Standard RT planning will be performed under conventional simulation, followed by CT-simulation (for study purposes only). Retrospectively, 3D treatment fields will be designed using the CT-simulation data, and compared to the actual treatment fields planned using x-rays. Coverage of the tumour volume will be assessed, together with doses, field sizes and beam positions, to determine relative undercoverage of tumour and overcoverage of normal tissue between the two planning methods, if any.
