LCV-Pluronic F-127 dosimeter for UV light dose distribution measurements

Abstract

This work reports on a radiochromic dosimeter for dose distribution measurement after irradiation with UV light. The dosimeter is composed of a 25 % copolymer of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127) that forms a physical gel matrix. The matrix is infused with leuco crystal violet (LCV, 2 mM), 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton X-100, 4 mM) and trichloroacetic acid (TCAA, 17 mM). This dosimeter was exposed to UVA, UVB and UVC radiation and the radiochromic reactions were followed with reflectance spectrophotometry and Raman spectroscopy. Exposition of the dosimeter to all UV light subranges caused LCV to convert to CV molecules absorbing visible light and affecting the dosimeter that changes colour to blue. The intensity of colour was related to absorbed UV dose. The dosimeter is the least sensitive to irradiation with UVA and the most sensitive to irradiation with UVB. The main dose-response characteristics of the dosimeter were obtained: threshold dose, linear and dynamic dose range, dose sensitivity as well as the stability over time after irradiation and stability of recorded dose distribution. Overall, the dosimeter coupled with reflectance spectrophotometry is effective in measuring doses in 1D, whereas using 3D optical scanning techniques should expand its application to 3D dosimetry. This work also provides an approach to using the LCV-Pluronic F-127 dosimeter for measurements of 2D dose distribution with a flat-bed optical scanner as a readout method. LCV-Pluronic F-127 may also be useful for solar radiation measurements.