Megavoltage Cone Beam CT for Dose-Guided Radiation Therapy
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Solution Overview
Problem
Current radiation therapy methods face inefficiencies and inaccuracies in determining three-dimensional dose distributions due to limitations in two-dimensional imaging and point dose measurements, which fail to account for patient anatomical changes and machine delivery errors.
Innovation Solution
A system and method for acquiring a three-dimensional megavoltage cone beam image, modifying it to correct for scatter radiation, and determining doses based on this image, allowing for adjustments to treatment beam parameters to ensure precise radiation delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-dimensional portal imaging is used for patient positioning, then patient position can be verified, but three-dimensional dose distribution cannot be accurately determined
Solution Approach 1:
The patent transitions from two-dimensional portal imaging to three-dimensional cone beam CT imaging. The CBCT system acquires multiple projection images from different angles and reconstructs them into a three-dimensional volumetric dataset, enabling accurate determination of three-dimensional dose distribution while maintaining patient position verification capabilities.
2Measurement precision
If point dose measurements are used, then dose at specific points can be measured, but three-dimensional dose distribution cannot be determined
Solution Approach 1:
The patent employs cone beam CT technology to acquire three-dimensional volumetric data of the patient's anatomy and combines it with treatment plan information to calculate and display three-dimensional dose distributions. This replaces point dose measurements with comprehensive volumetric dose mapping, showing dose gradients and hot/cold spots throughout the entire treatment volume.
3Reliability
If conventional imaging systems are used, then patient positioning can be confirmed, but anatomical changes between treatments cannot be detected
Solution Approach 1:
The patent implements a feedback mechanism where cone beam CT images acquired during treatment are compared with the original treatment planning CT images. This allows real-time detection of anatomical changes such as tumor shrinkage, weight loss, or organ movement, and enables adjustment of treatment parameters to account for these changes, ensuring continued treatment accuracy.
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 enables efficient and accurate determination of three-dimensional dose distributions, correcting for dosimetric errors and anatomical changes, thereby improving the precision of radiation therapy.
Implementation Method 1
The radiation beam delivers a predetermined dose of therapeutic radiation to the tumor according to an established treatment plan. The delivered radiation kills cells of the tumor by causing ionizations within the cells.
Implementation Method 2
acquire a three-dimensional megavoltage cone beam image... acquisition of a plurality of two-dimensional images using megavoltage radiation
Data Source
AI summary
A system includes acquisition of a three-dimensional cone beam image, and determination of a dose to be delivered based on the three-dimensional image and on parameters of a treatment beam to deliver the dose. Some systems may include modification of a three-dimensional cone beam image to correct for scatter radiation, and determination of a dose based on the modified three-dimensional cone beam image.