Non-collocated Imaging and Treatment in IGRT Systems
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Solution Overview
Problem
Conventional image-guided radiation treatment systems face interference issues between imaging and radiation systems, leading to low contrast and noisy images due to the use of high-energy radiation for both treatment and imaging, and physical constraints that limit patient positioning and treatment accuracy.
Innovation Solution
Implementing a non-collocated imaging and treatment system configuration with a robotic control arm and separate imaging and radiation centers, allowing for independent movement and alignment of the patient using 3D transformation calculations and tracking systems to ensure accurate targeting without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If imaging and radiation systems are collocated in conventional IGRT systems, then patient positioning and treatment alignment can be closely coupled, but the radiation treatment source blocks x-ray imaging beam paths and physically restricts patient positioning
Solution Approach 1:
The system divides the imaging and radiation functions into separate physical locations. The imaging system is positioned at one location while the radiation treatment source is positioned at a different location, allowing both functions to operate independently without mutual interference. This segmentation enables the imaging beam paths to remain unobstructed while maintaining accurate patient positioning and treatment alignment.
2Device complexity
If high-energy radiation is used for both treatment and imaging in conventional systems, then the same equipment serves dual purposes, but image contrast is reduced and noise increases
Solution Approach 1:
The imaging function is extracted from the radiation treatment system and positioned separately. This allows the imaging system to use optimized lower-energy x-ray beams specifically tuned for high-contrast imaging, while the radiation treatment source uses high-energy beams for therapy. The extraction eliminates the compromise that would otherwise be necessary when using a single high-energy system for both purposes.
3Device complexity
If the radiation source is rigidly attached to the gantry, then the system structure is simplified, but the treatment locations are limited by the rotation range and angular constraints
Solution Approach 1:
The system transitions from a rigid, fixed-attachment configuration to a dynamic, independently controllable arrangement. The radiation treatment source and imaging system can move independently to different positions and angles, allowing the radiation source to access treatment locations that would be constrained by gantry rotation limits while maintaining simplified structural relationships through independent mounting.
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 configuration enhances image quality by reducing noise and interference, improves patient positioning flexibility, and maintains treatment accuracy by decoupling imaging and radiation systems, enabling precise alignment and tracking of the radiation target.
Implementation Method 1
patient tracking during treatment is accomplished by comparing two-dimensional (2D) in-treatment x-ray images of the patient to 2D digitally reconstructed radiographs (DRRs)
Implementation Method 2
external beam radiation therapy, which typically uses a linear accelerator (LINAC) to generate x-rays
Data Source
AI summary
An image-guided radiation treatment system includes a robotic positioning system and a tracking system that enables a radiation target to be imaged and aligned at one location and treated at another location by transferring positional data from the imaging system to the positioning system and the radiation treatment system.