X-Ray Tube Current Control for Uniform 2D Image Acquisition
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Solution Overview
Problem
Existing X-ray imaging systems face challenges in varying tube current parameters quickly and uniformly across multiple 2D images to account for non-homogeneous patient anatomy, leading to inconsistent image quality and radiation exposure issues, especially in patients with high BMI or osteoporosis.
Innovation Solution
A method to model the response of the X-ray source's tube current using a first-order equation, allowing for the computation of a transitory setpoint value to achieve the desired tube current within a predetermined time frame, ensuring consistent image quality and reduced radiation exposure by adjusting tube current and exposure time parameters dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the tube current parameter is changed quickly to adapt to non-homogeneous patient anatomy, then image quality consistency is improved, but the filament cannot reach the required tube current value quickly enough due to thermal inertia
Solution Approach 1:
The control unit pre-calculates and applies a compensating factor based on the desired tube current change magnitude. This preliminary action anticipates the filament's thermal inertia and adjusts the setpoint accordingly, ensuring the tube current reaches the desired value within the acquisition time frame without waiting for natural thermal response.
Solution Approach 2:
The system dynamically changes the tube current setpoint parameter by applying a compensating factor that varies with the desired tube current change. This parameter adjustment allows the system to overcome the filament's thermal inertia and achieve rapid tube current modulation suitable for varying patient anatomy conditions.
2Ease of operation
If acquisition parameters are determined once using a reference position, then the control process is simplified, but image quality deteriorates for non-homogeneous patient anatomy in different positions
Solution Approach 1:
The system transitions from static, fixed acquisition parameters to dynamic, position-dependent parameters. The control unit continuously adjusts tube current and exposure time parameters based on the C-arm's real-time position and the patient's non-homogeneous anatomy, optimizing image quality for each specific acquisition scenario.
Solution Approach 2:
The system applies different acquisition parameters to different regions and positions along the acquisition path. By accounting for local variations in patient anatomy (e.g., varying tissue density and thickness at different C-arm positions), the system optimizes image quality for each specific location rather than using uniform parameters throughout.
3Manufacturing precision
If exposure time is reduced to avoid motion blur, then image sharpness is improved, but radiation dose increases for the same signal-to-noise ratio
Solution Approach 1:
The system dynamically adjusts both exposure time and tube current parameters to maintain optimal image quality while minimizing radiation dose. By coordinating these parameter changes based on patient anatomy and acquisition position, the system achieves adequate signal-to-noise ratio with shorter exposure times, reducing motion blur risk while controlling radiation exposure.
Data Source
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AI summary
The invention relates to a method for controlling a source (101) of an X-ray imaging system (100), comprising: - changing a desired output value of a tube current parameter of said source (100) from a first value to a second value different from the first value, - computing a third value of the tube current parameter different from the second value such that the output tube current value becomes substantially equal to the second value within a predetermined time frame (ΔT) from said change of the desired output value, - providing said computed third value as a setpoint value for the source (101). The invention also relates to a method for acquiring a plurality of 2D images of a region of interest of a patient's body (P) along a path of acquisition (T) with an X-ray imaging system (100), wherein acquisition parameters of the X-ray imaging system (100) vary along the path of acquisition (T), the acquisition parameters comprising a tube voltage parameter, a tube current parameter and an exposure time parameter, the method comprising: a) determining a set of values of acquisition parameters for each acquired image along the path of acquisition (T); b) if for an acquired image the value of the tube current parameter is modified with respect to a previous image acquisition, applying the above method to determine a third value to use as setpoint value for the source (101) of the X-ray imaging system (100), instead of the value determined in step a), to achieve the value determined in step a) as output of the source (101) at the time of the image acquisition.