Radiochromic leuco dye micelle hydrogels: I. Initial investigation
- 21 October 2009
- journal article
- research article
- Published by IOP Publishing in Physics in Medicine & Biology
- Vol. 54 (22), 6773-6789
- https://doi.org/10.1088/0031-9155/54/22/002
Abstract
This investigation reports the use of surfactants and colorless leuco triarylmethane dyes to form a new class of radiochromic micelle hydrogels for three-dimensional (3D) water-equivalent dosimetry. Gelatin gel samples with several surfactants and leuco dyes were prepared and evaluated for optical transparency, dose sensitivity and diffusion rates. The addition of Triton X-100, a non-ionic surfactant, at levels exceeding the critical micelle concentration provides a transparent hydrogel in which the water insoluble leuco Malachite Green (LMG) can dissolve. During irradiation, the LMG dye precursor converts to Malachite Green (MG(+)). The most sensitive reported LMG gel formulation contains 0.3 mM LMG leuco dye, 16 mM trichloroacetic acid, 7 mM Triton X-100 and 4% w/w gelatin. A diffusion coefficient of 0.14 mm(2) h(-1) was determined for MG(+) in this gel by fitting the time-dependent degradation of the transmission profile after irradiating half of the sample. The diffusion rate was three times lower than the standard radiochromic ferrous xylenol-orange (FX) gel. The primary feature of this 3D hydrogel is that it introduces transparent, radiochromic, micelle hydrogels. The radiochromic response to dose is instantaneous and images are stable for several hours. A dosimetric characterization revealed that the dose response is reproducible to within 10% over five separate batches and independent of both energy and dose rate. Uniform pre-irradiation of samples to 5 Gy provided a subsequent near linear response to greater than 110 Gy. LMG gels when read with a fast optical CT scanner can provide full 3D dose distributions in less than 30 min post-irradiation. LMG micelle gels scanned with a 633 nm light source are a promising system for quantitative water- or tissue-equivalent 3D dose verification in the 5-100 Gy dose range. These gels are useful for the scanning of larger volume dosimeters (i.e. >15 cm diameter) since they are easily prepared with inexpensive ingredients, are transparent and have a low initial optical absorbance prior to irradiation. In this gel, only one colored molecular species is produced. This results in a linear relation between the concentration of the colored dye product and optical absorption independent of the sampled wavelength.This publication has 28 references indexed in Scilit:
- Radiochromic leuco dye micelle hydrogels: II. Low diffusion rate leuco crystal violet gelPhysics in Medicine & Biology, 2009
- Three-dimensional dosimetry of small megavoltage radiation fields using radiochromic gels and optical CT scanningPhysics in Medicine & Biology, 2009
- An apparent threshold dose response in ferrous xylenol-orange gel dosimeters when scanned with a yellow light sourcePhysics in Medicine & Biology, 2008
- PRESAGETM - Development and optimization studies of a 3D radiochromic plastic dosimeter–Part 2Journal of Physics: Conference Series, 2006
- Characterisation of PRESAGE™: A new 3-D radiochromic solid polymer dosemeter for ionising radiationRadiation Protection Dosimetry, 2006
- Radiochromic gel dosemeter for three-dimensional dosimetryRadiation Physics and Chemistry, 2001
- Experimental determination of the diffusion coefficient in two-dimensions in ferrous sulphate gels using the finite element methodAustralasian Physics & Engineering Sciences in Medicine, 2001
- Spectroscopic and photochemical properties of Malachite Green noncovalently bound to bovine serum albuminDyes and Pigments, 1999
- Imaging of radiation dose by visible color development in ferrous‐agarose‐xylenol orange gelsMedical Physics, 1991
- RADIATION CHEMISTRY OF SOLUTIONS: II DOSE-RATE, ENERGY, AND TEMPERATURE DEPENDENCE OF A LEUCO TRIARYLMETHANE DOSIMETER SOLUTIONCanadian Journal of Chemistry, 1958