Buildup Layer for MV X-Ray Imaging
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Solution Overview
Problem
Current electronic portal imaging devices for radiation therapy are limited by their inability to provide high-quality 3D images using low-dose megavoltage x-rays, suffering from inferior image contrast and resolution, and require higher doses due to lower X-ray absorption at megavoltage energies, while also being unsuitable for real-time patient and tumor tracking.
Innovation Solution
The development of an x-ray imaging device with a detector array and an x-ray converting layer, incorporating a buildup layer made from materials like copper, aluminum, or cesium iodide, configured to enhance image quality by generating high-energy electrons that interact with scintillators to produce visible light, improving contrast and efficiency in both kilovoltage and megavoltage imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If megavoltage x-rays are used for imaging, then real-time patient tracking during radiation therapy is enabled, but image contrast and resolution deteriorate
Solution Approach 1:
A buildup layer made of high-Z materials (copper, aluminum, beryllium, titanium, lead, tantalum, tungsten, silver, gold, palladium, or platinum) is introduced as an intermediary between the MV x-ray source and the detector array. This buildup layer converts MV x-rays into high-energy electrons through the photoelectric effect and Compton scattering, which then interact with the scintillator to produce visible light. This intermediary mechanism enables MV imaging with improved contrast and resolution by converting the harmful low-absorption MV x-rays into detectable signals.
Solution Approach 2:
The patent changes the energy parameter of the x-rays by using a dual-energy approach. The imaging device can operate in both kilovoltage (kV) mode for high-contrast imaging and megavoltage (MV) mode for real-time tracking during radiation therapy. The buildup layer is specifically designed to optimize MV x-ray conversion efficiency, allowing the system to maintain image quality across different energy levels while enabling real-time monitoring.
2Reliability
If megavoltage x-rays are used for imaging, then patient setup confirmation is achieved, but radiation dose increases
Solution Approach 1:
The buildup layer acts as a mediator that increases the absorption efficiency of MV x-rays. By converting MV x-rays into high-energy electrons that produce visible light in the scintillator, the system achieves reliable patient setup confirmation and real-time tracking with lower radiation doses compared to conventional MV imaging without a buildup layer.
3Measurement precision
If a buildup layer is added to enhance MV x-ray absorption, then image quality improves, but device complexity increases
Solution Approach 1:
The detector is segmented into distinct functional layers: a detector array, an x-ray converting layer with scintillator material, and a buildup layer made of high-Z materials. This segmentation allows each layer to perform its specific function optimally - the buildup layer converts MV x-rays to electrons, the scintillator converts electrons to visible light, and the detector array detects the light. This modular structure improves image quality while keeping the device manufacturable and maintainable.
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
The solution enables the production of high-quality images with improved contrast and detective quantum efficiency, allowing for reliable real-time 3D patient tracking and reduced radiation dose, making it suitable for both kilovoltage and megavoltage imaging.
Implementation Method 1
The x-ray converting layer may comprise a scintillator configured to produce light by interacting with x-rays having a kilovoltage energy level and/or a megavoltage energy level
Implementation Method 2
incorporating a buildup layer made from materials like copper, aluminum, or cesium iodide, configured to enhance image quality by generating high-energy electrons that interact with scintillators to produce visible light
Data Source
AI summary
An x-ray imaging device may include a detector array and an x-ray converting layer coupled to the detector array. The detector array and the x-ray converting layer may be configured such that x-rays traverse the detector array before propagating in the x-ray converting layer. The x-ray imaging device may also include a buildup layer behind the x-ray converting layer. The x-ray imaging device may be used as a “universal” imager for both MV and kV imaging.