Folie 1

Recently… New identical Linac…

Why did QART fail?

•

Full tests from CT scanning to irradiation of phantoms have

been performed. The measurements were performed on the

right linac.

But

the calculations were performed using the

existing Linac model in the TPS.

•

Routinely EPID patient dosimetry QA is performed at this

institution.

But

this is a relative measurement (scaled to

coincide with calculations in normalisation point).

Occasionally Matrix-measurements are performed at a linac,

e.g., if beams do not fit on the EPID.

But

on the new linac only

small fields were used. (HD 2.5 mm MLC)