• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.651-660
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• 2020

The purpose of this study was to create a phantom with a HU value similar to that of the human Femur using a 3D printer to replace the existing pig bone. A total of 372 people were analyzed to determine the HU value of human Femur. Using a 3D printer, a human bone model phantom was fabricated using PLA-Cu 20% and subjected to CT examination. Pig bones were 6 months old pigs, and bones 2 days after slaughter were used. As a result of the examination, the 3D printing phantom made with 80% of the internal filling showed a similar value to all data of the human body (p<0.05), and there was a difference from the pig bone (p>0.05). In addition, in the case of the HU value of Femur by age group, it was confirmed that the value of HU decreased as the age group increased (p<0.05). 3D printing and HU values confirmed a weak negative correlation with respect to the stacking height, but confirmed a strong positive correlation (R² = 0.996) with 182.13±1.290 in the inner filling (p<0.05). In conclusion, it was confirmed that the human body model phantom using 3D printing can exhibit a similar level of HU value to the human body compared to the existing pig bone phantom, and this study will provide basic data for the production of a human body model phantom using a 3D printer.

• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.895-900
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• 2019

Ultrasound is known to be harmless to the human body and is widely used in obstetrics and gynecology to confirm the diagnosis and development status of fetus. Diagnosis Although long - term use of ultrasound may cause changes in body temperature, studies on the uterine temperature changes due to ultrasound have been lacking. The purpose of this study was to investigate the change of temperature according to ultrasonic scanning time using a self - produced uterine model phantom. Ultrasound equipment and a 4MHz convex probe were used to construct the uterine model phantom similar to the human uterus using acrylic and pig uterus, which are tissue equivalents. Three probe type thermometers were installed to measure the inside of the acrylic water tank, the uterus, and the atmospheric temperature. The temperature of the uterine phantom was ascertained by measuring the temperature of the subject for 6 hours, 361 times. In this study, the possibility of human body temperature elevation due to ultrasound could be confirmed and this study will be used as the basic data of ultrasonic heat absorption study.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.371-377
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• 2017

General phantom for practical X-ray photography Practical phantom is an indispensable textbook for radiology, but it is difficult for existing commercially available phantom to be equipped with various kinds of phantom because it is an expensive import. Using 3D printing technology, I would like to make the general phantom for practical X-ray photography less expensive and easier. We would like to use a skeleton model that was produced based on CT image data using a 3D printer of FDM (Fused Deposition Modeling) method as a phantom for general X-ray imaging. 3D slicer 4.7.0 program is used to convert CT DICOM image data into STL file, convert it to G-code conversion process, output it to 3D printer, and create skeleton model. The phantom of the completed phantom was photographed by X - ray and CT, and compared with actual medical images and phantoms on the market, there was a detailed difference between actual medical images and bone density, but it could be utilized as a practical phantom. 3D phonemes that can be used for general X-ray practice can be manufactured at low cost by utilizing 3D printers which are low cost and distributed and free 3D slicer program for research. According to the future diversification and research of 3D printing technology, it will be possible to apply to various fields such as health education and medical service.

• Journal of the Korean Society of Radiology
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• v.15 no.1
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• pp.21-28
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• 2021

Computed tomography (CT) has the problem of having more radiation exposure compared to other radiographic apparatus. There is a low-dose imaging technique for reducing exposure, but it has a disadvantage of increasing noise in the image. To compensate for this, various noise reduction algorithms have been developed that improve image quality while reducing the exposure dose of patients, of which the median modified Wiener filter (MMWF) algorithm that can be effectively applied to CT devices with excellent time resolution has been presented. The purpose of this study is to optimize the mask size of MMWF algorithm and to see the excellence of noise reduction of MMWF algorithm for existing algorithms. After applying the MMWF algorithm with each mask sizes set from the MASH phantom abdominal images acquired using the MATLAB program, which includes Gaussian noise added, and compared the values of root mean square error (RMSE), peak signal-to-noise ratio (PSNR), coefficient correlation (CC), and universal image quality index (UQI). The results showed that RMSE value was the lowest and PSNR, CC and UQI values were the highest in the 5 x 5 mask size. In addition, comparing Gaussian filter, median filter, Wiener filter, and MMWF with RMSE, PSNR, CC, and UQI by applying the optimized mask size. As a result, the most improved RMSE, PSNR, CC, and UQI values were showed in MMWF algorithms.

