  Purpose: To verify dose delivery and quality assurance of volumetric
modulated arc therapy (VMAT) for head and neck cancer.
  Method: The Imaging and Radiation Oncology Core Houston (IROC-H) head and
neck phantom with thermo- luminescent dosimeters (TLDs) and films, were imaged
with computed tomography scan and the reconstructed image was transferred to
pinnacle treatment planning system (TPS). On TPS the planning target volume
(PTV), secondary target volume (STV) and organ at risk (OAR) were delineated
manually and a treatment plan was made. The dose constraints were determined
for the concerned organs according to IROC-H prescription. The treatment plan
was optimized using adoptive convolution algorithm to improve dose homogeneity
and conformity. The dose calculation was performed using C.C Convolution
algorithm and a Varian True Beam linear accelerator was used to deliver the
treatment plan to the head and neck phantom. The delivered radiation dose to
the phantom was measured through TLDs and GafChromic EBT2 films. The dosimetric
performance of the VMAT delivery was studied by analysing percent dose
difference, iso-dose line profile and gamma analysis of the TPS computed dose
and linac delivered doses.
  Result: the percent dose difference of 3.8\% was observed between the planned
and measured doses of TLDs and a 1.5mm distance to agreement (DTA) was observed
by comparing iso-dose line profiles. Passed the gamma criteria of 3\%/3 mm was
with good percentages.
  Conclusion: The dosimetric performance of VMAT delivery for a challenging
head and neck radiotherapy can be verified using TLDs and films imbedded in an
anthropomorphic H\&N phantom.
