Lower GI 2017

Adaptive RT: choosing the adaptive scheme

- MRI @ half therapy (fraction 9)

70

- Concomitant boost in the last 6 (3 days left)

65

60

- Calculating d adapt to escalate to EQD2=54Gy ≈ 3Gy/fr in the last 6 fractions (out of 18) - Corresponding EQD2 for OAR (late tox, α/β=3) slightly lower than for T

T

55

OAR (late)

EQD2 (Gy)

50

45

40

2

2,5

3

3,5

4

4,5

Summary of ART scheme: Fractions 1-12: 2.3 Gy/fr (27.6 Gy) @ PTV1 Fractions 13-18: 2.3 Gy/fr (13.8 Gy) @ PTV1 concomitantly 3.0 Gy/fr (18Gy) @ PTV boost

daily dose (adaptive boost)

No boost ART

Total dose: 41.4Gy PTV1; 45.6Gy PTVboost (18 fractions)