• Journal of Radiation Industry
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• v.9 no.4
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• pp.199-207
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• 2015

Typical radiation cross-linked hydrogels has the characteristic that high water content, but low emission efficiency of active ingredients. Therefore, the hydrogel was prepared by the addition to collagen, which is closely related to the formation of skin wrinkles in biocompatibility and highly water-soluble carboxymethyl cellulose sodium salt (CMC) in order to preparation of hydrogels has excellent emission efficiency of active ingredients. Hydrogels were prepared by dissolving CMC and collagen each of 0.5%, 10% concentration in deionized water. Then, prepared hydrogels are performed by gamma-radiation at 1, 3, 5 kGy irradiation dose. The results showed that the gel fraction of after irradiated 3 kGy hydrogel was higher than before irradiated gelation as long as the 55.3%. The swelling rate of irradiated 3 kGy hydrogel was lower than the non-irradiated sample. The compressive strength of 3 kGy irradiated hydrogel was the highest. The visco-elastic did not show any significant differences, even after irradiation. The CMC hydrogel in this study suggested a potential use as a material for the mask pack for improved emission efficiency of the active ingredient and anti-wrinkles.

• Journal of radiological science and technology
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• v.42 no.5
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• pp.373-377
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• 2019

Radiation exposure is on the rise as the working hours of radiation workers increase. Accordingly, the importance of protection products for decreasing the dose of exposure has risen, and excellent X-ray shielding ability and light weight are required. The purpose of this study is to compare the Pb which use currently and other elements in order to reduce the exposure of workers to the most effective protection products. For experiment, we used the general X-ray equipment and angiography equipment, and obtained the Pb and apron's shielding rate. When the shielding rate of Pb and apron was compared in general X-ray equipment, the shielding rate was 95.1% for Pb 0.5 mm, 96.1% for apron 0.5 mmPb and 95.6% for Bi+W 0.5 mmPb. When compared the shielding rate of each aprons in angiography equipment, 0.5 mmPb apron was the highest as 96.4% and Bi+W 0.25 mmPb apron was the lowest as 90.2% at the 50 cm distance. The shielding rate of 0.5 mmPb apron was the highest as 95.7% and Bi+W 0.25 mmPb apron was the lowest as 85.9% at the 100 cm distance. As a result of evaluating the apron efficiency through this study, 0.5 mmPb apron showed the best shielding rate, but it was the heaviest apron. 0.35 mmPb apron and Bi+W 0.25 mmPb apron weighed light but had low shielding rate. Through the results of this experiment, it is recommended that radiation workers reduce radiation exposure by using more efficient protection products.

• Journal of the Korean Society of Radiology
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• v.83 no.3
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• pp.669-679
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• 2022

Purpose To evaluate the feasibility of pediatric low-dose facial CT reconstructed with filtered back projection (FBP) using adequate kernels. Materials and Methods We retrospectively reviewed the clinical and imaging data of children aged < 10 years who underwent facial CT at our emergency department. The patients were divided into two groups: low-dose CT (LDCT; Group A, n = 73) with a fixed 80-kVp tube potential and automatic tube current modulation (ATCM) and standard-dose CT (SDCT; Group B, n = 40) with a fixed 120-kVp tube potential and ATCM. All images were reconstructed with FBP using bone and soft tissue kernels in Group A and only bone kernel in Group B. The groups were compared in terms of image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Two radiologists subjectively scored the overall image quality of bony and soft tissue structures. The CT dose index volume and dose-length product were recorded. Results Image noise was higher in Group A than in Group B in bone kernel images (p < 0.001). Group A using a soft tissue kernel showed the highest SNR and CNR for all soft tissue structures (all p < 0.001). In the qualitative analysis of bony structures, Group A scores were found to be similar to or higher than Group B scores on comparing bone kernel images. In the qualitative analysis of soft tissue structures, there was no significant difference between Group A using a soft tissue kernel and Group B using a bone kernel with a soft tissue window setting (p > 0.05). Group A showed a 76.9% reduction in radiation dose compared to Group B (3.2 ± 0.2 mGy vs. 13.9 ± 1.5 mGy; p < 0.001). Conclusion The addition of a soft tissue kernel image to conventional CT reconstructed with FBP enables the use of pediatric low-dose facial CT protocol while maintaining image quality.

