Using beam profile inflection point in process of treatment planning system verification

Abstract

Background:The comparison between profiles during the commissioning of the treatment planning system is an essential procedure. It is impossible to designate a field size for off-axis, wedged, and FFF beams directly by using the definition of the on-axis symmetric field size. This work proposes the use of different characteristic points as indicators of the field size for commissioning and QA purposes. This work aimed to search for the beam profile's characteristic points and use them for the TPS commissioning purposes. Material and methods:The proposal is to use profile inflection points as the beam profile characteristic points. The usage of dedicated software allowed for comparing distances between inflection points and between points of 50% intensity. For the off-axis, wedged, and FFF fields, comparisons were made to the nominal field sizes.Results: Distances between inflection points proved to be different by less than 1 mm from nominal field sizes for all kinds of investigated beams.Conclusions: Inflection points are convenient for comparing the off-axis, wedged, and FFF field sizes because of their independence from profile normalization. With finite accuracy, the inflection points could be used for the above kind of beam sizes designation.

Inflection point kinetics: plasmonic transition of silver and copper doped glasses

“…The listed uncertainty in the last decimal place of the AE values reflects solely the slope uncertainty. The data suggests that the AE of the plasmonic precipitation evaluated at 4.8 (6) eV by the model-free IP P method, proposed herein, is in excellent agreement with the value obtained from the standard kinetic analysis, 5.0(6) eV. 8 In summary, the main steps in the standard kinetic approach published previously 8 are theoretically involved and include: (i) particle size was estimated based on Ag NP SPR peak position, following the theoretical approach reported by Arnold and Borders 11 and corroborated with HRTEM images done at the end of the precipitation process.…”

“…5 Inflection point considerations in 'non-sigmoidal' phenomena are suggested as well. In the area of dosimetry verification of radiotherapy treatment, Wendykier et al 6 proposed the use of the position of the beam inflection points as a reliable radiation characteristic, especially, for asymmetric, off-axis field profiles. In solar physics, Lantos 7 proposes a method using the slope at the inflection point of the ascending phase of the solar cycle to predict the sunspot maximum.…”

Optimal values of the Electron Monte Carlo dose engine parameters

“…4 ). Alfard software made it possible to find boundaries between these areas, based on a gradient value of 0.5%/mm [ 16 , 17 ].…”

“…The differences between the measurement and calculated graphs for specific intervals were computed in the last step, and the resulting data were used for analysis. The above method was described in more detail, on the example of determining the boundaries of the region of a large and small gradient of the photon beam profile, in the works [ 16 , 17 ].…”