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.

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Objective: To present patient dose levels for different CBCT scanners, acquired by a dose monitoring tool in a University Hospital, as a function of field of view (FOV), operation mode, and patient age. Methods: An integrated dose monitoring tool was used to collect radiation exposure data [type of CBCT unit, dose-area product (DAP), FOV size, and operation mode] and patient demographic information (age, referral department) performed on a 3D Accuitomo 170 and a Newtom VGI EVO unit. Effective dose conversion factors were calculated and implemented into the dose monitoring system. For each CBCT unit, the frequency of examinations, clinical indications, and effective dose levels were obtained for different age and FOV groups, and operation modes. Results: A total of 5163 CBCT examinations were analyzed. Surgical planning and follow-up were the most frequent clinical indications. For the standard operation mode, effective doses ranged from 35.1 to 300 µSv and 9.26-117 µSv using 3D Accuitomo 170 and Newtom VGI EVO, respectively. In general, effective doses decreased with increasing age and FOV size reduction. Conclusions: Effective dose levels varied notably between systems and operation modes.Operation mode selection and FOV size were indication-oriented, with larger FOV sizes election serving surgical planning and follow-up. Seeing the influence of FOV size on effective dose levels, manufacturers could be advised to move toward patient-specific collimation and dynamic FOV selection. Systematically monitoring patient doses could be recommended for steering future CBCT optimization.

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.

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