Nationwide survey of fluoroscopy: radiation dose and image quality.

PURPOSE: To determine the average abdominal entrance air kerma, low-contrast sensitivity, and spatial resolution in upper gastrointestinal tract fluoroscopy in the United States. MATERIALS AND METHODS: A random sample of fluoroscopic facilities was selected to be surveyed for the Nationwide Evaluation of X-ray Trends program. Measurements were performed by using a newly developed fluoroscopic phantom. The surveys were conducted by state radiation control personnel. RESULTS: Average air kerma rates 1 cm above the tabletop, free in air, were 43 mGy/min (n = 340). The rate increased to 64 mGy/min when a 1.6-mm-thick copper filter, which simulated the use of barium contrast medium, was added to increase attenuation. The average entrance air kerma, free in air, for radiographs was 3.4 mGy, and an average of 12 radiographs were obtained per examination. Of 352 facilities surveyed, 306 (87%) were able to resolve wire mesh with 20 or more lines per inch. Of 339 facilities for which percentage contrast could be calculated, 192 (57%) had minimum percentage contrast values of 4% or more. CONCLUSION: Spatial resolution for fluoroscopy is adequate for most of the facilities surveyed, but a substantial proportion of facilities could not visualize low-contrast test objects, which strongly suggests image quality problems.

Radiation protection requirements for medical x-ray film.

Previous darkroom shielding requirements for medical x-ray film-assumed that the film should not be exposed to diagnostic x-ray radiation levels greater than 2 microGy (0.2 mR) for the life of the film. Modern medical x-ray films are much less sensitive to ionizing radiation, with most films showing at least an order of magnitude less sensitivity than previously assumed. Conversely, these same films when loaded in cassettes using modern intensifying screens exhibit an order of magnitude greater sensitivity when these cassettes are exposed to ionizing radiation. These data suggest that protection of modern medical x-ray film, stored in a darkroom, may require less shielding than previously assumed. Conversely, film loaded in a cassette will require greater shielding.

National survey of mammographic facilities in 1985, 1988, and 1992.

PURPOSE: To determine trends in mammography in the United States. MATERIALS AND METHODS: A sample of mammographic facilities was selected for each year of the Nationwide Evaluation of X-ray Trends. The same protocol was followed for the 1985, 1988, and 1992 surveys. Data were collected with use of the same imaging phantom for all three surveys and also with a different phantom in the 1988 and 1992 surveys. RESULTS: Of the 356 facilities surveyed in 1992, 59% claimed to be in compliance with the Health Care Financing Administration (HCFA) mammography requirements, 42% were accredited by the American College of Radiology (ACR), and 23% did not hold credentials from either the HCFA or the ACR. Since 1985, there has been a 34% improvement in acceptable phantom image quality score and a 20% decrease in the mean glandular dose. CONCLUSION: Mammography as practiced today is essentially a screen-film technique. Mammographic phantom image quality has improved considerably. The overall mean glandular dose has decreased primarily because of the elimination of xeroradiography.

Automatic film processing: analysis of 9 years of observations.

A survey method known as the sensitometric technique for the evaluation of processing (STEP) has been used to monitor processing speed of over 2,000 automatic film processors in hospitals, private offices, and mammography facilities since 1981. Analysis of data obtained through this program revealed underprocessing at 33% (76 of 231) of observed hospitals in 1987, 7% (13 of 179) of mammography facilities in 1988, and 42% (101 of 241) of private practices in 1989. Underprocessing at mammography facilities decreased from 18% (25 of 139) in 1985, which was contrary to the trend in hospitals. The consequence of underprocessing is higher radiation exposure and a degradation in film contrast. Evaluation of automatic film processors is a necessary part of any comprehensive evaluation of a diagnostic radiography facility. The STEP procedure was designed only as a field survey test; to ensure optimal conditions for obtainment of diagnostic quality radiographs, facilities should perform quality assurance evaluations of their processing equipment and verify that processing recommendations of manufacturers are being followed.

Radiography of the lumbosacral spine: characteristics of examinations performed in hospitals and other facilities.

A survey of 523 facilities performing radiographic lumbosacral spine examinations was conducted as a part of the Nationwide Evaluation of X-Ray Trends program in 1987 and 1989. Average patient radiation exposure was measured by using a standard phantom developed by the Center for Devices and Radiological Health of the Food and Drug Administration, U.S. Public Health Service. Data pertaining to radiographic equipment, film processing, and radiographic techniques were obtained. The overall average entrance skin air kerma was 3.65 mGy (420 mR). Ninety-eight percent (496 of 506) of observed facilities used a grid, 89% (466 of 523) had tube potentials between 70 and 89 kVp, and 67% (280 of 418) used screen-film systems with a speed of 400. The most important finding is that underprocessing of film remains a major concern. Thirty-three percent (78 of 234) of the hospitals, 25% of the radiologists in private practice (four of 16), 33% of the nonradiologist private practitioners (27 of 82), and 48% (69 of 143) of the chiropractors underprocessed their film.

Average radiation dose in standard CT examinations of the head: results of the 1990 NEXT survey.

In 1990, as part of the Nationwide Evaluation of X-ray Trends (NEXT) program, 252 computed tomographic (CT) systems were evaluated to measure radiation doses associated with standard head CT in adults. The multiple-scan average dose (MSAD) was used as the dose descriptor. For most of the systems, the MSAD at the midpoint on the central axis of a standard dosimetry phantom was between 34 and 55 mGy. Doses were as high as 140 mGy, and dose sometimes varied by a factor of two or more for identical CT units. This range indicates that dose can potentially be reduced by careful selection of standard CT techniques. Users of CT systems should be aware of radiation dose delivered with CT, dose ranges associated with different systems, and doses delivered with their particular unit, which requires that dose performance of CT systems be assessed by means of a protocol that allows comparison of data collected for identical and/or different units.

