Strontium-90 Source With Central Shielding For Uniform Dose
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Solution Overview
Problem
Existing radiological sources used in brachytherapy and medical applications often emit isotropic radiation, exposing surrounding healthy tissues to unnecessary radiation and overexposing tissues at the center of the radiation beam, rather than concentrating radiation uniformly on diseased tissues.
Innovation Solution
A beta radiological source with increased radioactivity around its periphery and reduced radioactivity at its center, achieved through a toroidal or annular shape, or a minus lens meniscus shape, combined with central shielding and attenuating disks made of materials like silver, copper, or tungsten, to direct radiation more uniformly and reduce exposure to surrounding tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an isotropic (spherical) radiological source is used, then the source structure is simple and easy to manufacture, but the radiation is distributed uniformly in all directions causing overexposure at the center and underexposure at the periphery of the target tissue
Solution Approach 1:
The patent applies local quality by creating non-uniform radioactivity distribution within the source - higher activity at the periphery and lower activity at the center. This is achieved through techniques such as varying the thickness of the radioactive layer, using attenuating materials strategically placed, or modifying the density of the radioactive substance in different regions. This local variation in quality enables the source to produce a flat radiation profile that delivers uniform dose to the target tissue.
Solution Approach 2:
The patent employs asymmetry by deviating from the traditional symmetric spherical source design. The source is configured with asymmetric radioactivity distribution - either through an annular shape with a central void, or through asymmetric attenuation where the center has reduced activity compared to the periphery. This asymmetric configuration is specifically designed to compensate for the geometric factors in radiation delivery to achieve uniform dose distribution.
2Device complexity
If an isotropic radiological source is used, then the source design is straightforward, but surrounding healthy tissues are exposed to unnecessary radiation
Solution Approach 1:
By implementing local quality with enhanced peripheral activity and reduced central activity, the source directs radiation preferentially toward the target tissue at the periphery while minimizing radiation to the center and surrounding healthy tissues. This localized modification of the radiation emission pattern reduces harmful exposure to non-target areas.
Solution Approach 2:
The patent converts the potentially harmful isotropic radiation pattern into a beneficial collimated pattern. By strategically placing attenuating materials or creating activity voids in the center, the source transforms what would be harmful central radiation into a feature that protects healthy tissue, while the peripheral radiation that would naturally be present is enhanced to ensure adequate target coverage.
3Reliability
If a collimated distribution of radiation is implemented with peripheral concentration, then radiation is directed more accurately at target tissues, but the source structure becomes more complex
Solution Approach 1:
The patent achieves collimated radiation distribution through local quality modifications - varying the radioactivity concentration, thickness, or density in different regions of the source. By making the peripheral regions more active and the central region less active, the source inherently directs radiation toward the target without requiring complex mechanical collimation devices, thus achieving accurate targeting with moderate structural modifications.
Solution Approach 2:
The patent employs parameter changes by modifying physical parameters of the radioactive source - such as the thickness of the radioactive layer, the density of the radioactive substance, or the presence of attenuating materials - to control the radiation emission pattern. These parameter modifications enable collimated radiation distribution and improved targeting accuracy while avoiding the need for mechanically complex collimation systems.
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 configuration results in a flat radiation profile, providing a more constant absorbed dose rate throughout the target volume of tissue, minimizing exposure to healthy tissues and preventing overexposure at the center of the radiation beam.
Implementation Method 1
providing an encapsulation with increased shielding in the center of the face from which the therapeutic radiation is emitted, thereby substantially attenuating the radiation emitted from the central portion of a source
Implementation Method 2
a beta radiological source, containing strontium-90, wherein the radiological insert has increased radioactivity around its periphery and less radioactivity at its center
Data Source
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Figure 2
Figure 3A~3F
AI summary
The disclosure pertains to a strontium-90 sealed radiological or radioactive source, such as may be used with treatment of the eye or other medical or industrial processes. The sealed radiological source includes a radiological insert within an encapsulation. The encapsulation may include increased shielding in the center thereof.