Dose calculation for electron therapy using an improved LBR method
Purpose: To calculate the percentage depth dose (PDD) of any irregularly shaped electron beam using a modified lateral buildup ratio (LBR) method.Methods: Percentage depth dose curves were measured using 6, 9, 12, and 15 MeV electron beam energies for applicator cone sizes of 6 MultiplicationSign 6, 10 MultiplicationSign 10, 14 MultiplicationSign 14, and 20 MultiplicationSign 20 cm{sup 2}. Circular cutouts for each cone were prepared from 2.0 cm diameter to the maximum possible size for each cone. In addition, three irregular cutouts were prepared.Results: The LBR for each circular cutout was calculated from the measured PDD curve using the open field of the 14 MultiplicationSign 14 cm{sup 2} cone as the reference field. Using the LBR values and the radius of the circular cutouts, the corresponding lateral spread parameter [{sigma}{sub R}(z)] of the electron shower was calculated. Unlike the commonly accepted assumption that {sigma}{sub R}(z) is independent of cutout size, it is shown that its value increases linearly with circular cutout size (R). Using this characteristic of the lateral spread parameter, the PDD curves of irregularly shaped cutouts were calculated. Finally, the calculated PDD curves were compared with measured PDD curves.Conclusions: In this research, it is shown that the lateralmore »
 Authors:

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 Department of Physics and Astronomy, University of South Carolina, Columbia, South Carolina 29208 (United States)
 (United States)
 Publication Date:
 OSTI Identifier:
 22121618
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Medical Physics; Journal Volume: 40; Journal Issue: 7; Other Information: (c) 2013 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 61 RADIATION PROTECTION AND DOSIMETRY; 62 RADIOLOGY AND NUCLEAR MEDICINE; DEPTH DOSE DISTRIBUTIONS; DOSIMETRY; ELECTRON BEAMS; ELECTRONS; MEV RANGE 0110; MEV RANGE 10100; RADIATION DOSES; RADIOTHERAPY; SURFACES