Dosimetric Evaluation of the Mean Glandular Dose for Mammography in Korean Women: A Preliminary Report

The purpose of this study was to evaluate the thickness of the compressed breast in mediolateral oblique (MLO) and craniocaudal (CC) mammograms, to relate these thickness and breast patterns to mean glandular dose (MGD) in Korean women, and to evaluate the suitability of using the American College of Radiology's Recommendations for Korean women from a quality assurance standpoint. The study population consisted of 92 paired MLO and CC mammograms obtained on one mammographic unit. The digital readouts of compressed breast thickness, applied compression force and tube voltage were recorded. Entrance skin exposure was measured by dosimetry. MGD was calculated by multiplying entrance skin exposure by the exposure-to-absorbed dose conversion factor. The range of breast thickness was 1.3 - 6.2 cm in CC mammograms with a mean breast thickness of 3.6 cm, and 1.6 - 6.5 cm in MLO mammograms with a mean breast thickness of 3.9 cm. MGDs in CC and MLO mammograms were 1.77 mSv and 1.88 mSv per view, respectively. Breast composition patterns were divided into 4 groups according to ACR BI-RADS; P1 (n=20), P2 (n=16), P3 (n=48) and P4 (n=8). The MGDs for these groups were: 1.82, 1.84, 1.84, and 1.91 mSv, respectively. When subjects were subdivided by breast thickness into three groups, namely, below 3 cm, 3 cm to 4.2 cm, aaa and above 4.2 cm, the corresponding MGDs were 1.83, 1.86, and 1.91 mSv. According to our initial trial, the mean breast thickness and the MGDs of Korean women are lower than recommended by the American College of Radiology, which are commonly used for quality assurance purposes.

Dosimetric Evaluation of Average Glandular Absorption Radiation Dose in Mammography

PURPOSE: To evaluate the average glandular absorption radiation dose(AGARD) that results from tube voltage, target/filter material of the X-ray tube, enterance skin exposure, breast thickness and patterns in routine mammography. MATERIAL AND METHOD: After obtaining craniocaudal views of left breasts of 114 women, entrance skin exposure was measured by dosimetry. Under identical conditions of tube voltage and target/filter material of theX-ray tube, we obtained half value layer (HVL) and also calculated exposure-to-absorbed dose conversion factor(DgN) by Wu's methods. AGARD was calculated by entrance skin exposure multiplied by exposure-to-absorbed dose conversion factor. We analyzed AGARDs according to tube voltage, target/filter material, breast thickness and pattern using ANOVA method of the SPSS statistical packages. RESULT: Breast patterns were divided into 4 groups such as DY (n=72), P1 (n=1), P2 (n=10), and N1 (n=31), respectively. Their AGARDs were 161.5, 180, 172.8, and195.2 mrad respectively and showed no significant difference among groups. When divided by breast thickness into three groups, namely below 3cm, 3cm to 4.5cm, and above 4.5cm, the AGARD of each group was 178.3, 178.1, and 112.4mrad respectively and the last one was significantly low. Concerning the effect of tube voltages, AGARDs gradually decreased by increasing kVp. Furthermore, AGARD was lower when rhodium (Rh) rather than when molybdenum(Mo) was used as filter/target materials. CONCLUSION: There was no difference in AGARDs by breast pattern. Asmore increasing KvP or using Rh/Rh as the target/filter material of the X-ray tube, we reduced AGARD for the patient with dense or thick breasts.

The application of compensating filter to chest tomography

A wedge shape compensating filter composed of aluminium was made to equalise the density of lung and mediastinum. Total 68 patients were taken chest tomograph with compensating filter and the radiographic findings were correlated with the pathologic, bacteriologic prove or the clinical course. This simple device was turned out to be very useful in certain disease categories, especially central type of bronchogenic carcinoma.