Adjustable X-ray filter
Inventors
Assignees
Publication Number
US-9767935-B2
Publication Date
2017-09-19
Expiration Date
2033-06-28
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Abstract
The present invention pertains to a system and method for adaptive X-ray filtration comprising a volume of X-ray attenuating material with a central less attenuating three-dimensional region. The volume of X-ray attenuating material can be positioned within 10 cm from an X-ray source and rotated around an internal axis of rotation. The volume of X-ray attenuating material can be symmetric around the internal axis while the central less attenuating region can be asymmetric around the internal axis. Rotating the volume by a predetermined angle around the internal axis can change the amount of attenuation of an X-ray beam through the filter. The volume can be rotated by the same predetermined angle as an imaging subject or X-ray source and detector are rotated during X-ray image acquisition.
Core Innovation
The invention presents a system and method for adaptive X-ray filtration. It specifically comprises a volume of X-ray attenuating material that features a central, less attenuating three-dimensional region. This volume can be situated within 10 cm of an X-ray source and is constructed to rotate around an internal axis of rotation. The outer volume of attenuating material may be symmetric around this axis, while the central region is asymmetric, and by rotating the volume by a predetermined angle, the level and pattern of attenuation applied to the X-ray beam is altered.
The primary problem addressed is the difficulty in controlling the dynamic range of exposure seen by X-ray detectors, especially in computed tomography (CT) where images are acquired from multiple projection angles and patient profiles can vary widely. Traditional 'bowtie' filters have provided static solutions to this issue, but lack adaptability to varying patient sizes and changing projection angles, limiting their optimal effectiveness and making it challenging to minimize patient X-ray dose while maximizing image quality.
Embodiments of the invention offer a rotatable filter element, which may take the form of a cylinder, incorporating a less attenuating central region such as a hollow or elliptic cylinder. The central region’s shape or dimensions can be tailored to individual patient profiles or imaging subjects. By rotating in synchrony with the X-ray source, detector, or imaging subject during acquisition, the system adaptively modulates attenuation based on projection angle. Further, features such as flexible sheets, conformable attenuating media, reservoirs for surplus media, and shape controllers enable the device to adapt its physical and attenuative properties to the requirements of each specific imaging situation.
Claims Coverage
There is one independent claim in the patent, defining the inventive features of the X-ray filter.
Flexible sheet and conformable attenuating media structure
An X-ray filter comprising: - A first flexible sheet for constructing a portion of the filter. - A conformable attenuating media in contact with the first flexible sheet. - A second sheet (which may also be flexible) in contact with the attenuating media, forming a sandwich-like assembly. - A separator connecting the first and second sheets and maintaining a separation distance between them.
The inventive features defined by the independent claim focus on a structure involving flexible sheets enclosing a conformable attenuating media with controlled separation by a separator, offering adaptive filtration characteristics.
Stated Advantages
Provides adaptive bowtie filtration with relatively simple and fast implementation methods and enhanced flexibility relative to existing systems.
Documented Applications
Computed tomography (CT) X-ray imaging for medical applications, including imaging of human head and dental structures.
Metrology applications, including CT scans of workpieces and parts with customizable attenuation maps.
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