DaRT Source Radon Release for Lung Tumor Coverage
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Solution Overview
Problem
Existing radiotherapy methods using alpha particles struggle to effectively target tumor cells while minimizing damage to healthy tissue due to the short range of alpha radiation and lack of practical deployment methods, and there is a need for tailored radiation dosages to treat lung cancer tumors.
Innovation Solution
The use of diffusing alpha-emitter radiation therapy (DaRT) sources with controlled radon release rates and spacing to ensure adequate radiation coverage within lung cancer tumors, employing a method that includes implanting sources with a radon release rate between 1.08 and 2.42 microcurie per centimeter length and spacing of up to 4 millimeters, along with a treatment duration to achieve a cumulated activity of 5-11.3 MBq hour per centimeter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alpha particles are used for radiotherapy, then the destructive effect on tumor cells is enhanced, but the short range limits their deployment throughout the entire tumor volume
Solution Approach 1:
The patent segments the radiation delivery system by using multiple radionuclides with different properties. Radium-223 provides localized alpha emission at the implant site, while lead-212 diffuses to provide additional alpha emission throughout the tumor volume. This segmentation allows coverage of the entire tumor while maintaining high destructive effect.
Solution Approach 2:
The patent uses diffusion as an intermediary mechanism to transport lead-212 atoms from the implant site throughout the tumor. The lead-212 acts as a mediator that carries the alpha-emitting capability to regions that would otherwise be inaccessible to the short-range radium-223 alpha particles.
2Reliability
If higher radium activity is used to ensure sufficient radiation dosage, then more radon atoms may be cleared from the tumor through blood, but this could damage distant healthy tissue
Solution Approach 1:
The patent changes the key parameter from radium activity alone to radon release rate, which accounts for both the amount of radium and the probability of radon desorption. This parameter change allows optimization of the balance between delivering sufficient tumor dosage and minimizing systemic circulation of radioactive atoms.
Solution Approach 2:
The patent introduces feedback by measuring and controlling the radon release rate rather than simply the radium activity. This feedback mechanism allows adjustment of the source characteristics to achieve the optimal balance between tumor treatment efficacy and healthy tissue protection.
3Stability of the object's composition
If radium atoms are attached strongly to the source, then they remain confined to the source, but daughter radionuclides are retained and cannot diffuse into the tumor
Solution Approach 1:
The patent applies local quality by creating different retention characteristics for different radionuclides in the same source. The source material is selected and configured to strongly retain radium-223 atoms while allowing lead-212 atoms to diffuse out. This local quality difference in retention enables both stable radium confinement and effective daughter nuclide diffusion.
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 effectively destroys lung cancer tumors by ensuring sufficient radiation dosage while minimizing damage to surrounding healthy tissue, providing a tailored and safe treatment method.
Implementation Method 1
radium-223 or radium-224 atoms, which generate chains of several radioactive decays with a governing half-life of 3.6 days for radium-224
Implementation Method 2
the probability that the daughter radon atoms will leave the source into the tumor, upon radium's alpha decay. This probability is referred to herein as the 'desorption probability'
Implementation Method 3
These radionuclides, and their own radioactive daughter atoms, spread around the source by diffusion up to a radial distance of a few millimeters before they decay by alpha emission
Implementation Method 4
Alpha particles are a powerful means for radiotherapy since they induce clustered double-strand breaks on the DNA, which cells cannot repair
Data Source
AI summary
A method for treating a tumor, comprising identifying a tumor as a lung cancer tumor and implanting in the tumor identified as a lung cancer tumor, at least one diffusing alpha-emitter radiation therapy (DaRT) source with a suitable radon release rate and for a given duration, such that the source provides during the given duration a cumulated activity of released radon between 5 Mega becquerel (MBq) hour and 11.3 MBq hour, per centimeter length.