TY - JOUR
T1 - LET dependence of the response of EBT2 films in proton dosimetry modeled as a bimolecular chemical reaction
AU - Perles, L. A.
AU - Mirkovic, D.
AU - Anand, A.
AU - Titt, U.
AU - Mohan, R.
PY - 2013/12/7
Y1 - 2013/12/7
N2 - The dose response for films exposed to clinical x-ray beams is not linear and a calibration curve based on absorbed dose can be used to account for this effect. However for proton dosimetry the dose response of films exhibits an additional dependence because of the variation of the linear energy transfer (LET) as the protons penetrate matter. In the present study, we hypothesized that the dose response for EBT2 films can be mathematically described as a bimolecular chemical reaction. Furthermore, we have shown that the LET effect can be incorporated in the dose-response curve. A set of EBT2 films was exposed to pristine 161.6 MeV proton beams. The films were exposed to doses ranging from 0.93 to 14.82 Gy at a depth of 2 cm in water. The procedure was repeated with one film exposed to a lower energy beam (85.6 MeV). We also computed the LET and dose to water in the sensitive layer of the films with a validated Monte Carlo system, taking into account the film construction (polyester, adhesive and sensitive layers). The bimolecular model was able to accurately fit the experimental data with a correlation factor of 0.9998, and the LET correction factor was determined and incorporated into the dose-response function. We also concluded that the film orientation is important when determining the LET correction factor because of the asymmetric construction of the film.
AB - The dose response for films exposed to clinical x-ray beams is not linear and a calibration curve based on absorbed dose can be used to account for this effect. However for proton dosimetry the dose response of films exhibits an additional dependence because of the variation of the linear energy transfer (LET) as the protons penetrate matter. In the present study, we hypothesized that the dose response for EBT2 films can be mathematically described as a bimolecular chemical reaction. Furthermore, we have shown that the LET effect can be incorporated in the dose-response curve. A set of EBT2 films was exposed to pristine 161.6 MeV proton beams. The films were exposed to doses ranging from 0.93 to 14.82 Gy at a depth of 2 cm in water. The procedure was repeated with one film exposed to a lower energy beam (85.6 MeV). We also computed the LET and dose to water in the sensitive layer of the films with a validated Monte Carlo system, taking into account the film construction (polyester, adhesive and sensitive layers). The bimolecular model was able to accurately fit the experimental data with a correlation factor of 0.9998, and the LET correction factor was determined and incorporated into the dose-response function. We also concluded that the film orientation is important when determining the LET correction factor because of the asymmetric construction of the film.
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U2 - 10.1088/0031-9155/58/23/8477
DO - 10.1088/0031-9155/58/23/8477
M3 - Article
C2 - 24240474
AN - SCOPUS:84888597862
SN - 0031-9155
VL - 58
SP - 8477
EP - 8491
JO - Physics in medicine and biology
JF - Physics in medicine and biology
IS - 23
ER -