Retrospective reconstruction of three-dimensional radiotherapy treatment plans of the thorax from two dimensional planning data.

Abstract

A method for the retrospective reconstruction of three-dimensional (3-D) radiotherapy treatment plans from two-dimensional (2-D) planning data is detailed in this paper. With these techniques the user can register an arbitrarily shaped portal on a simulation film with a diagnostic computed tomography study of the patient and then generate the resultant 3-D dose distribution or dose-volume histogram. Seven treatment plans were reconstructed of patients who had previously undergone 3-D treatment planning for fields involving the thorax and who had had a diagnostic computed tomography (CT) scan. The dose-volume histograms and the spatial positions of the beams on the reconstructed plans were then compared to those of the original 3-D plan, which until then, were not made available to the investigators. The dose-volume histograms of the reconstructed plans did not differ from those of the original plans by more than 3% except in the low dose region. The error in positioning the beam in the reconstructed plan was determined to be approximately 5 mm. The technique of 3-D treatment plan reconstruction can be used, through retrospective studies, to obtain better assessments of normal tissue complication probabilities and tumor control probabilities.