The improved Dosestat QC has yielded significant benefits:

• Early detection of detector errors with precise localization, leading to timely recalibration or detector replacement before clinical use.
• Identification of detector changes over time, enabling proactive maintenance and equipment management.
• Financial savings through investment in detector insurance for the entire mammography department, based on the insights gained from the QC process.

Two case studies demonstrate the effectiveness of the improved QC system:

1. Detection of a dead pixel at the top edge - Top-Left section, of the homogenius image (Figure 7 and 8). The equipment was allowed for patient screening, with recalibration performed during a lunch break. The error disappeared, and the equipment continued to be used under supervision.
2. Detection of a dead pixel near the breast area- Bottom-Right, on the homogenius image of an another detector (Figure 9, 10 and 11). The equipment was immediately taken out of service for detector recalibration. When the error persisted, the clinic decided to replace the detector after consultation with the medical physicist, medical engineer, and supplier.

Fig 7: Case study 1. Dosstat QC warns of a QC error on a mammography device. The pixel errors result in the grayscale of the SNR in two ROIs becoming white in the Top-Left section of the image. Information about ROI positions and pixel errors was displayed in the user interface.

Fig 8: Case study 1. When the staff clicked further on the Top-Left section and the result of the ROI calculation was displayed. Two ROIs turned pink, one or more dead pixels were shown as red dots, SD and SNR deviated greatly. In this case, the mammography equipment allowed to be used for patient screening because the pixel errors were far away from the breast area. Total recalibration of the detector was successfully performed afterwards.

Fig 9: Case Study 2. Pixel errors on another mammography equiptment at a ROI on the Bottom-Right section were displayed on the Dosestat QC user interface almost immediately after a daily QC was performed. The gray scale of the ROI turned white due to extremely low SNR value.

Fig 10: Case Study 2. When the staff clicked on the Bottom-Right section, a pink ROI with two red dots appeared along with the calculated values of MV, SD, SNR and deviations that can be compared to other ROIs in the section.

Fig 11: Case Study 2. Once the location of the dead pixels is known, the staff/medical engineer can check the pixel errors precisely with 500% image magnification on the monitor. In this case, after recalibration, the pixel errors are still present and the damage is too close to the breast area so the new detector must be replaced before clinical use.