Mammography in the eighties.

Mammography has experienced the greatest change of any existing radiologic examination in recent years. In 1985, as a part of the Nationwide Evaluation of X-Ray Trends (NEXT) program, a national survey was conducted of a statistically selected sample (n = 232) of facilities performing mammography examinations in the United States. By 1988, the number of mammography facilities in the United States had increased to over 6,400, an increase of over 60% from the 1985 level. To assess the consequence of this expansion as well as the impact of recent technological and other significant developments on mammography, a NEXT survey of mammography facilities was repeated in 1988 (n = 226). Screen-film mammography accounted for 83% of the facilities surveyed in 1988, and dedicated equipment dominated screen-film systems (99%). There was a 26% increase in the overall mean phantom image score, over 45% increase in the use of grids, and 10% increase in mean glandular dose for systems using grids.

Average radiation exposure values for three diagnostic radiographic examinations.

National surveys of more than 600 facilities that performed chest, lumbosacral spine, and abdominal examinations were conducted as a part of the Nationwide Evaluation of X-Ray Trends program. Radiation exposures were measured with use of a set of standard phantoms developed by the Center for Devices and Radiological Health of the Food and Drug Administration, U.S. Public Health Service. X-ray equipment parameters, film processing data, and data regarding techniques used were collected. There were no differences in overall posteroanterior chest exposures between hospitals and private practices. Seventy-six percent of hospitals used grids, compared with 33% of private practices. In general, hospitals favored a high tube voltage technique, and private facilities favored a low tube voltage technique. Forty-one percent of private practices and 17% of hospitals underprocessed their film. Underprocessing in hospitals increased from 17% in 1984 to 33% in 1987. Average exposure values for these examinations may be useful as guidelines in meeting some of the new requirements of the Joint Commission on Accreditation of Healthcare Organizations.

Is the supply of mammography machines outstripping need and demand? An economic analysis.

The number of dedicated mammography machines installed in the United States has grown explosively. It is estimated that almost 10,000 machines will be installed by 1990, whereas the projected demand for screening mammography will require only approximately 2,600 machines, if the machines are used in a moderately efficient manner. The excess supply of mammography resources raises concern from an economic perspective for several reasons. First, such a condition means that health care resources are being used inefficiently. Second, the low average utilization rate of mammography equipment implied by these results necessitates charging a high price-over $100, on average-to cover costs. This price is above the $50 usually associated with low-cost screening mammography programs, and it may impede a desirable public health trend to increase use of mammography screening. Third, the existence of many mammography facilities operating at low capacity levels is inefficient from a health systems perspective, increasing the cost of quality assurance and medical record keeping. The current condition of excess supply is probably unsustainable over the long term.

Assessment and comparison of chest radiography techniques in the United States and Sweden.

The United States Center for Devices and Radiological Health and the Swedish National Institute of Radiation Protection started a collaborative project in 1983. The purpose of the project was to test the adequacy and practicability of the United States (US) Nationwide Evaluation of X-ray Trends (NEXT) programme in Sweden. The NEXT protocol for the postero-anterior chest projection was modified and expanded to make it both "statistical" and "investigational" (in the US, NEXT gives mainly "statistical" information). All chest X-ray units in Sweden were surveyed in 1986-87. The project showed that the NEXT programme is applicable to countries other than the United States and provides a standardized protocol that enables intercomparison of the radiological techniques. This paper presents the comparison of the radiological techniques used in Sweden and the United States. The results of the investigational modifications made to the protocol used in Sweden are discussed. Recommendations concerning expansion of the NEXT protocol to include these valuable tools for investigational surveys are presented.

Beam quality independent attenuation phantom for estimating patient exposure from x-ray automatic exposure controlled chest examinations.

The periodic assessment of exposures in diagnostic radiology is an important part of a comprehensive quality assurance program. The most frequent radiologic examination conducted in the United States is chest radiography. Automatic exposure controlled (AEC) techniques are often used for this exam, and a standard patient-equivalent chest phantom is useful when estimating patient exposures on such systems. This is of particular importance if exposures are to be compared among AEC systems with different entrance x-ray spectra. Such a phantom has been developed to facilitate surveys of the average patient exposure from AEC posteroanterior chest radiography. The phantom is relatively lightweight and easily transportable, sturdy and made of readily available and relatively inexpensive materials (Lucite and aluminum). It accurately simulates the primary and scatter transmission through the lung-field regions of a patient-equivalent anthropomorphic phantom for x-ray spectra typically used in chest radiography. A clinical evaluation has been conducted to verify the patient equivalence of the phantom. Measurements of patient entrance skin exposure were obtained for a large number of patients on a variety of x-ray systems operated in the AEC mode using one or both lung-field detectors. Comparison of these data with exposure estimates derived from the phantom indicate that the phantom attenuates the x-ray beam in such a way that it can be employed to accurately and consistently estimate the mean exposure of the average patient under a variety of radiographic conditions. The design, development, and evaluation of the patient-equivalent attenuation phantom is described.

Physician and patient exposure during cardiac catheterization.

A survey of the literature was conducted to establish the anticipated ranges of exposure to both physicians and patients during cardiac catheterization. A brief explanation of a technic for using time-lapse photography and a computer model for exposure calculation is presented. The thermoluminescent dosimeter (TLD) results used as controls for exposure values calculated by the developed technique are presented in detail. Physician eye exposures of approximately 20 mR per cardiac catheterization procedure were measured, which would suggest a limit of five procedures per week for physicians. The average patient skin entrance exposure of 28 R is high, as is the 12 mR gonadal exposure; however, they are accepted because of the possible benefits of the procedure.