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Early versus late reactions
Early reactions
Late reactions
Latency
(Time to onset of
clinical manifestion)
<90 days after onset RT; typically
3-9 weeks
Not influenced by dose,
but severity and duration of
damage are dose-dependent
>90 days after onset RT; typically
0,5-5 years
Inversely dependent on dose:
higher dose leads to shorter latent
period
Fractionation
sensitivity
Low (high α/β ~ 6-10 Gy)
High (low α/β ~ 1-5 Gy)
Influence of overall
treatment time (OTT)
Shorter OTT leads to greater
injury
No significant influence
Clinical course
Typically transient, but
consequential late reactions may
occur
Progressive and irreversible
Compensation may occur
Rehabilitation or treatment for
complications may relieve
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Relevant factors
•
Organs in the irradiated volume
•
Normal tissue constraints
•
Pathogenesis of functional tissue (L1.7)
•
Vascular component
•
Connective tissue
•
Specific functional tissue compartments
•
Previous irradations
•
Retreatment tolerance (L4.5)
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