title: Dose rate constants for 125I, 103Pd, 192Ir and 169Yb brachytherapy sources: an EGS4 Monte Carlo study.
abstract: An exhaustive revision of dosimetry data for 192Ir, 125I, 103Pd and 169Yb brachytherapy sources has been performed by means of the EGS4 simulation system. The DLC-136/PHOTX cross section library, water molecular form factors, bound Compton scattering and Doppler broadening of the Compton-scattered photon energy were considered in the calculations. The absorbed dose rate per unit contained activity in a medium at 1 cm in water and air-kerma strength per unit contained activity for each seed model were calculated, allowing the dose rate constant (DRC) A to be estimated. The influence of the calibration procedure on source strength for low-energy brachytherapy seeds is discussed. Conversion factors for 125I and 103Pd seeds to obtain the dose rate in liquid water from the dose rate measured in a solid water phantom with a detector calibrated for dose to water were calculated. A theoretical estimate of the DRC for a 103Pd model 200 seed equal to 0.669 +/- 0.002 cGy h(-1) U(-1) is obtained. Comparison of obtained DRCs with measured and calculated published results shows agreement within 1.5% for 192Ir, 169Yb and 125I sources.
authors.affiliation: Departamento de Física, Centro de Estudios Aplicados al Desarrollo Nuclear, Miramar, La Habana, Cuba. mainegra@ceaden.edu.cu
authors.forename: E
authors.initials: E
authors.lastname: Mainegra
authors.forename: R
authors.initials: R
authors.lastname: Capote
authors.forename: E
authors.initials: E
authors.lastname: López
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D001918:Brachytherapy / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D007496:Iridium Radioisotopes / Q000627:therapeutic use; D009010:Monte Carlo Method; D010165:Palladium / Q000627:therapeutic use; D019047:Phantoms, Imaging; D011868:Radioisotopes / Q000627:therapeutic use; D011874:Radiometry / Q000706:statistics & numerical data; D011879:Radiotherapy Dosage; D012542:Scattering, Radiation; D013679:Technology, Radiologic; D014867:Water; D015018:Ytterbium / Q000627:therapeutic use
chemical_list: D007457:Iodine Radioisotopes; D007496:Iridium Radioisotopes; D011868:Radioisotopes; D014867:Water; D010165:Palladium; D015018:Ytterbium