[Suggestions for standardisation of dose measurements and dose recording during mammography (author's transl)]

Standardisation of dose measurement and recording of the dose during mammography appears desirable in relation to judgements concerning image quality, quality control and radiation risk. It is suggested - arising from our own investigations - that a suitable method is the use of a plexiglass phantom of 5 cm thickness; the entrance and exit dose of suitable radiation (20 keV less than or equal to Eeff less than or equal to 35 keV) can be measured by a suitable ionisation chamber. The mean parenchymal dose can then be calculated, making certain assumptions which are discussed.

[Quality control during mammography-II (author's transl)]

The results of a pilot study on mammographic quality control in 58 x-ray departments in West Berlin are reported. Using a systematically developed phantom, an insight was gained into the present state of mammography and various unexpected faults which were diagnostically important, were revealed. Standard values for the type of radiation, effective image contrast, resolution, geometry and radiation dose could be ascertained, which can serve as a basis for mammographic quality control.

Quality control in mammary radiography

The doses, the image qualities and the factors affecting these were determined for all equipments used for mammary radiography in Finland. It was found that the quality of the equipment tested varied greatly. This is particularly well illustrated by the 5 000-fold difference between the highest and lowest surface doses. Large differences in image quality were also found.

A test object for assessing image quality in mammography

The problems inherent in the design and manufacture of mammographic test objects are discussed and a test object is described which may be used for assessing image quality. Some typical results from both good and bad mammographic machine/film combinations are presented.

[Quality criteria in Mammography (author's transl)]

Definite quality criteria must be observed to achieve optimum diagnostic success in mammography. These criteria refer to the apparatus, film, development of film, method and interpretation of findings. Cooperation with a mamma centre is discussed in case extended diagnosis of breast findings is required, or in case it becomes necessary to mark any non-palpable changes.

A mammography quality assurance test program

The design and implementation of a program to investigate remote quality assurance testing for film mammography is described. The measurements included tube output, x-ray machine and processor stability, and film quality. Mammography phantoms and film sensitometric strips were distributed monthly to 24 regional hospitals. Most of the hospital processors and x-ray machines performed in a stable manner during the 12-month test period. It was found that x-ray machine useful beams could be reliably measured using nonscreen films. The main utility of the phantom was to identify cases of poor image quality. The measurements performed on the phantom image could not be used to diagnose specific causes of poor images.

Controlled single-blind clinical evaluation of low-dose mammographic screen--film systems

The ability of five low-dose mammographic screen--film systems to portray normal and abnormal breast structures was evaluated in parallel with a study of physical image properties. Single-blind evaluations of the visibility of normal breast architecture, mass lesions, and calcifications were made on the mammograms of 100 patients radiographed with each of the systems. There was increased noise and slightly poorer resolution for the faster recording systems, but there was no difference in final diagnostic impressions among the five systems. These results suggest that the faster systems will result in substantial dose reduction without sacrificing diagnostic accuracy.

Breast exposure: nationwide trends; a mammographic quality assurance program--results to date

BENT (Breast Exposure: Nationwide Trends), a federal-state sponsored mammographic quality assurance program has demonstrated that unproductive radiation exposure can be reduced by identifying and correcting problems that result in poor image quality. BENT provides clinical personnel with knowledge on the performance of their mammographic system as a basis for possible improvements in image quality and for reductions in patient exposure.

[The efficiency of mammographic mass screening (author's transl)]

After commenting the assessment of the benefits of medical measures some remarks are made concerning the risk of mammography which has been discussed in detail else where. The benefit of mammography for screening asymptomatic women is estimated on the basis of figures from the literature applying four criteria; 1. Results of the HIP-study, 2. clinically occult breast cancers, 3. clinically occult cancers without axillary nodal involvement, 4. clinically occult "minimal" cancers. On the basis of 10 years-survival it follows that 7% of all breast cancers will be additionally "curable" through screening by mammography. This age-independent value has to be considered apart from risk of radiation induced cancer and benefit/risk-ratios, which are strongly agedependent. Costs of mammography and the screening of high-risk groups are briefly considered.

