title: Simulation of medical electron linac bremsstrahlung beam transport in typical shielding materials.
abstract: The Monte Carlo N-particle code MCNP version 4C3 was used to investigate the backscattering and transmission of high-energy photons in concrete, iron and lead at deep penetration. A typical bremsstrahlung beam from a 24 MV linac was used, and the transmission up to 15 mean-free paths was studied. Broad beam slab geometry was used. Estimates of the transmission in terms of absorbed dose to tissue ratio and air kerma ratio were performed for the primary and secondary components of the transmitted beam in the three materials. The tissue dose and air kerma buildup factors were calculated and fitted to Berger's equation. Finally, the differential dose albedo values for common reflected angles were determined.
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, 1530 MSC, 1300 University Avenue, Madison, WI 53706-1532, USA. maavilarodri@wisc.edu
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Avila-Rodriguez
authors.forename: Paul M
authors.initials: PM
authors.lastname: DeLuca
authors.forename: Tim D
authors.initials: TD
authors.lastname: Bohm
mesh_terms: D003198:Computer Simulation; D003252:Construction Materials / Q000032:analysis*; D004583:Electrons; D018499:Linear Energy Transfer; D008422:Materials Testing / Q000379:methods; D015233:Models, Statistical; D009010:Monte Carlo Method; D010315:Particle Accelerators / Q000295:instrumentation*; D017785:Photons / Q000627:therapeutic use*; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D012984:Software