Dosimetric Comparison of Split Field and Fixed Jaw Techniques for Large IMRT Target Volumes in the Head and Neck
- Department of Radiation Oncology, Reid Hospital and Health Care Services Richmond, IN (United States)
- Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States)
Some treatment planning systems (TPSs), when used for large-field (>14 cm) intensity-modulated radiation therapy (IMRT), create split fields that produce excessive multiple-leaf collimator segments, match-line dose inhomogeneity, and higher treatment times than nonsplit fields. A new method using a fixed-jaw technique (FJT) forces the jaw to stay at a fixed position during optimization and is proposed to reduce problems associated with split fields. Dosimetric comparisons between split-field technique (SFT) and FJT used for IMRT treatment is presented. Five patients with head and neck malignancies and regional target volumes were studied and compared with both techniques. Treatment planning was performed on an Eclipse TPS using beam data generated for Varian 2100C linear accelerator. A standard beam arrangement consisting of nine coplanar fields, equally spaced, was used in both techniques. Institutional dose-volume constraints used in head and neck cancer were kept the same for both techniques. The dosimetric coverage for the target volumes between SFT and FJT for head and neck IMRT plan is identical within {+-}1% up to 90% dose. Similarly, the organs at risk (OARs) have dose-volume coverage nearly identical for all patients. When the total monitor unit (MU) and segments were analyzed, SFT produces statistically significant higher segments (17.3 {+-} 6.3%) and higher MU (13.7 {+-} 4.4%) than the FJT. There is no match line in FJT and hence dose uniformity in the target volume is superior to the SFT. Dosimetrically, SFT and FJT are similar for dose-volume coverage; however, the FJT method provides better logistics, lower MU, shorter treatment time, and better dose uniformity. The number of segments and MU also has been correlated with the whole body radiation dose with long-term complications. Thus, FJT should be the preferred option over SFT for large target volumes.
- OSTI ID:
- 21486878
- Journal Information:
- Medical Dosimetry, Vol. 36, Issue 1; Other Information: DOI: 10.1016/j.meddos.2009.10.002; PII: S0958-3947(09)00121-6; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0958-3947
- Country of Publication:
- United States
- Language:
- English
Similar Records
SU-E-T-59: A Novel Multi-Beam Dynamic IMRT with Fixed-Jaw Technique for Left Breast Cancer Patients with Regional Lymph Nodes Radiotherapy
Dosimetric Comparison of Manual and Beam Angle Optimization of Gantry Angles in IMRT