• Journal of Radiation Protection and Research
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• v.39 no.1
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• pp.1-6
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• 2014

A whole body counter (WBC) is used in nuclear power plants (NPP) to identify and measure internal radioactivity of workers who is likely to ingest or inhale radionuclides. WBC has several counting geometry, i.e. the thyroid, lung, whole body and gastrointestinal tract, considered with the location where radionuclides are deposited in the body. But only whole body geometry is used to detect internal radioactivity during whole body counting at NPPs. It is overestimated internal exposure dose because this measured values are indicated as the most conservative radioactivity values among the them of others geometry. In this study, experiments to measure radioactivity depending on the counting geometry of WBC were carried out using a WBC, a phantom, and standard radiation sources in order to improve overestimated internal exposure dose. Quantitative criteria, could be selected counting geometry according to ratio of count rates of the upper and lower detectors of the WBC, are provided through statistical analysis method.

• Journal of Radiation Protection and Research
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• v.34 no.1
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• pp.37-42
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• 2009

Whole body counters (WBCs) are used to monitor radiation workers for internal contamination of radionuclides at domestic nuclear power plants (NPPs). A WBC is a scintillation detector using sodium iodide (NaI) and provides the identification of inhaled radionuclide and the measurement of its internal radioactivity in a short time. However, it is often possible to estimate external contamination as internal contamination due to radionuclides attached to the skin of radiation workers and this leads to an excessively conservative estimation of radioactive contamination. In this study, several experiments using a WBC and the Korean humanoid phantom were performed to suggest the more systematic method of discrimination between external and internal contamination. Furthermore, a WBC geometry experiment was conducted to suggest the optimal WBC geometry in consideration of deposited areas inside the body for dominant radionuclides at NPPs. The procedure of measurement and estimation of internal radioactivity for radiation workers at NPPs was improved on the basis of experimental results. Thus, it is expected to prevent from estimating internal exposure dose conservatively owing to the application of accurate whole body counting program to NPPs.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.2
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• pp.101-108
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• 2016

Purpose : The purpose of this study was to evaluate the Retro recon in SRS planning using BranLAB when stereotactic location error occurs by metal artifact. Materials and Methods : By CT simulator, image were acquired from head phantom(CIRS, PTW, USA). To observe stereotactic location recognizing and beam hardening, CT image were approved by SRS planning system(BrainLAB, Feldkirchen, Germany). In addition, we compared acquisition image(1.25mm slice thickness) and Retro recon image(using for 2.5 mm, 5mm slice thickness). To evaluate these three images quality, the test were performed by AAPM phantom study. In patient, it was verified stereotactic location error. Results : All the location recognizing error did not occur in scanned image of phantom. AAPM phantom scan images all showed the same trend. Contrast resolution and Spatial resolution are under 6.4 mm, 1.0 mm. In case of noise and uniformity, under 11, 5 of HU were measured. In patient, the stereotactic location error was not occurred at reconstructive image. Conclusion : For BrainLAB planning, using Retro recon were corrected stereotactic error at beam hardening. Retro recon may be the preferred modality for radiation treatment planning and approving image quality.

