Self-developing, instant radiochromic films based on the solid-state polymerization of diacetylenes (R-C?C-C?C- R, where R and R are substituent groups) are used for measuring radiation therapy dose. Currently available radiochromic films, e.g., the GafChromic EBT films from Ashland (Bridgewater, NJ, USA), have many drawbacks such as they are very expensive, sensitive to water and ambient UV light, requiring cold storage and shipping, a short shelf-life, delamination of the coating if bent sharply or cut, non-uniform coating requiring a yellow dye for thickness correction, etc. These shortcomings have prevented their broader use in radiation therapy clinics. Hence, there is a strong need for more economical radiochromic films, which do not have the drawbacks of commercially available radiochromic films. One of the principal investigators, G.N. Patel, is one of the early pioneers in the field of diacetylenes and is still active in the field. His company, JP Laboratories, Inc., has developed radiation dosimeters and radiochromic films for radiation protection and other non-medical applications. Utilizing his extensive experience in diacetylene chemistry and synthesis, we will synthesize a class of diacetylenes, which have a chromophoric group as a substituent group, e.g., R = (CH2)n-OCONH-(CH2)n-A, where n=1-4, A is a light yellow color chromophoric group. The chromophoric diacetylenes (CD) will be produced by reacting diacetylene diols with chromophoric isocyanates. Then, CD-based emulsion, a coating formulation, will be prepared and uniformly coated on a polyester film substrate to create a CD film. Diacetylene diols are significantly less expensive than those used to make GafChromic films. The radiochromic films made from chromophoric diacetylenes, the CD film, will have none of the drawbacks of GafChromic films. The chromophoric group will absorb UV light. Hence the CD film will not develop color upon exposure to ambient UV light. The CD film will not require a yellow marker for the thickness correction because the CD is yellow. Diacetylenes with urethane (- OCONH-) functionality usually have a higher melting point (above 100°C), resulting in a longer shelf-life, and are not affected by water/humidity. Because of the high melting point of CD, the CD film can be briefly heated to eliminate the post-irradiation change of measured dose, allowing an instant reading of the radiation dose. In the first stage of the project, small quantities of chromophoric diacetylenes will be synthesized, inks/emulsions made of CD will be coated on a substrate to make the radiochromic films, and the prototype films will be evaluated. The best performing CD film will be selected, and a sufficient quantity of the film will be made for the extensive evaluation for radiation therapy applications. In the second stage, the chosen CD film will be assessed for the effect of dose, dose rate, energy, UV light, water/humidity, and heat (shelf-life). JP Labs and the University of Minnesota facilities are fully equipped to carry out the proposed work.
Public Health Relevance Statement: Project narrative: Currently available radiochromic films used for measuring radiation dose in radiation therapy are very expensive, susceptible to ambient UV light, have a short shelf-life, and require additional yellow dye for thickness-related correction. This work will produce a novel radiochromic film for dosimetry in radiation therapy using chromophoric diacetylenes. Due to the unique composition, the proposed radiochromic film will be significantly less expensive, unaffected by ambient UV light, self-correcting for variation in thickness, have a longer shelf-life at room temperature, be resistant to ambient humidity, and be waterproof.
Project Terms: absorption; Chemistry; Color; Cryopreservation; Cryofixation; cold preservation; cold storage; Dyes; Coloring Agents; Emulsions; Film Dosimetry; Film Badge Dosimetry; Glycols; diol; Goals; Humidity; Ink; Laboratories; Light; Photoradiation; Minnesota; Patients; Polyesters; Polymers; polymer; polymeric; Radiation Protection; Radioprotection; Radioprotective; radio-protection; radio-protective; Radiation therapy; Radiotherapeutics; Radiotherapy; radiation treatment; treatment with radiation; Reading; Technology; Temperature; Testing; Ultraviolet Rays; Actinic Rays; UV light; UV radiation; UV rays; ultra violet light; ultra violet radiation; ultra violet rays; ultraviolet light; ultraviolet radiation; Universities; Urethane; Ethyl Carbamate; Ethyl Urethan; ethyl ester carbamic acid; Water; Hydrogen Oxide; Work; Measures; Film; Isocyanates; improved; Clinical; Penetration; Variation; Variant; Medical; Evaluation; Susceptibility; Predisposition; Measurement; polymerization; Exposure to; tool; Nature; Knowledge; Life; Investigation; Clinic; Reaction; Techniques; Postdoctoral Fellow; Postdoc; Research Associate; post-doc; post-doctoral; post-doctoral trainee; research associates; Radiation Dose Unit; Radiation Dose; experience; Performance; solid state; tumor growth; melting; dosimetry; skills; novel; Radiation; response; Thickness; Thick; irradiation; preventing; prevent; Dose; Dose Rate; Resolution; resolutions; Preparation; preparations; Principal Investigator; Characteristics; Shipping; Development; developmental; cost; manufacturing process; cost effective; resistant; Resistance; clinical applicability; clinical application; 2-dimensional; two-dimensional; prototype; Self Correction; Formulation; therapeutic toxicity; therapy associated toxicity; therapy related toxicity; therapy toxicity; treatment toxicity; treatment-associated toxicity; Treatment-related toxicity; experiment; experimental research; experiments; experimental study; clinical implementation; safe patient
