Efficacy of CT-assisted two dimensional treatment planning: analysis of 45 patients.

A method is presented for quantitatively assessing the impact of CT assistance in treatment planning for radiation therapy. A three-phased analysis of treatment plans for 45 patients was undertaken. Nonuniformity and local efficiency of dose delivered were compared without and with the utilization of CT information. Good agreement between the objective assessment of treatment plans and independent subjective optimization of the plans by a radiotherapist support the validity of this technique. On the basis of nonuniformity of dose, 31 of the 45 cases were planned more poorly in the absence of CT information. The addition of CT information permitted optimization by the physician in 25 of the 45 patients. Twenty-three of these showed improved local efficiency (92%). This study indicates that measurable improvements in treatment plans are available by taking advantage of CT information. These were greatest in the brain, lung, and retroperitoneum in this small group of patients.