Abstract: A scanning type radiographic imaging system is disclosed which employs novel means to produce comparable radiation intensity in the object regions being radiographed. Such result is achieved with variable radiation attenuating elements having their attenuation controlled during this scanning process with novel feedback control means. The feedback control is produced with a stationary detection unit having circuit means which generates the electrical control signals.

Abstract: A method and apparatus for providing dual energy radiation images of a patient in a kinestatic charge detection system utilizes first and second kinestatic charge detectors commonly connected to apparatus for rotating the detectors about a radiation source at a predetermined velocity. The detectors are adjusted such that ion drift velocity in each detector is equal in magnitude but opposite in direction to the velocity of rotation of the detectors. The radiation from the radiation source is modulated such that relatively low average energy radiation impinging on the patient is received by the first detector and relatively high average energy radiation impinging on the patient is received by the second detector. As the radiation is scanned across the patient and received by the detectors, output data from each detector provides information representative of the intensity of radiation received during the scan. The output data is then combined by a imaging system to form a difference image.

Abstract: In digital subtraction angiography a low X-ray energy temporal subtraction image is displayed on a video monitor. Regions in the temporal image frame that contain motion artifacts are outlined by using a cursor. The coordinates of the pixels in the defined outlined region are stored in a processor memory. The data for a related hybrid subtraction image are developed and stored. The processor then effects substitution of the hybrid subtraction image pixels, that fall within the same defined region, into the temporal subtraction image. The combined image data are transferred to a display controller memory which controls display of the combined image on a monitor. A method and means are provided for automatically determining the optimum value of the weighting coefficient applied to the high energy temporal subtraction image that results in the most complete cancellation of everything in the two images except the contrast medium filled blood vessel when the high and low energy temporal images are subtracted.

Abstract: In a subtraction angiography hybrid difference images are generated and reviewed visually. Hybrid images that exhibit no x-ray contrast medium and are free of artifacts are identified and selected for forming an integrated mask image. Hybrid images that exhibit contrast medium and are free of artifacts are identified and selected for forming an integrated contrast medium image. The selected images that exhibit no contrast medium are integrated and those that exhibit contrast medium are integrated separately. The result of one integration is subtracted from the other to yield a single final image that exhibits substantially only the contrast medium in a blood vessel. In an alternate method temporal difference images are reviewed and a similar selection of some that exhibit no contrast medium and some that exhibit contrast medium is made. These images are separately integrated and subtracted to yield a single final image that exhibits substantially only contrast medium in the blood vessel.

Abstract: Apparatus and methods are provided for performing temporal and hybrid subtraction of X-ray images. In one mode, using three memories, a pair of low and high energy X-ray exposures are made before an X-ray contrast medium arrives in a blood vessel to provide mask images. After contrast arrival additional high and low energy exposures are made and the low energy mask is subtracted from the low energy post-contrast images and the high energy mask is subtracted from the high energy post-contrast images and the resulting sequence of low and high energy temporal difference images are stored. The low energy temporal difference images are displayed. If motion artifacts are perceived, hybrid subtraction of low and high energy temporal difference images is undertaken to produce an image data set in which motion artifacts are removed. In an alternate mode, which uses four memories, low and high energy pre-contrast mask images are stored in one pair of memories.

Abstract: In a digital fluoroscopy system, analog video signals representative of successive x-ray image frames are converted to digital pixel values that are used as addresses, respectively. A digital memory stores at its respective locations a digital value corresponding to the logarithm of an address value so that when a digital pixel value represented by an address is fed from the analog-to-digital converter to the memory the memory will output the logarithm of the pixel value in digital form. Pixel values for successive x-ray images are subtracted in-phase on a pixel-by-pixel basis to produce digital difference pixel signals which are converted to analog video signals for driving a television monitor that displays an image representative of the difference between x-ray images.

Abstract: Image frames produced consecutively with x-ray beams having different spectral bands or average energy levels are converted to analog video signals and then to digital data. The digital data for an image at one energy is stored in a memory and the ensuing data for the next image is subtracted from the stored data in an alternate or cyclic fashion. The resulting difference data is converted to analog video signals and displayed on a television monitor at standard frame rates. The same system can be used to store a digitized data mask frame and the digital data for ensuing frames can be subtracted from the mask. In some embodiments a buffer is used to allow removal of data from memory without having the data from a preceding frame overwritten by ensuing frames.

Abstract: An x-ray source projects successive high and low energy x-ray beam pulses through a body and the resultant x-ray images are converted to optical images. Two image pick-up devices such as TV cameras that have synchronously operated shutters receive the alternate images and convert them to corresponding analog video signals. In some embodiments, the analog signals are converted to a matrix of digital pixel signals that are variously processed and subtracted and converted to signals for driving a TV monitor display and analog storage devices. In other embodiments the signals are processed and subtracted in analog form for display. The high and low energy pulses can follow each other immediately so good registration between subtracted images is obtainable even though the anatomy is in motion. The energy levels of the x-ray pulses are chosen to maximize the difference in attenuation between the anatomical structure which is to be subtracted out and that which remains.