Abstract: Systems and methods for localizing a target for radiotherapy based on digital tomosynthesis are provided. According to one method, DTS verification image data of a target located within or on a patient is generated. The DTS verification image data is compared with DTS reference image data of the target. Radiotherapy positioning information is determined based on the comparison of the DTS verification and reference image data.

Abstract: The present invention describes improvements to digital tomosynethesis, whereby a plurality of x-ray projection images are shifted and summed to form a matrix of tomographs at variable plane heights. Prior to tomosynthesis, the projection images are weighted by a weighting function which falls off towards shallower angles of the x-ray tube during acquisition, in order to improve the reconstructability of between-plane structures. A matrix of blurring functions is then determined, describing the blurring of structures in all planes for every tomosynthesis reconstruction. Actual patient structures are then reconstructed by solving a matrix equation containing the matrix of tomosynthesized images and the matrix of blurring functions. The patient structure images are then improved by a hybrid correction routine which combines low spatial frequencies from a wide swing of the x-ray source with high and mid spatial frequencies from a narrow swing of the x-ray source.

Abstract: Method and apparatus for variably compensating a radiographic image irradiates the patient with an x-ray beam. X-ray attenuation (or transmission) variations within the patient are detected and used to modulate the x-ray beam in order to produce an image with equalized exposure and increased SNR. The beam modulation information is used to produce a beam profile image which is an image of the exposure modulation given to the x-ray beam. After the modulated x-ray beam passes through the patient, a compensated image is produced. Both the beam profile image and the compensated image are logarithmically transformed and combined. The logarithmically transformed beam profile image is selectively weighted in order to alter the appearance of the compensated image by various degrees. The combined image is then retransformed and provided to a video monitor for display.

Abstract: X-ray compensation masks (51) are prepared by exposing an X-ray target object (43), such as a patient, to a first beam of X-rays. The X-ray fluence from the patient is received by an electronic image receptor (44) which provides an output signal indicating the intensity of the X-rays at all positions in the image field. The image information is converted by an image processor (47) to transformed X-ray intensity values for a plurality of pixels which cover the image field. A mask generating controller (48) determines the minimum transformed intensity value for any pixel, assigns to each pixel an attenuation number which is proportional to the difference between the transformed intensity value for the pixel and the minimum transformed intensity value, and issues control signals to a mask former (49) which deposits on a non-attenuating substrate (50) attenuating masses in a two dimensional array of pixels with the mass thickness in each pixel proportional to the attenuation number.