[Measurement of Average Glandular Dose Using Multiparameter X-ray Measuring Instrument].

The average glandular dose (AGD) is very important in the quality control of mammography. The AGD calculation requires measurements of half-value layer (HVL) and entrance surface air karma (ESAK). The HVL is measured by the Al-attenuation method using a non-energy-dependent ionization dosimeter. As the Al-attenuation method performs measurements using a succession of added filters, it requires lots of X-ray exposure and measurement time. In recent years, measuring instruments that can measure tube voltage, irradiation time, exposure dose, HVL, and other factors, at the same time, using one shot of X-rays have been developed. In this study, measurement of the AGD using multiparameter X-ray measuring instrument about rhodium (Rh) and tungsten (W) anode X-ray tubes. A comparative study was performed using standard ionization dosimeters. The error in measurements was as follows: HVL 5.8%, ESAK 3.3%, and AGD 2.9%. The AGD measurement using a multiparameter X-ray measuring instrument is simple and can significantly reduce the measurement time while maintaining accuracy.

Opportunistic breast cancer screening by mammography in Japan for women in their 40s at our preventive medical center: harm or benefit?

BACKGROUND: After recent revised grading by the US Preventive Services Task Force of mammography (MMG) recommendations for women in their 40s, it is urgent to collect data on the benefits and harm of MMG screenings in Japan. In this paper, we study the actual status and effectiveness of opportunistic breast cancer screening by MMG for women in their 40s. METHODS: From January to December 2008, the total number of opportunistic breast cancer screenings by MMG at our institute was 12823. Of them, 398 (3.1 %) who were diagnosed as category 3 or more on MMG required further exams. The data were compared between two groups (women in their 40s, women aged 50 and older). Recall rate, detection rate of breast cancers, and implementation rate of further exams were evaluated. RESULTS: Recall rate was 4.0 % (166/4138) for women in their 40s and 2.4 % (166/6949) for women aged 50 and older. Detection rate of breast cancers was higher in women in their 40s (0.56 %) than women aged 50 and older (0.26 %). Non-cancer rate among women receiving invasive examination was higher in women in their 40s (0.76 %) than women aged 50 and older (0.42 %) (p = 0.02). The number of false positives required to detect one true cancer patient was smaller in women in their 40s (4.5) than women aged 50 and older (5.3). CONCLUSION: The results from our single institute revealed that opportunistic breast cancer screening by MMG for women in their 40s shows higher net benefits than for women aged 50 and older.

Role of breast tomosynthesis in diagnosis of breast cancer for Japanese women.

INTRODUCTION: Mammography is the most basic modality in breast cancer imaging. However, the overlap of breast tissue depicted on conventional two-dimensional mammography (2DMMG) may create significant obstacles to detecting abnormalities, especially in dense or heterogeneously dense breasts. In three-dimensional digital breast tomosynthesis (3DBT), tomographic images of the breast are reconstructed from multiple projections acquired at different angles. It has reported that this technology allows the generation of 3D data, therefore overcoming the limitations of conventional 2DMMG for Western women. We assessed the detectability of lesions by conventional 2DMMG and 3DBT in diagnosis of breast cancer for Japanese women. METHODS: The subjects were 195 breasts of 99 patients (median age of 48 years, range 34~82 years) that had been pathologically diagnosed with breast cancer from December 20, 2010 through March 31, 2011. Both conventional 2DMMG and 3DBT imaging were performed for all patients. Detectability of lesions was assessed based on differences in category class. RESULTS: Of the affected breasts, 77 (75.5%) had lesions assigned to the same categories by 2DMMG and 3DBT. For 24 (23.5%) lesions, the category increased in 3DBT indicating improvement in diagnostic performance compared to 2DMMG. 3DBT improved diagnostic sensitivity for patients with mass, focal asymmetric density (FAD), and architectural distortion. However, 3DBT was not statistically superior in diagnosis of the presence or absence of calcification. CONCLUSIONS: In this study, 3DBT was superior in diagnosing lesions in form of mass, FAD, and/or architectural distortion. 3DBT is a novel technique that may provide a breakthrough in solving the difficulties of diagnosis caused by parenchyma overlap for Japanese women.