Multi-Slit Collimator for Prompt Gamma Detection in Hadron Therapy
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Solution Overview
Problem
Current detection systems for charged hadron beam range in radiation therapy, such as those using prompt gamma measurements, face challenges in achieving precise online measurements due to limited statistical accuracy and spatial resolution, making it difficult to accurately determine the Bragg peak position and spare healthy tissue.
Innovation Solution
A multi-slit prompt gamma camera system with optimized collimator dimensions, including slit width, depth, and fill factor, is used to enhance the detection of prompt gamma emissions, allowing for improved statistical accuracy and spatial resolution, enabling precise determination of beam range shifts during treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a collimator with narrow slits and deep depth is used to improve spatial resolution, then measurement precision is improved, but the statistical accuracy of detected prompt gammas deteriorates
Solution Approach 1:
The invention changes the geometric parameters of the collimator, specifically using a shallower depth (50-200 mm instead of deeper configurations) and optimized width (3 mm or higher), which transforms the detection characteristics to achieve sufficient statistical accuracy while maintaining adequate spatial resolution for clinical beam range verification
Solution Approach 2:
The invention accepts a moderate reduction in spatial resolution compared to ideal deep-narrow slit designs, but achieves sufficient measurement capability for clinical purposes by optimizing the balance between resolution and statistical accuracy, making the system practical for online verification
2Measurement precision
If a collimator with narrow slits is used to improve spatial resolution, then beam range determination accuracy is improved, but the number of detected prompt gammas decreases
Solution Approach 1:
The invention modifies the collimator parameters by using wider slits (3 mm or higher) and shallower depth (50-200 mm), which increases the solid angle for gamma detection and thus the number of detected prompt gammas, while maintaining sufficient beam range determination accuracy for clinical verification
3Measurement precision
If a deep collimator is used to improve directional selectivity, then spatial resolution is improved, but the fill factor increases and detection efficiency decreases
Solution Approach 1:
The invention uses a shallower collimator depth (50-200 mm) which reduces the fill factor requirement, allowing for larger opening widths that increase detection efficiency and prompt gamma transmission while maintaining sufficient spatial resolution for beam range verification applications
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 system achieves better Falloff Retrieval Precision and spatial resolution, allowing for accurate detection of beam range shifts and Bragg peak location, even with lower spatial resolution, thereby improving the precision of radiation delivery in charged hadron therapy.
Implementation Method 1
a collimator comprising a plurality of collimator slabs of thickness t, spaced apart so as to form an array of slit-shaped openings, configured to be placed at a right angle to the beam line, so as to allow the passage of prompt gamma emission from the target
Implementation Method 2
a detection means suitable for detecting said prompt gamma emission, comprising at least a portion of scintillator material aligned with each of said slit-shaped openings
Implementation Method 3
detecting prompt gammas produced when irradiating a target with a charged hadron beam
Data Source
Figure 1~2
Figure 3
AI summary
The invention is related to an apparatus and method for charged hadron therapy verification. The apparatus comprises a collimator (1) comprising a plurality of collimator slabs (2) of thickness t, spaced apart so as to form an array of mutually slit-shaped openings (3), configured to be placed at a right angle to the beam line, so as to allow the passage of prompt gammas from the target, the collimator being defined at least by three geometrical parameters being : the width (s) and depth (D) of the slit-shaped openings and the fill factor (f), with f equal to t/(t+s), wherein s ≥ 3mm, D is between 50mm and 200mm and f < 0.5. The invention is equally related to a method for charged hadron therapy verification with a multi-slit camera wherein s ≥ 2 mm, D is between 50 mm and 200 mm and f < 0.7, and wherein J > 1% with J defined as S.AATOF wherein S = 1-f, A = s/D, ATOF = the ratio of neutron background emission that is conserved after application of the TOF discrimination to the total neutron background emission, with ATOF = 1 when no TOF discrimination is applied.