title: Optimum parameters of TLD100 powder used for radiotherapy beams calibration check.
abstract: External audit of the absorbed dose determination from radiotherapy machines is performed using Lithium fluoride (LiF) TLD-100. Optimal parameters needed to obtain highly accurate dosage from LiF powder was investigated, including the setup of the Harshaw 4000 reader. A linear correspondence between the thermoluminescent signal and the mass of the powder was observed, demonstrating that the dose can be evaluated with small samples of powder. The reproducibility of the thermoluminescence dosimeter (TLD) readings obtained with up to 10 samples from 1 capsule containing 160 mg of powder was around 1.5% (1 standard deviation [SD]). The time required for the manual evaluation of TLDs can be improved by 3 readings without loss of accuracy. Better reproducibility is achieved if the capsules are evaluated 7 days after irradiation using a nitrogen flow of 300 cc/min.
authors.affiliation: Laboratoire Secondaire des Etalons en Dosimétrie, Centre de Recherche Nucléaire d'Alger, Alger Gare, Algeria. mehenna.arib@comena-dz.org
authors.forename: M
authors.initials: M
authors.lastname: Arib
authors.forename: A
authors.initials: A
authors.lastname: Yaich
authors.forename: A
authors.initials: A
authors.lastname: Messadi
authors.forename: F
authors.initials: F
authors.lastname: Dari
mesh_terms: D002138:Calibration; D005459:Fluorides / Q000737:chemistry*; D018020:Lithium Compounds / Q000737:chemistry*; D011208:Powders; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation* / Q000592:standards; D013997:Time Factors
chemical_list: D018020:Lithium Compounds; D011208:Powders; C027651:lithium fluoride; D005459:Fluorides