Radiochromic EBT 2 and EBT 3 sensitometry based on growth of two color phases of the polymer
| Autor: | César Rodríguez Rodríguez, Luis Carlos Martínez |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Film Dosimetry
Materials science Absorption spectroscopy Phantoms Imaging Polymers Calibration curve Sensitometry Analytical chemistry Phase (waves) Color Equipment Design General Medicine Radiation Dosage 030218 nuclear medicine & medical imaging Equipment Failure Analysis Absorbance 03 medical and health sciences 0302 clinical medicine 030220 oncology & carcinogenesis Absorbed dose Calibration Humans Linear combination Visible spectrum |
| Zdroj: | Medical Physics. 46:1896-1904 |
| ISSN: | 2473-4209 0094-2405 |
| DOI: | 10.1002/mp.13424 |
| Popis: | PURPOSE The aim of this work is to develop a sensitometry model of EBT2 and EBT3 radiochromic films based on the observation that radiation induces growth of two polymer color phases. METHODS Previously published data of the active layer absorption spectrum have been used to characterize the contribution to the total absorbance of each polymer color phase. Through a prior proposed external beam therapy absorption spectrum model the total absorbance has been deconvolved into two polymer phase contributions. The integral absorbance in the visible spectrum of each color phase has been calculated and parametrized as an absorbed dose function. A sensitometry model employing linear relationships with the color phase integral absorbances has been investigated. The phase linear coefficient ratio for each color channel is proposed to be a constant. Films belonging to six different production batches, three EBT2 and three EBT3, have been used to verify this model. RESULTS Each polymer color phase integral absorbance in the visible spectrum has been expressed as a simple saturation function of the absorbed dose to the film. The data coming from the six production batches have been fitted to the proposed sensitometry model. This model predicts the measured dose variation in the active layer light attenuation up to fluctuations attributable to uncertainties. CONCLUSIONS The calibration curve can be written as a linear combination of simple functions describing the dose dependence of the integral absorbance of each polymer color phase. These functions are characteristics of the active layer material, and not dependent on the model and production batch. According to the proposed model, to calibrate a batch in terms of the active layer light attenuation consists of determining just one linear coefficient. |
| Databáze: | OpenAIRE |
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