• The Journal of Korean Society for Radiation Therapy
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• v.28 no.1
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• pp.35-46
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• 2016

Purpose : BoS(Base of Skull) Frame, the fixation tool which is used for the proton of brain cancer increases the lateral penumbra by increasing the airgap (the distance between patient and beam jet), due to the collision of the beam of the posterior oblique direction. Thus, we manufactured the fixation tool per se for improving the limits of BoS frame, and we'd like to evaluate the utility of the manufactured fixation tool throughout this study. Materials and Methods : We've selected the 3 patients of brain cancer who have received the proton therapy from our hospital, and also selected the 6 beam angles; for this, we've selected the beam angle of the posterior oblique direction. We' ve measured the planned BoS frame and the distance of Snout for each beam which are planned for the treatment of the patient using the BoS frame. After this, we've proceeded with the set-up that is above the location which was recommended by the manufacturer of the BoS frame, at the same beam angle of the same patient, by using our in-house Bos frame fixation tool. The set-up was above 21 cm toward the superior direction, compared to the situation when the BoS frame was only used with the basic couch. After that, we've stacked the snout to the BoS frame as much as possible, and measured the distance of snout. We've also measured the airgap, based on the gap of that snout distance; and we've proceeded the normalization based on each dose (100% of each dose), after that, we've conducted the comparative analysis of lateral penumbra. Moreover, we've established the treatment plan according to the changed airgap which has been transformed to the Raystation 5.0 proton therapy planning system, and we've conducted the comparative analysis of DVH(Dose Volume Histogram). Results : When comparing the result before using the in-house Bos frame fixation tool which was manufactured for each beam angle with the result after using the fixation tool, we could figure out that airgap than when not used in accordance with the use of the in-house Bos frame fixation tool was reduced by 5.4 cm ~ 15.4 cm, respectively angle. The reduced snout distance means the airgap. Lateral Penumbra could reduce left, right, 0.1 cm ~ 0.4 cm by an angle in accordance with decreasing the airgap while using each beam angle in-house Bos frame fixation tool. Due to the reduced lateral penumbra, Lt.eyeball, Lt.lens, Lt. hippocampus, Lt. cochlea, Rt. eyeball, Rt. lens, Rt. cochlea, Rt. hippocampus, stem that can be seen that the dose is decreased by 0 CGE ~ 4.4 CGE. Conclusion : It was possible to reduced the airgap by using our in-house Bos frame fixation tool for the proton therapy; as a result, it was possible to figure out that the lateral penumbra reduced. Moreover, it was also possible to check through the comparative analysis of the treatment plan that when we reduce the lateral penumbra, the reduction of the unnecessary irradiation for the normal tissues. Therefore, Using the posterior oblique the Brain cancer proton therapy should be preceded by decreasing the airgap, by using our in-house Bos frame fixation tool; also, the continuous efforts for reducing the airgap as much as possible for the proton therapy of other area will be necessary as well.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.2
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• pp.411-416
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• 1999

Purpose : This study was done to evaluate the absorbed doses in organs of the head and neck for the conventional temporomandibular joint tomography. Materials and Methods : Dosimetry was performed with 32 LiF thermoluminescent dosimeters, which were placed in a tissue-equivalent phantom when the temporomandibular joint was examined by both lateral and frontal temporomandibular joint tomography. Results : For lateral tomography, parotid gland and preauricular area towards tube showed relatively high absorbed dose of 1056.9 μGy and 519.9 μGy respectively. For frontal tomography, the two largest absorbed doses were 259.2 μGy in orbit towards tube and 212.0 μGy in lens towards tube. Conclusion : Conventional temporomandibular joint tomography showed relatively low absorbed doses on critical organs. Thus, responsible use of it may not be limited.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.175-183
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• 2019

