Marker-Guided Cephalometric Reconstruction to Reduce Chatter Marks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing linear scan cephalometric x-ray systems suffer from image artifacts known as chatter marks due to mechanical and motor-related deviations, leading to reduced image quality and diagnostic suitability, and existing solutions either increase system complexity or patient dose.
Innovation Solution
A computer-implemented method using x-ray opaque markers in the collimator to adjust the position of projection images during reconstruction, reducing chatter marks through a shift & add technique, thereby improving image quality without increasing mechanical demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If linear scan systems with secondary aperture and ceph detector are used, then x-ray dose is reduced, but mechanical deviations cause chatter marks that reduce image quality
Solution Approach 1:
The system detects the real position of the ceph detector and secondary aperture during the linear scan using x-ray opaque markers, compares it with the target position, and applies compensatory shifts to the projection images during reconstruction. This feedback mechanism corrects mechanical deviations in real-time, eliminating chatter marks while maintaining the dose-reducing configuration.
Solution Approach 2:
The system changes the positional parameters of the projection images during reconstruction by applying shifts based on the detected marker positions. This parameter adjustment compensates for mechanical deviations without requiring physical repositioning of the ceph detector or secondary aperture, thereby maintaining image quality while preserving the low-dose configuration.
2Reliability
If one-shot ceph sensors are used, then chatter marks are eliminated, but system cost and sensor size increase significantly
Solution Approach 1:
The system replaces the need for expensive one-shot ceph sensors with a linear scan system that uses software-based correction. Instead of relying on a single high-cost sensor to capture the entire image in one shot, the system uses multiple low-cost projection images acquired during linear scanning, then applies digital shifting and adding during reconstruction to eliminate chatter marks.
Solution Approach 2:
The system introduces x-ray opaque markers as intermediaries to detect and track the position of the ceph detector and secondary aperture during scanning. These markers enable the system to measure mechanical deviations and apply appropriate corrections, serving as a bridge between the mechanical scanning system and the image reconstruction process.
3Productivity
If scan speed is increased to maintain constant dose without secondary aperture, then dose is maintained, but image quality reduces
Solution Approach 1:
The system uses marker detection to provide feedback on the actual positions of the ceph detector and secondary aperture during scanning. This feedback enables the reconstruction algorithm to compensate for position deviations, allowing the system to maintain higher scan speeds without sacrificing image quality, as the digital correction offsets the effects of faster scanning.
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
Enhances diagnostic capability and reduces chatter marks in cephalometric images, allowing for more reliable orthodontic treatment planning and implementation while maintaining cost-effectiveness and patient safety.
Implementation Method 1
acquiring a sequence of projection images by exposing the patient's head with x-rays from an x-ray source
Implementation Method 2
the x-ray ceph collimator has an aperture and one or more x-ray opaque markers which can be detected in the projection images
Data Source
Figure 1
Figure 2~3
Figure 4A~4C
AI summary
The present invention relates to a computer-implemented method of generating a cephalometric image (23) of a patient's head, comprising: a step of acquiring a sequence of projection images (22) by exposing the patient's head with x-rays from an x-ray source (2) while linearly moving an x-ray ceph detector (6) and an x-ray ceph collimator (8) on opposing sides along the patient's head, wherein the x-ray ceph collimator (8) has an aperture (10) and one or more x-ray opaque markers (11) which can be detected in the projection images (22), and wherein the projection images (22) are sequentially read out at a predetermined rate from a predetermined frame (7) of the x-ray ceph detector (6); a step of detecting the real position of the at least one x-ray opaque marker (11) in each of the projection images (22) relative to a target position on the ceph detector (6); a shift & add reconstruction step of adding the projection images (20) after shifting each projection image (22) relative to its preceding projection image (22) by a predetermined shift amount based on the predetermined rate; wherein the positions of the shifted projection images (22) are individually adjusted by an amount corresponding to a difference in the real position and the target position of the least one marker (11) detected in the corresponding projection image (22) to reduce chatter marks prior to the adding in the shift & add reconstruction step.