A differential scatter method for dose estimation of small irregular electron fields

Full text: Estimation of dose output factors of small and especially irregular electron fields create a demanding challenge to radiotherapy physicists. Commercial treatment planning systems become increasingly inaccurate as the electron field size decreases. This results in the need to measure directly the dose output of small irregular electron fields. This is not only tedious, but the measurements themselves are not without pitfalls. The contribution of dose from all sources, direct/patient scatter, applicator scatter, and bremsstrahlung have been investigated and a series of measurements performed to determine their contribution at different field sizes. A program has been developed which uses the measured data to estimate the dose output by sector integration of the differential scatter component. Copyright (2000) Australasian College of Physical Scientists and Engineers in Medicine