Dosimetric beam matching analysis of MV photons and electrons therapy

Background: for various practical reasons in radiotherapy practice, it is very advantageous to have linear accelerators dosimetrically matched. the present work assesses the extent of beam matching by investigating the similarity of dosimetric data from three clinac-ix accelerators in photons (6, 18 mv) and electrons (6, 9, 12, 16 and 20 mev) mode. materials and methods: the following study is based on detailed comparisons of measured and determined parameters such as percent depth doses (pdds), cross-plane beam profiles, flatness, symmetry, penumbra and dosimetric leaf gap, mlct interleaf transmission factor, quality index, relative output factor, in addition of depth r50, therapeutic range r90 and particle range rp of electron beam. results: the current measured data, for both photons and electrons, exhibited satisfactory degree of agreement among the three clinac-ix. for 6 mv and 18 mv photons energies the maximum deviation of percentage depth does not exceed 0.4 %. for electron depth dose measurements (dmax, r50, r90, rp) the results revealed a maximum deviation of 0.54 mm for all electron energies and applicators. as a direct clinical application, a left breast and prostate cancer cases were planned on the three clinac-ix machines and compared for their dose volume histograms. conclusion: in clinical applications, the patient’s treatment can be shifted from one clinac-ix to another without reducing the treatment quality in the case of periodic preventive maintenance or interruption of the functioning of the clinacs; the treatment can be preserved without having to replan.