• Journal of radiological science and technology
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• v.32 no.3
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• pp.307-312
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• 2009

The purpose of our study was to determine the eyeradiation dose when performing routine multi-detector computed tomography (MDCT). We also evaluated dose reduction and the effect on image quality of using a bismuth eye shield when performing head MDCT. Examinations were performed with a 64MDCT scanner. To compare the shielded/unshielded lens dose, the examination was performed with and without bismuth shielding in anthropomorphic phantom. To determine the average lens radiation dose, we imaged an anthropomorphic phantom into which calibrated photoluminescence glass dosimeter (PLD) were placed to measure the dose to lens. The phantom was imaged using the same protocol. Radiation doses to the lens with and without the lensshielding were measured and compared using the Student t test. In the qualitative evaluation of the MDCT scans, all were considered to be of diagnostic quality. We did not see any differences in quality between the shielded and unshielded brain. The mean radiation doses to the eyewith the shield and to those without the shield were 21.54 versus 10.46 mGy, respectively. The lens shield enabled a 51.3% decrease in radiation dose to the lens. Bismuth in-plane shielding for routine eye and head MDCT decreased radiation dose to the lenswithout qualitative changes in image quality. The other radiosensitive superficial organs specifically must be protected with shielding.

• Journal of the Korea Convergence Society
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• v.8 no.2
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• pp.113-120
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• 2017

The purpose of this present study was to evaluate the surface radiation dose reduction and radiograph artifact images in computed tomography (CT) for the manufactured radiation shields by using sea-shells. The radiation convergence shields were made from silicons, sea-shells, barium powders, producted circle types of diameter 50 mm, thickness 3.5 mm for 5 kinds (only silicon shield, only barium shield, mixed sea-shells with silicon shield, mixed barium with silicon shield, mixed sea-shells with barium and silicon shield). Radiation generation and acquisition were used 4-channel multi-detector CT. The results of this study showed that mixed sea-shells with silicon shields could reduce the surface dose of 5.3% without radiograph artifact images. In the future, we will expect the radiation convergence shield as environmentally friendly materials by using the recycling of sea-shells with the advantages of silicon which can make various shapes.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.2
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• pp.71-76
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• 2011

Because interventional procedure operates looking at premier as real time when perate intervention enemy, by patient is revealed during suitableness time in radiation, side effect such as radiation injury of skin is apt to happen. It established by purpose of study that measure exposure dose that patient receives about these problem, and find solution for radiation injury and repletion method. In this study, we used Rando phantom of identical structure with the human body which becomes accomplished with 4 branch ingredient of the attempt and system equivalent material them and absorbed dose were measured by TLD. According to the laboratory, it shows that operations such as TFCA procedure or uterine myoma embolization are more dangerous than TACE procedure. If both operations are inspected during a short time, it is not affected in being bombed. However, it can lead to palliative agenesis or depilate, definitive agenesis only if operations are repeated more than three times. Dose distibution based on experiment, to reduce radiation exposure to patients result from reduction of scatter ray as we control field size of radiation and protection of side organs except for tumor. also we knew that we can protect patients form radiation exposure, if we increas SOD and decrease SID.

• Radiation Oncology Journal
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• v.7 no.2
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• pp.293-297
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• 1989

Electron contamination due to the interaction between radiation beam and material was analyzed for the factors such as source-skin distance (SSD), field size, tray characteristics and position of filter, which can affect the surface dose in Cobalt teletherapy. Surface dose in open beam was more influenced by SSD with increasing field size. Relative surface charge (RSC) increased with the use of tray (solid, circular hole, slotted), compared with open beam, which is thought to be due to increased electron contamination of the tray. To reduce the surface dose, 0.4mm thick Lipowitz metal filter was used. Compared with open beam, RSC decreased by 8.8%, 11.3%, 13.3%, 16.6%, 19.3% and 21.7% for the field size of $5{\times}5$, $10{\times}10$, $15{\times}15$, $20{\times}20$, $25{\times}25$ and $30{\times}30cm^2$, respectively. On the contrary, use of Lipowitz metal filter increased RSC at 60cm or less SSD. Surface dose was effectively reduced with Lpowitz metal filter placed right below solid tray in Cobalt teletherapy.

