A cost-outcome analysis of Image-Guided Patient Repositioning in the radiation treatment of cancer of the prostate

Abstract

Background and purpose With Image-Guided Radiation Therapy (IGRT) rapidly gaining acceptance in the clinic it is timely to commence an assessment of its potential outcome benefit versus costs. Materials and methods Using Activity-Based Costing we have calculated the incremental cost of adding Image-Guided Patient Repositioning (IGPR), a significant component of IGRT, to both Intensity-Modulated Radiation Therapy (IMRT) and Three-Dimensional Conformal Radiation Therapy (3DCRT) for prostate cancer. The dosimetric outcome benefit resulting from the implementation of IGPR is estimated from a publication describing the improvement in set-up accuracy using each of four correction protocols. In our study outcome is quantified using a metric based on the Equivalent Uniform Dose. Our discussion is limited to image-guided corrective translations of the patient and does not specifically address margin reduction, rotations, organ deformation or major equipment failure modes, all of which are significant additional justifications for implementing an IGRT program. Results Image guidance used solely for translational patient repositioning for prostate cancer adds costs with relatively little improvement in dosimetric quality. Full exploitation of the potential of IGRT, particularly through margin reduction, can be expected to result in a reduction in the cost-outcome ratios reported here. Conclusions IMRT benefits more than 3DCRT from IGPR with the Weekly Shrinking Action Level approach yielding the lowest cost-outcome ratio.