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Calibration curve for converting the film optical density readings to absorbed dose in gray The absorbed dose measurement by the ionization chamber was plotted against the NOD of the films.
Source publication
Purpose
In vivo dosimetry is a quality assurance tool that provides post-treatment measurement of the absorbed dose as delivered to the patient. This dosimetry compares the prescribed and measured dose delivered to the target volume. In this study, a tissue-equivalent water phantom provided the simulation of the human environment. The skin and entr...
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Citations
... Various Gafchromic films (RCFs) are utilized in preclinical applications, including x-rays, gamma rays, electrons, and heavy ions for radiation dose mapping [4][5][6]. The dose-response of Gafchromic EBT2 radiochromic film having effective atomic number Z eff = 6.84, which is a tissue equivalent material, is corrected for thickness uniformity by adding a yellow marker dye incorporated into the active layer of the film [7,8]. The dose-response effectiveness of Gafchromic EBT2 films is correlated with the absorbed dose and exhibits a slight correlation with the energy of the incident radiation [3]. ...
... 8) with respect to distance (x) produces the line spread function as follows and represented infigure 10 ...
In the current study, the edge spread function, the spatial resolution (σ), and the response of Gafchromic EBT2 film to low-energy alpha particle doses were investigated. The Gafchromic EBT2 films were peeled-off to permit the 4 MeV alpha particles to reach the active layer. The peeled-off Gafchromic EBT2 films were irradiated with different doses of 4 MeV alpha particles from ²⁴¹Am, where a razor blade was kept in close contact with the active layer in the middle of the alpha particles beam to produce two distinct halves (edges). The measured edge spread function (ESF) for different color channels as well as the weighted and unweighted gray images were fitted using the error function and thereafter differentiated to produce the line spread function (LSF). The blue channel exhibits an anomalous response to the 4 MeV alpha particle dose, leading to a dynamic range reduction of the peeled-off Gafchromic EBT2 film. The pixel values of red and green channels decrease by increasing alpha particle doses, with a descending sensitivity at higher doses. The pixel values of weighted and unweighted gray images decrease with the increase in alpha particle doses but with lower sensitivity. The spatial resolution of the peeled-off Gafchromic EBT2 film is independent of the 4 MeV alpha particle doses for red, green color channels, and weighted and unweighted gray images; the spatial resolution is close to that of single-color channels but with less contrast and visibility. The average spatial resolution, within the same channel, in terms of 1σ (standard deviation), amounts to (21.9 ± 1.5), (19.5 ± 1.4), (19.4 ± 1.3), and (19.4 ± 1.3) μm for red and green channels, weighted and unweighted gray images, respectively. Finally, the LSF peak was found to be proportional to the associated absorbed dosage. This can be utilized for forecasting the alpha-particle absorbed dose within the boundaries of the current study.
