MO-A-BRB-04: Treatment Plan Data Collection, Beam Modeling and Clinical Validation for Unfiattened Beams

The use of an unfiattened photon beam for radiotherapy treatment is a new concept in the Radiation Oncology field. In the past, the non-optimal radiation area coverage obtained with unfiattened photon beams was of concern, and the flattening filter was introduced to overcome this pitfall. With the advance of technology, Intensity Modulated Radiotherapy (IMRT) emerged and non-optimal coverage was no longer an issue since the beam intensity could be modulated to obtain the desired target coverage. Unfiattened photon beams offer several advantages over flattened beams, namely: (1) they provide 2 to 4 times the dose rate, which significantly shortens the treatment time, especially for the high dose irradiation techniques, (2) they provide a purer beam spectrum, which is easier to model in a treatment planning system, (3) the head scatter is dramatically reduced, giving a lower dose outside of the field and (4) they provide a sharper penumbra, which makes planning easier. This lecture will provide an overview of the data collection, the treatment planning system (TPS) parameter modeling and the TPS validation for clinical implementation of unfiattened photon beams.

1. Understand the physics data collection and related issues. 2. Understand the TPS parameter modeling, planning validation and related issues. 3. Understand the optimal usage of unfiattened beams with clinical examples.