title: Clinical implementation of electron energy changes of varian linear accelerators.
abstract: Modern dual photon energy linear accelerators often come with a few megavoltage electron beams. The megavoltage electron beam has limited range and relative sharp distal falloff in its depth dose curve compared to that of megavoltage photon beam. Its radiation dose is often delivered appositionally to cover the target volume to its distal 90% depth dose (d90), while avoiding the normal--sometimes critical--structure immediately distal to the target. Varian linear accelerators currently offer selected electron beams of 4, 6, 9, 12, 16 and 20 MeV electron beam energies. However, intermediate electron energy is often needed for optimal dose distribution. In this study we investigated electron beam characteristics and implemented two intermediate 7 and 11 MeV electron beams on Varian linear accelerators. Comprehensive tests and measurements indicated the new electron beams met all dosimetry parameter criteria and operational safety standards. Between the two new electron beams and the existing electron beams we were able to provide a choice of electron beams of 4, 6, 7, 9, 11, 12, 16 and 20 MeV electron energies, which had d90 depth between 1.5 cm and 6.0 cm (from 1.5 cm to 4.0 cm in 0.5 cm increments) to meet our clinical needs.
authors.affiliation: Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.
authors.forename: Sean
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.
authors.forename: Praimakorn
authors.initials: P
authors.lastname: Liengsawangwong
authors.affiliation: Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.
authors.forename: Patricia
authors.initials: P
authors.lastname: Lindsay
authors.affiliation: Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.
authors.forename: Karl
authors.initials: K
authors.lastname: Prado
authors.affiliation: Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.
authors.forename: Tzouh-Liang
authors.initials: TL
authors.lastname: Sun
authors.affiliation: Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.
authors.forename: Roy
authors.initials: R
authors.lastname: Steadham
authors.affiliation: Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Salehpour
authors.affiliation: Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.
authors.forename: Michael
authors.initials: M
authors.lastname: Gillin
mesh_terms: D004583:Electrons / Q000627:therapeutic use*; D006801:Humans; D010315:Particle Accelerators / Q000295:instrumentation* / Q000592:standards*; D010865:Pilot Projects; D011786:Quality Control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted