The Halcyon comes with a reference beam data (RBD) set including percentage depth dose (PDD) curves, profiles, and output factors. Varian generates a pre-configured beam model in Eclipse treatment planning system (TPS) using this RBD. The aim of the current study is to validate RBD set of Halcyon 3.0, newly installed in our institute.
METHODS
The PDD and lateral dose profiles were measured for open fields with sizes from 4×4 cm2 to 28×28 cm2
in a water tank using a semiflex ionization chamber. The PDD and profiles were calculated with the
AAA v17.1 in Eclipse for the same field sizes as described in ion chamber measurements. The depth of
maximum dose (dmax), PDD value at depth of 10 cm, penumbra, field size, and lateral distance from the
central axis at 90%, 75%, and 60% dose points of profile were analyzed.
RESULTS
The difference of dmax values was 0.08 cm for all PDDs. A good agreement was obtained between calculated
and measured PDD10 with a maximum difference of 0.35%. The measured field size and penumbra
values indicated an excellent agreement with calculated values with a maximal discrepancy of 0.17
cm and 0.50 mm for all field sizes, respectively. The discrepancies between calculated and measured
lateral distances for all field sizes were within 0.20 mm.
CONCLUSION
The TPS-calculated data using pre-configured beam model for Halcyon 3.0 were in good agreement
with the measurements.