Cross-validation of two commercial methods for volumetric high-resolution dose reconstruction on a phantom for non-coplanar VMAT beams.
OBJECTIVE
Delta(4) (ScandiDos AB, Uppsala, Sweden) and ArcCHECK with 3DVH software (Sun Nuclear Corp., Melbourne, FL, USA) are commercial quasi-three-dimensional diode dosimetry arrays capable of volumetric measurement-guided dose reconstruction. A method to reconstruct dose for non-coplanar VMAT beams with 3DVH is described. The Delta(4) 3D dose reconstruction on its own phantom for VMAT delivery has not been thoroughly evaluated previously, and we do so by comparison with 3DVH.


METHODS
Reconstructed volumetric doses for VMAT plans delivered with different table angles were compared between the Delta(4) and 3DVH using gamma analysis.


RESULTS
The average γ (2% local dose-error normalization/2mm) passing rate comparing the directly measured Delta(4) diode dose with 3DVH was 98.2 ± 1.6% (1SD). The average passing rate for the full volumetric comparison of the reconstructed doses on a homogeneous cylindrical phantom was 95.6 ± 1.5%. No dependence on the table angle was observed.


CONCLUSIONS
Modified 3DVH algorithm is capable of 3D VMAT dose reconstruction on an arbitrary volume for the full range of table angles. Our comparison results between different dosimeters make a compelling case for the use of electronic arrays with high-resolution 3D dose reconstruction as primary means of evaluating spatial dose distributions during IMRT/VMAT verification.
Department of Radiation Oncology, Moffitt Cancer Center, Tampa, USA. Electronic address: vladimir.feygelman@moffitt.org.
Vladimir
V
Feygelman
Department of Radiation Oncology, Moffitt Cancer Center, Tampa, USA; Department of Physics, University of South Florida, Tampa, USA.
Cassandra
C
Stambaugh
Department of Radiation Oncology, Moffitt Cancer Center, Tampa, USA.
Daniel
D
Opp
Department of Radiation Oncology, Moffitt Cancer Center, Tampa, USA.
Geoffrey
G
Zhang
Department of Radiation Oncology, Moffitt Cancer Center, Tampa, USA.
Eduardo G
EG
Moros
Canis Lupus LLC, Merrimac, USA.
Benjamin E
BE
Nelms
D006801:Humans; D019047:Phantoms, Imaging; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*
3D dose reconstruction; 3D dosimetry; Dosimetry array; VMAT dosimetry; VMAT verification