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Evaluate the movement:
Head
à
minimize the compliance of mask, neck support &
bite
block
Eye :
Involuntary:
drift (ex: 0.5 -1 mm/sec)
oscillations
(ex: amp 0.5mm, freq 2-3 Hz)
Voluntary or fainted :
«how long is the treatment ?? »
(1cm, 0.1 sec)
II. Adopt the strategy :
Positioning with Xrays & clips
à
set-up with tenths of mm
Transfert referential to video : monitoring without X rays
Gating (manual or automatic) with video & Coaching
Back to X rays if necessary. If mouvement ++: sucker/lens, margins or abandon
III. Requirements/Consequences :
- Orthogonal X rays, panels, infrared camera, electronic pen or screen,…
-
Dose rate
high enough to make a short session (15sec -1 min),
low enough to minimize doses if need to interrupt
make your calculations… : 30 Gy/min; tot dose 4x15= 60Gy
1 sec target off
à
0.5 Gy ( ~ 1 %), ~1 mm