How flatbed scanners upset accurate film dosimetry
| Autor: | Henk Huizenga, R M Verdaasdonk, S. Heukelom, L J van Battum |
|---|---|
| Přispěvatelé: | Physics and medical technology, Radiation Oncology |
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Scanner
Materials science Dosimeter Film Dosimetry Radiological and Ultrasound Technology business.industry X-Rays Polarizer Polarization (waves) Light scattering 030218 nuclear medicine & medical imaging law.invention 03 medical and health sciences 0302 clinical medicine Optics law 030220 oncology & carcinogenesis Dosimetry Anisotropy Radiology Nuclear Medicine and imaging business Optical path length Rare cancers Radboud Institute for Health Sciences [Radboudumc 9] |
| Zdroj: | Physics in Medicine and Biology, 61, 2, pp. 625-49 Physics in Medicine and Biology, 61, 625-49 Physics in Medicine and Biology, 61(2), 625-649. IOP Publishing Ltd. van Battum, L J, Huizenga, H, Verdaasdonk, R M & Heukelom, S 2016, ' How flatbed scanners upset accurate film dosimetry ', Physics in Medicine and Biology, vol. 61, no. 2, pp. 625-649 . https://doi.org/10.1088/0031-9155/61/2/625 |
| ISSN: | 0031-9155 |
| DOI: | 10.1088/0031-9155/61/2/625 |
| Popis: | Item does not contain fulltext Film is an excellent dosimeter for verification of dose distributions due to its high spatial resolution. Irradiated film can be digitized with low-cost, transmission, flatbed scanners. However, a disadvantage is their lateral scan effect (LSE): a scanner readout change over its lateral scan axis. Although anisotropic light scattering was presented as the origin of the LSE, this paper presents an alternative cause. Hereto, LSE for two flatbed scanners (Epson 1680 Expression Pro and Epson 10000XL), and Gafchromic film (EBT, EBT2, EBT3) was investigated, focused on three effects: cross talk, optical path length and polarization. Cross talk was examined using triangular sheets of various optical densities. The optical path length effect was studied using absorptive and reflective neutral density filters with well-defined optical characteristics (OD range 0.2-2.0). Linear polarizer sheets were used to investigate light polarization on the CCD signal in absence and presence of (un)irradiated Gafchromic film. Film dose values ranged between 0.2 to 9 Gy, i.e. an optical density range between 0.25 to 1.1. Measurements were performed in the scanner's transmission mode, with red-green-blue channels. LSE was found to depend on scanner construction and film type. Its magnitude depends on dose: for 9 Gy increasing up to 14% at maximum lateral position. Cross talk was only significant in high contrast regions, up to 2% for very small fields. The optical path length effect introduced by film on the scanner causes 3% for pixels in the extreme lateral position. Light polarization due to film and the scanner's optical mirror system is the main contributor, different in magnitude for the red, green and blue channel. We concluded that any Gafchromic EBT type film scanned with a flatbed scanner will face these optical effects. Accurate dosimetry requires correction of LSE, therefore, determination of the LSE per color channel and dose delivered to the film. |
| Databáze: | OpenAIRE |
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