NDLI: Smoothing intensity modulated beam profiles to facilitate delivery

Content Provider	IEEE Xplore Digital Library
Author	Spirou, S.V. Yang, J. Chen-Shou Chui Ling, C.C.
Copyright Year	2000
Description	Author affiliation: Dept. of Med. Phys., Memorial Sloan-Kettering Cancer Center, New York, NY, USA (Spirou, S.V.)
Abstract	Intensity-modulated radiation therapy (IMRT) is rapidly gaining ground as a means of delivering dose distributions that conform more closely to the target and provide greater organ-sparing. The optimization algorithms that determine the IM beam profiles are computationally complex and intensive. Moreover, for reasons of efficiency, these algorithms often contain simplifications, such as the use of partial scattering. Consequently, the resulting IM beam profiles are inherently uncertain and noisy, often exhibiting narrow and sharp peaks and valleys. Such profiles are difficult to generate, requiring long treatment times, while affecting the final dose distribution only marginally. In this work the authors discuss techniques of smoothing the beam profiles. The simplest approach is to smooth at the end of each iteration. Alternatively, penalty terms for the "unsmoothness" of the beam profiles can be included within the objective function used to drive the optimization process. The functional form of these terms is similar to those used in the first approach, thus essentially applying the same filter. The latter method achieves better dose distributions in situations where a low-tolerance critical organ is in the middle of the field, with much sharper dose gradients at the interfaces between the critical organ and the target. In addition, it is more efficient, requiring fewer iterations, because the process of smoothing does not undo the process of optimization, as the case is in the former method.
Starting Page	445
Ending Page	448
File Size	382365
Page Count	4
File Format	PDF
ISBN	0780364651
ISSN	1094687X
DOI	10.1109/IEMBS.2000.900771
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2000-07-23
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Smoothing methods Intensity modulation Optical modulation Biomedical applications of radiation Filters Scattering Optimization methods Uncertainty Degradation
Content Type	Text
Resource Type	Article

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