Measurement of scatter in x-ray imaging

In a medical diagnosis x-ray imaging system with scatter radiation effects having an x-ray source transmitting a collimated beam through a first object for producing a first intensity image onto an image detector, a method for calibrating the first intensity image by measuring a scatter radiation intensity image comprising the steps of:

• (A) positioning a second object, having a plurality of dispersed openings to allow passage of a corresponding plurality of unattenuated beam areas, in the beam to attenuate a large area of the beam to produce a second intensity image such that the unattenuated beam areas are not concentrated in one location on the image detector, the attenuation of the second object outside the area of each opening being less than 100 percent in the x-ray frequency spectrum;
• (B) replacing the second object with a uniform sheet of material of identical composition and areal density as the second objects to produce a third image intensity onto the image detector;
• (C) generating the scatter radiation intensity image from the first, second and third intensity images;
• (D) subtracting the scatter radiation intensity image from the first intensity image to remove any scattering effects in order to calibrate the first intensity image.

In a medical diagnosis x-ray imaging system with scatter radiation effects having an x-ray source transmitting a collimated beam through a first object for producing a first intensity image onto an image detector comprised of an array of pixels, a method for calibrating the first intensity image by measuring a scatter radiation intensity image comprising the steps of:

• (A) positioning a second object in the beam to attenuate a small area of the beam to produce a second intensity image having a reduced intensity in the area corresponding to a position of the second object, the attenuation of the second object being less than 100 percent in the x-ray frequency spectrum;
• (B) replacing the second object with a uniform sheet of material attenuating the entire beam, the sheet of material having identical composition and areal density as the second object, to produce a third image intensity onto the image detector;
• (C) generating a discriminator image from any variation in intensity between the first intensity image and the second intensity image so that the discriminator image produces intensity values indicative of presence or absence of the second object;
• (D) repeating step (A) through step (C) to generate a plurality of discriminator images corresponding to a plurality of second intensity images;
• (E) forming a sum of the plurality of second intensity image;
• (E) forming a sum of the plurality of the discriminator images;
• (G) dividing the sum of the plurality of second intensity images by the sum of the plurality of the discriminatory images to produce a composite scatter intensity image;
• and
• (H) subtracting the composite scatter radiation intensity image from the first intensity image to remove any scattering effects in order to calibrate the first intensity image.

In a medical x-ray diagnosis system with scatter radiation effects, the system having an x-ray source transmitting a collimated beam for producing an image on an image detector, a method for correcting the image for scatter effects comprising the steps of:

• (A) generating a diagnostic image of a patient having a first intensity on the image detector by interposing the patient in the x-ray beam impinging on the detector;
• (B) generating a first test image by inserting an attenuator having less than one hundred percent attenuation at x-ray frequencies into the beam passing through the patient, the attenuator attenuating predetermined dispersed areas of the beam corresponding to locations of the attenuators to form a reduced intensity image in said locations;
• (C) measuring the image intensity in said locations;
• (D) determining the difference in measured intensity of the image in said locations and an intensity proportional to a predetermined attenuation of the attenuator;
• and
• subtracting the determined difference from the diagnostic image to correct for x-ray scatter.

In a medical x-ray diagnosis system with scatter radiation effects, the system having an x-ray source transmitting a collimated beam for producing an image on an image detector, a method for correcting the image for scatter effects comprising the steps of:

• (A) generating a diagnostic image of a patient having a first intensity on the image detector by positioning the patient in the x-ray beam impinging on the detector;
• (B) generating a first test image by inserting a first attenuator into the beam passing through the patient at predetermined dispersed positions;
• (C) determining an intensity of the first test image in areas of the detector corresponding to the positions of the first attenuator;
• (D) generating a second test image by inserting a second attenuator having identical attenuation characteristics as the first attenuator into the beam so as to attenuate the entire beam;
• (E) determining the intensity of the second test image in the areas of the detector corresponding to the positions of the first attenuator;
• (F) subtracting the intensity obtained in step (E) of determining from the intensity obtained in step (C) of determining to yield an intensity corresponding to the effects of scatter radiation;
• and
• (G) subtracting the scatter radiation intensity from the intensity of the diagnostic image to yield a scatter corrected image.