A method that significantly improves accuracy of MU/time calculations for wedged asymmetric fields

L. Leybovich, Nesrin Dogan, A. Sethi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Wedged asymmetric fields are commonly encountered in radiation therapy. Most treatment planning systems (TPSs) calculate the off-axis wedge factors (WFoc) by multiplying the central axis wedge factor (WFc) by the ratio of transmissions along the off-axis ray to that along the central-axis. Therefore the wedge shape determines the off-axis wedge factors. However, during TPS commissioning, it is often necessary to modify the physical wedge shape in order to fit the measured wedged dose distributions. This can result an inaccurate calculation of WFoc. To determine the accuracy of TPS calculations, WFoc measurements for various asymmetric beams produced by dual energy VARIAN 2100C and 6/100R linear accelerators and a Theratronics-1000 Co-60 unit were done. For the 2100C linear accelerator, the FOCUS calculated WFoc's for all wedges were in good agreement with measured values (< 2% for 15°, 30°, and 45° wedges, and approximately 3% for 60° wedge). For 6/100R and Co-60 unit, the difference between calculated and measured WFoc varied from 4 - 10% depending on the wedge angle and off-axis distance. To improve the accuracy of WFoc calculations, wedges were represented in the TPS in two versions: planning and calculational. The planning wedge has a shape that produces accurate calculations of dose distributions and the calculational wedge shape assures an accurate (within ≈ 1%) calculation of WFoc's.

Original languageEnglish (US)
Title of host publicationAnnual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings
EditorsJ.D Enderle
Pages1085-1087
Number of pages3
Volume2
StatePublished - 2000
Externally publishedYes
Event22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society - Chicago, IL, United States
Duration: Jul 23 2000Jul 28 2000

Other

Other22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society
CountryUnited States
CityChicago, IL
Period7/23/007/28/00

Fingerprint

Planning
Linear accelerators
Radiotherapy

Keywords

  • Asymmetric fields
  • Off-axis wedge factors
  • Treatment planning

ASJC Scopus subject areas

  • Bioengineering

Cite this

Leybovich, L., Dogan, N., & Sethi, A. (2000). A method that significantly improves accuracy of MU/time calculations for wedged asymmetric fields. In J. D. Enderle (Ed.), Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings (Vol. 2, pp. 1085-1087)

A method that significantly improves accuracy of MU/time calculations for wedged asymmetric fields. / Leybovich, L.; Dogan, Nesrin; Sethi, A.

Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings. ed. / J.D Enderle. Vol. 2 2000. p. 1085-1087.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Leybovich, L, Dogan, N & Sethi, A 2000, A method that significantly improves accuracy of MU/time calculations for wedged asymmetric fields. in JD Enderle (ed.), Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings. vol. 2, pp. 1085-1087, 22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Chicago, IL, United States, 7/23/00.
Leybovich L, Dogan N, Sethi A. A method that significantly improves accuracy of MU/time calculations for wedged asymmetric fields. In Enderle JD, editor, Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings. Vol. 2. 2000. p. 1085-1087
Leybovich, L. ; Dogan, Nesrin ; Sethi, A. / A method that significantly improves accuracy of MU/time calculations for wedged asymmetric fields. Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings. editor / J.D Enderle. Vol. 2 2000. pp. 1085-1087
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