X-ray or gamma ray systems or devices – Specific application – Absorption
Reexamination Certificate
2001-01-31
2002-10-22
Bruce, David V. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Absorption
C378S004000, C378S901000, C378S037000
Reexamination Certificate
active
06470071
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method, system, and apparatus for controlling, acquiring and processing digital radioscopic image data, and in particular to a method, system and apparatus for controlling and communicating acquired digital radioscopic x-ray image data to a computer running a non-real time operating system.
Medical imaging is a specialty that uses radiation, such as gamma rays, x-rays, high-frequency sound waves, magnetic fields, neutrons, or charged particles to produce images of internal body structures. In diagnostic radiology, radiation is used to detect and diagnose disease, while in interventional radiology, radiation is used to treat disease and bodily abnormalities.
Radiography is the technique of producing an image of any opaque specimen by the penetration of radiation, such as gamma rays, x-rays, neutrons, or charged particles. When a beam of radiation is transmitted through any heterogeneous object, the radiation is differentially absorbed depending upon varying object thickness, density, and chemical composition. The radiation emergent from the object forms a radiographic image, which may then be realized on an image detection medium, such as photographic film directly or by using a phosphor to first create a light image. Radiography is a non-destructive technique of testing a gross internal structure of an object, and is conventionally used in medical and industrial applications. Radiography is used to non-destructively detect medical conditions such as tuberculosis and bone fractures, as well as manufacturing imperfections in materials such as cracks, voids, and porosities.
X-ray radiography finds particular usefulness in medical and industrial applications. X-rays are a form of electromagnetic radiation, and were accidentally discovered in 1895 by Wilhelm Conrad Roentgen. X-rays are alternately referred to as roentgen rays. In circa 1895, Roentgen found that x-rays propagate through an internal object such as a hand and expose photographic film, thereby revealing an internal structure. X-rays exhibit different properties than visible light rays, and were designated by Roentgen as “x-rays,” with “x” referring to the unknown. For example, x-rays are not focused with a traditional optical light lens, but rather use sophisticated focusing techniques. Today, x-rays are categorized as electromagnetic radiation having a frequency range extending between 2.4×1016 Hz to 5×1019 Hz. Most x-rays have a wavelength smaller than an atom and therefore interact with matter in a granular fashion, that is, like bullets of photon energy. X-rays are absorbed by materials according to the exponential absorption law
I
x
=I
O
e
−&mgr;x
=I
O
e
−(&mgr;/&rgr;)&rgr;x
(1.0)
where I
O
is the initial intensity of the x-ray beam; I
x
is the intensity after passage through an object, the object having a thickness x, density &rgr;, linear absorption coefficient &mgr;, and mass absorption coefficient &mgr;/&rgr;.
X-rays are formed through celestial phenomenon, such as internal reactions of stars and quasars, and through electronic x-ray generation devices, such as x-ray tubes. X-ray tubes generally produce x-rays by accelerating a charged particle, such as an electron, through an electrostatic field and then suddenly stopping the x-ray through collision with a solid target. This collision ionizes the solid target by transporting closely held electrons to a higher energy state. As the electrons in the solid target return to their original energy state, x-rays are produced. X-rays are produced within x-ray tubes by accelerating electrons in a vacuum from a cathode toward an anode, with or without particle beam shaping and accelerating through placement of electrodes.
The electronic detection of x-rays is generally referred to as electronic radiography or radioscopy. Prior to electronic detection, radiographic images were captured on photographic film or displayed on a fluorescent screen. Real time visual observation of x-rays on a fluorescent screen is referred to as fluoroscopy. However, as early as the 1930s photo-multiplier tubes (a form of vacuum tube) were developed to produce an electrical signal in response to received light. Photo-multiplier tubes generally respond well to optical range light rays and are therefore often optically coupled with a scintillating material to detect non-optical electromagnetic radiation. The scintillating material converts non-optical radiation, such as gamma rays (emitted by radio-active isotopes used in nuclear medicine) and x-rays into optical radiation. Beginning circa 1980, photo-multiplier/scintillator detectors are generally being replaced by amorphous silicon based photo-cells.
Radioscopy includes one shot x-ray detection, also known as fluorography, and multiple shot x-ray detection, also known as fluoroscopy. Radio-mammography is a form of radioscopy in which the breast is vigorously compressed prior to exposure to maximize detail and minimize radiation exposure. Computed tomography (“CT”), also called computed axial tomography (“CAT”), is a form of radioscopy in which an x-ray tube is rotated around the body while emitting a narrow x-ray beam. The received x-ray beam information is then combined in a computer to produce a two or three dimensional anatomic medical image. Magnetic resonance imaging (“MRI”) is a diagnostic procedure in which a high strength magnet aligns the spin of nuclei within cells of a body, such that each nuclei acts like a radio, both receiving and transmitting radio signals. External radio frequency signals are then applied to the body to disturb the spinning cellular nuclei. After the radio signal is stopped, the nuclei realign with the applied magnetic field while emitting faint radio signals. These faint radio signals correspond to different body tissues and are detected to produce an anatomical image.
Radioscopy and related medical diagnostic imaging technologies use precision control over penetrating radiation and well as precision timing for detection and processing of resultant image data. Medical diagnostic imaging generally acquires and controls a very large amount of image data, which in turn is communicated to computer processing equipment at a very high data rate. To provide control over the generation, detection, and processing of medical diagnostic imaging, computer workstations employ the use of a real time operating system (“RTOS”) to control operation. A real time operating system, such as VXWORKS® by Wind River Systems, Inc. of Alameda, Calif., is an operating system that immediately responds to real time signaling events. On the other hand, non-real time operating systems, such as a WINDOWS® platform or a UNIX® platform, process operations in the form of tasks until the task is complete. Both WINDOWS® and UNIX® are non-real time, multi-task operating systems in which a processor or processors are continuously interrupted to respond to multiple task based system events. Due to the high speed of commercially available processors, multi-tasking operating systems may appear to control a number of simultaneous events. However, a multi-tasking operating system, by design, cannot respond in real time to the high through-put demands of real time processing equipment, such as used in medical diagnostic imaging.
BRIEF SUMMARY OF THE INVENTION
It is therefore desirable to provide an imaging system to control a radiation generation system and an image detection system in real time. The imaging system includes a host computer having a host memory and at least one host processor. The imaging system also includes a detector framing node, which is programmed to receive image data from a plurality of different flat panel detectors. The detector framing node communicates the image data to the at least one host processor over a communication bus independent of a host operating system.
It is further desirable to provide a detector framing node, including a computer communication interface to communicate image data with a host memory of a hos
Baertsch Richard Dudley
Dixon Walter Vincent
Staver Daniel Arthur
Tkaczyk John Eric
Van Stralen Nick Andrew
Breedlove Jill M.
Thompson John F.
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