Comparison of Mean Glandular Dose between Full-Field Digital Mammography and Digital Breast Tomosynthesis

Early detection of breast cancer is diagnosed using mammography, the gold standard in breast screening. However, its increased use also provokes radiation-induced breast malignancy. Thus, monitoring and regulating the mean glandular dose (MGD) is essential. The purpose of this study was to determine MGD for full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT) in the radiology department of a single centre. We also analysed the exposure factors as a function of breast thickness. A total of 436 patients underwent both FFDM and DBT. MGD was auto calculated by the mammographic machine for each projection. Patients’ data included compressed breast thickness (CBT), peak kilovoltage (kVp), milliampere-seconds (mAs) and MGD (mGy). Result analysis showed that there is a significant difference in MGD between the two systems, namely FFDM and DBT. However, the MGD values in our centre were comparable to other centres, as well as the European guideline (<2.5 mGy) for a standard breast. Although DBT improves the clinical outcome and quality of diagnosis, the risk of radiation-induced carcinogenesis should not be neglected. Regular quality control testing on mammography equipment must be performed for dose monitoring in women following a screening mammography in the future.

At Which Mean Glandular Dose Does the Benefit of Breast Cancer Deaths Averted Equal the Risk of Lives Lost to Screening From Radiation-induced Malignancy for Mammography With and Without Tomosynthesis?

Objective To estimate benefit-to-radiation-risk mean glandular dose (MGD) equivalence values for screening mammography, defined as the yearly MGD (over a 10-year period) at which the estimated benefit of mammography in terms of deaths averted equals the estimated risk of lives lost to screening due to radiation exposure (a benefit-to-risk ratio of 1). Methods Benefit-to-risk ratios were calculated as the ratio of breast cancer deaths averted and lives lost to screening over 10-year intervals starting at age 40 for mammography and tomosynthesis using previously published methodology. The MGD values at which estimated benefit equals risk were tabulated. Results The MGD values at which benefit-to-risk equivalence points were met for digital screening mammography are 63 milligray (mGy) (ages 40–49), 88 mGy (ages 50–59), 176 mGy (ages 60–69), and 336 mGy (ages 70–79). The MGD values that met benefit-to-risk equivalence for screening tomosynthesis plus digital mammography or synthetic mammography are 80 mGy (ages 40–49), 111 mGy (ages 50–59), 224 mGy (ages 60–69), and 427 mGy (ages 70–79). Conclusion Cutoff MGD values at which the estimated benefit from screening equals the estimated risk are well above standard screening MGD exposures. Care is necessary to ensure that threshold values are not exceeded during a screening exam, particularly for women ages 40–49 years old when using digital mammography plus tomosynthesis (due to an approximate doubling of dose per exam that will more readily exceed cutoff MGD values) and when many additional views are obtained.

Mean Glandular Dose Measurement in Three Mammography Centers in Kashan: An approach to Provide a Local DRL

Purpose: Mammography is the most important diagnostic modality for early detection of breast cancer, however, concerns related to the side effects induced by ionizing radiation are still present. In the current study, the Mean Glandular Dose (MGD) values for mammography examinations as well as a local Diagnostic Reference Level (DRL) were obtained for mammography centers in Kashan, Iran. Materials and Methods: Three mammography devices from three radiology centers were selected to obtain the MGD values of mammography examinations. To assess the MGD values, the technical parameters for patients’ imaging at these three radiology centers were extracted. Then, the incident air kerma (in mGy) value received by each patient was measured by a UNIDOS E electrometer (PTW, Germany) along with a SFD mammography ionization chamber (PTW, Germany). Finally, the incident air kerma values were converted to the MGD values by specific conversion factors. Based on the obtained MGD values, a local DRL was also established for mammography examinations. Results: Mean MGD values per exposure were obtained 2.39 ± 1.46 mGy for Right Craniocaudal (RCC), 2.64 ± 1.67 mGy for Left Craniocaudal (LCC), 2.82 ± 1.89 mGy for Right Mediolateral Oblique (RMLO), and 3.09 ± 1.90 mGy for left mediolateral oblique views. Moreover, a local DRL obtained from mammography examinations, which was established as the overall median of MGD value, was 1.72 mGy (1.91 mGy for digital and 1.32 mGy for analog mammography). Conclusion: The MGD values for different views obtained in this study are in the range of previously reported values. Considering the European guidelines for quality assurance in breast cancer screening and diagnosis, it can be mentioned that the obtained DRL was less than the recommended dose level (2.0 mGy).

