EFFECTIVE DOSE MEASUREMENT FOR CONE BEAM COMPUTED TOMOGRAPHY USING GLASS DOSIMETER

During image-guided radiation therapy, the patient is exposed to unwanted radiation from imaging devices built into the medical LINAC. In the present study, the effective dose delivered to a patient from a cone beam computed tomography (CBCT) machine was measured. Absorbed doses in specific organs listed in ICRP Publication 103 were measured with glass dosimeters calibrated with kilovolt (kV) X-rays using a whole body physical phantom for typical radiotherapy sites, including the head and neck, chest, and pelvis. The effective dose per scan for the head and neck, chest, and pelvis were 3.37±0.29, 7.36±0.33, and 4.09±0.29 mSv, respectively. The results highlight the importance of the compensation of treatment dose by managing imaging dose

Preparation of Cu2ZnSnS4 thin films via electrochemical deposition and rapid thermal annealing

We fabricated metallic Cu-Zn-Sn (CZT) precursor thin films via electrochemical deposition from aqueous metal salt solution on Mo-coated soda-lime glass substrates, and the influence of the subsequent sulfurization condition on the morphology, composition and structure of the final Cu2ZnSnS4 (CZTS) thin films was investigated. A rapid thermal annealing equipment was used for a systematic control of the sulfurization process parameters. The as-deposited films are composed of binary metallic alloys, which can be converted to the highly crystalline CZTS phase after sulfurization at temperatures above 500 degrees C. The composition of the CZT film barely changes during the sulfurization, and a small amount of CuS-based secondary phases exists even at 550 degrees C. However, a quick post-annealing KCN treatment effectively and selectively removes the secondary phase, evidenced by the Raman spectroscopy and elemental

Activity concentrations and radiological hazard assessments of 226Ra, 232Th, 40K, and 137Cs in soil samples obtained from the Dongnam Institute of Radiological & Medical Science, Korea

The radioactivity concentration of environmental radionuclides was analyzed for soil and sand at eight locations within a radius of 255 m centered on the Dongnam Institute of Radiological & Medical Science (DIRAMS), Korea. The average activity concentrations of 40K, 137Cs, 226Ra, and 232Th were 661.1 Bq/kg-dry, 0.9 Bq/kg-dry, 21.9 Bq/kg-dry, and 11.1 Bq/kg-dry, respectively. The activity of 40K and 137Cs was lower than the 3-year (2017–2019) average reported by the Korea Institute of Nuclear Safety, respectively. Due to the nature of granite-rich soil, the radioactivity of 40K was 0.6-fold higher than in other countries, while 137Cs was in the normal fluctuation range (15–30 Bq/kg-dry) of the concentration of radioactive fallout from nuclear tests. The activity of 226Ra and 232Th was lower than in Korean soils reported by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The average activity concentrations of 232Th and 40K for the soil and sand samples from DIRAMS were within the range specified by UNSCEAR in 2000. The radium equivalent activity and internal and external hazard index values were below the recommended limits (1 mSv/y). These radionuclide concentration (226Ra, 232Th, 40K, and 137Cs) data can be used for regional environmental monitoring and ecological impact assessments of nuclear power plant accidents

Highly Efficient Copper-Zinc-Tin-Selenide ( CZTSe) Solar Cells by Electrodeposition

Highly efficient copper-zinc-tin-selenide (Cu2ZnSnSe4; CZTSe) thin-film solar cells are prepared via the electrodepostion technique. A metallic alloy precursor (CZT) film with a Cu-poor, Zn-rich composition is directly deposited from a single aqueous bath under a constant current, and the precursor film is converted to CZTSe by annealing under a Se atmosphere at temperatures ranging from 400 degrees C to 600 degrees C. The crystallization of CZTSe starts at 400 degrees C and is completed at 500 degrees C, while crystal growth continues at higher temperatures. Owing to compromises between enhanced crystallinity and poor physical properties, CZTSe thin films annealed at 550 degrees C exhibit the best and most-stable device performances, reaching up to 8.0% active efficiency; among the highest efficiencies for CZTSe thin-film solar cells prepared by electrodeposition. Further analysis of the electronic properties and a comparison with another state-of-the-art device prepared from a hydrazine-based solution, suggests that the conversion efficiency can be further improved by optimizing parameters such as film thickness, antireflection coating, MoSe2 formation, and p-n junction properties