Syntax:
DFDM: RBI={relative beam intensity}
Example:
XBRT: TD4F=2 NTD=30 !60 Gy delivered as 30 daily 2-Gy fractions
DFDM: ADR=10000 NBD=5 RBI=RR1 !4 minutes to deliver ea. 2 Gy fraction
RR1 = 2 1 1 1 / !Intensity of beam 1 is 2x stronger than beam 2, 3 or 4 NOTE: In the above example, beam 1 delivers 0.8 Gy, and the other beams each deliver 0.4 Gy. The total dose delivered in each fraction = 0.8 Gy + (3 x 0.4 Gy) = 2.0 Gy. The fraction delivery time is approximately 4 minutes.
Purpose: Set the relative intensity of the radiation beams.
Data Type: real
Unit: n/a
Default: 1/NBD (same intensity for all beams)
Comments: In step and shoot intensity modulated radiation therapy (IMRT), fractions are typically delivered in 10 to 20 or 30 minutes using 5 to 9 beams directed at the patient (each beam may be shaped by multiple leaf configurations). The NBD, RBI, BSEQ and TTO parameters can be used to model the temporal pattern of radiation deliver to some region of the tumor in great details. The total time to deliver each fraction is ~ (NBD-1)*TTO. Some references related to these phenomena are: J.Z. Wang, X.A. Li., W. D’Souza, R.D. Stewart. Impacts of prolonged dose-delivery time on tumor control: a note of caution for IMRT, Int. J. Radiat. Oncol. Biol. Phys. Accepted (2003). - R.D. Stewart and R.J. Traub, Radiobiological Modeling in Voxel Constructs. In A. Kling F. Barão, M. Nakagawa, L. Távora, P. Vaz, eds. Proceedings of the MC2000, An International Conference on Advanced Monte Carlo for Radiation Physics, Particle Transport Simulation and Applications. New York, USA: Springer-Verlag Publishing, 285-290 (2001).
- R.D. Stewart and R.J. Traub, Temporal Optimization of Radiotherapy Treatment Fractions In: Proceedings of the ANS Topical Meeting on Radiation Protection for our National Priorities, Medicine, the Environment, and the Legacy (RPS 2000). Illinois, USA. Published by the American Nuclear Society, Inc. La Grange Park, Illinois, p 372-378 (2000).
|
