[Use experience and problems in the optimization of intensity modulated radiation therapy (IMRT)--Focus on head & neck].
We present the main points of the optimization in IMRT. The skin surface of the planned target volume was reduced by a few millimeters, in view of the limitations of a calculation grid in accurately estimating the influence of build-up or contamination of electrons. Air cavities such as nasal or oral cavities were, in general, filled with water equivalent density in the dose calculation. Planned target volume was contracted by 5 mm when PTV of a higher prescribed dose was delineated adjacent to it. The 5 mm width of ring-shaped ROI was set at 5 mm outside of the entire PTV to eliminate hot spots. Physical quality assurance is extremely important to eradicate unexpected dose inhomogeneity, and meticulous efforts are required.
Department of radiology, National Canser Center Hospital East.
Takaki
T
Ariji
Takashi
T
Ueda
Satoshi
S
Kitoh
Tomonori
T
Goka
Satoru
S
Kameoka
Ryosuke
R
Kohno
Teiji
T
Nishio
Mitsuhiko
M
Kawashima
D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*