Comparative planning evaluation of intensity-modulated radiotherapy techniques for complex lung cancer cases.

Abstract

Lung cancer treatment can be one of the most challenging fields in radiotherapy. The aim of the present study was to compare different modalities of radiation delivery based on a balanced scoring scheme for target coverage and normal tissue avoidance. Treatment plans were developed for 15 patients with stage III inoperable non-small cell lung cancer using 3D conformal technique and intensity-modulated radiotherapy (IMRT). Elective nodal irradiation was included for all cases to create the most challenging scenarios with large target volumes. A 2 cm margin was used around the gross tumour volume (GTV) to generate PTV2 and 1cm margin around elective nodes for PTV1 resulting in PTV1 volumes larger than 1000 cm(3) in 13 of the 15 patients. 3D conformal and IMRT plans were generated on a commercial treatment planning system (TheraPlan Plus, Nucletron) with various combinations of beam energies and gantry angles. A 'dose quality factor' (DQF) was introduced to correlate the plan quality with patient specific parameters. A good correlation was found between the quality of the plans and the overlap between PTV1 and lungs. The patient feature factor (PFF), which is a product of several pertinent characteristics, was introduced to facilitate the choice of a particular technique for a particular patient. This approach may allow the evaluation of different treatment options prior to actual planning, subject to validation in larger prospective data sets.