Monte Carlo calculation of beam quality correction factors in proton beams using PENH | Semantic Scholar (2024)

KQ factors calculated in this work were found to agree within 1% or better with experimentally determined kQ factors provided in the literature, with only two exceptions with deviations of 1.4% and 2.4%.

FLUKA can be used to calculate Monte Carlo calculated beam quality correction factorskQ for monoenergetic proton beams using the Monte Carlo code FLUKA and shows a general good agreement for low energies, while differences for higher energies were pronounced.

The perturbation factors p Q were shown to deviate from unity for the investigated chambers, contradicting the assumptions made in dosimetry protocols and the approximation of ionization chamber perturbations in proton beams by the respective water-to-air mass stopping power ratio shall be revised.

The latest ICRU 90 recommendations on key data for ionizing-radiation dosimetry were used to calculate the electronic stopping powers and to select the mean energy necessary to create an ion pair in air.

Analysis of currently available data on beam quality correction factors, kQ, for ionization chambers in clinical proton beams and derive their current best estimates for the updated recommendations of the IAEA TRS-398 Code of Practice showed that except for the beam quality dependence of the water-to-air mass stopping power ratio and of the displacement correction factor, there is no remaining beam quality Dependency pQ.

There is a need for updating the current recommendations, which assume a constant P of unity in carbon-ion beams, to recommendations that consider chamber-induced differences, as shown in the results.

The precise measurement of beam quality correction factors for mono-energy proton beams using the Monte Carlo technique is required in future studies.

The results indicate that PHITS can calculate the [Formula: see text] and [Formula: see text] with high precision and compare with that of a previous study, which was calculated using other Monte Carlo codes under similar conditions.

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It is concluded that perturbation correction factors in proton beams—currently assumed to be equal to unity—are in fact significantly different from unity for some of the ionization chambers studied.

Ionization chamber perturbation factors are shown to be energy dependent and nuclear interactions must be taken into account for accurate calculation of the ionization chamber's response and need to be considered in dosimetry procedures.

The results support the suggestion that the IAEA TRS-398 reference conditions for monoenergetic proton beams should be revised so that the effective point of measurement of cylindrical ionization chambers is taken into account when positioning the reference point of the chamber at the reference depth.

This study aims to demonstrate, using Monte Carlo (MC) simulations, that kQ factors computed/measured for broad beams can be used with scanned beams for similar reference dose distributions with no additional significant uncertainty, and the Alfonso formalism was applied to scanned proton beams.

The use of the proton-calibrated reference ionization chamber, in conjunction with the beam quality correction factor kQp, significantly reduced the systematic uncertainty of the absorbed dose determination.

Based on the Fano cavity test, the Geant4/TOPAS Monte Carlo code, in its investigated version, can provide reliable results for IC calculations.

Users of the addendum to the TG-51 protocol for reference dosimetry of high-energy photon beams, which recommends Monte Carlo calculated kQ factors, can rest assured that the recommendations of ICRU report 90 on basic data have little impact on this central dosimetric parameter.

The impact of the ICRU Report 90 recommendations on Monte Carlo calculated stopping power ratios sw, a, perturbation factors p and beam quality correction factors kQ was investigated and confirmed a decrese of sw,a by a fraction of a percent for photon and electron beams.

The objectives of this study are to design a new Fano cavity test for proton MC and to implement the methodology in two MC codes: Geant4 and PENELOPE extended to protons (PENH).

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