• Journal of Digital Convergence
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• v.12 no.3
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• pp.353-358
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• 2014

This study was conducted to analyze the patient's exposed dose targeting the patients who had acute ischemic stroke symptoms and CT brain perfusion scan, by comparing fixed time technique and bolus tracking technique which was provided by the manufacturer and to identify the Time graph to implement the usability of contrast medium's tracking technique the best contrast enhancement intervals. $CTDI_{VOL}$ of PCT in patient appeared to be 431.72mGy in fixed scan delay protocol, whereas 323.61mGy in Bolus tracking technique. The value of DLP appeared to be $1243.47mGy{\cdot}cm$ in fixed scan delay protocol, whereas $932mGy{\cdot}cm$ in Bolus tracking technique. Time graph appeared to be various in fixed scan delay protocol, whereas the optimal time graph could be obtained in Bolus tracking. The exposure dose could be reduced by 25% applying Bolus tracking technique when taking brain perfusion CT scan.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.697-698
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• 2002

The dispersion of an aerosol bolus in acinus is analyzed numerically. Model geometry is a straight duct surrounded by an axisymmetric semicircular annulus which is expanding or contracting with breathing. Unsteady Wavier-Stokes equation is solved by CFX-F3D, an FVM commercial code and the trajectory of massless particle Is computed by Lagrangian method. For steady flow with no wall motion, mean velocity of aerosol bolus in alveolated duct is a little smaller than that in straight duct and dispersion in alveolated duct is comparable with the dispersion in straight tube. For expanding duct mean velocity of aerosol bolus approaches half of that in straight tube and effective diffusivity is smaller than that of straight tube. For contracting duct mean velocity of aerosol bolus becomes slightly larger than that in straight tube and effective diffusivity is comparable with the case of straight tube.

• Journal of Gastric Cancer
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• v.16 no.3
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• pp.177-181
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• 2016

Purpose: The International Organization for Standardization-5fluorouracil (FU) 10 trial found that bolus 5-FU and l-leucovorin was not inferior to S-1 in the treatment of gastric cancer (GC). Continuous 5-FU and the rapid injection of 5-FU have different anti-cancer effects. Thus, bolus 5-FU and l-leucovorin treatment might be useful for oral FU-resistant GC. Materials and Methods: We retrospectively analyzed the medical records of all patients with S-1 or capecitabine-resistant, unresectable, or recurrent GC treated with bolus 5-FU and l-leucovorin between January 2010 and December 2015 at Hokkaido University Hospital. The bolus 5-FU and l-leucovorin regimen consisted of intravenous l-leucovorin ($250mg/m^2/2h$) and bolus 5-FU ($600mg/m^2$) administered once weekly followed by a 2-week rest period; each cycle was repeated every 8 weeks. Results: A total of 14 patients were identified. The disease control rate was 35.7%. The median progression-free survival was 1.6 months (95% confidence interval [CI], 1.3~2.0 months), and the median overall survival was 6.3 months (95% CI, 4.7~7.9 months). No patient died from treatment-related causes. The most common severe adverse event associated with bolus 5-FU and l-leucovorin was neutropenia, which occurred in 21.4% of patients. Conclusions: Bolus 5-FU and l-leucovorin treatment might be useful for oral FU-resistant GC. We are planning a multi-center prospective phase II trial to evaluate the efficacy and safety of bolus 5-FU and l-leucovorin treatment for pre-treated unresectable or recurrent GC to confirm the results of this limited, retrospective study.

• 대한방사선치료학회:학술대회논문집
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• 2005.06a
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• pp.27-32
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• 2005

Electron is used for the treatment of skin cancer, breast cancer, and head and neck cancer in clinic. Our study is performed to check the isodose distribut ion in source surface distance(SSD) and source bolus distance(SBD) setup, nipple influence to isodose distribution of electron, junctional area isodose variation of photon and electron field. Dosimetry is carried out with phantom, acryl, and film as the same condition of treatment setup. $8\%$ of isodose difference is noted with the surface distance(SSD) and source bolus distance(SBD) setup. To reduce the influence of nipple. corresponding volume of bolus should be removed. And bolus covering all the electron field reduced hot and cold spot of junctional area of photon.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.1001-1007
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• 2023