• Journal of radiological science and technology
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• v.46 no.3
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• pp.239-246
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• 2023

In this study, we assessed the effect of reduction of tumor volume in the head and neck cancer by using RANDO phantom in Static Intensity-Modulated Radiation Therapy (S-IMRT) and Volumetric-Modulated Arc Therapy (VMAT) planning. RANDO phantom's body and protruding volumes were delineated by using Contour menu of Eclipse™ (Varian Medical System, Inc., Version 15.6, USA) treatment planning system. Inner margins of 2 mm to 10 mm from protruding volumes of the reference were applied to generate the parameters of reduced volume. In addition, target volume and Organ at Risk (OAR) volumes were delineated. S-IMRT plan and VMAT plan were designed in reference. These plans were assigned in the reduced volumes and dose was calculated in reduced volumes using preset Monitor unit (MU). Dose Volume Histogram (DVH) was generated to evaluate treatment planning. Conformity Index (CI) and R² in reference S-IMRT were 0.983 and 0.015, respectively. There was no significant relationship between CI and the reduced volume. Homogeneity Index (HI) and R² were 0.092 and 0.960, respectively. The HI increased when volume reduced. In reference VMAT, CI and R² were 0.992 and 0.259, respectively. There was no relationship between the volume reduction and CI. On the other hand, HI and R² were 0.078 and 0.895, respectively. The value of HI increased when the volume reduced. There was significant difference (p<0.05) between parameters (D_mean and D_max) of normal organs of S-IMRT and VMAT except brain stem. Volume reduction affected the CI, HI and OAR dose. In the future, additional studies are necessary to incorporate the reduction of the volume in the clinical setting.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.27-34
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• 2018

Purpose : To evaluate the effect of carbon couch side rail and vacuum immobilization device in case of lung RPO irradiation. Materials and Methods : The 10, 20, 30 mm thickness of vac-lok's right side were obtained. To measure of doses, glass dosimeters were used and measured reference point is left lung center at the phantom. A, B, C, and D points are left, right, down, and up directions based on the center point. In the state of Side-Rail-Out, place the without vac-lok, with the thickness of 10, 20, and 30 mm vac-lok. After the glass dosimeters was inserted in center, A, B, C, and D points, 100 MU of 6 MV X-ray were irradiated to the referenced center point in the condition of $10{\times}10cm^2$ field size, SAD 100 cm, gantry angle 225, 300 MU/min dose rate. Five measurements were made for each point. In the state of Side-Rail-In, five measurement were made for each point under the same conditions. The average is measured on each of the five Side-Rail-Out and Side-Rail-In measurements. Results : In the presence of side rail, the dose reduction ratio was -11.8 %, -12.3 %, -4.1 %, -12.3 %, -7.3 % for each A, B, C, and D points. In the state of Side-Rail-Out, the dose reduction ratio for the using 10 mm thickness of vac-lok was -0.9 % than without vac-lok. The dose reduction ratio for the using 20 mm thickness of vac-lok was -2.0 %, for the using 30 mm thickness of the vac-lok was -3.0 % than without vac-lok. In the state of Side-Rail-In, the dose reduction ratio for the using 10 mm thickness of vac-lok was -1.0 % than without vac-lok. The dose reduction ratio for the using 20 mm vac-lok was -2.1 %, for the using 30 mm vac-lok was -3.0 % than without vac-lok. Based on the value of no vac-lok dose in the Side-Rail-In state, The dose reduction ratios for the using 10 mm, 20 mm and 30 mm thickness of vac-loks In the Side-Rail-Out that the center point were -12.7 %, -13.7 %, -14.2 % and -12.8 %, -13.8 %, -14.5 % respectively at point A. The dose reduction ratios for the same conditions to the B point were -4.9 %, -6.1 %, -7.1 % and -13.4 %, -14.4 %, -15.5 % respectively at point C. The dose reduction ratios for the same conditions to the D point were -8.4 %, -9.0 %, -10.4 % respectively. Conclusion : The attenuation was caused by presence of side rails and thickness of vac-lok. Pay attention to these attenuation factors, making it a more effective radiation therapy.

