The present invention relates generally to an x-ray target assembly, and more particularly, to an x-ray target assembly incorporating multiple focal spots.
X-ray production is traditionally accomplished through the process of colliding an electron beam of charged particles with a target assembly. X-rays are produced from the interaction of the electron beam and atoms within the target assembly. This is accomplished through the use of target assemblies with high atomic numbers. The electrons are usually produced by a hot filament and are accelerated to the target by a large potential. When they strike the target, they are deflected by the target atoms and this generates the x-rays. This is the principal mechanism for the production of x-rays for use in computed tomography systems.
Unfortunately, in many target assemblies utilized in CT systems a large percentage of the electron energy is dissipated as heat. This generates a multitude of problems. Many existing target assemblies may not generate sufficient x-rays without a significant introduction of electron energy. Increase in electron energy in these designs, however, further increases the energy that must be dissipated as heat. This, in turn, creates a danger to the target surface and is known to melt the target surface if not carefully controlled. Heat dissipation in combination with adequate x-ray production can also place difficulties on the reduction of x-ray focal spot dimensions.
Flat-panel transmission x-ray source designs are presently utilized to generate multiple focal spots on the imaging object simultaneously. The use of such multiple focal spot imaging can improve volumetric CT imaging. Existing multiple focal spot designs, however, often suffer from the aforementioned concerns regarding the difficulty of generating sufficient x-rays in order to generate good CT images without melting the target assembly.
It would, therefore, be highly desirable to have an improved target assembly capable of generating an increase number of x-rays without melting the target assembly. It would additionally be highly desirable to have an improved target assembly that could provide reduced focal spot dimensions. Finally it would be highly desirable to have an improved target assembly suitable for use in multi-focal spot imaging such that volumetric CT imaging and perfusion studies can be improved.
A flat panel x-ray tube assembly is provided comprising a cathode assembly including a plurality of emitter elements. An anode substrate is included having a substrate upper surface facing the plurality of emitter elements and a substrate lower surface. The substrate upper surface is positioned parallel to the plurality of emitter elements. A plurality of target wells are formed in the substrate upper surface. Each of the plurality of target wells comprises a first angled side surface positioned at an acute angle relative to the substrate upper surface. A plurality of first target elements is applied to each to one of the first angled side surfaces. The first target elements generate x-rays in a direction perpendicular to the plurality of emitter elements in response to electrons received from one of the plurality of emitter elements.
Other features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.
Referring now to
The rotation of the scanner assembly 12 and the operation of the flat panel x-ray tube assembly 14 are preferably governed by a control mechanism 26. The control mechanism 26 preferably includes an x-ray controller 29 that provides power and timing signals to the flat panel x-ray tube assembly 14 and a scanner motor controller 30 that controls the rotational speed and position of the scanner assembly 12. A data acquisition system (DAS) 32 in control mechanism 26 samples analog data from the detector elements 20 and converts the data to digital signals for subsequent processing. An image reconstructor 34 receives sampled and digitized x-ray data from DAS 32 and performs high speed image reconstruction. The reconstructed image is applied as an input to a computer 36 which stores the image in a mass storage device 38.
The computer 36 also can receive commands and scanning parameters from an operator via console 40 that has a keyboard or similar input device. An associated display 42 allows the operator to observe the reconstructed image and other data from the computer 36. The operator supplied commands and parameters are used by computer 36 to provide control signals and information to the DAS 32, x-ray controller 28, and scanner motor controller 30. In addition, the computer 36 operates a table motor controller 44 which controls a motorized table 46 to position patient 22 within the scanner assembly 12. Particularly, the table 46 moves portions of the patient 22 through the scanner opening 48.
A detailed illustration of the flat panel x-ray tube assembly 14 is illustrated in
The electron beams 54 are generated and directed toward the anode substrate 56 for the purpose of generating x-rays and specifically a plurality of x-ray focal spots 64. An individual x-ray focal spot 64 is associated with each the target wells 58 such that imaging such as volumetric imaging can be performed. The x-rays are generated by impacting the electron beams 54 into a target element 66. The present invention provides a unique approach to this methodology by including a plurality of first angled side surface 68 within the anode substrate 56. The plurality of first angled side surfaces 68 are orientated at an acute angle 70 relative to the substrate upper surface 60 (see
The advantages of the present invention are easily demonstrated in
It is contemplated that the present invention can further include a plurality of second angled side surfaces 80 formed in the anode substrate 56. It is contemplated that each of the plurality of second angled side surfaces 80 faces a corresponding one of the plurality of first angled side surfaces 68. In this fashion, a v-shaped target well 82 is formed (see
Although the plurality of target wells 58 and target elements 56 have thus far been illustrated in a line of target wells 86 producing a plurality of focal spots 64 along a linear line, it should be understood that the plurality of target elements 56 may in fact be arranged in two dimensional matrix of target wells 88 that generate focal spots 64 along a two-dimensional matrix. This particular embodiment, when taken in light of the advantages provided by the structure of the present invention, can provide numerous benefits to imaging applications such as volumetric CT imaging.
While particular embodiments of the invention have been shown and described, numerous variations and alternative embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.