• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.53-59
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• 2011

Purpose: To evaluate the dosimetry and image of very low does CT attenuation correction for phantom using pediatric PET/CT. Materials and methods: three PET / CT scanners (Discovery STe, BiographTruepoint 40, Discovery 600) as a child-size acrylic phantom and ion chamber dosimeter (Unfous Xi CT, Sweden) using a CT image acquisition parameters (10, 20, 40, 80, 100, 160 mA; 80, 100, 120, 140 kVp) by varying the depth dose and evaluate $CTDI_{vol}$ value. And each attenuation corrected PET/CT images used NEMA PET Phantom$^{TM}$ (NU2-1994) was evaluated by SUV. Results: Abdominal diagnosis CT dose in general pediatric (about 10 ages) parameter (100 kVp, 100 mA) than very low dose CT parameter (80 kVp, 10 mA) at the depth dose was reduced approximately 92%, $CTDI_{vol}$ was reduced to about 88%. Each CT attenuation corrected parameters PET images showed no change in the value of SUV. Conclusion: for pediatric patients, PET/CT scan can be obtained with very low dose attenuation correction CT (80 kVp, 10 mA), and such attenuation correction CT dose was reduced 100 fold than diagnosis CT dose. PET / CT scan used very low dose CT attenuation correction in pediatric patients can be helpful in reducing radiation dose.

• Journal of radiological science and technology
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• v.40 no.3
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• pp.355-361
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• 2017

Pediatrics are more sensibility to radiation than adults and because they are organs that are not completely grown, they have a life expectancy that can be adversely affected by exposure. Therefore, the management of exposure dose is more important than the case of adult. The purpose of this study was to determine the suitability of the 10 year old phantom for the 5 year old pediatric's recommendation and the incident surface dose, and to measure the organ absorbed dose. This study is compared the organ absorbed dose and the entrance surface dose in the clinical conditions at 5 and 10 years old pediatric. Clinical 5 year old condition was slightly higher than recommendation condition and 10 year old condition was very high. In addition, recommendation condition ESD was found to be 43% higher than the ESD of the 5 year old group and the ESD of the 10 year old group was 126% higher than that of the 5 year old group. The recommended ESD at 5 years old and the ESD according to clinical imaging conditions were 31.6%. There was no significant difference between the 5 year old recommended exposure conditions and the organ absorbed dose due to clinical exposure conditions, but there was a large difference between the Chest and Pelvic. However, it was found that there was a remarkable difference when comparing the organ absorbed dose by 10 year clinical exposure conditions. Therefore, more detailed standard exposure dose for the recommended dose of pediatric should be studied.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.285-295
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• 2023

With the development of technology, efforts to reduce the exposure dose received by patients in CT scans are continuing with the development of new reconstruction techniques. Recently, deep learning reconstruction techniques have been developed to overcome the limitations of repetitive reconstruction techniques. This study aims to evaluate the usefulness of images according to reconstruction techniques in pediatric chest CT images. Patient study conducted a study on 85 pediatric patients who underwent chest CT scan at P-Hospital in Gyeongsangnam-do from January 1, 2021 to December 31, 2022. The phantom used in the Phantom Study is the Pediatrics Whole Body Phantom PBU-70. After the test, the images were reconstructed with FBP, ASIR-V (50%) and DLIR (TF-Medium, High), and the images were evaluated by obtaining SNR and CNR values by setting ROI of the same size. As a result, TF-H of deep learning reconstruction techniques had the lowest noise value compared to ASIR-V (50%) and TF-M in all experiments, and SNR and CNR had the highest values. In pediatric chest CT scans, TF images with deep learning reconstruction techniques were less noisy than ASiR-V images with adaptive statistical iterative reconstruction techniques, CNR and SNR were higher, and the quality of images was improved compared to conventional reconstruction techniques.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.931-936
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• 2020

This study was conducted to observe the changes in radiation exposure dose and image quality of pediatric patients according to the presence and size of the gonadal shield when using the AEC system. X-ray equipment was used to measure the radiation exposure dose in the abdominal and gonads of the pediatric phantom when no shielding body was used and when three different sizes of shielding body were used, and SNR and CNR were measured through the obtained images. As a result of the study, the radiation exposure dose to the gonads decreased in proportion to the size of the radiation shield, but the radiation exposure dose to the abdomen was rather increased, and the image quality did not change. It is recommended to use a shield with a size optimized for the age, weight, and body size of the pediatric patient so as not to be overexposed by the increased radiation due to the radiation shield due to the use of the AEC System. For this purpose, information about the pediatric patient with the nurse It is believed that exchange is necessary.

• Journal of Radiation Protection and Research
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• v.27 no.3
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• pp.155-164
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• 2002

Methodology to evaluate the effective doses to adults undergoing various diagnostic x-ray examinations were established by Monte Carlo simulation of the x-ray examinations. Anthropomorphic mathematical phantoms, the MIRD5 male phantom and the ORNL female phantom, were used as the target body and x-ray spectra were produced by the x-ray spectrum generation code SPEC78. The computational procedure was validated by comparing the resulting doses to the results of NRPB studies for the same diagnostic procedures. The effective doses as well as the organ doses due to chest, abdomen, head and spine examinations were calculated for x-rays incident from AP, PA, LLAT and RLAT directions. For instance, the effective doses from the most common procedures, chest PA and abdomen AP, were 0.029 mSv and 0.44 mSv, respectively. The fact that the effective dose from PA chest x-ray is far lower than the traditional value of 0.3 mSv(or 30 mrem), which results partly from the advances of technology in diagnostic radiology and partly from the differences in the dose concept employed, emphasizes necessities of intensive assessment of the patient doses in wide ranges of medical exposures. The methodology and tools established in this study can easily be applied to dose assessments for other radiology procedures; dose from CT examinations, dose to the fetus due to examinations of pregnant women, dose from pediatric radiology.

