title: Determination of energy absorption and exposure buildup factors by using G-P fitting approximation for radioprotective agents.
abstract: Recently, there has been an increase in interest into research into radioprotective agents. Radioprotectors are compounds that protect against radiation injury when given orally (through drinking water) prior to radiation exposure. The purpose is to achieve preferred protection of normal tissues against injury inflicted by ionizing radiation used to treat tumors. The main aim of this work is to investigate energy absorption (EABF) and exposure buildup factors (EBF) of commonly used some radioprotective agents.
  
  
  
  We have used the Geometric Progression (G-P) fitting method for calculating the equivalent atomic number (Zeq), for EABF and EBF buildup factors of the radioprotective agents in the energy range 0.015-15 MeV for penetration depths up to 40 mean free path.
  
  
  
  Significant variations in both EABF and EBF values were observed for several agents at the moderate energy region. At energies below 0.1 MeV, EABF and EBF values increased with decreasing equivalent atomic number Zeq of the samples. At energies >0.15 MeV, EABF and EBF values were found to decrease with decreasing Zeq of all agents. In addition, EABF and EBF were the largest for carnosin, tempol, melatonin, interferon gamma and orientine at 0.05 and 0.06 MeV, respectively, and the minimum values of buildup factors were at 0.1 MeV for cysteine, amifostine, penicillamine and glutathione.
  
  
  
  Cysteine and amifostine are good compounds for gamma rays absorption applications among the selected compounds. The presented results in this study are expected to be helpful in radiation dosimetry.
authors.affiliation: a Department of Physics, Faculty of Sciences , Ataturk University , Erzurum ;
authors.forename: Esra
authors.initials: E
authors.lastname: Kavaz
authors.affiliation: a Department of Physics, Faculty of Sciences , Ataturk University , Erzurum ;|b Department of Materials Science and Engineering, Faculty of Engineering , Hakkari University , Hakkari , Turkey.
authors.forename: Ufuk
authors.initials: U
authors.lastname: Perişanoğlu
authors.affiliation: a Department of Physics, Faculty of Sciences , Ataturk University , Erzurum ;
authors.forename: Neslihan
authors.initials: N
authors.lastname: Ekinci
authors.affiliation: a Department of Physics, Faculty of Sciences , Ataturk University , Erzurum ;
authors.forename: Yüksel
authors.initials: Y
authors.lastname: Özdemır
mesh_terms: D065638:Absorption, Radiation; D000465:Algorithms; D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D004735:Energy Transfer / Q000528:radiation effects; D008422:Materials Testing; D008956:Models, Chemical; D011829:Radiation Dosage; D011837:Radiation-Protective Agents / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: D011837:Radiation-Protective Agents
keywords: Buildup factor; dosimetry; progression; radioprotective agent