Dose limits are not applied to medical radiation exposure therefore justification and optimization should be essential for protecting radiation. This study explores methods to reduce exposure dose undergoing general radiation exam by bolus(tissue equivalent material) with keeping image quality. Hand PA projection with 50 kVp, 5 mAs, SID 100 cm, and 8×10 inch is referred by covered bolus of thickness 0, 3, 5, 8, and 10 mm for evaluation entrance dose and SNR. The entrance dose (μGy) to the hand by bolus thickness was 125.41±0.288, 106.85±0.255, 104.97±0.221, 91.68±0.299, and 90.94±0.106 showing a significant reduction in radiation exposure depending on if the bolus was used and bolus thickness. The SNR of the image was 13.997, 13.906, 12.240, 12.538, and 12.548 at each bolus thickness, showing no significant difference. It was confirmed that if appropriate thickness and size of bolus is used depending on the type of radiological imaging exam and the body site, a significant radiation dose reduction effect can be achieved without deteriorating image quality.

• Toxicological Research
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• v.20 no.4
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• pp.375-380
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• 2004

The toxicity of CKD-602 was investigated at doses of 0, 3, 9, and 27 mg/kg in rats, by administering the same total dose over 24-hr continuous infusion or bolus injection. CKD-602 treatment caused gastrointestinal symptoms such as diarrhea, soft stool, and soiled perineal region. It also decreased body weight at doses of 9 and 27 mg/kg in a dose-dependant manner. At 3 mg/ kg, clinical signs and body weight decrease were more severe in the infusion group than in the bolus group. In the bolus group, mortalities were 0/8, 0/8, 1/8, and 3/8 at 0, 3, 9, and 27 mg/kg, respectively, whereas those were 0/8, 1/8, 8/8, and 8/8 in the infusion group. $LD_{50}$ values were 36.25 mg/kg for bolus and 3.50 mg/kg for infusion, respectively. This finding indicates that the toxic potency of CKD-602 by continuous infusion is about 10 times higher than by bolus injection. Our findings suggest that the toxic effects of CKD-602 are dependant upon the duration of intravenous administration.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1091-1097
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• 2023

Bolus is used in radiation therapy to prescribe an even dose to the tumor when the skin surface is inclined or has irregularities. At this time, the dose to the skin surface increases. Due to the patient's unique body structure and irregular skin, voids may occur between the bolus and the skin, which may reduce the accuracy of treatment. Therefore, in this study, the existing bolus and the self-produced bolus through 3D printing were applied to the nasal area, and the difference between the surface dose after treatment plan and the dose directly measured with an Optically Stimulated luminescence(OSL) dosimeter was compared to the existing bolus. The bolus rate was 97%, PLA 100.33%, ePETELA 75A 100.53%, and ePETELA 85A 100.36%. It was confirmed that there was little error in the measurement values and treatment plan values for each material. In addition, compared to when applying a conventional bolus, a difference of -3% to +0.5% for a 3D printed bolus can be confirmed, so a customized bolus produced through 3D printing can complement the shortcomings of the existing bolus. It is believed that there will be.

• Radiation Oncology Journal
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• v.26 no.3
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• pp.189-194
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• 2008

