, exceeding the annual maximum permissible dose to the eyes and thyroid, can be expected after only 10 cases. Suggested radiation protection measures include the use of finger, wrist and neck radiation monitors, eye and thyroid shields and improved shielding of both collimator and patient scatter radiation.

Fluoroscopy↗
PubMed1983

Anticrossover emulsions evaluated by observer performance tests.

Observer performance in the detection of pulmonary nodules and infiltrates was measured using film coated with anticrossover emulsion, a recent innovation in radiographic film that is expected to produce sharper images because of improved resolution. Test radiographs of an anthropomorphic phantom were shown to six experienced observers. Radiographs containing pseudonodule and pseudoinfiltrate images were obtained with the anticrossover film and the same type of film without the anticrossover coating. Test images contained single nodules, single infiltrates, or both; approximately 45% of the test radiographs were normal. Individual receiver operating characteristic (ROC) curves were formed, and sensitivity and specificity values were calculated. The results demonstrated an improvement in observer performance with the anticrossover film as measured by sensitivity and the area under the average ROC curves.

Humans↗
PubMed1983

Factors affecting perception of pulmonary lesions.

The authors review some of the factors that influence the perception of pulmonary lesions: the observer and his environment, the film or other image-recording and display media, the lesion and its qualities, and the technique or modality of examination used.

Humans↗