Investigation of the dose profiles in the junction region between the supraclavicular and tangential fields

Abstract

Aim: To evaluate the homogeneity of the dose at the junction for fields used in breast radiotherapy using a different technique.

Methods: A total of 4 fields, including 2 tangential fields and AP-PA fields, were planned on the phantom on the RayStation treatment planning system. Gamma analysis was used to compare the results of the measurement and treatment planning system.

Results: When the graphs are analyzed, it is seen that the dose obtained in the junction region on the 2D measurement system as a result of the 1st tangential field and AP field irradiation is 8.3% less than the dose obtained in the treatment planning system. For the 2nd tangential field and PA field, this difference was obtained as 11.8%. When the horizontal profile in the junction region was analyzed as a result of irradiation of all areas, dose differences were measured between 12.5-8.2%. Due to the examination of a region with a high dose gradient, parameters such as the tongue-and-groove effect of MLCs, jaw calibration, parameters included in the treatment planning system's calculations, and measurement setup can directly impact the obtained data.

Conclusions: The results of our study indicate that doses in the connection area should be planned by treatment centers with different techniques, examined with different dosimetric devices, and the acceptability of the obtained doses should be verified.