[Phantom experiments and early clinical experience with a mammogram apparatus using a grid (author's transl)]

The effect of a grid on film quality and dose was investigated in a newly developed mammographic apparatus (Mammo Diagnost U--C. H. F. Müller). It was shown that available film-screen combinations used with a grid produced practically the same picture quality as Definix Medical used without screen or grid. Although the dose required is almost doubled by the use of the grid, the latter, nevertheless, produces a reduction of surface dose to about a quarter (4 cm. plexiglass phantom). Using a film-screen combination not at present commercially available, there was some improvement in the demonstration of microcalcification, but the improvement resulted in an increase in the required radiation dose.

Image information content and patient exposure

Presently, patient exposure and x-ray tube kilovoltage are determined by image visibility requirements on x-ray film. With the employment of image-processing techniques, image visibility may be manipulated and the exposure may be determined only by the desired information content, i.e., by the required degree of tissue-density descrimination and spatial resolution. This work gives quantitative relationships between the image information content and the patient exposure, give estimates of the minimum exposures required for the detection of image signals associated with particular radiological exams. Also, for subject thickness larger than approximately 5 cm, the results show that the maximum information content may be obtained at a single kilovoltage and filtration with the simultaneous employment of image-enhancement and antiscatter techniques. This optimization may be used either to reduce the patient exposure or to increase the retrieved information.

[The appropiate film for mammography (author's transl)]

Comparison of industrial film with long processing time and "90-second-Film" with film-screen combination showed the first type with long processing time to be distinctly superior. Number and shape of tiny clustered microcalcification were taken as criteria for correct visualization. Under present technical and geometrical conditions only industrial type film with long processing time gives high diagnostic accuracy in early breast cancer which depends to a large degree on proper delineation of microcalcifications.

[Proposals for standardizing the image quality of mammography (author's transl)]

The radiography of phantoms is not sufficient to test the image quality of mammography. In addition, patients mammograms have to be evaluated using our proposed quality criteria.

[Problems of image quality in mammography. Avoidable technical errors in performance and evaluation of mammograms (author's transl)]

Frequent serious technical errors in mammorgraphy proved to be due to incomplete outlining of the breast, underexposure and blurring. These errors are in most cases secondary to incorrect positioning, absence or improper adjustment of automatic exposure system, insufficient quality of x-ray tube, and use of inappropriate films. Each mammogram should be exposed in such a way so that the film reading can be done using a bright halogen lamp and a twofold magnifying glass. Grain, blurring and artefacts should not interfere with the visibility of diagnostically important details such as microcalcifications of the size of about 0,1 mm.

Indications and guidelines for mammographic examinations

The value of mammography in evaluating the asymptomatic patient has been clearly demonstrated by the HIP program, as well as the National Cancer Institute's breast demonstration projects. A one-third reduction in mortality from breast cancer in mammographically screened women has been substantiated. Nonetheless, questions concerning the long-term effects of repeated radiation exposure associated with mammography have been raised, and for this reason judicious selection of women is urged. In general, women who are asymptomatic or at high risk for breast carcinoma should be evaluated with a planned regimen. Mammographic guidelines and recommendations for attaining the greatest benefit at the lowest possible risk are suggested.

[Film quality in film mammography. Article II: Signal/noise ratio of the recording system as a quantitative measure of quality. Final evaluation of recording systems (author's transl)]

During consideration of three film mammographic systems (see article I), the concept of signal/noise ratio is developed as a quantitative measure of film quality. The ability to recognise detail related to detail size, film blackening and exposure geometry was studied for various systems, and the quality profiles are discussed. There is a considerable difference in quality between industrial films without screens and film-screen combinations; however, exposure geometry during mammography has a considerable effect which tends to reduce the difference. Consequently, detail sizes of 200 mu to 1,000 mu (including the majority of mammographic micro-calcifications) are shown about equally well. Contrast for the lo-dose system (D = 1.1) is somewhat less than for adequately exposed industrial film (D = 2.0) or for Cronex 75 m with lo-dose screen (D = 1.5 to 2.0). The lo-dose system (D = 1.1) is 8.6 times more sensitive than Cronex 75 m (D = 2.0), and the system Cronex 75 m with lo-dose screens is 11.6 times more sensitive. Over-exposure with the lo-dose system, contrary to industrial film, rapidly leads to unsatisfactory results (loss of contrast and increased granularity for D greater than 1.5). On the other hand it is often not possible to obtain an adequate exposure (D = 2.0) when using industrial film. For these reasons it is often an advantage to examine large breasts (with considerable geometric unsharpness) and the dense breasts of young women with a film-screen combination (eg. lo-dose system) which requires approximately one eighth of the dose necessary for industrial film. For small or easily compressable breasts (little geometric unsharpness) best results are obtained, using an adequate exposure by employing industrial film; radiation dose it then acceptable. Detailed analysis of the systems has shown that the recording system unsharpness of film-screen combinations in mammography should be reduced.

