• Nuclear Engineering and Technology
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• v.56 no.11
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• pp.4921-4928
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• 2024

The present study employed statistical methods to evaluate the possible radiological hazards linked to granitic rocks-bearing mineralization in the ELgarra region of Egypt. The geological structures influence the occurrence of uranium mineralization in this area and are primarily associated with altered granites. Gamma-ray spectrometry was utilized to examine the quantities of ²³⁸U, ²³²Th, and ⁴⁰K in granitic rock samples. The recorded levels of radioisotope activity concentrations in the analyzed regions ranged from 374 to 1740 Bq.kg^{-1 238}U, with an average of 1018 Bq.kg^-1. For ²³²Th, the range was between 71 and 163 Bq.kg^-1, with an average of 119 Bq.kg^-1. Lastly, for ⁴⁰K, the range was 756-1789 Bq.kg^-1, with an average of 1212 Bq.kg^-1. The detected levels of ²³⁸U, ²³²Th, and ⁴⁰K in the examined rock samples were observed to exceed the permissible limits of 35, 45, and 412 Bq.kg^-1, respectively. The primary radiological risks linked to these granitic rocks were attributed to the gamma rays released by the radioactive elements. Estimations of the radiological hazards in the granitic rocks were made, and statistical approaches were utilized to demonstrate the associations among radionuclides and radiological factors. The assessment confirmed that uranium, potassium, and their respective minerals in the granitic rocks were the key factors contributing to the radiological risks. As a result, the study determined that the granite rocks found in the study area needed precautions to be taken due to their high levels of radioactivity.

• Korean Journal of Veterinary Research
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• v.48 no.4
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• pp.393-399
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• 2008

We investigated the potential of fucoidan for its ability to provide protection from gamma rayinduced damage. In our results, the fucoidan significantly improved the counts of endogenous colony forming unit to $9.5 {\pm} 1.5$, from $5.5 {\pm} 2.5$ compared with un-treated irradiated control group at 10 day after 7 Gy whole body irradiation. After 2 Gy irradiation, fucoidan treatment attenuated the percent of tail DNA of splenocytes, parameters of DNA damage, from $30.17 {\pm} 1.7%$ to $13.67 {\pm} 2.81%$ 2.81% by comet assay and also accelerated the proliferation of splenocytes, compared with un-treated irradiated control group by 3Hthymidine incorporation assay. Furthermore, fucoidan decreased the number of apoptotic fragments per intestinal crypt by 31.8% at 1 days after 2 Gy irradiation. These results indicated that the fucoidan significantly improved the hematopoietic recovery, prevented the DNA damage in immune cells and enhanced their proliferation, which had been suppressed by ionizing radiation. in addition, fucoidan rescued intestinal cells from radiation-induced apoptosis. Thus, this study raises the possibility of using fucoidan as adjuvant therapeutic agent after radiotherapy.

• Progress in Medical Physics
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• v.31 no.4
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• pp.145-152
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• 2020

Purpose: In ionization-chamber dosimetry for high-dose-rate electron beams-above 20 mGy/pulse-the ion-recombination correction methods recommended by the International Atomic Energy Agency (IAEA) and the American Association of Physicists in Medicine (AAPM) are not appropriate, because they overestimate the correction factor. In this study, we suggest a practical ion-recombination correction method, based on Boag's improved model, and apply it to reference dosimetry for electron beams of about 100 mGy/pulse generated from an electron linear accelerator (LINAC). Methods: This study employed a theoretical model of the ion-collection efficiency developed by Boag and physical parameters used by Laitano et al. We recalculated the ion-recombination correction factors using two-voltage analysis and obtained an empirical fitting formula to represent the results. Next, we compared the calculated correction factors with published results for the same calculation conditions. Additionally, we performed dosimetry for electron beams from a 6 MeV electron LINAC using an Advanced Markus^® ionization chamber to determine the reference dose in water at the source-to-surface distance (SSD)=100 cm, using the correction factors obtained in this study. Results: The values of the correction factors obtained in this work are in good agreement with the published data. The measured dose-per-pulse for electron beams at the depth of maximum dose for SSD=100 cm was 115 mGy/pulse, with a standard uncertainty of 2.4%. In contrast, the k_s values determined using the IAEA and AAPM methods are, respectively, 8.9% and 8.2% higher than our results. Conclusions: The new method based on Boag's improved model provides a practical method of determining the ion-recombination correction factors for high dose-per-pulse radiation beams up to about 120 mGy/pulse. This method can be applied to electron beams with even higher dose-per-pulse, subject to independent verification.