Cerebral nervous system intervention has been reported frequently due to radiation exposure such as blistering of the skin, hair loss, and erythema due to prolonged procedures. By applying ergonomically manufactured Bismuth (atomic number 83; Bi) shield to endovascular treatment of cerebral aneurysms, we aimed to minimize radiation exposure of scalp and lens from medical radiation exposure. The measurement site was the posterior part of the head, bilateral temporal part, bilateral quadriceps part, nose part, and the measuring part was attached to the optically stimulated Luminescence dosimeter (OSLD) Before and after the use, the entrance surface dose was compared and analyzed. The average entrance surface dose of group A (unshield) was 92.44 mGy, and group B was measured at 67.55 mGy. The average decrease in Group B was 26.92% compared to Group A. The entrance surface dose mean of the occipital region was measured at 146.08 mGy B group at 103.23 mGy and decreased by an average of 29.32% in group B compared to group A. The average entrance surface dose of the bilateral temporal part was measured in group A at 101.90 mGy group B at 72.69 mGy and decreased by an average of 28.67% in group B compared to group A. The average entrance surface dose for bilateral quadriceps part was measured at 27.51 mGy group B at 21.39 mGy and averaged 22.26% less in group B than group A. It is believed that the use of bismuth shields will be an alternative to reducing radiation disturbance due to temporary hair loss and other stochastic effects that may occur after the endovascular treatment of cerebral aneurysms procedure.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.194-201
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• 2015

We have investigated the EPR signal properties in 12 components of two mobile phones (LCD, OLED) using electron paramagnetic resonance (EPR) spectrometer in this study.EPR measurements were performed at normal atmospheric conditions using Bruker EXEXSYS-II E500 spectrometer with X-band bridge, and samples were irradiated by $^{137}Cs$ gamma-ray source. To identify the presence of radiation-induced signal (RIS), the EPR spectra of each sample were measured unirradiated and irradiated at 50 Gy. Then, dose-response curve and signal intensity variating by time after irradiation were measured. As a result, the signal intensity increased after irradiation in all samples except the USIM plastic and IC chip. Among the samples, cover glass(CG), lens, light guide plate(LGP) and diffusion sheet have shown fine linearity ($R^2$ > 0.99). Especially, the LGP had ideal characteristics for dosimetry because there were no signal in 0 Gy and high rate of increase in RIS. However, this sample showed weakness in fading. Signal intensity of LGP and Diffusion Sheet decreased by 50% within 72 hours after irradiation, while signals of Cover Glass and Lens were stably preserved during the short period of time. In order to apply rapidly EPR dosimetry using mobile phone components in large-scale radiation accidents, further studies on signal differences for same components of the different mobile phone, fading, pretreatment of samples and processing of background signal are needed. However, it will be possible to do dosimetry by dose-additive method or comparative method using unirradiated same product in small-scale accident.

• Journal of the Korean Society of Radiology
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• v.12 no.6
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• pp.707-712
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• 2018

The number of CT examinations is increasing, and radiation exposure is also increasing. repeated tests can affect the lens and thyroid. In hospitals, there is a tendency to lack interest in major long-term radiation exposure compared to the interest in increasing image information and image quality with head CT. In this study, we analyzed the improvement of image quality by proposed method to the noisy CT images. The proposed denoising method total variance optimization only for the impulsive noise candidate pixels. Experimental results show that edge information is well preserved and impulse noise can be effectively removed. and worked very well for the images according to tube voltage and rotation time. applied to the clinical setting, it can be used as the lowest exposure condition without worrying about the image quality and it will be helpful for the CT application.

• The Journal of the Korea Contents Association
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• v.14 no.8
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• pp.233-242
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• 2014

The purpose of this study is to compare the reduction of the dose radioactivity by CARE kV with that of the Bismuth shielding. First, CT was performed with transparent materials, including a Bismuth shielder which is a well-known material for decreasing the dose of radiation. Moreover, we have estimated and compared the affects of the reduction of dose on eye lens, thyroid, breast and genitals. These steps aim to compare reactions with and without the application of the Rando phantom with PLD as well as with CARE kV or not. As a result, during the Brain angio scan, the dose of CARE kV set inspection test methods showed the least dose. Depending on whether we use CARE kV, which showed the effect of dose reduction by 63%. During the Carotid angio scan, the dose was increased by 13% by how to set CARE kV+Bismuth. During the Cardiac angio scan, which showed the effect of dose reduction by 31% by how to set CARE kV+Bismuth. During the Lower extremity angio scan, the dose was measured least by how to set up the whole Bismuth. Compared with CARE kV set of test methods, which showed the effect of dose reduction by 9%.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.101-108
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• 2021

