Mammography Equipment Research Articles

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.

Mammography Quality Assurance in Washington State

Poor mammography quality control results in the loss of important diagnostic information. Several organizations and agencies recommend or require that mammography quality assurance procedures include the periodic evaluation of equipment. The objective of this study was to assess compliance with published guidelines pertaining to the monitoring of mammography equipment. One hundred eighty-four Washington state mammography facilities were surveyed by mail during late 1989 and early 1990. The response rate was 71%. A large proportion of facilities was not complying with published guidelines concerning the frequency of evaluation of processor parameters and phantom image quality. Results suggest that many facilities were not in compliance with American College of Radiology recommendations concerning annual system evaluation by a physicist. The results of this study reinforce the importance of establishing minimum quality assurance standards and indicate a need for more mammography quality assurance technologist training.

NEW AND FUTURE DEVELOPMENTS IN SCREEN-FILM MAMMOGRAPHY EQUIPMENT AND TECHNIQUES

Two improvements in mammography equipment during the last 4 years will greatly affect the practice of mammography during the next decade: dose reduction and improved testing equipment for monitoring the quality of mammography. The increased use of digital radiography has stimulated studies comparing digital mammography with screen-film mammography. Some digital algorithms for detecting clusters of calcifications may have application in screening mammography within the next decade.

Influence of anode and filter material on image quality and glandular dose for screen-film mammography

The influence of anode and filter materials on the performance (image quality and dose) of a mammography system is investigated. The image quality is evaluated with the image quality index method. A computer simulation has been developed to calculate the physical parameters of the image quality index (contrast, resolution and noise) as well as the mean glandular dose. The calculations take into account the successive steps of the process: X-ray production, filtration, interaction with the test object, anti-scatter grid, interaction with the image detector (screen-film system). An excellent correlation is obtained between the results predicted by the model and those of experimental measurements, suggesting that the model may be used for the prediction of the performance of mammographic equipment. The experimental conclusions are confirmed: the use of a tungsten anode with a rhodium filter allows a dose reduction without a significant degradation of image quality. The computer program can also be used to simulate the influence of factors which are difficult to combine in practice, e.g., various anode and filter materials, monoenergetic X-rays, etc.

A new apparatus for the localization of nonpalpable mammary lesions

A new apparatus has been used for the localization of 46 nonpalpable mammary lesions seen in either of two radiological projections. This device compresses and immobilizes the breast independently of the mammography equipment and permits a three-dimensional localization of the lesion by using the technique of X-ray angulation. The results demonstrate the efficiency of the procedure. Transfixation of the lesions was established in 30 cases (65.2%), the guidewire passed very close to the lesion in 14 cases (30.4%), and in 2 cases (4.4%) the guidewire was seen to be less than 10 mm away from the lesion. Correct preoperative localization of the lesions permitted a correct diagnosis with minimal

Book reviews

This is a comprehensive booklet of mammographic equipment tests. Its main commendation lies in practical advice which accompanies the tests; as such it is excellent. The attempt to wrap the tests up in the language of quality systems is not entirely convincing (Ch. 2). “Commissioning” and routine tests are said to comprise the operating techniques of quality control. They are essentially inspection methods.

Is the Supply of Mammography Machines Outstripping Need and Demand?

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.

Errata

HomeRadiologyVol. 174, No. 2 PreviousNext ArticlesErrataPublished Online:Feb 1 1990https://doi.org/10.1148/radiology.174.2.582-bMoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In AbstractRadiology 1989; 173(P):164The following are the correct abstract for scientific paper 461 and the missing abstract for scientific paper 462:10:51 AM461. Mammography in the '80sBurton J. Conway, MS, Rockville, MD • John L. McGrohan, MS • Fred C. Rueter, DSc • Orhan H. Suleiman, PhDA national survey of 232 mammographic units was conducted in 1985 as a part of the Nationwide Evaluation of X-Ray Trends (NEXT) program. Another national survey was conducted in 1988 on 226 mammographic units. These surveys clarified trends in potential dose for film-screen and xerox systems, improvements in image scores, and trends in mammographic equipment (including the effects of grid usage on dose and image score); they also provided data regarding the phantoms used and how these relate to the phantom used in the American College of Radiology Accreditation Program.11:03 AM462. Daily Mammography Quality Control with Test Object, Sensitometer Strip, and Exposure measurements: Are They NecessaryCarolyn Kimme-Smith, PhD, Los Angeles, CA • Christopher H. Cagnon, BA, CRT • Lawrence W. Bassett, MD • Richard H. Gold, MDDaily sensitometry strips for processor quality control were matched with a physicist's measurements of MR/mAs and radiation exposure of a CIRS phantom. Technologists' evaluations of daily films of three CIRS phantoms imaged on three mammographic units were also correlated with the sensitometry strips and physicist's results. The phantom images were evaluated for consistent density, resolution targets, and contrast targets. Test-object imaging was the least responsive to equipment malfunction. Daily measurements by the physicist were found to be unnecessary, but such measurements were continued on a weekly basis. Usefulness of sensitometer-strip results depends on automation and statistical error analysis, because daily variations may be within normal processor variability.Article HistoryPublished in print: Feb 1990 FiguresReferencesRelatedDetailsRecommended Articles RSNA Education Exhibits RSNA Case Collection Vol. 174, No. 2 Metrics Altmetric Score PDF download