• Progress in Medical Physics
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• v.33 no.4
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• pp.53-62
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• 2022

In this study, we have investigated the shielding evaluation methodology for facilities using kV energy generators. We have collected and analysis of safety evaluation criteria and methodology for overseas facilities using radiation generators. And we investigated the current status of shielding evaluation of domestic industrial radiation generators. According to the statistical data from the Radiation Safety Information System, as of 2022, a total of 7,679 organizations are using radiation generating devices. Among them, 6,299 facilities use these devices for industrial purposes, which accounts for a considerable portion of radiation. The organizations that use these devices evaluate whether the exposure dose for workers and frequent visitors is suitable as per the limit regulated by the Nuclear Safety Act. Moreover, during this process, the safety shields are evaluated at the facilities that use the radiation generating devices. However, the facilities that use radiating devices having energy less than or equal to 6 MV for industrial purposes are still mostly evaluated and analyzed according to the National Council on Radiation Protection and Measurements 49 (NCRP 49) report published in 1976. We have investigated the technical standards of safety management, including the maximum permissible dose and parameters assessment criteria for facilities using radiation generating devices, based on the NCRP 49 and the American National Standards Institute/Health Physics Society N.43.3 reports, which are the representative reports related to radiation shielding management cases overseas.

• Journal of radiological science and technology
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• v.47 no.3
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• pp.175-182
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• 2024

Advanced modeled iterative reconstruction (ADMIRE) represents a repetitive reconstruction method that can adjust strength and kernel, each of which are known to affect computed tomography (CT) image quality. The aim of this study was to quantitatively analyze the noise and spatial resolution of CT images according to ADMIRE control factors. Patient images were obtained by applying ADMIRE strength 2 and 3, and kernel B40 and B59. For quantitative evaluations, the noise level, spatial resolution, and overall image quality were measured using coefficient of variation (COV), edge rise distance (ERD), and natural image quality evaluation (NIQE). The superior values for the average COV, ERD, and NIQE results were obtained for the ADMIRE reconstruction conditions of ADMIRE 2 + B40, ADMIRE 3 + B59, and ADMIRE3 + B59. NIQE, which represents the overall image quality based on no-reference, was about 6.04 when using ADMIRE 3 + B59, showing the best result among the reconstructed image acquisition conditions. The results of this study indicate that the ADMIRE strength and kernel chosen for use in ADMIRE reconstruction have a significant impact on CT image quality. This highlights the importance of adjusting to the control factors in consideration of the clinical environment.

• Journal of radiological science and technology
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• v.21 no.2
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• pp.53-56
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• 1998

Highly sensitive $CaSO_4:Tm$ TLD is fabricated and their trap parameters are determined. The glow curve of $CaSO_4:Tm$ consists of three glow peaks and these peaks are isolated by the thermal bleaching method. The isolated glow peaks are fitted by a least squares method. The activation energies are 0.68, 0.82 and 1.03 eV. The frequency factors are $8.09{\times}10^8,\;9.14{\times}10^8$ and $1.03{\times}10^9/s$, and the kinetic orders are 1.37, 1.54 and 1.68, respectively. The optimum temperature range of the main peak for radiation dosimetry is between 220 and $290^{\circ}C$.

• Progress in Medical Physics
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• v.29 no.2
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• pp.73-80
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• 2018

Accelerated partial breast irradiation (APBI) is a new treatment delivery technique that decreases overall treatment time by using higher fractional doses than conventional fractionation. Here, a quantitative analysis study of CyberKnife-based APBI was performed on 10 patients with left-sided breast cancer who had already finished conventional treatment at the Inha University Hospital. Dosimetric parameters for four kinds of treatment plans (3D-CRT, IMRT, VMAT, and CyberKnife) were analyzed and compared with constraints in the NSABP B39/RTOG 0413 protocol and a published CyberKnife-based APBI study. For the 10 patients recruited in this study, all the dosimetric parameters, including target coverage and doses to normal structures, met the NSABP B39/RTOG 0413 protocol. Compared with other treatment plans, a more conformal dose to the target and better dose sparing of critical structures were observed in CyberKnife plans. Accelerated partial breast irradiation via CyberKnife is a suitable treatment delivery technique for partial breast irradiation and offers improvements over external beam APBI techniques.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.222-228
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• 2023

