Characterization of dose delivery in a hard X-ray irradiation facility

2022

Sci Rep

Self Cite

DNA double-strand break (DSB) induction is one of the phenotypes of cellular damage from radiation exposure and is commonly quantified by γ-H2AX assay with the number of excess fluorescent foci per cell as the main component. However, the number of foci alone may not fully characterize the state of DNA damage following exposures to different radiation qualities. This study investigated the feasibility of utilizing the focus size distribution and dephosphorylation rate of γ-H2AX to identify the type of causative radiation and dose. Human lung epithelial cells and mouse vascular endothelial cells were used to observe the expression changes of γ-H2AX foci due to alpha particle and X-ray exposures. Results showed that the average number of excess foci per cell linearly increased with the dose. The focus size distribution showed a consistent pattern depending on the causative radiation type. Three criteria for the identification of causative radiation type were derived from experimental focus size distributions and were validated in blind testing with correct identification of 27 out of 32 samples. The dose could be estimated based on the proportionality constant specific to the identified radiation type with a difference of less than 15% from the actual value. The different dephosphorylation rates of γ-H2AX produced from alpha particle and X-ray exposures were effectively utilized to determine the individual dose contributions of alpha particles and X-rays under mixed beam exposure. Individual doses were estimated to have differences of less than ~ 12% from actual values.

Section: Methodsmentioning

confidence: 99%

Characterization of γ-H2AX foci formation under alpha particle and X-ray exposures for dose estimation

Lee

2022

Sci Rep

Self Cite

“…X-ray beam exposure was made in the HardX-SNU facility installed with an YXLON X-ray tube (Model 450-D08, Germany) [17]. The tube was operated at 150 kVp to generate bremsstrahlung X-rays in a tungsten target.…”

Section: X-ray Exposure Rate Measurementmentioning

confidence: 99%

“…Previous studies calculated the exposure rates of continuous or pulsed X-rays delivered to the voids by adopting attenuation coefficients of the structure materials containing voids, but such approximation can result in considerable uncertainties. Instead, we measured the exposure rate in voids using Gafchromic EBT3 films (International Specialty Products, USA) [17][18]. A slice of the film was placed between a pair of semicylindrical epoxy-alumina composite ( Figure 1c) and was positioned the same way as the experimental setup.…”

Section: X-ray Exposure Rate Measurementmentioning

confidence: 99%

See 1 more Smart Citation

Characteristics of partial discharge induced by continuous X-ray exposure of void defects in insulator

Shin

IEEE Trans. Dielect. Electr. Insul.

et al. 2019

Self Cite

Partial discharge (PD) diagnosis is a part of a routine testing of solid insulating materials to detect void defects. However, the conventional diagnosis is prone to inception delays due to lack of initiatory electron production, especially inside small voids. In this study, we employed continuous irradiation of X-rays to induce and sustain discharge inside the voids. The PD characteristics of void samples under different exposure rates of X-rays were observed. Compared with the conventional diagnosis, this continuous X-rayinduced partial discharge diagnosis enhanced the detection efficiency by eliminating the inception delays and reducing the discharge inception voltage. We focused on the changes in PD characteristics due to varying X-ray exposure rates. As the exposure rates were increased, the number of PD signals per minute increased while the average pulse height of PD signals decreased. Continuous X-ray exposure at rates between 0.5 and 294 mR/s successfully eliminated the inception delays even when the voids were as small as 1.63 mm in diameter of equivalent spherical volume.

Effects of chronic exposure to acidic environment on the response of tumor cells to radiation

International Journal of Radiation Biology

2016