• Imaging Science in Dentistry
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• v.44 no.1
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• pp.21-29
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• 2014

Purpose: To determine the conversion coefficients (CCs) from the dose-area product (DAP) value to effective dose in cone-beam CT. Materials and Methods: A CBCT scanner with four fields of view (FOV) was used. Using two exposure settings of the adult standard and low dose exposure, DAP values were measured with a DAP meter in C mode ($200mm{\times}179mm$), P mode ($154mm{\times}154mm$), I mode ($102mm{\times}102mm$), and D mode ($51mm{\times}51mm$). The effective doses were also investigated at each mode using an adult male head and neck phantom and thermoluminescent chips. Linear regressive analysis of the DAP and effective dose values was used to calculate the CCs for each CBCT examination. Results: For the C mode, the P mode at the maxilla, and the P mode at the mandible, the CCs were 0.049 ${\mu}Sv/mGycm^2$, 0.067 ${\mu}Sv/mGycm^2$, and 0.064 ${\mu}Sv/mGycm^2$, respectively. For the I mode, the CCs at the maxilla and mandible were 0.076 ${\mu}Sv/mGycm^2$ and 0.095 ${\mu}Sv/mGycm^2$, respectively. For the D mode at the maxillary incisors, molars, and mandibular molars, the CCs were 0.038 ${\mu}Sv/mGycm^2$, 0.041 ${\mu}Sv/mGycm^2$, and 0.146 ${\mu}Sv/mGycm^2$, respectively. Conclusion: The CCs in one CBCT device with fixed 80 kV ranged from 0.038 ${\mu}Sv/mGycm^2$ to 0.146 ${\mu}Sv/mGycm^2$ according to the imaging modes and irradiated region and were highest for the D mode at the mandibular molar.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.1
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• pp.103-112
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• 1990

The purpose of this study was to estimate absorbed dose of each important anatomic site of phantom (RT-2l0 Head & Neck Section/sup R/, Humanoid Systems Co., U.S.A.) head in occlusal radiography. X-radiation dosimetry at 12 anatomic sites in maxillary anterior topography, maxillary posterior topography, mandibular anterior cross-section, mandibular posterior cross-section, mandibular anterior topographic, mandibular posterior topographic occlusal projection was performed with calcium sulfate thermoluminescent dosimeters under 70Kvp and 15mA, 1/4 second (8 inch cone) and 1 second (16 inch cone) exposure time. The results obtained were as follows: Skin surface produced highest absorbed dose ranged between 3264 mrad and 4073 mrad but there was little difference between projections. In maxillary anterior topographic occlusal radiography, eyeballs, maxillary sinuses, and pituitary gland sites produced higher absorbed doses than those of other sites. In maxillary posterior topographic occlusal radiography, exposed eyeball site and exposed maxillary sinus site produced high absorbed doses. In mandibular anterior cross-sectional occlusal radiography, all sites were produced relatively low absorbed dose except eyeball sites. In mandibular posterior cross-sectional occlusal radiography, exposed eyeball site and exposed maxillary sinus site were produced relatively higher absorbed doses than other sites. In mandibular anterior topographic occlusal radiography, maxillary sinuses, submandibular glands, and thyroid gland sites produced high absorbed doses than other sites. In mandibular posterior topographic occlusal radiography, submandibular gland site of the exposed side produced high absorbed dose than other sites and eyeball site of the opposite side produced relatively high absorbed dose.

• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.288-294
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• 2013

Chest digital tomosynthesis was the most advanced digital radiography technology, but it was higher patient dose than conventional chest radiography. Thus we tried to reduce a patient dose of chest digital tomosynthesis and evaluated its image quality. Result shows that radiation dose such as ESD, DAP and ED were 1.95 mGy, 17.66 $dGycm^2$ and 0.133 mSv respectively in default setting and 0.312 mGy, 2.27 $dGy.cm^2$ and 0.052 mSv in use additional filter, respectively. Doses were decrease 66.2%, 73.6% and 57.4% in ESD, DAP and ED, respectively. At the image quality assessment, overall sensitivities of use additional filter for nodule detection were not inferior to default mode for peripheral, central and peripheral micro nodules. However, sensitivity of low dose mode was significantly inferior to the default for central micro-nodules(p < .001).

• Applied Biological Chemistry
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• v.51 no.2
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• pp.148-152
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• 2008

This study was to elucidate the effect of low dose gamma (${\gamma}$)-ray irradiation on the germination, seedling growth and antioxidant activity in sunflower seeds. The seed germination was stimulated in the range of 2.7${\sim}$8.0% by low dose ${\gamma}$-ray irradiation compared with that of the control; however, the germination of seeds stored for 4 months after irradiated was decreased at all low dose ${\gamma}$-ray irradiation groups. Especially, the germination rate of 32 Gy-irradiated seed group was much lower than that of the other groups and 8 Gy was the optimal radiation dose for germination at room temperature. Though there was variation with storage time and temperature, seedling growth stored at 10$^{\circ}C$ for 4 months after irradiated was promoted at the 1 Gy ${\gamma}$-ray irradiation group compared to seed stored at 25$^{\circ}C$. For the antioxidant activity of ${\gamma}$-ray irradiated seeds extract, 4 Gy and 32 Gy groups were significantly increased by 68.83% and 95.44%, respectively, compared to control at the concentration of 100 ${\mu}g$/ml.