The CT can accurately present the anatomical structure of an organ in the human body, and the resolution of the image is excellent. On Brain CT examination, the radiation sensitivity of the orbit is high and it is subject to many exposure effects. To reduce exposure dose of lens, this study compares change of exposure dose and shielding rate about non-shielding and shielding in a way of using two shielding materials, bismuth and tungsten. In this study, we used bismuth and tungsten filament as shielding materials made by 3D printing to measure the exposure dose according to the materials thickness and each of slices. To compare each shielding rate, 1 mm to 5 mm of two materials was measured with the head phantom fixed and the Magicmax universal dosimeter placed on the eye when the shielding material is not placed, and the shielding material is placed on it. In the 1 mm thick filament, the bismuth filament showed 26.8% and the tungsten filament showed 43.1% shielding rate. Therefore, tungsten presents much greater shielding effect than bismuth.

• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.215-221
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• 2023

Among brain CT scan conditions including the lens, the tube voltage was changed to 80, 100, and 120 kVp and applied. The change in dose was analyzed using lead, lead goggles and barium sulfate silicon shielding materials, and the degree of influence of the shielding materials on image quality was compared and analyzed by applying the SNR, CNR, and SSIM index analysis methods. As a result, it was analyzed that although the dose was reduced by applying all shielding materials, the difference in dose reduction was not large (P > 0.05). In addition, as for the change in image quality due to the application of the shielding material, SNR and CNR were the highest when lead goggles were applied, and the structural similarity was measured to be the best as it was closest to the reference value of 1 in SSIM analysis. Therefore, based on the results of this study, it is thought that if more diverse shielding materials and clinical test results are derived and applied, it will be helpful for the clinical application criteria in the case of shielding utilization inspection.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.209-216
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• 2018

In the field of angiography and interventional radiology, it is said that the risk of radiation exposure to the eyes is high due to the characteristics of work, but currently divided dose assessment and management are not carried out in reality. Therefore, in this study, in order to evaluate the dose of the operator in the surgical environment and to analyze the shields, firstly, we selected the point where the operator is mainly located, evaluated the exposure dose of the eye after attaching the pocket dosimeter to the lateral angle point of the head and neck phantom, and evaluate shielding effect when wearing lead glasses that is currently commercialized. Secondly, we evaluated the tendency of the exposure dose of the eye and the shielding effect through simulation in the same geometric structure as the actual measurement. As a result, in the case of measurement using a dosimeter, the cumulative dose increased with the increase of the fluoroscopic time, and the tendency was different according to the position of the operator. Simulation results show that the dose distribution of the eye lens in the mathematical phantom is about 1.1 ~ 1.3 times higher than that of the cornea. Also, The protective effect of the lead glasses showed a shielding effect of at least 3.7 ~ 21.4% in each eye.

• Journal of the Korean Society of Radiology
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• v.7 no.2
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• pp.121-129
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• 2013

In this study measured patient exposure dose for purpose exposure area and peripheral critical organs by using optically stimulated luminescence dosimeters (OSLDs) from computed tomography (CT), based on the measurement results, we predicted the radiobiological effects, and would like to advised ways of reduction strategies. In order to experiment, OSLDs received calibration factor were attached at left and right lens, thyroid, field center, and sexual gland in human body standard phantom that is recommended in ICRP, and we simulated exposure dose of patients in same condition that equal exposure condition according to examination area. Average calibration factor of OSLDs were $1.0058{\pm}0.0074$. In case of left and right lens, equivalent dose was measure in 50.49 mGy in skull examination, 0.24 mGy in chest, under standard value in abdomen, lumbar spine and pelvis. In case of thyroid, equivalent dose was measured in 10.89 mGy in skull examination, 7.75 mGy in chest, 0.06 mGy in abdomen, under standard value in lumber spine and pelvis. In case of sexual gland, equivalent dose was measured in 21.98 mGy, 2.37 mGy in lumber spine, 6.29 mGy in abdomen, under standard value in skull examination. Reduction strategies about diagnosis reference level (DRL) in CT examination needed fair interpretation and institutional support recommending international organization. So, we met validity for minimize exposure of patients, systematize influence about exposure dose of patients and minimize unnecessary exposure of tissue.