• The Journal of Korean Society for Radiation Therapy
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• v.21 no.2
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• pp.67-74
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• 2009

Purpose: To evaluate the results of absorbed and effective doses using two different modes, standard mode (A-mode) and low-dose mode (B-mode) settings for prostate cancer IGRT from CBCT. Materials and Methods: This experimental study was obtained using Clinac iX integrated with On Board Imager (OBI) System and CBCT. CT images were obtained using a GE Light Speed scanner. Absorbed dose to organs from ICRP recommendations and effective doses to body was performed using A-mode and B-mode CBCT. Measurements were performed using a Anderson rando phantom with TLD-100 (Thermoluminescent dosimeters). TLD-100 were widely used to estimate absorbed dose and effective dose from CBCT with TLD System 4000 HAWSHAW. TLD-100 were calibrated to know sensitivity values using photon beam. The measurements were repeated three times for prostate center. Then, Evaluations of effective dose and absorbed dose were performed among the A-mode and B-mode CBCT. Results: The prostate absorbed dose from A-mode and B mode CBCT were 5.5 cGy 1.1 cGy per scan. Respectively Effective doses to body from A mode and B-mode CBCT were 19.1 mSv, 4.4 mSv per scan. Effective dose from A-mode CBCT were approximately 4 times lower than B-mode CBCT. Conclusion: We have shown that it is possible to reduce the effective dose considerably by low dose mode(B-mode) or lower mAs CBCT settings for prostate cancer IGRT. Therefore, we should try to select B-mode or low condition setting to decrease extra patient dose during the IGRT for prostate cancer as possible.

• Progress in Medical Physics
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• v.24 no.1
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• pp.48-53
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• 2013

Monte Carlo method has been known as the most accurate method for calculating absorbed dose in the human body, and an anthropomorphic phantom has been mainly used as a method of simulating internal organs for using such a calculation method. However, various efforts are made to extract data on several internal organs in the human body directly from CT DICOM files in recent Monte Carlo calculation using Geant4 code and to use by converting them into the geometry necessary for simulation. Such a function makes it possible to calculate the internal absorbed dose accurately while duplicating the actual human anatomical structure. Thus, this study calculated the absorbed dose in the human body by using Geant4 associating with DICOM files, and aimed to confirm the usefulness by compare the result with the measured dose using a Gafchromic EBT2 film. This study compared the dose calculated using simulation and the measured dose in beam central axis using the EBT2 film. The results showed that the range of difference was an average of 3.75% except for a build-up region, in which the dose rapidly changed from skin surface to the depth of maximum dose. In addition, this study made it easy to confirm the target absorbed dose by internal organ and organ through the output of the calculated value of dose by CT slice and the dose value of each voxel in each slice. Thus, the method that outputs dose value by slice and voxel through the use of CT DICOM, which is actual image data of human body, instead of the anthropomorphic phantom enables accurate dose calculations of various regions. Therefore, it is considered that it will be useful for dose calculation of radiotherapy planning system in the future. Moreover, it is applicable for currently-used several energy ranges in current use, so it is considered that it will be effectively used in order to check the radiation absorbed dose in the human body.

• Progress in Medical Physics
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• v.14 no.2
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• pp.74-80
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• 2003

The purpose of this study was to evaluate the performance of the teflon encapsulated TLD rod, which may be used in nuclear medicine for the direct in vivo measurements of radiation dose. We analyzed the influence of teflon encapsulation for measuring absorbed dose. An experiment was carried out to evaluate and observe the response of a LiF TLD-100 rod in a thin-wall teflon capsule at different depths in a solid phantom. An adult anthropomorphic phantom was used to measure the absorbed dose using thin teflon encapsulated TLD. The measurements of PDD-, and TMR in solid phantom and athe bsorbed dose in humanoid phantom performed with normal TLD were compared with values obtained by teflon encapsulated TLD. It was demonstrated that the difference of TL response of LiF in phantom with and without teflon thin-wall capsule was less than 3％ under the same conditions beyond the build-up region. However, significant differences were observed near the phantom surface because of the build-up effect caused by the thin-wall thickness of the teflon capsule. Thus, our study showed that the contribution of teflon thin-wall capsule to TLD response for the megavoltage photon beams was negligible and that it did not significantly effect dose measurement. The teflon encapsulated TLD described in this work has been proven to be appropriate for in vivo dosimetry in therapeutic environments.