Résumé
Objective To evaluate the method of measurement of total scatter calibrate factor (Sc,p). Methods To measure the Sc,p at different depths on central axis of 6?MV, 15?MV photon beams through different ways. Results It was found that the measured data of Sc,p changed with the different depths to a range of 1%～7%. Using the direct method, the Sc,p measured depth should be the same as the depth in dose normalization point of the prescription dose. If the Sc,p ( fsz, d) was measured at the other depths, it could be obtained indirectly by the calculation formula. Conclusions The Sc,p in the prescription dose can be obtained either by the direct measure method or the indirect calculation formula. But emphasis should be laid on the proper measure depth.