X-ray Apparatus Collimator Offset for Detector Area Expansion
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Solution Overview
Problem
The cost and size limitations of flat panel X-ray detectors restrict the maximum aperture of X-ray apparatus, particularly for large patients, and existing solutions that increase aperture by offsetting the X-ray beam result in lower image resolution or require X-ray tubes with inadequate performance.
Innovation Solution
An X-ray apparatus with a rotatable support and a collimator that allows the X-ray source to be offset by a few degrees, enabling the X-ray beam to be directed non-orthogonally, thus utilizing the full field of the X-ray tube and avoiding edge effects, while maintaining image quality through efficient beam collimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the flat panel detector size is increased to cover larger patients, then the aperture is improved, but the cost and device complexity increase
Solution Approach 1:
The detector is made movable relative to the X-ray source through a translation stage, allowing dynamic adjustment of the detector position to offset locations. This dynamic capability enables the system to achieve effective aperture for large patients without requiring a permanently large detector, thus reducing device complexity and cost while maintaining the ability to handle various patient sizes.
2Area of stationary object
If the X-ray beam is offset from the central axis to increase aperture, then the aperture is improved, but the image resolution deteriorates
Solution Approach 1:
The system dynamically adjusts both the detector position and the X-ray beam offset in a coordinated manner. By moving the detector to offset locations and simultaneously adjusting the beam direction, the system maintains proper geometric relationships that preserve image resolution while achieving the desired aperture for large patients.
Solution Approach 2:
The system changes multiple parameters simultaneously - both the detector position and the beam offset angle are adjusted together. This coordinated parameter change allows the system to maintain the geometric relationships necessary for high-resolution imaging while achieving increased aperture, rather than sacrificing resolution for aperture gain.
3Area of stationary object
If an X-ray tube with wider beam capability is used to accommodate offset beams, then the aperture is improved, but the choice of suitable tubes is limited and performance may be inadequate
Solution Approach 1:
By making the detector movable rather than requiring a fixed wide beam capability, the system can achieve aperture expansion through detector repositioning. This dynamic approach allows the use of standard X-ray tubes with conventional beam widths, as the detector offset compensates for the beam geometry requirements, thereby maintaining tube selection flexibility and avoiding the need for specialized wide-beam tubes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for a wider choice of X-ray tube designs, optimizing performance by utilizing the full extent of the X-ray beam and maintaining image quality, even for larger patients, without the need for excessively wide field tubes.
Implementation Method 1
a source of X-rays emitting a cone beam centred on a beam axis
Implementation Method 2
a collimator to limit the extent of the beam
Data Source
AI summary
An investigative X-ray apparatus comprises a source of X-rays emitting a cone beam centred on a beam axis, a collimator to limit the extent of the beam, and a two-dimensional detector, the apparatus being mounted on a support which is rotatable about a rotation axis, the collimator having a first state in which the collimated beam is directed towards the rotation axis and the second state in which the collimated beam is offset from the rotation axis, the two-dimensional detector being movable accordingly, the beam axis being offset from the rotation axis by a lesser amount than the collimated beam in the second state. The X-ray source is no longer directed towards the isocentre as would normally be the case; the X-ray source is not orthogonal to the collimators. This is advantageous in that the entire field of the X-ray tube can be utilised. As a result, a lesser field is required of the X-ray tube and the choice of tube designs and capacities can be widened so as to optimise the performance of the X-ray tube in other aspects.