dorsal/arxiv
View SchemaA Method to Determine the In-Air Spatial Spread of Clinical Electron Beams
| Authors | M. Vilches, J. C. Zapata, D. Guirado, D. Fernández, D. Burgos, A. M. Lallena |
|---|---|
| Categories | |
| ArXiv ID | physics/9902030 |
| URL | https://arxiv.org/abs/physics/9902030 |
| DOI | 10.1118/1.598556 |
Abstract
We propose and analyze in detail a method to measure the in-air spatial spread parameter of clinical electron beams. Measurements are performed at the center of the beam and below the adjustable collimators sited in asymmetrical configuration in order to avoid the distortions due to the presence of the applicator. The main advantage of our procedure lies in the fact that the dose profiles are fitted by means of a function which includes, additionally to the Gaussian step usually considered, a background which takes care of the dose produced by different mechanisms that the Gaussian model does not account for. As a result, the spatial spread is obtained directly from the fitting procedure and the accuracy permits a good determination of the angular spread. The way the analysis is done is alternative to that followed by the usual methods based on the evaluation of the penumbra width. Besides, the spatial spread found shows the quadratic-cubic dependence with the distance to the source predicted by the Fermi-Eyges theory. However, the corresponding values obtained for the scattering power are differing from those quoted by ICRU nr. 35 by a factor ~2 or larger, what requires of a more detailed investigation.
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"abstract": "We propose and analyze in detail a method to measure the in-air spatial\nspread parameter of clinical electron beams. Measurements are performed at the\ncenter of the beam and below the adjustable collimators sited in asymmetrical\nconfiguration in order to avoid the distortions due to the presence of the\napplicator. The main advantage of our procedure lies in the fact that the dose\nprofiles are fitted by means of a function which includes, additionally to the\nGaussian step usually considered, a background which takes care of the dose\nproduced by different mechanisms that the Gaussian model does not account for.\nAs a result, the spatial spread is obtained directly from the fitting procedure\nand the accuracy permits a good determination of the angular spread. The way\nthe analysis is done is alternative to that followed by the usual methods based\non the evaluation of the penumbra width. Besides, the spatial spread found\nshows the quadratic-cubic dependence with the distance to the source predicted\nby the Fermi-Eyges theory. However, the corresponding values obtained for the\nscattering power are differing from those quoted by ICRU nr. 35 by a factor ~2\nor larger, what requires of a more detailed investigation.",
"arxiv_id": "physics/9902030",
"authors": [
"M. Vilches",
"J. C. Zapata",
"D. Guirado",
"D. Fern\u00e1ndez",
"D. Burgos",
"A. M. Lallena"
],
"categories": [
"physics.med-ph"
],
"doi": "10.1118/1.598556",
"title": "A Method to Determine the In-Air Spatial Spread of Clinical Electron Beams",
"url": "https://arxiv.org/abs/physics/9902030"
},
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