• Archives of Pharmacal Research
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• v.20 no.3
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• pp.212-217
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• 1997

Induction of an adaptive response to ionizing radiation in mouse lymphoma (EL4) cells was studied by using cell survival fraction and apoptotic nucleosomal DNA fragmentation as biological end points. Cells in early log phase were pre-exposed to low dose of ${\gamma}$-rays (0.01 Gy) 4 or 20 hrs prior to high dose ${\gamma}$-ray (4, 8 and 12 Gy for cell survival fraction analysis; 8 Gy for DNA fragmentation analysis) irradiation. Then cell survival fractions and the extent of DNA fragmentation were measured. Significant adaptive response, increase in cell survival fraction and decrease in the extent of DNA fragmentation were induced when low and high dose .gamma.-ray irradiation time interval was 4 hr. Addition of protein or RNA synthesis inhibitor, cycloheximide or 5,6-dichloro-1-.betha.-d-ribofuranosylbenzimidazole (DRFB), respectively during adaptation period, the period from low dose ${\gamma}$-ray irradiation to high dose ${\gamma}$-ray irradiation, was able to inhibit the induction of adaptive response, which is the reduction of the extent DNA fragmentation in irradiated EL4 cells. These data suggest that the induction of adaptive response to ionizing radiation in EL4 cells required both protein and RNA synthesis.

• International Journal of Contents
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• v.7 no.4
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• pp.103-107
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• 2011

The effective dose and the organ absorbed dose, which are given to a breast in the cases of using and not using the bismuth breast protection shield for the protection of a breast with the coronary artery CT angiography, have been measured and compared for the manual exposure control (MEC)and the automatic exposure control (AEC). In the cases of using and not using the bismuth breast protection shield, it has been found that the measured dose shows the reduction of about 23 to 26% for the MEC and about 22 to 25% for the AEC when the shield is used compared to the case of not using it. By comparing the shield and non-shield cases for the AEC and the MEC, it can be said that the value measured by carrying out the scanning process with the AEC mode has decreased by about 24 to 30% compared to the case of applying the MEC mode. Such a result shows that it is recommended to use the AEC mode for the reduction of the patient's exposure dose during the CT examination.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.117-123
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• 2021

This paper is to establish a basis for a dose reduction strategy by confirming correlations with the factors that may affect the radiation dose based on the dose records in low-dose chest CT and abdominal non-contrast CT. In order to find out the causes of unnecessary exposure, the correlation between seven factors (age, gender, height, weight, BMI, patient status [inpatient and outpatient], and use of dose modulation) and CT dose were identified. Logistic regression was used as the statistical analysis for correlation verification. In the low dose chest CT, as the higher values of height and BMI and dose modulation off were associated with lowering the risk exceeding Diagnostic Reference Levels(DRL) (odds ration<1, p<0.05). However, as woman compared to man and the higher values of weight were associated with highering the risk exceeding DRL (odds ration>1, p<0.05). In the abdomen CT, as dose modulation off were associated with lowering the risk exceeding DRL (odds ration<1, p<0.05). Therefore It is necessary to conduct research on the relationship between various factors affecting radiation exposure and patient radiation dose for reducing the dose.

• Radiation Oncology Journal
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• v.35 no.1
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• pp.90-100
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• 2017

Purpose: To Study the dosimetric advantage of the Jaw tracking technique in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) for Head and Neck Cancers. Materials and Methods: We retrospectively selected 10 previously treated head and neck cancer patients stage (T1/T2, N1, M0) in this study. All the patients were planned for IMRT and VMAT with simultaneous integrated boost technique. IMRT and VMAT plans were performed with jaw tracking (JT) and with static jaw (SJ) technique by keeping the same constraints and priorities for a particular patient. Target conformity, dose to the critical structures and low dose volumes were recorded and analyzed for IMRT and VMAT plans with and without JT for all the patients. Results: The conformity index average of all patients followed by standard deviation (${\bar{x}}{\pm}{\sigma}_{\bar{x}}$) of the JT-IMRT, SJ-IMRT, JT-VMAT, and SJ-VMAT were $1.72{\pm}0.56$, $1.67{\pm}0.57$, $1.83{\pm}0.65$, and $1.85{\pm}0.64$, and homogeneity index were $0.059{\pm}0.05$, $0.064{\pm}0.05$, $0.064{\pm}0.04$, and $0.064{\pm}0.05$. JT-IMRT shows significant mean reduction in right parotid and left parotid shows of 7.64% (p < 0.001) and 7.45% (p < 0.001) compare to SJ-IMRT. JT-IMRT plans also shows considerable dose reduction to thyroid, inferior constrictors, spinal cord and brainstem compared to the SJ-IMRT plans. Conclusion: Significant dose reductions were observed for critical structure in the JT-IMRT compared to SJ-IMRT technique. In JT-VMAT plans dose reduction to the critical structure were not significant compared to the SJ-IMRT due to relatively lesser monitor units.