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Introduction
•
Retreatment tolerance depends on the level of cell
kill and regeneration
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D1
D2
Cell survival
“E”
Retreatment dose (D2)
Δt
Level of cell kill
for tissue damage
Courtesy: Gordon Steel
Introduction
•
Some concepts
•
EQD
2
: equivalent dose in 2-Gy fractions
•
Calculated using LQ-model with α/β values
•
10 Gy for early reactions
•
3 Gy for late reactions
•
EQD
2tol
: tolerance doses
•
Threshold doses above which defined grades of toxicity are
observed
•
% EQD
2tol
: intensity of the initial treatment or the
retreatment
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