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Fractionation parameters for human tissues and tumors
H D Thames1, S M Bentzen, I Turesson
1Department of Biomathematics, University of Texas M.D. Anderson Cancer Center, Houston 77030.
International Journal of Radiation Biology
|November 1, 1989
Summary
Fractionation sensitivity (alpha/beta) can be estimated from clinical data for normal tissues and tumors. Alpha/beta values are generally higher for acute-responding tissues than late-responding ones, with variations observed in human tumors.
Area of Science:
- Radiation oncology
- Radiobiology
- Clinical physics
Background:
- Fractionation sensitivity (alpha/beta) is a key radiobiological parameter.
- Estimating alpha/beta from clinical data is valuable for treatment optimization.
- Wide variations in dose, fraction size, and treatment time allow for such estimations.
Purpose of the Study:
- To summarize estimates of fractionation parameters derived from clinical results.
- To compare alpha/beta values for normal tissues and human tumors.
- To discuss implications for radiation therapy planning.
Main Methods:
- Analysis of clinical data with significant variations in time-dose factors.
- Estimation of fractionation sensitivity (alpha/beta) parameters.
- Comparison of derived parameters with existing radiobiological models and animal data.
Main Results:
- Alpha/beta is higher for acutely responding normal tissues compared to late-responding ones, consistent with animal data.
- Many human tumors exhibit high alpha/beta values, but exceptions like melanomas exist.
- Tumor regeneration in head and neck cancers is estimated at <= 1 Gy/day, while mucosal regeneration is ~1.8 Gy/day.
Conclusions:
- Clinical data can provide valuable estimates of radiobiological parameters like alpha/beta.
- Understanding tissue-specific alpha/beta values and repair kinetics is crucial for personalized radiation therapy.
- Further research into repair halftime and tumor-specific parameters is warranted.