Fiber Optic Dosimeter Probe for MR-Guided Radiotherapy
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Solution Overview
Problem
Current dosimeters used in radiotherapy for monitoring radiation dose delivery are complex, expensive, and introduce errors due to non-tissue equivalence and metallic components that alter dose distribution, particularly in MR-guided radiotherapy and brachytherapy.
Innovation Solution
A fiber optic dosimeter probe with a radiation-sensitive layer made of radiochromic material, integrated with an optical fiber and a reflector, providing a water-equivalent and MR-compatible solution for real-time dose monitoring, using a biocompatible sheath and adhesive to minimize interaction with radiation and maintain geometric integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current commercially available dosimeters (TLDs, MOSFETs, ion-chambers, scintillators) are used for radiation dose monitoring, then dose measurement capability is achieved, but device complexity, cost, and metallic component interference with radiation field increase
Solution Approach 1:
The patent extracts and removes metallic components from the dosimeter structure, using only non-metallic, MR-compatible materials (optical fiber, radiochromic film, polymer encapsulation) to eliminate the harmful interaction with radiation fields while maintaining dosimetry functionality
Solution Approach 2:
The patent replaces electronic readout mechanisms (MOSFETs, ion-chambers, scintillators) with an optical-based system using radiochromic film that changes optical properties upon radiation exposure, eliminating complex electronics and metallic components
2Measurement precision
If dosimeters with metallic components are used, then dose measurement is enabled, but dose distribution accuracy deteriorates due to non-tissue equivalence and perturbation of radiation field
Solution Approach 1:
The patent uses homogeneous non-metallic materials (polymer encapsulation, optical fiber, radiochromic film) that are tissue-equivalent and do not perturb the radiation field, matching the physical and radiological properties of surrounding tissue
Solution Approach 2:
The patent employs composite material structure combining optical fiber, radiochromic film, and polymer encapsulation to achieve both dosimetry functionality and tissue-equivalence without metallic components
3Measurement precision
If MR-compatible dosimeters are required for MR-guided radiotherapy, then geometric integrity and localization accuracy are improved, but device selection and implementation complexity increase
Solution Approach 1:
The patent removes all ferromagnetic and MR-incompatible materials from the dosimeter construction, using only non-metallic components that are inherently MR-compatible and maintain geometric integrity during MRI scanning
Solution Approach 2:
The patent creates a universal dosimeter design that simultaneously achieves dosimetry, MR-compatibility, and real-time optical readout capabilities, applicable to both MR-guided radiotherapy and brachytherapy without modification
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 fiber optic dosimeter probe offers accurate, real-time radiation dose monitoring with minimal perturbation of the local field, maintaining geometric integrity and allowing for precise localization, reducing errors and costs associated with existing technologies.
Implementation Method 1
A radiation sensitive layer is provided between the sensitive end and a window. The radiation sensitive layer is made of a material which has an optical property that changes with absorbed radiation dose
Implementation Method 2
an optical fiber having a free end and a sensitive end
Implementation Method 3
A reflector is provided on a reflector side of the radiation sensitive layer. The reflector side is opposed to the fiber side
Data Source
AI summary
A fiber optic dosimeter probe for sensing radiation dose including an optical fiber having a free end and a sensitive end, a window having a sensitive side and a rear side; a radiation sensitive layer between the sensitive end of the optical fiber and a sensitive side of the window, the radiation sensitive layer being made of a material having an optical property that changes with absorbed radiation dose, an amount of the material corresponding to a predetermined sensitivity to radiation; wherein the window and the optical fiber have a near water equivalent interaction with radiation and are MR compatible.