SU‐FF‐T‐510: Comparison of Helical Tomotherapy, MLC‐Based IMRT, and 3D‐Conformal Radiation Modalities in BEUD Utilization and Analysis

Purpose: To examine the clinical effectiveness of radiobiologically‐centered treatment plans utilizing Helical Tomotherapy (HT), MLC‐based IMRT, and 3D‐Conformal Radiotherapy treatment plans by allowing the use of radiobiological parameters to supplement current treatment planning techniques and to develop P₊ ‐ D̿ diagrams that can further describe the efficacy of treatment plans. Finally, to provide a closer association between clinical outcome and treatment delivery. Method and Materials: Two cases of lung cancer were examined. Treatment plans were developed using the HT, IMRT, and 3D‐CRT modalities. The radiobiological analysis was based on the probabilities of complication‐free tumor control (P₊), overall injury (P_I), overall benefit (P_B), and the biologically effective uniform dose (D̿) as common prescription point. These radiobiological measures were used to evaluate the different treatment plans when used in concert with standard dosimetric criteria. Results: For both patients, P_I is lower and P₊ is higher in the HT modality than in both IMRT and 3D‐CRT. D̿ is lower for HT than in the other modalities. Between IMRT and 3D‐CRT exclusively, 3D‐CRT delivers better P_I in both patients. The DVHs show better treatment planning and delivery with HT. This implies a reduction in the delivered dose to the spinal cord and heart, which have much smaller volumes and have dose delivery controlled in the Treatment Planning System as OARs. Conclusion: The use of radiobiological parameters to improve treatment delivery and clinical outcome is shown to be effective in this examination. The HT modality showed lower P_I than both IMRT and 3D‐CRT. Furthermore, analysis with a greater number of lung cases and OARs is needed to establish whether radiobiologically‐based treatment planning can be established as an effective clinical tool for better radiation delivery and positive clinical outcomes.