Characterization of radiochromic films as a micrometer‐resolution dosimeter by confocal Raman spectroscopy

Purpose Micrometer spatial resolution dosimetry has become inevitable for advanced radiotherapy techniques. A new approach using radiochromic films was developed to measure a radiation dose at a micrometer spatial resolution by confocal Raman spectroscopy. Methods The commercial radiochromic films (...

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Bibliographic Details
Published in:Medical physics (Lancaster) 2019-11, Vol.46 (11), p.5238-5248
Main Authors: Mirza, Jamal Ahmad, Hernández Millares, Rodrigo, Kim, Geon Il, Park, So‐Yeon, Lee, Jaegi, Ye, Sung‐Joon
Format: Article
Language:English
Subjects:
Calibration
Film Dosimetry - instrumentation
high‐spatial resolution
microdosimetry
radiochromic film
Raman spectroscopy
Signal-To-Noise Ratio
Spectrum Analysis, Raman
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Summary:Purpose Micrometer spatial resolution dosimetry has become inevitable for advanced radiotherapy techniques. A new approach using radiochromic films was developed to measure a radiation dose at a micrometer spatial resolution by confocal Raman spectroscopy. Methods The commercial radiochromic films (RCF), EBT3 and EBT‐XD, were irradiated with known doses using 50, 100, 200, and 300 kVp, and 6‐MV x rays. The dose levels ranged from 0.3 to 50 Gy. The Raman mapping technique developed in our early study was used to readout an area of 100 × 100 µm2 on RCF with improved lateral and depth resolutions with confocal Raman spectrometry. The variation in Raman spectra of C‐C‐C deformation and C≡C stretching modes of diacetylene polymers around 676 and 2060 cm−1, respectively, as a function of therapeutic x‐ray doses, was measured. The single peak (SP) of C≡C and the peak ratio (PR) of C≡C band height to C‐C‐C band height with a spatial resolution of 10 µm on both types of RCF were evaluated, averaged, and plotted as a function of dose. An achievable spatial resolution, clinically useful dose range, dosimetric sensitivity, dose uniformity, and postirradiation stability as well as the orientation, energy, and dose rate dependence, of both types of RCFs, were characterized by the technique developed in this study. Results A spatial resolution on RCF achieved by SP and PR methods was ~4.5 and ~2.9 µm, respectively. Raman spectroscopy data showed dose nonuniformity of ~11% in SP method and
ISSN:0094-2405
2473-4209
DOI:10.1002/mp.13778