Particle Beam Therapy Planning System Corrects Water Equivalent Thickness
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Solution Overview
Problem
Current particle beam therapy systems face challenges in accurately determining the water equivalent thickness ratio distribution for each patient, leading to range errors during treatment, which can result in reduced treatment accuracy and increased margins around tumors, making it difficult to apply high doses without damaging critical organs.
Innovation Solution
A treatment planning system that calculates a correction amount for the water equivalent thickness ratio based on measured ranges during treatment, allowing for the creation of a revised treatment plan that improves accuracy by correcting the correlation between CT values and water equivalent thickness ratios without increasing treatment time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large margin is added to the tumor to account for range error, then the treatment safety is improved, but the ability to apply high dose to the tumor is reduced
Solution Approach 1:
The system measures the actual range of the particle beam in the patient's body and uses this measurement feedback to calculate a correction amount for the water equivalent thickness ratio. This corrected ratio is then applied to adjust the treatment plan, enabling more accurate dose delivery with reduced margins while maintaining treatment safety.
Solution Approach 2:
The system changes the parameter of water equivalent thickness ratio by calculating a correction amount based on measured range data. This parameter adjustment allows for more accurate representation of the patient's internal structure, enabling reduced margins and improved dose application capability.
2Measurement precision
If proton beam CT is used to measure water equivalent thickness ratio distribution, then measurement precision is improved, but treatment time is increased
Solution Approach 1:
The system performs range measurement and correction amount calculation during the treatment process itself rather than requiring a separate pre-treatment measurement session. This preliminary integration of measurement and treatment eliminates additional treatment time while maintaining measurement precision.
Solution Approach 2:
The system merges the range measurement function with the treatment delivery process. By using the treatment beam itself for range measurement and combining this with the treatment planning update, the system achieves precise water equivalent thickness ratio measurement without adding separate measurement time.
3Ease of manufacture
If a conversion table created by phantom is used to convert CT values to water equivalent thickness ratio, then the process is simplified, but manufacturing precision is reduced due to patient internal structure variation
Solution Approach 1:
The system applies a patient-specific correction amount to the water equivalent thickness ratio that is calculated based on the individual patient's measured range data. This local customization of the conversion accuracy for each patient improves precision while maintaining the simplicity of the CT-to-water-equivalent-thickness-ratio conversion process.
Solution Approach 2:
The system uses measured range feedback from the patient's actual tissue to calculate a correction amount that adjusts the water equivalent thickness ratio. This feedback mechanism maintains process simplicity while improving accuracy by accounting for individual patient variations in internal structure.
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 more accurate treatment planning by reducing range errors and minimizing margins, thereby improving the precision of particle beam therapy and allowing for higher doses to be applied to tumors while protecting critical organs.
Implementation Method 1
A particle beam such as a proton beam or a carbon beam applies a large dose immediately before stopping in a patient body. Due to the use of this large dose, that is, a so-called Bragg peak
Implementation Method 2
The distribution of the water equivalent thickness ratio used for the calculation of the range is calculated by converting an X-ray computed tomography (hereinafter, referred to as CT) image of a patient captured in advance by a conversion table of a CT value and a water equivalent thickness ratio
Implementation Method 3
a residual range measurement device that can emit a proton beam and a helium beam as charged particle beams and measures energy of the proton beam that has passed through a patient
Data Source
AI summary
A correlation between a CT value and a water equivalent thickness ratio distribution for each patient can be corrected without increasing a treatment time, and more accurate treatment can be realized. A treatment planning system 112 which generates a treatment plan for irradiating an irradiation target with a particle beam calculates a correction amount of a water equivalent thickness ratio of a first treatment plan created in advance, calculates a water equivalent thickness ratio distribution based on the correction amount and the first treatment plan, and creates a second treatment plan from the water equivalent thickness distribution.