X-ray Tube Focal Spot Temperature Reduction via Multi-Point Deflection
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Solution Overview
Problem
Traditional x-ray imaging systems face challenges in reducing focal spot temperatures on the target anode during double sampling techniques, leading to heat buildup and performance degradation, which current methods address by lowering power levels or increasing target rotation speed, but these solutions compromise image quality and efficiency.
Innovation Solution
Implementing a multi-point focal spot pattern and asymmetric electron beam biasing within the x-ray tube, where the electron beam wobbles among multiple focal points with a stationary dwell time, reducing continuous heat accumulation by interrupting deflection and allowing for improved cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-point wobbling is used to improve image quality and resolution, then modulation transfer function is improved, but focal spot temperature increases to greater than 3000 degrees Celsius
Solution Approach 1:
The patent divides the single two-point wobble into multiple discrete focal spots arranged in a multi-point pattern. Instead of continuously wobbling between two points, the electron beam is deflected to strike multiple distinct locations on the focal track, segmenting the heat generation across several points rather than concentrating it at two locations.
Solution Approach 2:
The patent implements periodic deflection of the electron beam among multiple focal spots in a controlled sequence. The beam alternates between different focal points with specific timing, creating a periodic pattern that allows thermal energy to dissipate between cycles, preventing continuous heat accumulation at any single location.
2Temperature
If power levels are lowered to reduce focal spot temperature, then temperature is reduced, but x-ray tube performance and peak power capability are compromised
Solution Approach 1:
By segmenting the focal spot into multiple discrete points along the focal track, the total x-ray power can be distributed across these points. This allows the system to maintain high peak power capability when needed while preventing excessive temperature buildup at any individual focal spot, as the heat is divided among multiple locations.
3Temperature
If target rotation speed is increased to lower focal spot temperature, then temperature is reduced, but image quality and efficiency are compromised
Solution Approach 1:
The patent employs dynamic control of the electron beam deflection to actively manage focal spot positioning among multiple points. This dynamic adjustment allows the system to optimize thermal management through multi-point distribution while maintaining the target rotation speed necessary for high imaging efficiency and productivity.
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 effectively reduces focal spot temperatures without compromising x-ray tube performance, achieving lower maximum temperatures and maintaining image quality by distributing heat dissipation across multiple focal points.
Implementation Method 1
The deflection coils and plates deflect an electron beam by creating either a local magnetic or an electrostatic field
Implementation Method 2
The electrons are accelerated by the high voltage potential and impinge on the target at a focal spot
Implementation Method 3
a filament contained within the cathode is heated to incandescence by passing an electric current therein
Implementation Method 4
The cathode or electron source is typically a coiled tungsten wire that is heated to temperatures approaching 2600° Celsius
Implementation Method 5
The anode, in a high power x-ray tube designed for current CT devices, is a tungsten target having a target face, that rotates at angular velocities of approximately 120 Hz or greater
Data Source
AI summary
An x-ray tube includes an anode comprising a focal track and a cathode assembly configured to emit an electron beam toward a focal spot on the focal track. The x-ray tube also includes a controller configured to wobble the electron beam among a plurality of focal points in a direction tangent to the focal track. The plurality of focal points includes at least one focal point that is bounded by a pair of boundary focal points. The controller is further configured to delay a wobble of the electron beam away from the at least one focal point for a pre-determined amount of time.