Determination of boundaries between ranges of high and low gradient of beam profile
Abstract Aim This work addresses the problem of treatment planning system commissioning by introducing a new method of determination of boundaries between high and low gradient in beam profile. Background The commissioning of a treatment planning system is a very important task in the radiation therapy. One of the main goals of this task is to compare two field profiles: measured and calculated. Applying points of 80% and 120% of nominal field size can lead to the incorrect determination of boundaries, especially for small field sizes. Materials and methods The method that is based on the beam profile gradient allows for proper assignment of boundaries between high and low gradient regions …
[P149] Beam profile characteristic points designation for off-axis, wedged and FFF beams
Purpose The main aim of this work is the search of characteristic points of a beam profile and application of these points for the TPS commissioning purposes. The comparison between profiles during the commissioning of the treatment planning system is a very important procedure. It is impossible to designate a field size for the off-axis, wedged and FFF beams directly using the definition of the on-axis symmetric field size. This work demonstrates how to compute good indicators of the field size that can be used for commissioning and QA purposes. Methods The proposal is to use profile inflection points as the beam profile characteristic points. The comparison of distances between inflection…