The quality mammographic image. A review of its components.

Seven major factors resulting in a quality or high contrast and high resolution mammographic image have been discussed. The following is a summary of their key features: 1) Dedicated mammographic equipment. --Molybdenum target material --Molybdenum filter, beryllium window --Low kVp usage, in range of 24 to 30 --Routine contact mammography performed at 25 kVp --Slightly lower kVp for coned compression --Slightly higher kVp for microfocus magnification 2) Film density --Phototimer with adjustable position --Calibration of phototimer to optimal optical density of approx. 1.4 over full kVp range 3) Breast Compression --General and focal (coned compression). --Essential to achieve proper contrast, resolution and breast immobility. --Foot controls preferable. 4) Focal Spot. --Size recommendation for contact work 0.3 mm. --Minimum power output of 100 mA at 25 kVp desirable to avoid movement blurring in contact grid work. --Size recommendation for magnification work 0.1 mm. 5) Grid. --Usage recommended as routine in all but magnification work. 6) Film-screen Combination. --High contrast--high speed film. --High resolution screen. --Specifically designed cassette for close film-screen contact and low radiation absorption. --Use of faster screens for magnification techniques. 7) Dedicated processing. --Increased developing time--40 to 45 seconds. --Increased developer temperature--35 to 38 degrees. --Adjusted replenishment rate and dryer temperature. All seven factors contributing to image contrast and resolution affect radiation dosage to the breast. The risk of increased dosage associated with the use of various techniques needs to be balanced against the risks of incorrect diagnosis associated with their non-use.(ABSTRACT TRUNCATED AT 250 WORDS)

X-ray protection considerations for mammography screening centres.

The inception of the National Breast Screening Programme, following publication of the report Department of Health and Social Security (DHSS), 1986) of a working group under the Chairmanship of Sir Patrick Forrest, led to the construction of a significant number of new mammography rooms including mobile units, with many more being proposed for the next few years. As a result, Radiation Protection Advisers (RPAs) are now being required to give advice on room construction for these units. The Guidance Notes For Health Authorities On Mammographic Equipment Requirements For Breast Cancer Screening published by the DHSS (1987), whilst giving clear guidelines to facilitate standardization on most technical aspects of mammography screening/ assessment centres, do not give any outline of the protection requirements, merely stating in paragraph 3.7.3. that “Radiation protection and operational features must meet the requirements of the local Radiation Protection Adviser.” Such Radiation Protection Advisers will need access to both attenuation data and scatter measurements on which to base their recommendations. This paper presents measurements at mammographic energies of both the attenuation properties of a range of materials that could be used in barrier construction, and phantom scatter measurements. In addition, the application of these results to the situation that will be found in the new screening centre and measurements performed to confirm the conclusions are presented.

Quality control of mammographic equipment: a 5-year follow-up.

A quality-control project covering 56 pieces of mammographic equipment was carried out in Finland. The evaluation was based on the determination of contrast, film optical density, resolution, focus size, tube voltage, exposure time, half-value thickness, reproducibility and linearity of exposure, surface and exit dose, and defects at each centre when employing routinely used techniques. Dose and image quality were assessed using three phantoms. The results are compared with those obtained 5 years earlier and by other authors. Although the situation has, in many ways, improved considerably over the last 5 years (for instance, the average whole-breast dose has fallen on average by 84%, 7.37----1.10 mGy), there is still room for further improvement, especially in the optimization of the developing processes.

The technology of mammography. Misunderstood and underutilized.

This article reviews milestones in the technological development of mammography since 1970. Mammography is particularly underutilized as a screening procedure for breast cancer and the reasons for its continued inappropriate and under use are explored. Although there are some known barriers to increased utilization among the female adult population, the majority of barriers reside within the domain of referring physicians. Remedies to address the low referral rates for screening mammography are outlined for federal agencies, radiology groups, mammography equipment companies, medical schools, and philanthropic groups. Until the developers of technological procedures such as mammography appreciate that the application of a technology and its appropriate utilization by professionals and the public are important to consider when the technology is developed, utilization rates may not do justice to the technology's potential.

