title: A modified formula for defining tissue phantom ratio of photon beams.
abstract: Tissue phantom ratio (TPR), for square fields of various dimensions has been determined at varying depths in water. The dose in water has been measured at a fixed source-to-surface distance (SSD) of 100 cm and reference depth of 5 cm for 6 MV photon beam of Siemens Linear Accelerator Primus 11 in German Cancer Research Center (DKFZ), Heidelberg, Germany. A modified formula has been developed to calculate the TPR value for isocentric treatment. The present article describes the conversion of the measured data values into a comprehensive and consistent data set by the modified formula, that gives the TPR from Percentage Depth Dose (PDD) with depth as a function of field sizes from 10 mm x 10 mm upto 300 mm x 300 mm) and depth (from 0 mm to 300 mm).
authors.affiliation: Department of Physics, University of Dhaka, Dhaka, Bangladesh.
authors.forename: M Jahangir
authors.initials: MJ
authors.lastname: Alam
authors.forename: K S
authors.initials: KS
authors.lastname: Rabbani
authors.forename: G A
authors.initials: GA
authors.lastname: Zakaria
authors.forename: S M Akram
authors.initials: SM
authors.lastname: Hussain
authors.forename: Adnan
authors.initials: A
authors.lastname: Kiber
authors.forename: Tanvir
authors.initials: T
authors.lastname: Baig
mesh_terms: D015502:Absorptiometry, Photon / Q000295:instrumentation*; D006801:Humans; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D017785:Photons; D011874:Radiometry / Q000295:instrumentation*