[Picture quality and film mammography. I. The physical parameters of the filming system (gradation, sensitivity, definition and granularity) and the effect of exposure geometry (author's transl)]

The physical parameters of three radiographic filming systems used for mammography were analysed (industrial film without screens, lo dose system (Dupont), industrial film with lo dose screens). Their effect on image quality was studied and the influence of the exposure geometry on sharpness and detail was investigated experimentally. Geometrical unsharpness so reduces the difference in definition between screenless industrial film and a film-screen combination that the total unsharpness at the centre of the breast parenchyma of an average breast becomes approximately the same. In particular, recognition of fine detail (microcalcification) is reduced by geometric unsharpness. Final grading of the three film systems is only possible after development of a concept of film quality which takes account of the parameters of the filming system and of exposlre geometry, together with physiological and practical requirements (paper II).

[Directions for mammography from a radiological viewpoint]

A significant decrease in mortality due to breast cancer is feasible only by earlier diagnosis. The decisive screening method is mammography, which permits identification of a malignancy in its earliest stages. Indirect and direct signs of malignancy exist whose detection necessitates biopsy. Radiological examination of the tissue sample permits evaluation of the adequacy of excision and thus renders possible specific histological examination of the region of interest. Pneumocystography is a method for simultaneous diagnosis and therapy of benign cysts.

The effect of x-ray spectra from molybdenum and tungsten target tubes on image quality in mammography

The measured x-ray spectra from a molybdenum anode Senographe mammography unit and a tungsten anode unit were used to calculate the x-ray energy spectra transmitted through various thicknesses of fat and water (breast-equivalent materials). The dependence of subject contrast and patient exposure on (a) x-ray spectra, (b) attenuation properties of two breast-equivalent materials, and (c) thickness of breast-equivalent material was predicted. Radiographs of resected breast tissue confirmed these predictions and demonstrated the general relative effects of x-ray beam quality on image contrast in mammography.

Developments in mammography

Mammography is presented for the primarily nonradiologic audience. A brief historical review calls attention to some of the milestones in mammography and how it has changed. Xerororadiography is discussed, as it is one of the newer developments and is rapidly gaining broad acceptance in the United States. Clinical applications are included, with a discussion of the various entities which the radiologist can identify on the mammogram. Although the mammographic examination can be extremely accurate in the hands of interested examiners, some carcinomas will not be identified; of these, some can be discovered by routine physical examination. If mammography is made to stand alone, without a physical examination, some women with breast cancer will not be identified and will not receive prompt, adequate treatment. Mammography is an adjunct and a complement to the physical examination. Breast cancer screening appears to be effective in finding small, nonpalpable tumors, many very early in their growth. Definite evidence is now available that early diagnosis of breast cancer leads to prolonged survival. There is promise of further developments in the field of mammography.

[The place of plate thermography in the diagnosis of breast cancer (author's transl)]

A report is presented of 319 unselected patients investigated by the method of plate thermography according to Tricoire, which is a comparatively new method in the diagnosis of breast cancer. 281 cases were additionally examined by mammography and those cases in whom malignancy was suspected underwent further cytological and histological investigation. The results of plate thermography and mammography are compared. The high degree of diagnostic accuracy achieved in the present series of cases by the use of plate thermography indicates that this procedure is not only a valable adjunct in the diagnosis of breast cancer but, moreover, seems to be recommendable as a screening method.

Evolution of the team approach in breast cancer

Dr. Wendell G. Scott hailed mammography as the first significant contribution to the control of breast cancer since Halsted described the radical mastectomy in 1903. Mammography as engendered new approaches and has supplied new concepts of breast cancer. Through the tenacity of a few physicians convinced something could be done for the breast cancer patient, the team against this dread disease has gradually, but solidly, been built and continues to grow.

Mammography: an aid in the treatment of carcinoma of the breast

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