Purpose: We designed a water-based bolus device for radiation therapy in Kaposi's sarcoma. This study evaluated the usefulness of this new device and compared it with the currently used rice-based bolus. Materials and Methods: We fashioned a polystyrene box and cut a hole in order to insert patient's extremities while the patient was in the supine position. We used a vacuum-vinyl based polymer to reduce water leakage. Next, we eliminated air using a vacuum pump and a vacuum valve to reduce the air gap between the water and extremities in the vacuum-vinyl box. We performed CT scans to evaluate the density difference of the fabricated water-based bolus device when the device in which the rice-based bolus was placed directly, the rice-based bolus with polymer-vinyl packed rice, and the water were all put in. We analyzed the density change with the air gap volume using a planning system. In addition, we measured the homogeneity and dose in the low-extremities phantom, attached to six TLD, and wrapped film exposed in parallel-opposite fields with the LINAC under the same conditions as the set-up of the CT-simulator. Results: The density value of the rice-based bolus with the rice put in directly was 14% lower than that of the water-based bolus. Moreover, the value of the other experiments in the rice-based bolus with the polymer-vinyl packed rice showed an 18% reduction in density. The analysis of the EDR2 film revealed that the water-based bolus shows a more homogeneous dose plan, which was superior by $4{\sim}4.4%$ to the rice-base bolus. The mean TLD readings of the rice-based bolus, with the rice put directly into the polystyrene box had a 3.4% higher density value. Moreover, the density value in the case of the rice-based bolus with polymer-vinyl packed rice had a 4.3% higher reading compared to the water-based bolus. Conclusion: Our custom-made water-based bolus device increases the accuracy of the set-up by confirming the treatment field. It also improves the accuracy of the therapy owing to the reduction of the air gap using a vacuum pump and a vacuum valve. This set-up represents a promising alternative device for delivering a homogenous dose to the target volume.

• Progress in Medical Physics
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• v.27 no.4
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• pp.224-231
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• 2016

The usefulness of Gel Bolus phantom was investigated by comparing the temperature distribution characteristic of the agar phantom produced to investigate the dose distribution characteristic of radiofrequency hyperthermia device with that of the Gel Bolus phantom under conditions similar to those of an agar phantom that can continuously carry out temperature measurement. The temperatures of the agar phantom and the Gel Bolus phantom were raised to $36.5{\pm}3^{\circ}C$ and a temperature sensing was inserted at depths of 5, 10, and 15 cm from the phantom central axis. The temperature increase rate and the coefficient of determination were analyzed while applying output powers of 100 W and 150 W, respectively, at intervals of 1 min for 60 min under conditions where the indoor temperature was in the range $24.5{\sim}27.5^{\circ}C$, humidity was 35~40%, internal cooling temperature of the electrode was $20^{\circ}C$, size of the upper electrode was 250 mm, and the size of the lower electrode was 250 mm. The coefficients of determination of 150 W output power at the depth point of 5 cm from the central axis of the phantom were analyzed to be 0.9946 and 0.9926 in the agar and Gel Bolus phantoms, respectively; moreover, the temperature change equation of the agar and Gel Bolus phantoms with time can be expressed as follows in the state the phantom temperature is raised to $36^{\circ}C:Y(G)$ is equation of Gel Bolus phantoms (in 5 cm depth) applying output power of 150 W. Y(G)=0.157X+36. It can be seen that if the temperature is measured in this case, the Gel Bolus phantom value can be converted to the measured value of the agar phantom. As a result of comparing the temperature distribution characteristics of the agar phantom of a human-body-equivalent material with those of the Gel Bolus phantom that can be continuously used, the usefulness of Gel Bolus phantom was exhibited.

• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.459-464
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• 2019

In order to minimize the radiation exposure dose of the thyroid site at dental cone-beam computer tomography, a protector using a Bolus was prepared, and the radiation shielding effect and the appropriateness of the image were evaluated. Using a dental cone-beam computed tomography (CBCT), a glass dosimeter was attached to the left and right sides of the thyroid for a dental radiation phantom, and the radiation dose was measured. The absorbed dose for each shield was measured by another method to 10 mm, 20 mm, and 30 mm-thickness, respectively. Eight evaluators evaluated whether or not the medical image is appropriate. When using a 30 mm Bolus shield at the left thyroid site, the resulting value is reduced by an average of $342.67{\mu}Gy$ by 20.7% from the average value of $431.22{\mu}Gy$ measured without using a Bolus shield, the right thyroid site In the case of using 30 mm Bolus shield, it showed a dose reduction effect of 21.9% with an average of $424.56{\mu}Gy$. The adequacy of the medical image was judged to be usable by both evaluators. In conclusion, the dental cone-beam computerized tomography can be used as a useful shielding material because it has a radiation shielding effect and it is possible to treat the diagnosis of the bolus protector in the thyroid without any obstruction shade in order to minimize the radiation dose.