title: Dose-response curve slope improvement and result reproducibility of ferrous-sulphate-doped gels analysed by NMR imaging.
abstract: Ferrous sulphate gel analysed by relaxation time measurements with NMR imaging is considered a useful dosimeter for 3D determinations of absorbed dose. A protocol for the gel preparation with agarose SeaPlaque that leads to a dosimeter with very high dose sensitivity is described. The dose-response curve slope is about 0.2 s(-1) Gy(-1) and the G factor turns out to be approximately 185 ions per 100 eV of absorbed energy. A method for making the measurements and analysing the results that brings about good result reproducibility is suggested. A thorough experimental study of the dependence of the dosimeter response on the elapsed time from preparation to irradiation and from irradiation to NMR measurement has revealed good reproducibility. The above characteristic of the gel system is very interesting, because it shows the possibility of utilizing the dosimeter for absolute dose determinations with satisfactory reliability.
authors.affiliation: Dipartimento di Fisica dell'Universitá di Milano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Gambarini
authors.forename: S
authors.initials: S
authors.lastname: Arrigoni
authors.forename: M C
authors.initials: MC
authors.lastname: Cantone
authors.forename: N
authors.initials: N
authors.lastname: Molho
authors.forename: L
authors.initials: L
authors.lastname: Facchielli
authors.forename: A E
authors.initials: AE
authors.lastname: Sichirollo
mesh_terms: D004307:Dose-Response Relationship, Radiation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005296:Ferrous Compounds / Q000032:analysis* / Q000528:radiation effects*; D005720:Gamma Rays; D005782:Gels / Q000032:analysis* / Q000528:radiation effects*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D005296:Ferrous Compounds; D005782:Gels; C020748:ferrous sulfate