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Dose calculation issues ‚in practice‘:
Dosimetric effects of the treatment table/setup devices
Reiner et al., DEGRO 2013
measured dose difference
with vs. without table [%]
6MV,
•
depending on the vendor/model,
treatment tables can have a water-
equivalent thickness of ~1 cm w.r.t
dose absorption
•
depending on beam angle, dose
absorption of several percent
→
should be explicitly considered
for dose calculation, especially for
rotational techniques (VMAT),
solid water phantom
with ionisation chamber
10x10 cm field,
different beam angles
ESTRO IMRT course 2016
Dose Calculation in Static and Rotational IMRT
London April 7th, 2016
-61-
gantry angle
15MV
different
depths in phantom
where oblique angles through the
table cannot be avoided
•
Methods: Dose calculation with
table/setup devices ‘as in CT’, or
dummy contour with water density
override. MIND: evaluate optimal
method for your TPS/dose
calculation algorithm!