This study aimed to analyze the applicability of the improved median filter in positron emission tomography (PET)/magnetic resonance (MR) fusion images based on parallel imaging using generalized autocalibrating partially parallel acquisition (GRAPPA). In this study, a PET/MR fusion imaging system based on a 3.0T magnetic field and ¹⁸F radioisotope were used. An improved median filter that can set a mask of the median value more efficiently than before was modeled and applied to the acquired image. As quantitative evaluation parameters of the noise level, the contrast to noise ratio (CNR) and coefficient of variation (COV) were calculated. Additionally, no-reference-based evaluation parameters were used to analyze the overall image quality. We confirmed that the CNR and COV values of the PET/MR fusion images to which the improved median filter was applied improved by approximately 3.32 and 2.19 times on average, respectively, compared to the noisy image. In addition, the no-reference-based evaluation results showed a similar trend for the noise-level results. In conclusion, we demonstrated that it can be supplemented by using an improved median filter, which suggests the problem of image quality degradation of PET/MR fusion images that shortens scan time using GRAPPA.

• Journal of Korean Neurosurgical Society
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• v.61 no.5
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• pp.582-591
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• 2018

Objective : To evaluate the magnetic resonance (MR) imaging features that have a statistically significant association with the need for a tracheostomy in patients with cervical spinal cord injury (SCI) during the acute stage of injury. Methods : This study retrospectively reviewed the clinical data of 130 patients with cervical SCI. We analyzed the factors believed to increase the risk of requiring a tracheostomy, including the severity of SCI, the level of injury as determined by radiological assessment, three quantitative MR imaging parameters, and eleven qualitative MR imaging parameters. Results : Significant differences between the non-tracheostomy and tracheostomy groups were determined by the following five factors on multivariate analysis : complete SCI (p=0.007), the radiological level of C5 and above (p=0.038), maximum canal compromise (MCC) (p=0.010), lesion length (p=0.022), and osteophyte formation (p=0.015). For the MCC, the cut-off value was 46%, and the risk of requiring a tracheostomy was three times higher at an interval between 50-60% and ten times higher between 60-70%. For lesion length, the cut-off value was 20 mm, and the risk of requiring a tracheostomy was two times higher at an interval between 20-30 mm and fourteen times higher between 40-50 mm. Conclusion : The American Spinal Injury Association grade A, a radiological injury level of C5 and above, an MCC ${\geq}50%$, a lesion length ${\geq}20mm$, and osteophyte formation at the level of injury were considered to be predictive values for requiring tracheostomy intervention in patients with cervical SCI.

• Journal of Magnetics
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• v.17 no.2
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• pp.153-157
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• 2012

This study evaluated the ability of Diffusion-Weight Image (DWI), which is one of pulse sequences used in MRI based on the T2 weighted images, to detect samples placed within phantoms according to their size. Two identically sized phantoms, which could be inserted into the breast coil bilaterally, were prepared. Five samples with different sizes were placed in the phantoms, and the T2 weighted images and DWI were obtained. The Breast 2 channel coil of SIEMENS MAGNETOM Avanto 1.5 Tesla equipment was used for the experiments. 2D T2 weighted images were obtained using the following parameters: TR/TE = 6700/74 msec, Thickness/gap = 5/1 mm, Inversion Time (TI) = 130 ms, and matrix = $224{\times}448$. The parameters of DWI were that TR/TE = 8100/90 msec, Thickness/gap = 5/1 mm, matrix = $128{\times}128$, Inversion Time = 185 ms, and b-value = 0, 100, 300, 600, 1000 s/mm. The ratio of the sample volume on DWI compared to the T2 weighted images, which show excellent ability to detect lesions on MR images, was presented as the mean b-value. The measured b-value of the samples was obtained: 0.5${\times}$0.5 cm=0.33/0.34 square ${\times}$ cm (103%), 1${\times}$1 cm=1.28/1.25 square ${\times}$ cm (102.4%), 1.5${\times}$1.5 cm = 2.28/2.67 square ${\times}$ cm (85.39%), 2${\times}$2 cm=3.56/4.08 square ${\times}$ cm (87.25%), and 2.5${\times}$2.5 cm=7.53/8.77 square ${\times}$ cm (85.86%). In conclusion, the detection ability by the size of a sample was measured to be over 85% compared to T2 weighted image, but the detection ability of DWI was relatively lower than that of T2 weighted image.