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Abstract
A photonic dosimeter accrues cumulative dose and includes: a substrate; a waveguide disposed on the substrate and that: receives a primary input light; transmits secondary input light from the primary input light to a dosimatrix; receives a secondary output light from the dosimatrix; and produces primary output light from the secondary output light; the dosimatrix disposed on the substrate and in optical communication with the waveguide and that: receives the secondary input light from the waveguide; produces the secondary output light that is communicated to the waveguide; and includes an active element that undergoes conversion from a prime state to a dosed state in response to receipt, by the active element, of a dose of radiation; and a cover layer disposed on waveguide and the dosimatrix.
Patent Description
Radiation-induced materials modification is ubiquitous. These applications rely on dosimetry to reliably deliver the desired amount of radiation to the right place. Currently the dosimetry standard is based on calorimetry of a large water phantom irradiated exclusively by Co-60 gamma rays. The thermistor used is large - half of a millimeter. The current dosimetry standards permit traceable dosimetry that is limited by the size of the probes used in primary standard calorimeters and the requirement of field uniformity over the probe (thus, field ~ 10x∙probe diameter). This works for bulk sterilization but for surfaces or small dimensions, this existing dose standard is too crude by several orders of magnitude. While higher-energy electron beams can penetrate matter, beams of low-energy electrons have the opposite characteristic: they penetrate no more than 100 microns or so into most materials. This makes them valuable for industrial processes like surface sterilization of medical instruments and bandages or curing of inks used on labels for food items – wherever the benefits of radiation dose are confined to the outside of something (and could harm what’s inside). Lack of traceability thus leaves huge industries without support needed to meet regulatory requirements. Thus, NIST has developed a chip-scale calorimeter for radiation dosimetry that could serve as a new standard to extend traceability and allow quantitative dosimetry on micron dimension.
Features
This invention is technically superior by enabling absolute dosimetry at an unprecedented physical scale due to micron-scale spatial resolution across six orders-of-magnitude of absorbed dose, from medical diagnostic and therapeutic procedures up through industrial materials processing, sterilization, and applications lead i ng to commercialization of space.