Effect of Compression Force and Target or Target/Filter Combination on Mean Glandular Dose for Japanese Women in Full-Field Digital Mammography System

We constructed a mammography database of 807 Japanese women and 2,772 images obtained using five commercial full-field digital mammography (FFDM) devices at four different facilities. Five types of mammography devices fabricated by four manufacturers were used: one with a Mo target (AMULET F), one with Mo and Rh targets (Senographe DS), one with Mo and W targets (AMULET), and two with a W target (MAMMOMAT Fusion and Selenia Dimensions). The purpose of this study was to focus on the mean glandular dose (MGD) in the database and analyze the difference in the MGD of Japanese women radiographed by mammographic devices with different targets or target/filter combinations. Furthermore, we clarify the difference between the displayed and measured MGDs for the three types of mammography devices. The average compression pressure and compression breast thickness of the Japanese women in the mammography in this study were 90.9±21.7 N and 43.3±12.9 mm, respectively. The breast compression pressure slightly varied depending on the facility or FFDM device, while the compression breast thickness decreased with the increase in the compression pressure for all FFDM devices. Differences in breast compression thickness existed depending on the mammography devices. The MGDs of the two types of mammography devices using the W target were smallest (1.335±0.358, 1.218±0.464 mGy). The displayed and measured MGDs of the three types of FFDM devices had a good correlation. However, the difference between the displayed and measured MGDs of the two devices increased with the MGD.

Average Absorbed Breast Dose (2ABD) to Mean Glandular Dose (MGD) Conversion Function for Digital Breast Tomosynthesis: A New Approach

Background: In this work a new method for the Mean Glandular Dose evaluation in digital breast tomosynthesis (DBT) is presented. Methods: Starting from the experimental-based dosimetric index, 2ABD, which represents the average absorbed breast dose, the mean glandular dose MGD2ABD was calculated using a conversion function of glandularity f(G), obtained through the use of Monte Carlo simulations.Results: f(G) was computed for a 4.5 cm thick breast: from its value MGD2ABD for different compressed breast thicknesses and glandularities was obtained. The comparison between MGD2ABD estimates and the dosimetric index provided in the current dosimetry protocols, following the Dance's approach, MGDDance, showed a good agreement (<10%) for all the analyzed breast thicknesses and glandularities. Conclusion: The strength of the proposed method can be considered an accurate mean glandular dose assessment starting from few and accessible parameters, reported in the header DICOM of each DBT exam.

Evaluation of Radiation Doses and Estimation of the Risk of Radiation-Induced carcinogenesis in Women Undergoing Screening Mammography Examinations

Digital Mammography is used as a screening tool to discover breast cancer at an early stage, the benefits and harms of this techniques is under scrutiny hence and Moroccan regulations governing radiation protection of patients have been strengthened, the need to investigate the dose received during screening mammography and the risk associated. This study is consisted of examining 126 mammography projections, for 63 women. All examinations were performed with a full digital mammography machine, technical and exposure parameters were recorded, statistical analysis was carried out using Microsoft Excel in order to calculate local DRLs and compare them with international standards. Cancer risk has been estimated using BEIR VII report methods. The mean glandular dose MGD was 1,09±0, 45 mGy and 1,26±0,74 mGy for craniocaudal (CC) and mediolateral oblique (MLO) respectively, DRLs were 1,34 for CC view and 1,36 for MLO view. Of the 100,000 women exposed, Lifetime Attributable Risk of cancer incidence has been found to be 0,76 for CC examination, 0.88 for MLO, and 1,64 for the full mammography protocol. Established local DRLs in this study are lower compared to that of United Kingdom and France and higher compared to that of Nigeria and Australia. A potential risk of radiation-induced carcinogenesis exists, and there is a need for optimization of screening mammography practices.