• Journal of radiological science and technology
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• v.36 no.1
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• pp.31-38
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• 2013

The prostate cancer is the most common malignant tumor in males. Prostate cancer is the most common malignant tumor that occurs in the male in Korea in 2007 to an annual average of 5,292 cases and 3.3% of the total cancer incidence seventh occurred. Our study compared property for tomotherapy and proton therapy in radiotherapy of prostate cancer patients. We analyzed DVH(Dose Volume Histogram) and dose distribution for prostate, bladder and rectum for radiation treatment planning of prostate cancer with 11 patients in Ilsan K cancer hospital from June to November 2011. There was no differences between tomotherapy and proton therapy in the purpose of prostate cancer therapy for PTV. The adjacent organs of bladder and rectum of average dose-volume were 2port proton therapy that it was low dose treatment comparing with tomotherapy and 5port proton therapy. $H{\cdot}I$ of proton therapy was less than $H{\cdot}I$ of tomotherapy. Also, 5port was less than 2port in $H{\cdot}I$ of proton therapy. However, 2port proton therapy has more advantage over 5port proton therapy that the bladder and rectum of average dose-volume and control time of equipment in radiotherapy of prostate cancer.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.105-109
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• 2020

Intensity-modulated radiotherapy(IMRT) has disadvantages such as increasing the low doses of irradiation to normal tissues and accumulated dose for the whole volume by leakage and transmission of the Multi Leaf Collimator (MLC). The accumulated dose and low dose may increase the occurrence of secondary malignant neoplasms. For this reasons, the jaw tracking function of the TrueBeam (Varian Medical Systems, Palo Alto, CA) was developed to reduce the leakage and transmission dose of the MLC with existing linear accelerators. But quantitative analysis of the dose reduction has not been verified. Therefore, in the present study, we intended to verify the clinical possibility of utilizing the jaw tracking function in brain tumor with comparison of treatment plans. To accomplish this, 3 types of original treatment plans were made using Eclipse11 (Varian Medical Systems, Palo Alto, CA): 1) beyond 2 cm distance from the Organs At Risk (OARs); 2) within 2 cm distance from the OARs; and 3) intersecting with the OARs. Jaw tracking treatment plans were also made with copies of the original treatment planning using Smart LMC Version 11.0.31 (Varian Medical Systems, Palo Alto, CA). A comparison between the 2 types of treatment planning methods was performed using the difference of the mean dose and maximum dose to the OARs in cumulative Dose Volume Histogram (DVH). In the DVH comparison, the maximum difference of 0.5 % was observed between the planning methods in the case of over 2 cm distance, and the maximum of 0.6 % was obtained for within the 2 cm distance. For the case intersecting with the OAR, the maximum difference of 2 % was achieved. According to these results, it could be realized that the differences of mean dose and maximum dose to the OARs was larger when the OARs and PTV were closer. Therefore, treatment plans with the jaw tracking function consistently affected the dose reduction and the clinical possibility could be verified.

• Radiation Oncology Journal
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• v.29 no.2
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• pp.71-82
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• 2011

Purpose: To evaluate the biochemical control rate and the rate of side effects after performing permanent brachytherapy of localized prostate cancer. Materials and Methods: 67 patients with localized prostate cancer were treated with brachytherapy between April 2007 and December 2008. Of these, 43 patients who were followed up and did not receive external radiotherapy were evaluated for the change in prostate specific antigen (PSA) level and the occurrence of side effects. In total, 18 patients were classified as low risk, 19 patients as intermediate risk, and 6 patients as high risk. The prescription dose was 145 Gy. Results: A PSA increase greater than 2 ng/mL occurred in 2 patients (4.7%). Radiation Therapy Oncology Group (RTOG) grade 1 and 2 acute urologic complications (UC) occurred in 40 and 3 patients, respectively. Further, 5 patients had RTOG grade 1 acute rectal complication (RC). The numbers of RTOG grade 1, 2, and 3 chronic UC were 1, 4, and 1, respectively. The numbers of RTOG grade 1, 2, and 4 chronic RC were 5, 10, and 3, respectively. The statistically significant risk factors (RF) of acute RC were the minimal dose in the most irradiated 0.1 cc volume ($D_{0.1cc}$, p=0.041) and absolute volume receiving 150% of the prescribed dose ($V_{150cc}$, p=0.038) in the entire rectum (ER). The percentage ($V_{100%}$, p=0.019) and absolute volume ($V_{100cc}$, p=0.047) in the involved rectum (IR) were also statistically significant. The RF of chronic RC were $V_{100%}$ (p=0.011) in the ER and the $D_{0.1cc}$ (p=0.049), $V_{100cc}$ (p=0.023) in the IR. The number of used seeds were related with acute UC (p=0.028). Conclusion: Permanent brachytherpy of localized prostate cancer showed a favorable short term biochemical control rate. As such, selective intermediate and high risk patients can be managed with permanent brachytherapy. The effort to reduce rectal complication is also necessary.