XACT/US Radiotherapy Imaging for Real-Time Dose Alignment
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Solution Overview
Problem
Current radiation therapy lacks high-resolution, real-time in vivo dosimetry techniques for accurately monitoring radiation dose distribution within patients during treatment, especially in dynamic delivery methods like IMRT and VMAT, leading to potential inaccuracies and collateral damage.
Innovation Solution
X-ray-induced acoustic computed tomography (XACT) combined with pulse and echo ultrasound imaging (XACT/US) to provide real-time imaging of radiation dose and beam alignment, utilizing a system that includes a radiation module and ultrasound module to generate and process X-ray acoustic and ultrasound images simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detectors such as Farmer ionization chamber are used for radiation dosimetry, then the system is simple and easy to operate, but the spatial resolution is insufficient and cannot provide high-resolution dose verification
Solution Approach 1:
The patent replaces conventional mechanical/electrical detectors (Farmer ionization chamber, diode arrays) with an acoustic detection system. X-ray induced acoustic waves are generated in the tissue phantom and detected by acoustic transducers, substituting the traditional electromagnetic detection mechanism with an acoustic field-based measurement approach. This enables high spatial resolution dose verification without the limitations of conventional detector geometries.
Solution Approach 2:
The patent changes the measurement parameter from direct electromagnetic interaction (ionization, scintillation) to acoustic wave generation. By detecting the acoustic pressure waves induced by X-ray absorption in the medium, the system achieves superior spatial resolution. The acoustic transducers can resolve fine spatial variations in dose distribution that are beyond the capability of conventional detectors.
2Measurement precision
If gel dosimetry is used for tissue equivalent dosimetry, then the measurement accuracy improves, but the readout time becomes unacceptably long and material-specific errors increase
Solution Approach 1:
The patent replaces the chemical/physical change-based detection method of gel dosimetry (which requires post-irradiation processing and scanning) with real-time acoustic wave detection. The acoustic transducers directly detect the pressure waves generated during irradiation, providing immediate dose verification without lengthy readout procedures. This substitution of detection mechanism eliminates the time delay inherent in gel dosimetry.
Solution Approach 2:
The measurement medium itself (tissue phantom or tissue) generates the acoustic signal during irradiation, serving as both the dosimetry medium and the signal source. The X-ray induced acoustic waves are produced in situ within the irradiated medium, eliminating the need for separate readout procedures or external processing steps required by gel dosimetry systems.
3Measurement precision
If transit dosimetry with scatter correction is used, then the dose reconstruction accuracy improves, but the system requires multiple assumptions about beam depth-dose curve and scatter correction models
Solution Approach 1:
The patent replaces the computational reconstruction approach of transit dosimetry (which requires complex scatter correction algorithms and depth-dose curve assumptions) with direct acoustic wave detection. The acoustic transducers measure the actual pressure waves generated in the medium, providing direct information about the dose distribution without requiring iterative reconstruction or correction models.
Solution Approach 2:
The measurement medium generates its own acoustic signal that directly reflects the local energy deposition. Each point in the irradiated medium produces acoustic waves proportional to the absorbed dose at that location, providing self-contained local measurement information that eliminates the need for global reconstruction assumptions and scatter correction models.
4Loss of time
If Cherenkov emission or radioluminescence imaging is used for in vivo dosimetry, then real-time monitoring is achieved, but the spatial resolution is limited to surface dosimetry applications only
Solution Approach 1:
The patent extends the applicability of real-time acoustic detection from surface-only measurements to deep tissue dosimetry. Acoustic transducers can detect pressure waves generated at any depth within the irradiated medium, providing real-time dose monitoring throughout the treatment volume. This multi-depth capability makes the system universally applicable to both surface and deep-seated tumors.
Solution Approach 2:
The patent replaces optical detection methods (Cherenkov emission, radioluminescence) with acoustic wave detection. While optical methods are limited by tissue penetration depth, acoustic waves can propagate through and be detected from deep within the tissue, enabling real-time dosimetry at any depth. The acoustic transducers detect pressure waves regardless of their origin depth, overcoming the fundamental penetration limitation of optical-based dosimetry.
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
Enables precise real-time monitoring of radiation dose and geometric misalignments, improving tumor targeting and reducing side effects by providing high-resolution 3D in vivo dosimetry.
Implementation Method 1
X-rays are absorbed and converted to heat; subsequent thermoelastic expansion generates an acoustic wave, which can be imaged by acoustic detectors
Implementation Method 2
traditional pulse and echo ultrasound imaging
Data Source
AI summary
Embodiments are directed to a new imaging modality called X-ray-induced acoustic computed tomography (XACT) technology and can be combined with traditional pulse and echo ultrasound imaging. It has the capability of real-time monitoring of geometric and morphological misalignments of the X-ray field with respect to the target tissue, thus improving radiotherapy tumor eradication and limiting treatment side effects. The XACT/US image-guided radiotherapy system according to embodiments holds great potential for personalized cancer treatment and better outcomes.