title: Influence of electron density spatial distribution and X-ray beam quality during CT simulation on dose calculation accuracy.
abstract: Impact of the various kVp settings used during computed tomography (CT) simulation that provides data for heterogeneity corrected dose distribution calculations in patients undergoing external beam radiotherapy with either high-energy photon or electron beams have been investigated. The change of the Hounsfield Unit (HU) values due to the influence of kVp settings and geometrical distribution of various tissue substitute materials has also been studied. The impact of various kVp settings and electron density (ED) distribution on the accuracy of dose calculation in high-energy photon beams was found to be well within 2%. In the case of dose distributions obtained with a commercially available Monte Carlo dose calculation algorithm for electron beams, differences of more than 10% were observed for different geometrical setups and kVp settings. Dose differences for the electron beams are relatively small at shallow depths but increase with depth around lower isodose values.
authors.affiliation: Biomedical Physics Department, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia. anobah@kfshrc.edu.sa
authors.forename: Ahmad
authors.initials: A
authors.lastname: Nobah
authors.forename: Belal
authors.initials: B
authors.lastname: Moftah
authors.forename: Nada
authors.initials: N
authors.lastname: Tomic
authors.forename: Slobodan
authors.initials: S
authors.lastname: Devic
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004583:Electrons; D006801:Humans; D009010:Monte Carlo Method; D017785:Photons / Q000627:therapeutic use; D011829:Radiation Dosage; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014965:X-Rays