ABSTRACT
Current digital mammography (DM) X-ray systems are equipped with advanced automatic exposure control (AEC) systems, which determine the exposure factors depending on breast composition. In the supplement of the European guidelines for quality assurance in breast cancer screening and diagnosis, a phantom-based test is included to evaluate the AEC response to local dense areas in terms of signal-to-noise ratio (SNR). This study evaluates the proposed test in terms of SNR and dose for four DM systems. The glandular fraction represented by the local dense area was assessed by analytic calculations. It was found that the proposed test simulates adipose to fully glandular breast compositions in attenuation. The doses associated with the phantoms were found to match well with the patient dose distribution. In conclusion, after some small adaptations, the test is valuable for the assessment of the AEC performance in terms of both SNR and dose.
Subject(s)
Breast Neoplasms/radiotherapy , Mammography/methods , Polymethyl Methacrylate/chemistry , Radiographic Image Interpretation, Computer-Assisted/methods , Adult , Europe , Female , Guidelines as Topic , Humans , Middle Aged , Phantoms, Imaging , Radiation Dosage , Radiographic Image Enhancement , Signal-To-Noise RatioABSTRACT
Recently, Siemens introduced a software-based scatter correction in combination with grid-less digital mammography for dose-reduced breast imaging. In this study, the potential dose reduction when compared with using a grid was calculated. Image quality was evaluated using the CDMAM phantom. Nine hundred and sixty CDMAM measurements were performed with and without grid. The images were analysed with the CDCOM software. The correlation of CDCOM readings of gold thickness thresholds with human readings for grid-less imaging was found to be linear, with slope 2.157 and off-set 0.024 (R(2) = 1), validating the further use of CDCOM. Dose reduction for 21, 32, 45, 60, 75 and 90 mm equivalent breast thickness was found to be 28, 17, 21, 18, 8 and 3 %. Scatter correction did not influence CDCOM readings, but image homogeneity was improved. Grid-less acquisitions, with or without scatter correction, can be used for reducing the dose while maintaining image quality as evaluated from the CDMAM phantom.