title: [Estimation of activities caused by black spots in digital radiography systems: analysis of black spots by the low concentrate radioisotopes adhered directly to the surface of the phosphor plate].
abstract: Because of an accident of the nuclear power plants in the Fukushima, many radioisotopes (RI) have been diffused to the environment. As a result, black spots were appearing on the medical images which were taken by the phosphor plate. The aim of this study is to evaluate the activity (Bq) of radioactive contaminated IP based on the experiment using RI. The radioactive material ((134)Cs and/or (137)Cs) in the form of liquid was dropped on filter paper (25 mm(2)), and radioactive sources having 40-240 Bq activities were made. These sources were closely attached to the IP with irradiation times of 2-22 h. Then, we obtained the relationship between pixel values and products of activities and irradiation times. Using these relationships, we evaluated the activity in the contaminated IP. The evaluated value of approximately 7 Bq was in good agreement with a value which was inhered in a chemical wiper used for the decontamination of the IP. Based on the results, we summarized that almost all black spots were created by the RI adhered directly to the IP.
authors.affiliation: Institute of Health Bioscience, The University of Tokushima Graduate School.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hayashi
authors.forename: Sadamitsu
authors.initials: S
authors.lastname: Nishihara
authors.forename: Satoru
authors.initials: S
authors.lastname: Takashi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Hanamitsu
authors.forename: Michiko
authors.initials: M
authors.lastname: Mori
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Miyoshi
authors.forename: Yoji
authors.initials: Y
authors.lastname: Onuma
mesh_terms: D000268:Adhesiveness; D004784:Environmental Monitoring / Q000379:methods*; D004866:Equipment Contamination; D011834:Radiation Monitoring / Q000379:methods*; D011848:Radioactive Pollutants / Q000032:analysis*; D011856:Radiographic Image Enhancement / Q000295:instrumentation / Q000379:methods*; D011868:Radioisotopes / Q000032:analysis*; D014963:X-Ray Intensifying Screens
chemical_list: D011848:Radioactive Pollutants; D011868:Radioisotopes