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M Säbel

Publications and source records attributed to M Säbel.

At least 19 recordsLinked to original sources
PubMed1999

[Image quality and radiation exposure in digital mammography with storage phosphor screens in a magnification technic].

PURPOSE: Comparison of image quality between digital phosphor storage plate mammography in magnification technique and a conventional film screen system regarding the special aspect of radiation exposure. MATERIALS AND METHODS: Radiograms of a RMI-mammography phantom were acquired using a conventional film screen system and two digital storage plate systems. Additionally, the radiograms of one digital system were post-processed emphasizing contrast and included in the comparison. RESULTS: The detectability of details in storage plate mammographies with magnification technique is almost equal to that of film screen mammographies. Thereby, lower radiation exposures were necessary using the digital systems. CONCLUSIONS: Based on these results, storage plate mammography in magnification technique is used in clinical routine at our institution. The correct parameters in image postprocessing are of elementary importance for detail detectability. Future studies must show, whether the lower radiation exposure in digital radiograms of the breast, revealing much higher background noise, will allow the same detail detectability as film screen mammographies.

Female↗
PubMed1998

[Pelvic wall recurrence of cervix carcinomas. Combined surgical-radio-chemotherapeutic procedure (CORCT)].

PURPOSE: The prognosis of patients with pelvic wall recurrences after primary therapy of cervical cancer is bad. In selected patients treated exclusively by surgery as primary therapy the 5-year survival rate was between 5 and 25%. Additionally the combination of operation and radiotherapy (CORT) improved the survival so far. We developed a new concept for the treatment of pelvic wall recurrences. This concept includes the combination of radical surgery, interstitial radiation and chemotheray--CORCT (combined operative- and radiochemotherapy). PATIENTS AND METHODS: After radical surgery, interstitial HDR (Ir-192) brachytherapy in afterloading technique (2.5 Gy, 2 fractions/day in 5 days) was performed. Additionally a chemotherapy with cisplatin 25 mg/m2/day in 5 days and 5-fluorouracil 1000 mg/day in 5 days was applicated. RESULTS: After combined operative- and radiotherapy 3 of 3 patients died after treatment within 8 months (median) because of distant metastases. After additive radiochemotherapy 3 of 4 patients had no evidence of disease (NED) after a follow-up period of 14 (12 to 30) months. CONCLUSION: The first treatment results of the new designed combined operative- and radiochemotherapy concept (CORCT) led us to expect an improvement of the prognosis of patients with recurrences of cervical cancer at the pelvic wall.

Adult↗
PubMed1997

Determination of average glandular dose with modern mammography units for two large groups of patients.

Until recently, for mammography Mo anode-Mo filter x-ray tube assemblies were almost exclusively used. Modern mammography units provide the possibility to employ a variety of anode-filter combinations with the aim of adapting the x-ray spectrum to compressed breast thickness and composition. The present contribution provides information on the radiation exposure of two large groups of patients (one of 1678 and one of 945 women) who were mammographed with modern x-ray equipment, and on the dosimetry necessary for the evaluation. For dosimetric purposes spectral information is essential. X-ray spectra have been determined for various anode-filter combinations from measurements with a Ge detector. Based on these spectra, conversion factors from air kerma free in air to average glandular dose (g factors) have been calculated for different anode-filter combinations, compressed breast thickness ranging from 2 to 9 cm and breast compositions varying from 0 to 100% glandular tissue. Determinations of various quantities, including entrance surface air kerma (ESAK), tube output, tube loading (TL), fraction of glandular tissue (FGL) and compressed breast thickness, were made during actual mammography. Average glandular dose (AGD) was determined using g factors corrected for tissue composition as well as g values for standard breast composition, i.e. 50% adipose tissue and 50% glandular tissue by mass. It is shown that, on average, the influence of the actual breast composition causes variations of the order of about 15%. For group 1 and group 2, the mean values of average glandular dose (using g factors corrected for tissue composition) were 1.59 and 2.07 mGy respectively. The number of exposures per woman was on average 3.4 and 3.6 respectively. The mean value of compressed breast thickness was 55.9 and 50.8 mm respectively. The mean age of group 1 was 53.6 years (for group 2 the age was not recorded). The fraction by mass of glandular tissue FGL decrease with increasing compressed breast thickness and age of patient (from 75% at 25 mm to 20% at 80 mm, and from 65% at 20 years to 30% at 75 years). For a medium-sized breast, i.e. a compressed breast thickness of 55 mm, FGL is about 35%, indicating that the standard mix (FGL = 50%) might need some modification, particularly because of additional evidence from another investigation with similar results on FGL.

