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Improved Automatic Exposure Control (AEC) using estimate of Breast density prior to scanning X-ray image acquisition

IP.com Disclosure Number: IPCOM000245210D
Publication Date: 2016-Feb-18
Document File: 4 page(s) / 84K

Publishing Venue

The IP.com Prior Art Database

Abstract

Scan time during AEC acquisition on certain X-ray systems is adjusted to fit a target CNR. This leads to significant differences in scan time between fatty and dense breasts. User have complained that the scan time is too long for dense breasts.

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2015ID03076

Title of the invention:


Improved Automatic Exposure Control (AEC) using estimate of Breast density prior to scanning X-ray image acquisition

Abstract of the invention:


Scan time during AEC acquisition on certain X-ray systems is adjusted to fit a target CNR. This leads to significant differences in scan time between fatty and dense breasts. User have complained that the scan time is too long for dense breasts.

The scan time can be optimized by the choice of the High Voltage generator kV setting for the X-ray tube. By adjusting the kV prior to image acquisition based on the breast density and not only the compressed breast thickness the kV can be chosen to better match the imaged object.

This invention disclosure details three solutions for addressing this problem.

1) The system could give user the possibility to define breast density prior to acquisition.

2) The system can use the rate of increase in the breast compression pressure to adjust the kV setting automatically prior to image acquisition.

3) The system can use the information from previous examinations or previous images acquired in the same examination.

A side effect of decreasing the scan time is that the filament and X-ray tube life time can be improved.

Keywords related to the invention:
1. Scan speed optimization
2. Digital Breast Tomosynthesis (DBT) scanning X-ray Mammography system
3. FFDM
4. AEC

Detailed description of the invention

Background of the invention

The invention relates to a scanning X-ray mammography system. Automatic Exposure Control (AEC) is a feature that regulates the X-ray exposure parameters to ensure correct exposure of the object,
i.e. breast. During image acquisition, the detector scans over the breast acquiring readouts during the movement. The MicroDose AEC (pat.nr. US7496176B2, and WO2005077277A1) uses the information, i.e. flux, in the readouts from the first detector lines in the scanning direction to adjust the exposure to the object.

The AEC uses the thickness of the compressed breast to estimate the absorption of the breast (related to the breast glandularity) and sets the parameters for the scan in order to reach a target CNR, this includes initial scan speed, target flux and X-ray parameters kV and mA. During the scan the system uses the target flux and compares it with the readouts from the detector to adjust the speed of the scan and thereby adjusting the mAs, while the kV and mA remain constant.

As the estimated X-ray absorption of the breast is based on average population curves in relation to its compressed thickness, the variation between the estimated and real absorption of the image object can be quite large. This results in substantially different scan times for dense vs fatty breasts for same compressed breast thickness. The scan time for a dense breasts becomes long which is not perceived positively by patient and users. By choosing a higher kV, the scan time for these dense breasts could be shortened maintainin...