A new sigmoidal function describing the small field dose profile data from a linear accelerator
作者:
Chan F. Lam,
期刊:
Medical Physics
(WILEY Available online 1998)
卷期:
Volume 22,
issue 5
页码: 543-547
ISSN:0094-2405
年代: 1998
DOI:10.1118/1.597554
出版商: American Association of Physicists in Medicine
数据来源: WILEY
摘要:
Dose profile data from small circular fields have been used in treatment dose planning for stereotactic radiosurgery. Generally, a two‐dimensional interpolation of the measured beam profiles from circular collimators is used to calculate the dose at any axial depth and radial distance from the central axis. Instead, the dose profile data can be transformed into a sigmoidal form. A new three parameter sigmoidal function was developed to fit the transformed (sigmoidal) dose profile data. The values of the three estimated parameters were found to follow either linearly or exponentially as a function of axial depth. Thus, instead of linear interpolation, these formulas can be used to calculate dose at any axial depth and radial distance from the central axis for circular collimators of various diameters. This new sigmoidal function provides another formula to describe dose profile data from circular collimator of small fields.
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