Proton CT Scanner Using Scintillator Screen for Accurate Dose Calculation
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Solution Overview
Problem
Current technologies lack a commercially available device for acquiring proton CT scans, with existing research devices being large, heavy, and difficult to rotate around patients due to the need for high proton beam energy to traverse subjects without stopping inside, leading to inaccuracies in dose calculation in proton therapy.
Innovation Solution
A proton CT scanner method using a scintillator screen to measure sigma at the exit beam for each pencil beam scanned across an object, modeling sigma with a Monte Carlo model to establish correlations with exiting energy, and scanning over 360 degrees to determine total energy loss for each beam path, allowing for more accurate dose calculations and imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high proton beam energy (~250 MeV) is used to traverse the subject without stopping inside, then the proton beam can exit the subject for measurement, but the device becomes large and heavy, making it difficult to rotate around patients
Solution Approach 1:
The patent extracts only the essential measurement function from the complex proton CT system. Instead of using a full-scale proton detector that must stop the beam, the invention uses a simplified scintillator screen coupled with a camera to detect proton track information. This extracted measurement approach eliminates the need for heavy beam-stopping detectors while maintaining the ability to measure proton energy loss and range, thereby reducing device weight and complexity.
Solution Approach 2:
The patent changes the measurement parameter from direct Bragg peak position detection to sigma (standard deviation) measurement of proton track positions. By measuring the spread of proton tracks rather than the absolute stopping position, the system can use lower proton energies (e.g., 70-200 MeV) that do not require the beam to traverse the entire patient body. This parameter change enables the use of compact, lighter equipment while still providing accurate proton CT imaging capability.
2Reliability
If high proton beam energy is used to traverse the subject, then the beam can be measured at exit, but the device complexity increases making it difficult to implement clinically
Solution Approach 1:
The patent extracts the core measurement capability from complex proton detector systems. Instead of using elaborate detectors with multiple layers and readout systems, the invention uses a simple scintillator screen that converts proton energy deposition into visible light, which is then captured by a standard camera. This extracted approach maintains measurement accuracy while dramatically simplifying the device architecture for clinical implementation.
Solution Approach 2:
The patent replaces complex mechanical detector systems with an optical measurement system. Instead of using mechanical beam stops, position-sensitive detectors, or complex electronics to measure proton tracks, the invention uses a scintillator screen that optically records proton positions, which are then read out by a camera. This substitution of mechanical/electronic systems with optical systems reduces device complexity while maintaining or improving measurement precision.
3Measurement precision
If proton CT scanning is implemented with traditional methods, then accurate dose calculation can be achieved, but no commercially-available device exists and research devices are not suitable for human use
Solution Approach 1:
The patent employs inexpensive, readily available components for the proton CT detector system. The scintillator screen and camera system are standard, commercially available items that can be manufactured and deployed at low cost. This approach makes proton CT imaging commercially viable and suitable for human use, unlike previous research devices that required custom-built, expensive detector systems. The use of disposable or easily replaceable components also simplifies maintenance and clinical deployment.
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 accurate determination of energy loss and stopping power in each voxel, reducing errors in dose calculation and providing a more precise imaging tool for proton therapy, while being compact enough for clinical use.
Implementation Method 1
measuring sigma with a scintillator screen at an exit beam for each pencil beam scanned across an object
Data Source
AI summary
A method includes providing a proton computed tomography (CT) scanner, and measuring sigma with a scintillator screen at an exit beam for each pencil beam scanned across an object for each gantry angle necessary to determine a total energy loss as the beam traverses an object of unknown thickness or material.