Practical solutions to common mammographic problems: tailoring the examination.

Received January 8. 1988; accepted after revision March 1,1988. Presented at the annual meeting of the American Roentgen Ray Society, San Francisco, CA, May 1988. 1Department of Radiology, Box 0628, Lk iversity of CaliforniaSchool of Medicine, San Francisco, CA 94143. AJR 151:31-39, July 1988 0361 -803X/88/151 1-0031 © American Roentgen Ray Society It is quite common for standard two-view-per-breast mammography to produce inconclusive results, especially among symptomatic patients and in interpreting baseline screening examinations. Many of these cases are read as indeterminate simply because the imaging evaluation is incomplete. In such circumstances, additional views prove invaluable in solving the mammographic “problems” raised on the standard examination. The ability to decide which extra views to obtain, and when to use them, is an important part of the expertise that every mammographer should develop. In discussing the problem-solving approach to mammography, I have assumed the use of dedicated mammographic equipment, capable of imaging in the craniocaudal projection with a vertical X-ray beam, in the lateral projection with a horizontal X-ray beam, and in all intermediate degrees of the oblique projection. I also have assumed that a properly designed breast compression device is used [1 ]. These features are essential for screen-film mammography and preferable for xeroradiography as well [1]. Use of a ceiling-mounted X-ray unit produces acceptable xeroradiographic images in standard projections, but the radiologist using this general-purpose equipment is limited in the ability to take full advantage of many special projections devised to solve mammographic problems. Every busy xeroradiographic breast imaging practice should have at least one dedicated mammographic unit available for such problem-solving examinations. There are so many potential approaches to completing the evaluation of inconclusive mammography examinations that an almost innumerable array of imaging permutations exists from which the radiologist may choose. To simplify the subject, I have concentrated on some of the more commonly encountered mammographic problems, indicating those solutions most likely to succeed. The reader is advised at the outset that every mammographic problem can be solved by a variety of acceptable methods and that my failure to discuss one of your personal favorites indicates only my own preference rather than the inadequacy of a specific alternative approach.

Survey of mammography practices.

Of the 319 radiologists who responded to a survey concerning mammography practices, 50% were employed in a private hospital and 26% in a private office. Film-screen mammography was used most often (54%) followed by xeromammography (30%) and a combination of film-screen and xeromammography (16%). Of the respondents, 62% had changed their method of performing mammography in the last 10 years. Of these, 50% had switched from xeromammography to film-screen, 23% from direct film to film-screen, 15% from direct film to xeromammography, and 6% from film-screen to xeromammography. Mammographic equipment had been purchased by 71% of respondents after 1983. Most respondents (71%) monitored mammography equipment doses, usually at 6- to 12-month intervals. Manual breast examinations were done at the time of mammography at 42% of the facilities, and breast self-examination was taught at 32%. For screening, 87.4% used a two-view examination, 92% required the name of a referring physician to whom the report could be sent, 28% accepted self-referred patients, and only 12% charged a reduced fee for screening. Breast sonography was performed by 53% (93% hand-held vs 7% automated), but none used sonography for screening. Only one respondent reported using thermography; three used light scanning. A need for postgraduate mammography courses for radiologists was indicated by 81%, while 69% recommended technologist courses and 64% recommended 1-week fellowships for radiologists.

Measurement procedures for determining the switch-off dose in mammographic equipment

The usual measurement of the switchoff dose direct on x-ray film plane cannot be employed in mammography equipment without interfering with the switching device, because the chamber for monitoring the automatic exposure is situated behind the film holder and one cannot eliminate the film holder since it is an equipment-specific absorber. We are therefore presenting a method which allows to determine the switchoff dose on x-ray film plane via determination of the attenuating factor of the equipment (influenced by scattered radiation) and the phantom exit dose measured before the compression plate, the film holder having been pushed into position. The ratio of phantom influx to exit dose, standardised for a standard distance, serves additionally to easily recognise major deviations of the x-ray tube voltage from the adjusted value.

