High dynamic range mammography using a restricted dynamic range full field digital mammogram
View Patent ↗Methods of imaging a breast comprising acquiring a sequence of image data sets having differing exposure parameters; and combining the image data sets into a mammography image having greater dynamic range than the dynamic range of any single component image data set. Disclosed methods may further comprise determining an exposure parameter of one or more component image data sets prior to acquiring the sequence of image data sets. The step of determining an exposure parameter of one or more component image data sets may comprise determining exposure duration or an exposure irradiation level. Also disclosed are mammography apparatus and systems to obtain images according to the disclosed methods.
1. A method of imaging a breast comprising:
providing an x-ray source;
providing a full field digital x-ray detector;
acquiring a sequence of sub-images having differing exposure parameters by projecting x-rays from the source to the detector at a selected view angle while varying an exposure level between sub-images, wherein a frame integration time is varied between a first sub-image of the sequence of sub-images and a second sub-image of the sequence of sub-images and an x-ray beam energy is held constant between the first sub-image and the second sub-image; and
combining all of the sub-images of the sequence of sub-images into a two-dimensional composite mammography image having greater dynamic range than the dynamic range of any single sub-image.
2. The method of imaging a breast of claim 1 further comprising determining an exposure parameter of one or more sub-images prior to acquiring the sequence of sub-images.
3. The method of imaging a breast of claim 2 wherein determining an exposure parameter of one or more sub-images comprises determining a sub-exposure integration time or a sub-exposure irradiation level.
4. The method of imaging a breast of claim 3 wherein the determination of an exposure parameter is based upon one or more of x-ray beam quality, x-ray beam intensity, information about the imaged object, breast thickness, patient age and the response of the detector.
5. The method of imaging a breast of claim 1 where the full field digital x-ray detector electron well density is below 500 electrons per square micron.
6. The method of imaging a breast of claim 1 further comprising limiting the frame integration time of the first sub-image to a frame integration time which is less than a frame integration time determined to cause sensor saturation when the sensor is unobstructed.
7. The method of imaging a breast of claim 6 further comprising causing the frame integration time of the second sub-image to be:
greater than the frame integration time of the first sub-image; and
equal to or less than the frame integration time of the first sub-image multiplied by a projected signal level at a selected location for the composite mammography image showing a selected dense tissue divided by the measured signal level at the selected location of the first sub-image showing the selected dense tissue.
8. The method of imaging a breast of claim 1 further comprising combining the sub-images into a two-dimensional composite mammography image by adding the sub-images.
9. An apparatus for imaging a breast comprising:
an x-ray source;
an x-ray detector; and
image processing apparatus configured to:
acquire a sequence of sub-images having differing exposure parameters by projecting x-rays from the x-ray source to the detector at a selected view angle while varying an exposure level between sub-images, wherein a frame integration time is varied between a first sub-image of the sequence of sub-images and a second sub-image of the sequence of sub-images and an x-ray beam energy is held constant between the first sub-image and the second sub-image; and
combine all of the sub-images of the sequence of sub-images into a two-dimensional composite mammography image having greater dynamic range than the dynamic range of any single sub-image.
10. The apparatus for imaging a breast of claim 9 wherein the x-ray detector comprises a digital flat panel detector having an electron well density below around 500 electrons per square micron.
11. The apparatus for imaging a breast of claim 9 wherein the image processing apparatus is further configured to limit the frame integration time of the first sub-image to a frame integration time which is less than a frame integration time determined to cause sensor saturation when the sensor is unobstructed.
12. The apparatus for imaging a breast of claim 9 wherein the image processing apparatus is further configured to cause the frame integration time of the second sub-image to be:
greater than the frame integration time of the first sub-image; and
equal to or less than the frame integration time of the first sub-image multiplied by a projected signal level at a selected location for the composite mammography image showing a selected dense tissue divided by the measured signal level at the selected location of the first sub-image showing the selected dense tissue.
13. The apparatus for imaging a breast of claim 9 wherein the image processing apparatus is further configured to combining the sub-images into a two-dimensional composite mammography image by adding the sub-images.