Panoramic X-ray Image Reconstruction Using Software Focus Adjustment
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Solution Overview
Problem
Conventional panoramic x-ray devices struggle to produce a well-focused image of the human jaw, which is not a perfect circular arc, as they can only adjust the focus position and detector strip width during exposure, leading to incorrect focusing if the jaw does not match the pre-programmed contour or is positioned differently.
Innovation Solution
Software that processes x-ray data to generate a panoramic image by selectively summing data from sensors at specific intervals, allowing for post-exposure adjustment of the line and depth of focus, enabling sharper imaging of the dental arch by allowing users to adjust a control curve to match the actual jaw contour.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focus position is adjusted during exposure to match the jaw contour, then the image sharpness is improved, but the device complexity increases due to complicated movement mechanisms
Solution Approach 1:
The patent replaces the mechanical movement system with a computational approach. Instead of physically moving the detector or source to track the jaw contour, the system uses software to reposition and reweight projection data from a fixed circular scan geometry, achieving focus adjustment without mechanical complexity
Solution Approach 2:
The patent creates a virtual model of the jaw contour and uses this digital representation to guide the repositioning of projection data. The actual physical scan remains simple circular motion, while a computational copy of the jaw geometry enables post-exposure focus adjustment
2Measurement precision
If the detector strip width is narrowed to increase depth of focus, then the area of sharp focus is improved, but the exposure time or intensity must be increased
Solution Approach 1:
The patent changes the parameter of detector strip width dynamically during image reconstruction. Instead of using a fixed narrow strip that requires long exposure, the system reconstructs images with variable strip widths, using wider strips for regions requiring less depth of focus to maintain adequate signal intensity
3Measurement precision
If the focus position is adjusted during exposure, then the image quality is improved, but the adaptability to different jaw contours is limited to pre-programmed shapes
Solution Approach 1:
The patent makes the focus adjustment dynamic and adaptive rather than static and pre-programmed. The system allows real-time modification of the virtual jaw contour model and recalculates the focus position accordingly, enabling adaptation to actual patient anatomy rather than predetermined shapes
Solution Approach 2:
The patent implements a feedback mechanism where the actual jaw contour (determined from preliminary imaging or user input) is used to adjust the reconstruction parameters. The system continuously refines the focus position based on the measured or specified jaw geometry, ensuring optimal image quality for the specific patient
4Measurement precision
If the detector strip width is adjusted during exposure, then the depth of focus is improved, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical detector movement or resizing mechanism with a computational approach. The physical detector remains fixed, but the effective detection width is adjusted through software by selecting and weighting different detector elements during image reconstruction
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
Enables sharper and more accurate panoramic imaging of the dental arch by allowing post-exposure adjustment of focus, improving image quality and ensuring the entire jaw is in focus, even if it deviates from the pre-programmed contour or position.
Implementation Method 1
A panoramic x-ray image is conventionally made by placing the target between a source of x-rays and a detector of the x-rays
Implementation Method 2
X-ray absorbing structures in the target cast an x-ray shadow on the detector strip
Implementation Method 3
More recent panoramic x-ray machines use a charge-coupled device (CCD) or a CMOS detector array, and a similar panoramic image can also be produced utilizing an Amorphous Silicon Flat Panel detector
Implementation Method 4
By stepping the acquired charge across the detector array and integrating the image at a controlled speed, the focusing action of a moving film can be exactly imitated
Data Source
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AI summary
A method and apparatus for generating a panoramic image of part of a target, comprises providing a scanner having a source of penetrating radiation facing a detector having an array of sensors for the penetrating radiation. The target is positioned between the source of penetrating radiation and the detector, and scanned with relative rotation of the scanner and the target. Radiation received at a plurality of the sensors spaced apart in the circumferential direction of the relative rotation is separately recorded. A panoramic image is generated by combining for each pixel of the panoramic image outputs from different sensors at different times during the relative rotation, the combined outputs being selected to represent rays of radiation passing through a point on a defined curve. The generated panoramic image and a graphical representation of the defined curve are displayed. Instructions are received from a user to alter the defined curve. The generating and displaying of the panoramic image are repeated using the altered curve.