No abstract available.
Mammography*

The Monte Carlo (MC) method was utilized widely to various problems like an absorbed dose calculation as the method able to apply in a complex geometry such as mammography. Since 1980, the approach was utilized in mammographic dosimetry to calculate the backscatter factor and absorbed dose in breast phantoms because it was considered as the most accurate dose calculation algorithm in several experimental setup. This paper provides a review of the applications of Monte Carlo simulation (MC) for the process dosimetry in mammography. In comparison to experimental measurements, this approach poses a minimum calculation uncertainty (less than 2%), realistic measurement positions, and appropriate for low-energy radiation simulation. The applications of the MC codes in mammography, such as radiation modelling, organ dose calculation, tumor growth analysis, etc., were discussed in this review.
Mammography

PURPOSE: To measure the mammographic radiation dose of different mammographic units and views as compared to the American College of Radiology Recommendations. MATERIALS AND METHODS: We measured the kVp, entrance dose and average glandular dose for three mammo-graphic units(two Giotto Hi-Tech Mammography, IMS, Bologna, Italy, one Senographe 500T, GE Medical Systems, Milwaukee, Wis., U.S.A.) in the 26 -33 kV range. Dose measurement for magnification compression view was obtained for two machines and dose measurement for stereotactic views was obtained for one machine. RESULTS: For each machine, the entrance dose was within the range of 3.400 -6.077, 4.383 -11.403, 3.790 -6 . 497 mSv, respectively, and the average glandular dose was within the range of 0.74 -1.96 mGy. The entrance and average glandular dose were 17.14, 18.00 mSv, and 3.73, 3.92 mGy for the magnification compression view and 2.41 -2.92 mSv, 0.50 -0.61 mGy for stereotactic views. The error range of kVp was ~1 1 . 3 ~+1.9 %. CONCLUSION: The entrance dose and average glandular dose were above the limit of the American College of Radiology Recommendations. It is necessary to develop a Korean standard on the basis of the above data.
Italy ; Mammography

Background: Different target-filter combinations in computed radiography have different impacts on the dose and image quality in digital radiography. This study aims to evaluate the mean glandular dose (MGD) and modulation transfer function (MTF) of various target-filter combinations by investigating the signal intensities of X-ray beams. Methods: General Electric (GE) Senographe DMR Plus mammography unit was used for MGD and MTF evaluation. The measured MGD was compared with the dose reference level (DRL), whereas the MTF was evaluated using ImageJ 1.46o software. A modified Mammography Accreditation Phantom RMI 156 was exposed using different target-filter combinations of molybdenum-molybdenum (Mo-Mo), molybdenum-rhodium (Mo-Rh) and rhodium-rhodium (Rh-Rh) at two different tube voltages, 26 kV and 32 kV with 50 mAs. Results: In the MGD evaluations, all target-filters gave an MGD value of < 1.5 mGy. The one-way ANOVA test showed a highly significant interaction between the MGD and the kilovoltage and target-filter material used (26 kV: F (2,12) = 49,234, P = 0.001;32 kV: F (2,12) = 89,972, P = 0.001). A Tukey post-hoc test revealed that the MGD for 26 kV and 32 kV was highly affected by the target-filter combinations. The test of homogeneity of variances indicates that the MGD varies significantly for 26 kV and 32 kV images (0.045 and 0.030 (P < 0.05), respectively). However, the one-way ANOVA for the MTF shows that no significant difference exists between the target-filter combinations used with 26 kV and 32 kV images either in parallel or perpendicular to the chest wall side F (2,189) = 0.26, P > 0.05). Conclusions: Higher tube voltage and atomic number target-filter yield higher MGD values. However, the MTF is independent of the X-ray energy and the type of target-filter combinations used.
Mammography ; Radiography

No abstract available.
Breast Neoplasms* ; Breast* ; Mammography

No abstract available.
Breast Neoplasms* ; Breast* ; Mammography*

Mammography is an invaluable method for the in detection of breast cancer, especially in asymptomaticpa-tients. Occasionally, however, mammography fails to detect cancer, resulting in false reassurance and delayeddi-agnosis. In this paper we describe various causes and the mammographic findings of false-negative mammo-grams.
Breast Neoplasms ; Mammography

The purpose of this study is to comprehensively compare and evaluate the characteristics of image quality for digital mammography systems which use a direct and indirect conversion detector. Three key metrics of image quality were evaluated for the direct and indirect conversion detector, the modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE), which describe the resolution, noise, and signal to noise performance, respectively. DQE was calculated by using a edge phantom for MTF determination according to IEC 62220-1-2 regulation. The contrast to noise ratio (CNR) was evaluated according to guidelines offered by the Korean Institute for Accreditation of Medical Image (KIAMI). As a result, the higher MTF and DQE was measured with direct conversion detector compared to indirect conversion detector all over spatial frequency. When the average glandular dose (AGD) was the same, direct conversion detector showed higher CNR value. The direct conversion detector which has higher DQE value all over spatial frequency would provide the potential benefits for both improved image quality and lower patient dose in digital mammography system.
Accreditation ; Humans ; Mammography ; Noise

250 patients with ages of 30-50 received the mammography in the Institute of Mother and Infant Protection and Care during 4/1998 - 4/1999. The results showed that patients came to examine because of the mechanical symptoms and X-ray (37.2%) in which 72% found having the physical lesion. The physical symptoms accounted for 62.8% of which 92% found having lesion on the X-ray. The lesion of the right breast, left breast and both breast were 44%, 56% and 40%, respectively. The lesion included fibrosis, tumor and complex lesion.
mammography ; Expert Testimony ; patients

PURPOSE: To evaluate morphologic characteristics of the clustered microcalcifications in benign lesions and to compare with that of malignant lesions. MATERIALS AND METHODS: We retrospectively reviewed 33 patients with clustered microcalcifications( five calcifications in number per square centimeter)on mammography. We analyzed mammographic findings with regard to shape, size, number/cm2, irregularity of size and shape, presence of central lucency, and accompanied mass density. RESULTS: Of 12 benign lesions, the most frequent shape was dot or round form (4/12, 33.3%) followed by ring form (3/12, 25%). The size was smaller than 0.5mm in 5 patients (41.7%), 0.5-1 mm in one and more than 1 mm in 6 patients(50%). The number of calcifications per square centimeter were five to ten in 41.7%, more than ten in 58.3%. Of all 21 malignant lesions, the most frequent shape was branching form (8/21, 38.1%). The sizes of calcification were less than 0.5ram in 76.1%(16/21). Central lucency within the calcification was seen only in benign lesions (3/14, 21%). Irregularity ih size and shape of calcifictions was noted in both benign and malignant lesions. Accompanied parenchymal mass density was more commonly associated with malignant lesions(80. 9%) than benign lesions(58.3%). CONCLUSION: Our results suggest that benign clutered microcalcifications on mammography could be differentiated from malignant calcifications with the criteria of larger size, central lucency and infrequent accompanied mass.
Humans ; Mammography* ; Retrospective Studies