Comparison of intensity-modulated radiotherapy with conventional conformalradiotherapy for complex-shaped tumors

Purpose: Conformal and intensity-modulated radiotherapy (IMRT) plans for 9 patients were compared based on characterization of plan quality and effect s on the oncology department. Methods and Materials: These clinical cases, treated originally with confor mal radiotherapy (CRT), required extraordinary effort to produce conformal treatment plans using nonmodulated, shaped noncoplanar fields with multilea f collimators (MLCs). IMRT plans created for comparison included rotational treatments with slit collimator, and fixed-field MLC treatments using equi spaced coplanar, and noncoplanar fields. Plans were compared based upon tar get coverage, target conformality, dose homogeneity, monitor units (MU), us er-interactive planning time, and treatment delivery time. The results were subjected to a statistical analysis. Results: IMRT increased target coverage an average of 36% and conformality by 10%. Where dose escalation was a goal, IMRT increased mean dose by 4-6 G y and target coverage by 19% with the same degree of conformality. Rotation al IMRT was slightly superior to fixed-field IMRT. All IMRT techniques incr eased integral dose and target dose heterogeneity. IMRT planning times were significantly less, whereas MU increased significantly; estimated delivery times were similar. Conclusion: IMRT techniques increase dose and target coverage while continu ing to spare organs-at-risk, and can be delivered in a time frame comparabl e to other sophisticated techniques. (C) 2000 Elsevier Science Inc.