Calculated beam quality correction factors for ionization chambers in MV photon beams.

Calculated beam quality correction factors for ionization chambers in MV photon beams. Phys Med Biol. 2020 Jan 28;: Authors: Tikkanen JS, Zink K, Pimpinella M, Teles P, Borbinha J, Ojala J, Siiskonen T, Pinto M, Gomà C Abstract The beam quality correction factor,kQ, which corrects for the difference in the ionization chamber response between the reference and clinical beam quality, is an integral part of radiation therapy dosimetry. The uncertainty ofkQis one of the most significant sources of uncertainty in the dose determination. To improve the accuracy of availablekQdata, four partners calculatedkQfactors for 10 ionization chamber models in linear accelerator beams with accelerator voltages ranging from 6 MV to 25 MV, including flattening-filter-free (FFF) beams. The software used in the calculations were EGSnrc and PENELOPE, and the ICRU report 90 cross section data for water and graphite were included in the simulations. Volume averaging correction factors were calculated to correct for the dose averaging in the chamber cavities. A comparison calculation between partners showed a good agreement, as did comparison with literature. ThekQvalues from TRS-398 were higher than our values for each chamber where data was available. ThekQvalues from TRS-398 were higher than our values for each chamber where data was available. ThekQvalues for the FFF beams did not follow the same TPR20,10,kQrelation as beams with flattening filter (valu...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research