948 / 1245
Summary: the use of plastic phantoms for TPS QA & PSQA
•Representation of solid plastics in CT datasets is influenced on whether the material is water-equivalent in the kV energy range.
•Systematic discrepancies in the verification of calculated dose in solid plastics can occur if these are not properly represented in
the TPS.
•We have been working on the assumption that homogeneous solid phantoms which are shown to be water-equivalent for
reference dosimetry and relevant dosimetry using an ionization chamber are also water-equivalent under a multiple beam
arrangements (for the verification of treatment plans).
•The interpretation of measurements from complex phantoms with embedded detector systems might not be straightforward if
there is limited understanding on how these phantoms are represented in the TPS and how the phantom software processes the
measured signal by the detectors.
Does what I
see agree
with
calculations?
Are we
comparing
the same
thing?
TPS (often referred to as ‘black box’)
The detector in plastic phantom
(by Nuria Jornet)