Adipose Tissue↗
PubMed1996

Recent developments in breast imaging.

A review of breast imaging has already appeared in 1982 in this journal. Consequently, the present article concentrates on a discussion of only those developments of a more recent nature. Although the emphasis is placed on the physical aspects of the different imaging methods concerned, the essential factors relating to the clinical background and the associated radiation risk are also outlined. The completeness of detail depends on the present clinical importance of the method under discussion. X-ray mammography, which is still the most important breast imaging technique and has proved to be an effective method for breast cancer screening, is therefore treated in greater detail. Since the early 1980s, ultrasound B-mode scanning has evolved to an indispensable adjunct to x-ray mammography. For Doppler sonography, diaphanography, contrast-enhanced MRI, CT and DSA, the visualization of a tumour depends essentially on the enhanced vascularity of the lesion. Whether this will prove to be a reliable indicator for malignancy remains to be shown in controlled clinical studies. Common to all imaging systems is the increasing use of digital methods for signal processing, which also offers the possibility of computer-aided diagnosis by texture analysis and pattern recognition.

Angiography, Digital Subtraction↗
PubMed1995

[An improved method for determining the mean parenchyma dose in mammography].

In mammography, it is currently assumed that the mean dose to glandular tissue DG is relevant to characterize the risk of carcinogenesis. The mean glandular dose DG results from the measured air kerma Ka at the location of the entrance surface of the breast multiplied by the conversion factors g, which usually are calculated with the help of Monte-Carlo-Simulations and which are mostly given for a standard composition of tissue (50% glandular/50% adipose tissue). By means of the signals of the double-detector of the automatic-exposure-control of the mammographic device, it is possible to obtain information about the mean composition of the breast-tissue. The knowledge of this composition enables a better calculation of the mean glandular dose DG by using conversion factors that are adapted to the tissue. This method was applied to a total of 1020 women. The comparison with the evaluation by using the conventional method shows, on average, deviations in the mean glandular dose of 9%, in specific cases the differences can be as much as 35%.

Breast↗
PubMed1993

Nipple discharge and abnormal galactogram. Results of a long-term study (1964-1990).

In case of abnormal nipple discharge of the female breast, galactography can detect variations of ductal calibre, intraductal alterations and ductal discontinuities. Between 1964 and 1990 we examined 2588 women by galactography and performed 826 duct excisions. In one out of 8 patients (13.4%) we diagnosed invasive carcinoma or ductal carcinoma in situ. In more than 40% a solitary ductal papilloma was detected. 13.7% of the patients were found to have extensive intraductal solid papillary or adenomatous epithelial proliferations. Comparison with collected statistical data reveals that other investigators are able to detect malignant changes in 1-23% of cases. We have managed the largest number of cases and have diagnosed pathologic ductal secretion in more than 3% of women we screened by physical inspection, mammography and sonography. The colour of the ductal discharge is of minor importance, as histologic analysis is mandated by the presence of ductal system alterations.

Breast Neoplasms↗
PubMed1991

[Film-screen combinations for mammography].

Optimizing and standardizing mammography as well as its quality assurance are gaining in importance with regard to the screening programmes that are being initiated for the early detection of breast cancer. In Germany, the guidelines of the Bundesärztekammer, the directives implementing section 4 and section 16 of the Röntgenverordnung and the standards DIN 6868, Part 7 and 52 are available. The data in these standards concerning tolerances and guide values for physical variables of the imaging system are only partially consistent. This also applies to the comparison with the document "Quality criteria for x-ray exposures in medical diagnostics" of the Commission of the European Communities. The different statements concerning the switch-off value of the dose in particular, reflect an uncertainty as to how unsharpness and noise of the image receptor impair the medical value of the images. With regard to the increased demands for visual resolution capacity, it can be stated that the "Medical quality requirements" and the "Radiographic guide-lines" harmonize with one another only inadequately. Contrast is one of the most important image quality parameters in mammography. Practically no statement is made on this in the available documents. One reason for the present unsatisfactory situation is certainly the especially high demands placed on image quality in mammography. In the present paper, these points of criticism are discussed in detail and proposals for closer specification and better delineation of the physical image quality parameters are submitted.

Breast Neoplasms↗
PubMed1988

[Studies on image quality in mammography using a tungsten anode tube in conjunction with edge filters].

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.

Female↗