IMRT

Dose calculation issues ‚in practice‘: Dosimetric effects of the treatment table/setup devices Reiner et al., DEGRO 2013

• 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), 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!

solid water phantom with ionisation chamber

10x10 cm field, different beam angles

6MV, different depths in phantom

15MV

gantry angle

measured dose difference with vs. without table [%]

ESTRO IMRT course 2015 Dose Calculation in Static and Rotational IMRT Brussels October 8th, 2015

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