TITLE:
A Dosimetric Comparison of Double Arc Volumetric Modulated Arc Therapy with Large Field Intensity Modulated Radiation Therapy for Head and Neck Cancer
AUTHORS:
Jayapalan Krishnan, Suresh Rao, Sanath Hegde, Jayarama Shetty, Shambhavi
KEYWORDS:
Head and Neck, Rapid Arc, VMAT, IMRT, Planning Study
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.4 No.4,
November
18,
2015
ABSTRACT:
Background:
This Study Evaluate two state of Art techniques, Rapid Arc and large-field
sliding window IMRT in terms of dosimetric end points and delivery time for
head and neck cancer. Materials and Methods: 22 patients with head and neck
cancer were selected for a planning comparative study. All patients went to
CT-simulation in supine position. PTVs were delineated for two dose level of
prescription 70 Gy to the boost-PTV70Gy and 54 Gy to the
elective-PTV54Gy in 35 equal fraction/day. Simultaneous Integrated
Boost (SIB) technique plan was generated for all patients and optimized with
both techniques, Rapid Arc and IMRT with similar planning objectives. Dose of
all plans of both techniques were calculated for 6MV photon using AAA
implemented in Eclipse treatment planning system (10.0.39) with calculating
grid size of 2.5 mm. Results: Comparison of Rapid Arc and IMRT plans in every
patient showed significantly higher conformity index (CI95%) (p = 0.021) and sparing of the all OARs
with Rapid Arc. The average homogeneity Index (HI95%) of lower prescribed dose target PTV54Gy which is in proximity to Higher dose prescribed target PTV70Gy was improved significantly with rapid Arc (p = 0.0001). D1% of spinal cord dose reduced significantly (p = 0.047) with Rapid Arc and the
average mean dose of both left-parotid (21.26 ± 8.5 Gy), right-parotid (22.37 ±
7.44 Gy) were received lesser than with IMRT (22.78 ± 11.2 Gy and 24.1 ± 7.96
Gy) respectively. A significantly less monitor unit (MU) was required to
deliver the plan (p p