Alternating X-ray Tubes for Stereoscopic Tracking
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Solution Overview
Problem
Current stereoscopic X-ray tracking systems in radiotherapy and radiosurgery expose patients to high radiation levels due to simultaneous activation of X-ray imaging units, which is detrimental for prolonged treatments.
Innovation Solution
A non-diagnostic, stereoscopic X-ray tracking method using two X-ray tubes that alternate in capturing images along intersecting lines of sight, allowing for precise object tracking by determining intersection points and minimum traversals to approximate the three-dimensional position of moving objects, thereby reducing radiation exposure by up to 50% without compromising temporal resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both X-ray imaging units are activated simultaneously to track moving objects in real time, then the temporal resolution and accuracy of object position determination is improved, but the patient's radiation exposure increases significantly
Solution Approach 1:
The patent implements periodic action by alternating the activation of two X-ray imaging units in time sequence rather than operating them simultaneously. The first imaging unit captures images at specific time points, then the second imaging unit captures images at intermediate time points, creating a periodic sampling pattern that reduces cumulative radiation exposure while maintaining adequate temporal resolution for tracking moving objects
2Speed
If X-ray imaging rate is increased to accurately track fast moving objects, then the temporal resolution is improved, but the radiation exposure and heat load on X-ray tubes increase
Solution Approach 1:
The system uses periodic action by alternating between two X-ray tubes in a time sequence, allowing each tube to operate at high scanning rates during its active periods while the other tube rests and cools. This periodic operation pattern enables high temporal resolution for tracking fast moving objects while distributing the thermal load and preventing excessive heat accumulation in individual tubes
Solution Approach 2:
The patent applies segmentation by dividing the continuous high-rate imaging task into alternating segments handled by two separate X-ray tubes. Each tube is activated for specific time intervals to capture images, then deactivated while the other tube takes over, effectively segmenting the imaging workload to reduce continuous heat generation in a single tube
3Measurement precision
If two X-ray tubes operate simultaneously to provide stereoscopic imaging, then the three-dimensional tracking accuracy is improved, but the system complexity and radiation dose increase
Solution Approach 1:
The system achieves three-dimensional tracking accuracy through periodic action by alternating two X-ray tubes in time sequence rather than operating them simultaneously. The first tube captures images from its viewing angle, then the second tube captures images from its different angle at intermediate time points. This temporal alternation with known switching patterns allows computational reconstruction of three-dimensional positions while simplifying system control compared to simultaneous operation
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 method significantly reduces patient radiation exposure, extends system operational time by minimizing X-ray tube activation, and maintains high temporal resolution, particularly along the main axis of object movement, while providing accurate real-time tracking.
Implementation Method 1
two X-ray tubes are used to repeatedly acquire x-ray images of an object along two different lines of sight
Data Source
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AI summary
A non-diagnostic, stereoscopic x-ray tracking method uses two x-ray tubes (1, 2) to alternately and repeatedly record x-ray images of an object (O[1]-O[3]) along two different viewing lines (X[1,1], X[1,2], X[1,3], X[2,1'], X[2,2'], X[2,3']). An extrapolated object trajectory is ascertained by determining surfaces and intersecting points. The minimum traverse from the object trajectory onto a current viewing line is ascertained and the three-dimensional position of the tracked object is approximated at the point at which the object trajectory meets the viewing line. The non-diagnostic, stereoscopic x-ray tracking method involves using two x-ray devices to repeatedly record x-ray images of an object along two different point of views through a target area of an irradiating apparatus, the two different points of view intersecting at a known angle. The two x-ray devices are controlled such that each x-ray device alternately obtains an image of the object as the object moves through the target area, and with the assistance of a computer. The method includes determining a first surface that is spanned by a first viewing line from the first x-ray device to the object in an image recorded at an earlier point in time and a second viewing line from the first x-ray device to the object in an image recorded at a later point in time; determining a first intersecting point from a third viewing line from the second x-ray device to the object in an image recorded at a point in time between the earlier point in time and the later point in time, and the first spanned surface; determining a second surface, where the later point in time becomes a new earlier point in time, and where the second surface is spanned by the second viewing line from the first x-ray device to the object in an image recorded at the new earlier point in time and a fourth viewing line from the first x-ray device to the object in an image recorded at a new later point in time; and determining a second intersecting point from a fifth viewing line from the second x-ray device to the object in an image recorded at a point in time between the new earlier point in time and the new later point in time, and the second spanned surface. A spatial straight connecting line that connects the first and second intersecting points is calculated. A minimum transversal between the spatial straight connecting line and the fourth viewing line of the object at the new later point in time is calculated. A three-dimensional position of the tracked object is approximated from an intersecting point of the minimum transversal and the fourth line of site at the new later point in time. Independent claims are included for: (1) computer program embodied on a computer readable medium for non-diagnostic, stereoscopic x-ray tracking of moving objects in the context of radiotherapy and radiosurgery; and (2) stereoscopic x-ray tracking device for tracking moving objects in the context of radiotherapy and radiosurgery.