Radio-Fluorogenic Gel Dosimetry with Coumarin

Peter A Sandwall; Brandt P Bastow; Henry B Spitz; Howard R Elson; Michael Lamba; William B Connick; Henry Fenichel

doi:10.3390/bioengineering5030053

Radio-Fluorogenic Gel Dosimetry with Coumarin

Bioengineering (Basel). 2018 Jul 10;5(3):53. doi: 10.3390/bioengineering5030053.

Authors

Peter A Sandwall¹, Brandt P Bastow², Henry B Spitz³, Howard R Elson⁴, Michael Lamba⁵, William B Connick⁶, Henry Fenichel⁷

Affiliations

¹ Department of Radiation Oncology, OhioHealth, 330 Glessner Ave., Mansfield, OH 44903, USA. [email protected].
² Department of Chemistry, College of Arts and Sciences, University of Cincinnati, Cincinnati, OH 45221, USA. [email protected].
³ Department of Nuclear Engineering, College of Engineering, University of Cincinnati, Cincinnati, OH 45221, USA. [email protected].
⁴ Department of Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, OH 45221, USA. [email protected].
⁵ Department of Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, OH 45221, USA. [email protected].
⁶ Department of Chemistry, College of Arts and Sciences, University of Cincinnati, Cincinnati, OH 45221, USA. [email protected].
⁷ Department of Physics, College of Arts and Sciences, University of Cincinnati, Cincinnati, OH 45221, USA. [email protected].

Abstract

Gel dosimeters are attractive detectors for radiation therapy, with properties similar to biological tissue and the potential to visualize volumetric dose distributions. Radio-fluorogenesis is the yield of fluorescent chemical products in response to energy deposition from ionizing radiation. This report shares the development of a novel radio-fluorogenic gel (RFG) dosimeter, gelatin infused with coumarin-3-carboxlyic acid (C3CA), for the quantification of imparted energy. Aqueous solutions exposed to ionizing radiation result in the production of hydroxyl free radicals through water radiolysis. Interactions between hydroxyl free radicals and coumarin-3-carboxylic acid produce a fluorescent product. 7-hydroxy-coumarin-3-carboxylic acid has a blue (445 nm) emission following ultra-violet (UV) to near UV (365⁻405 nm) excitation. Effects of C3CA concentration and pH buffers were investigated. The response of the RFG was explored with respect to strength, type, and exposure rate of high-energy radiation. Results show a linear dose response relationship independent of energy and type, with a dose-rate dependency. This report demonstrates increased photo-yield with high pH and the utility of gelatin-RFG for phantom studies of radiation dosimetry.

Keywords: gel dosimetry; luminescent dosimetry; radiation dosimetry; radio-fluorogenic gel.