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SU-E-T-252: Consolidating Duodenal/Small Bowel Toxicity Data via Iso-Effective Dose Calculations Based on Compiled
P Prior1, A Tai1, B Erickson1
1Medical College of Wisconsin, New Berlin, WI.
This study consolidates duodenal toxicity data using the modified linear quadratic (MLQ) model, enabling dose-volume constraint estimation for radiotherapy planning. Findings support consistent dose-response calculations across different normal tissue complication probability levels.
Area of Science:
- Radiation Oncology
- Medical Physics
- Clinical Oncology
Background:
- Duodenal toxicity is a critical concern in radiotherapy, influenced by dose and fractionation.
- Existing data on duodenal toxicity is challenging to consolidate due to varying fractionation schemes.
- Accurate dose-volume constraints are essential for safe and effective radiation treatment planning.
Purpose of the Study:
- To consolidate duodenal toxicity data from diverse clinical studies using the modified linear quadratic (MLQ) model.
- To develop a methodology for adjusting dose-volume parameters across different normal tissue complication probability (NTCP) levels.
- To estimate reliable dose-volume constraints for radiotherapy treatment planning.
Main Methods:
- Estimated modified Lyman model parameters for duodenal NTCP using chi-squared fitting with tolerance dose and equivalent uniform dose (EUD) data.
- Converted dose-volume pairs to iso-effective dose (in 2 Gy per fraction)-volume pairs using MLQ model parameters.
- Derived a relationship to convert DMLQED2 between different NTCP levels.
Main Results:
- Six reports were utilized to estimate duodenal toxicity, yielding TD50 = 60.9 ± 7.9 Gy, m = 0.21 ± 0.05, and α = 0.09 ± 0.03 Gy-1.
- Toxicity rates from hypo-fractionated radiotherapy (HBRT) were consistent with conventional fractionation data.
- DMLQED2 conversions between NTCP levels showed consistency within a narrow range.
Conclusions:
- Modified linear quadratic (MLQ) model-based iso-effective calculations for Grade > 2 duodenal toxicity are consistent within model parameter uncertainties.
- The derived dose-volume conversion methodology allows estimation of duodenal/small bowel dose-volume constraints for novel fractionation and dose escalation strategies.
- This approach aids in optimizing radiotherapy planning to minimize duodenal toxicity.
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