Mammography Equipment: Principles, Features, Selection

1. Three-phase and constant potential generators may offer advantages over single-phase generators. These include shorter exposure times with less chance for motion unsharpenss, more adequate exposure and possible lower dose, and longer tube life. 2. Control of tube voltage in increments of 1 kVp are desirable for screen-film mammography and 2 kVp for xeromammography. 3. Tube loading limitations should be capable of allowing an adequate mA and mAs output. A mammography unit with a lower mA output may require longer exposure times with consequent motion unsharpness and/or higher dose. The maximum mA output is limited by the power rating of the tube and not by the power rating of the generator, which is usually much higher. Thus, tube rating charts rather than generator power rating should be used to compare the mA output of different mammography units. 4. Phototimer capability can reduce exam time, facilitate proper exposure, and reduce radiation dose. Units with a greater number of density steps and three or more photocell locations, one of which is near the edge of the film holder, provide better phototimer results. 5. A molybdenum target, beryllium window tube with 0.03 mm molybdenum added filtration is presently preferred for screen-film mammography. A tungsten target tube with 1 to 2 mm added aluminum filtration is advised for xeromammography. 6. Effective local spot size for contact mammography should be in the range of 0.2 to 0.5 mm. However, high resolution also requires sufficiently long source-to-image-receptor distances. Using measured focal spot size and source-to-image-receptor distance, it has been shown that some mammography units do not fully utilize the resolution capabilities of some available screen-film systems. On the other hand, a focal spot that is too small may limit the field size and lead to uneven energy distribution in the x-ray field. 7. In order to perform standard and supplementary mammographic projections, the C arm assembly must be capable of being located at multiple positions within a 180 degrees rotation. Greater degrees of rotation are not required. 8. The heat dissipation capability should be adequate to accommodate the anticipated work-load in terms of number of patients and patient scheduling. A mammographic unit with an anode heat capacity of 90,000 heat units or more should be adequate for most practices. A mammography unit with a heat capacity of 20,000 heat units or less may require waiting time between exposures or studies in a high-volume mammography practice. 9. The compression plate should be made of plastic, usually 1 to 4 mm thick.(ABSTRACT TRUNCATED AT 400 WORDS)

Development and implementation of a quality assurance program for mammography.

As a pilot study for a national campaign to promote the use of screening mammography, the Virginia Division of the American Cancer Society conducted a breast cancer awareness project with mammography screening. An important part of the program was the development of a quality assurance program for mammography. Guidelines were established for equipment, image recorders, processing, dose, and patient positioning. A survey of information about the mammographic equipment was conducted, and the mammograms from each facility were reviewed. A total of 63 mammographic units in 56 facilities statewide were included in the month-long program during which approximately 9,000 women were screened.

Sonographic diagnosis of foreign bodies of the distal extremities.

Sonography was performed by using high-resolution linear-array real-time scanners (Toshiba SAL-22A, SAL-30A, Aloka 21 0 DX) and 5-MHz, and more recently 7.5-MHz, probes with focal distances of 3.1 and 1 .8 cm, respectively. A commercially available stand-off gel material (Kitecko, 3M, Roseville, MN) was used to give the appropriate contact between the probe and the skin and to provide accurate visualization of the skin and the superficial soft tissues [2]. Gel blocks of various thicknesses were cut in the pad and were used according to the frequency and beam profile of the probe and the depth of the foreign body. A study of the lesions during mobilizing maneuvers was performed whenever the adjacent muscles and tendons might have been involved. In all cases of sonographically visualized foreign bodies, an accurate three-dimensional localization was easily obtained by using longitudinal and transverse scans. The orthogonal projection of the foreign body was marked on the skin, and its depth was measured accurately on the scan so that the surgeon could retrieve it through the shortest route and with the least damage to the surrounding structures. Radiographs were obtained by using mammographic equipment (Philips Mammo-Diagnost, Shelton, CT) and screen-film technique at about 30 kV with automatic exposure. They were performed routinely after sonographic examination. Ten patients suspected of having a foreign body either in the hand (nine cases) or in the foot (one case) had both sonograms and radiographs. All subsequently underwent surgery.

Mammography–State of the art

In recent years, the criticism of mammography as a diagnostic and/or survey procedure has decreased, primarily due to the perception that there has been an increase in quality and a concomitant decrease in risk. A review of the physical changes in mammographic equipment, the characteristics of current image receptors and dosimetry indicates that this assumption is correct. The results of the examination of 280,000 women from the Breast Cancer Detection Demonstration Project centers also support this conclusion. When all factors are considered it is reasonable to conclude that the potential benefits of mammography far outweigh the minimal risk incurred by the examination.

Mammography. State of the art.

In recent years, the criticism of mammography as a diagnostic and/or survey procedure has decreased, primarily due to the perception that there has been an increase in quality and a concomitant decrease in risk. A review of the physical changes in mammographic equipment, the characteristics of current image receptors and dosimetry indicates that this assumption is correct. The results of the examination of 280,000 women from the Breast Cancer Detection Demonstration Project centers also support this conclusion. When all factors are considered it is reasonable to conclude that the potential benefits of mammography far outweigh the minimal risk incurred by the examination.