Untersuchungen zur Bildgüte bei der Mammographie mit einer Wolframanodenröhre in Verbindung mit Kantenfiltern

Abstract

At present, mammography is usually performed using a molybdenum anode tube and a molybdenum filter. Theoretical considerations and experiments suggest that radiation from a tungsten anode and a filter with a K-edge in the region of 20 to 25 keV is better adapted to the size of the object to be examined than radiation from a molybdenum anode/molybdenum filter combination. As a result, a reduction in radiation exposure is possible for thicker objects. Comparison of image quality with various film-screen combinations has shown that the differences caused by the radiation from the tungsten anode and filter has less effect on the image quality than is due to variation in kV, object thickness and image receptor. It has further been shown that recognition of microcalcifications is limited to about 200 micron.

Recent developments in breast imaging

“…Jones (1982) has already pointed out that, depending upon the radiographic system (cf figure 1), the lower limit of the diameter (for a calcification to be imaged) ranges from about 100 µm to 300 µm. This has been confirmed in the meantime by experiment (Barnes and Chakraborty 1982, John et al 1982, Sickles 1982, Wurm et al 1982, Hessler et al 1985a, b, Karila 1987, 1989b, Minski et al 1988, Oestmann et al 1988a, b, Rimondi et al 1989, Karssemeijer et al 1993 and by calculation (Klein 1979, Brodie and Gutcheck 1982, Gurvich et al 1983, Kratzat 1988, Desponds et al 1991b, Hunger et al 1992. As a result of all these Table 6.…”

“…To pass the test for the American College of Radiology Mammography Screening Accreditation Program a fibre of 750 µm diameter in a 4.3 cm thick phantom must be imaged (Hendrick 1990). At about the same breast thickness, nylon fibres of about 250 µm diameter were just detectable in some ROC studies (Wurm et al 1982, Minski et al 1988.…”

“…These combinations use asymmetric screens and emulsions (Haus 1990). Kimme-Smith et al (1987b) and Minski et al (1988) have reported on one such combination, which gives a dose reduction of up to 50%, but also results in decreased detail detectability.…”

“…ROC analysis has been applied to mammography, e.g. by John et al (1982), Wurm et al (1982), Wurm et al (1983), Säbel et al (1986), Chan et al (1987b), Minski et al (1988), Oestmann et al (1988a, b), Boone (1991), Nab et al (1992) and Karssemeijer et al (1993). Sometimes the response of the observer is also measured by evaluation of images of a contrast-detail phantom (Thijssen et al 1989, Karssemeijer et al 1993.…”

Die Strahlenexposition bei der Röntgen-Mammographie*

“…So zeigten z. B. experimentelle und klinische Studien[41,62] mit einer Wolfram-Anodenröhre mit K-Kantenfiltern aus Molybdän und Rhodium, dass bei groûen Mammae ± im Vergleich zu Systemen mit Molybdän-Anode/Molybdän-Filter ± Mammogramme mit unbedeutender Kontrastreduktion bei etwa der Hälfte der mittleren Parenchymdosis möglich sind. Ferner wurde vorgeschlagen, für groûe Mammae einen Rhodium-oder Palladium-Filter in Kombination mit einer Molybdän-Anode zu verwenden.…”