Radiat Oncol J.  2017 Mar;35(1):90-100. 10.3857/roj.2016.02054.

Influence of jaw tracking in intensity-modulated and volumetric-modulated arc radiotherapy for head and neck cancers: a dosimetric study

• Mani KR
• Upadhayay
• Das KJ

• KMID: 2401804
• DOI: http://doi.org/10.3857/roj.2016.02054

Abstract

PURPOSE
To Study the dosimetric advantage of the Jaw tracking technique in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) for Head and Neck Cancers.
MATERIALS AND METHODS
We retrospectively selected 10 previously treated head and neck cancer patients stage (T1/T2, N1, M0) in this study. All the patients were planned for IMRT and VMAT with simultaneous integrated boost technique. IMRT and VMAT plans were performed with jaw tracking (JT) and with static jaw (SJ) technique by keeping the same constraints and priorities for a particular patient. Target conformity, dose to the critical structures and low dose volumes were recorded and analyzed for IMRT and VMAT plans with and without JT for all the patients.
RESULTS
The conformity index average of all patients followed by standard deviation (x¯±Ïƒ(x¯)) of the JT-IMRT, SJ-IMRT, JT-VMAT, and SJ-VMAT were 1.72 ± 0.56, 1.67 ± 0.57, 1.83 ± 0.65, and 1.85 ± 0.64, and homogeneity index were 0.059 ± 0.05, 0.064 ± 0.05, 0.064 ± 0.04, and 0.064 ± 0.05. JT-IMRT shows significant mean reduction in right parotid and left parotid shows of 7.64% (p < 0.001) and 7.45% (p < 0.001) compare to SJ-IMRT. JT-IMRT plans also shows considerable dose reduction to thyroid, inferior constrictors, spinal cord and brainstem compared to the SJ-IMRT plans.
CONCLUSION
Significant dose reductions were observed for critical structure in the JT-IMRT compared to SJ-IMRT technique. In JT-VMAT plans dose reduction to the critical structure were not significant compared to the SJ-IMRT due to relatively lesser monitor units.

Keyword

Jaw tracking; IMRT; VMAT; Dosimetric study

MeSH Terms

Brain Stem
Head and Neck Neoplasms
Head*
Humans
Jaw*
Neck*
Radiotherapy*
Radiotherapy, Intensity-Modulated
Retrospective Studies
Spinal Cord
Thyroid Gland