Loading patent…
AssigneeThe United States of America as represented by the Department of Health, Education and Welfare
InventorRodney A. Brooks
Estimating the term…
A dual-energy detector system for use in computer assisted tomography. This system produces two independent sets of information from one scan, namely, high-energy and low-energy data. The system employs two cooperating detectors. The first one responds primarily to low-energy photons, allowing most high-energy photons to pass through. The second detector lies behind the first and detects the remaining photons. Thus, two electrical signals are generated which contain information in two different energy ranges, which signals can be computer-processed. The attenuation coefficients at these two energies are sufficiently different so that differential diagnosis and chemical identification may be aided. The computer-processed signals may be employed to provide any of (a) beam-hardening correction, (b) chemical identification and composition of tissues, such as lesions, bone, etc., (c) localization of injected contrast material, or (d) attenuation coefficients for radiation therapy planning.
In a computerized tomography apparatus of the type including a detector system and having means to generate an X-ray scanning beam and to pass said beam through material to be examined, the improvement wherein the detector system comprises two overlapping energy-sensing portions which are located in the exit path of said scanning beam, one of said portions being a front energy sensing portion including a first input crystal of calcium fluoride responsive primarily to low-energy photons and allowing most high-energy photons to pass therethrough, the other sensing portion including a second input crystal of sodium iodide responsive to said high energy photons, said portions generating respective signals derived from two different but overlapping energy ranges of the X-ray beam which is to be processed to provide energy dependent attenuation data resulting from the passage of said scanning beam through the material under study.
In a method of computer assisted tomography including employing a polyenergetic X-ray scanning beam directed through material under examination and obtaining energy-dependent attenuation data, the improvement wherein the obtaining step comprises simultaneously intercepting selected different energy ranges of photons in the exit X-ray beam leaving the material by first passing the X-ray beam through crystalline calcium fluoride to capture low-energy photons and then passing the remainder of said exit beam into crystalline sodium iodide to capture the remaining high-energy photons, and converting the selected different-energy photons into respective two output electrical signals which are in accordance with the attenuation characteristics of the material at the selected different photon energy ranges.
In a method of computer assisted tomography including employing a polyenergetic X-ray scanning beam directed through material under examination and obtaining energy-dependent attenuation data, the improvement wherein the obtaining step comprises intercepting the low-energy photons in the exit beam and converting said low-energy photons into a "low-energy" electrical signal, and simultaneously intercepting the high-energy photons in the exit beam and converting said high-energy photons into a "high energy" electrical signal,
Dependencies are inferred from the claim text.