Respiratory-Gated Gantry Speed Modulation for 4D Cone Beam CT
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Solution Overview
Problem
Current 4DCBCT imaging techniques suffer from poor image quality and streak artifacts due to inadequate angular separation of projections, especially in patients with irregular breathing, leading to increased radiation dose and suboptimal image reconstruction.
Innovation Solution
A method that optimizes 4DCBCT imaging by varying the time interval and acceleration of the gantry rotation and projection acquisition based on real-time analysis of the patient's respiratory signal, using mathematical optimization models to regulate the gantry angle and projection pulse rate, ensuring more even angular spacing and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If constant gantry rotation speed and fixed projection acquisition rate are used, then the imaging process is simple to implement, but the angular separation of projections becomes uneven leading to poor image quality and streak artifacts
Solution Approach 1:
The patent implements dynamic gantry rotation speed modulation and variable projection acquisition timing based on real-time respiratory phase detection. The system transitions from fixed constant-speed rotation to adaptive speed control that varies the time intervals between projections according to the patient's breathing cycle, ensuring optimal angular separation during different respiratory phases while maintaining manageable system complexity through automated feedback control.
Solution Approach 2:
The system dynamically changes multiple parameters including gantry rotation speed, projection acquisition timing, and pulse rate based on respiratory phase. By modulating these parameters in real-time according to detected breathing patterns, the system achieves improved angular separation and image quality without requiring overly complex manual control mechanisms, as the changes are automated based on physiological feedback.
2Manufacturing precision
If more projections are acquired to improve image quality, then the radiation dose increases, but acquiring fewer projections reduces image quality
Solution Approach 1:
The patent utilizes periodic respiratory cycles as the basis for structuring projection acquisition. By synchronizing projection timing with the periodic nature of breathing, the system concentrates acquisitions during optimal phases (such as end-inspiration or end-expiration when motion is minimal) rather than distributing them uniformly throughout the cycle. This periodic synchronization improves image quality with fewer total projections, thereby reducing radiation dose while maintaining diagnostic utility.
Solution Approach 2:
The system performs preliminary respiratory phase detection and planning before actual projection acquisition begins. By pre-characterizing the patient's breathing pattern and identifying optimal acquisition windows in advance, the system can efficiently schedule projections during phases that yield the best image quality, minimizing the total number of projections needed and thus reducing radiation exposure while ensuring sufficient image quality.
3Productivity
If the gantry rotates faster to reduce imaging time, then productivity increases, but the angular separation between projections becomes insufficient leading to poor image reconstruction
Solution Approach 1:
The system employs dynamic speed adjustment where the gantry rotation velocity is continuously adapted during the imaging process. Rather than maintaining a fixed high speed that would compromise angular separation, the rotation speed varies dynamically to ensure adequate angular spacing between projections while still completing the scan in reduced time. This is achieved by accelerating during phases where angular separation is less critical and decelerating when precise separation is needed.
Solution Approach 2:
The system incorporates real-time feedback from respiratory sensors to continuously monitor the actual angular separation between projections. This feedback information is used to adjust gantry speed on-the-fly, ensuring that angular separation requirements are met while maintaining efficient imaging speed. The closed-loop control allows the system to optimize both productivity and image quality by making real-time corrections based on actual performance rather than relying on pre-set fixed parameters.
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 enhances the angular separation of projections, reduces the radiation dose, and improves image quality, particularly in patients with irregular breathing, allowing for more accurate tumor targeting and reduced exposure to healthy tissue.
Implementation Method 1
For each projection, a cone shaped beam is emitted by the source and the attenuation of the beam is recorded by the detector
Data Source
AI summary
A method of optimizing 4D cone beam computed tomography (4DCBCT) imaging is provided that includes using a scanner to generate projections of a target, where the projections are used to form a cone beam computed tomography (CBCT) scan of the target, where the CBCT includes a 3D image of the target, and using an appropriately programmed computer to control rotation speed of a gantry and projection acquisition of the CBCT in real-time according to a measured patient respiratory signal, where the real-time acquisition of the CBCT forms an optimized 4DCBCT image set.