• Proceedings of the Korea Contents Association Conference
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• 2017.05a
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• pp.107-108
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• 2017

3차원 위상대조도 기법의 단점인 긴 검사시간으로 인해 임상적 유용성이 떨어진다. 본 논문은 시간매개변수인 병렬영상기법(Grappa) 변경에 따른 혈류정보의 정량적 평가를 통해 차이점을 알아보고 임상적 활용정도를 평가하였다. 자체 제작한 혈류팬텀을 통해 실험하였으며, Grappa을 5번 변경하여 실험하였다. 연구결과, Grappa를 적용하지 않았을 경우 혈류속도는 평균 9.42로 총 4단계를 적용한 혈류속도 차이율은 각각(1.4, 1.5, 0.4, 1.5%)이었으며 flow와 WSS도 각각(1.4, 1.6, 0.8, 25%), (2.1, 1.4, 1.1, 0.8%)이었다. 통계적으로도 유의하지 않아 Grappa를 적용하지 않은 검사법과 혈류정보가 동일하였다.(P>0.05) 긴 검사 시간으로 인해 임상적 활용이 떨어지는 짧은 검사시간을 요하는 소아환자나 중등도 환자 또는 폐쇄공포증 환자에게 시간을 단축한 3차원 위상대조도 기법을 사용하여 단점을 보완한다면 임상적 활용가치가 높아질 것이라 사료된다.

• Journal of radiological science and technology
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• v.39 no.3
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• pp.407-414
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• 2016

This study is to minimize the patient dose and maintain the image quality according to change of source to image receptor distance and applying additional filter. In this study, we used the DR system, the tissue-equivalent abdomen phantom and the aluminium filter. The exposure conditions were set to 80 kVp using AEC mode. The collimation size was $16{\times}16inch$. The exposure dose were measured 10 times when the SID was changed with 100, 110, 120 and 130 cm, respectively. The pirana 657 for dosimeter was located on center of radiation irradiation. The acquired images were analyzed by using the image J. In the results, the tube current was increased with increasing the SID but ESD was decreased with increasing the SID. The decrease of ESD attribute to use of filter that remove the photon of lower energy. In the histogram results using image J, there were differences between the ESD and the exposure conditions according to change of SID. However, there were not differences in histogram. Therefore, the exposure dose could reduced when set the longer SID. For pediatric exam, the exposure dose could reduced when used the aluminium filter.

• Journal of radiological science and technology
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• v.42 no.4
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• pp.271-277
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• 2019

CareDose 4D which is the Siemens's Automatic Exposure Control (AEC) can adjust the level of radiation dose distribution which is based on organ characteristic unlike other manufacturer's AEC. Currently, a wide scan range containing different organs is sometimes examined at once (defined as one scan). The purpose of this study was to figure out which organ characteristic option is suitable when one scan method is utilized. Two types of anthropomorphic phantoms were scanned in the same range which were from frontal bone to carina level according to three different organ characteristics such as Thorax, Abdomen, and Neck. All scans and image reconstruction parameters were equally applied and radiation dose were compared. Radiation dose with Thorax organ characteristic was lower than that with Neck. Also, that with Abdomen oran characteristic was lower than Thorax. There were significant differences in radiation dose according to different organ characteristics at the same parameters (P<0.05). Usage of Neck organ characteristic had a result of the highest radiation dose to all phantom. On the other hand, utilization of Abdomen organ characteristic showed the lowest radiation dose. As a result, it is desirable to set appropriate organ characteristic according to examined body part when you checkup patients. Also, when you implement one scan method, selection of Abdomen-based organ characteristic has reduced more radiation dose compared with two different organ characteristic.

• The Journal of the Korea Contents Association
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• v.19 no.8
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• pp.284-292
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• 2019

To evaluate the usefulness of pediatric chest CT scans by comparing the dose, examination time, and image quality by applying Helical mode, High-pitch mode, and Volume Axial mode to minimize the radiation exposure and obtain high diagnostic value. Revolution (GE Healthcare, Wisconsin USA) was used to divide PBU-70 phantom into Helical mode, High-pitch mode, and Volume Axial mode. After acquiring images, ROI is set for each image, heart, bone, lung, and back-ground air, and the average value is obtained by measuring CT number (HU) and noise (SD). SNR and CNR were measured and compared with DLP values provided directly by the equipment. Determining statistical significance Statistical analysis was performed using ONE-WAY-ANAOVA using SPSS 21.0. In this experiment, it was possible to inspect at a short time without deterioration of image quality with the lowest dose when using volume axial mode. Although the detector coverage of 16 cm is limited to all pediatric chest CT scans, it is recommended to be actively used in pediatric patients, and further study is needed to apply other test sites in volume axial mode.

• Progress in Medical Physics
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• v.22 no.4
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• pp.163-171
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• 2011

The purpose of this study was to investigate the effect of various technical parameters for the dose optimization in pediatric chest radiological examinations by evaluating effective dose and effective detective quantum efficiency (eDQE) including the scatter radiation from the object, the blur caused by the focal spot, geometric magnification and detector characteristics. For the tube voltages ranging from 40 to 90 kVp in 10 kVp increments at the FDD of 100, 110, 120, 150, 180 cm, the eDQE was evaluated at the same effective dose. The results showed that the eDQE was largest at 60 kVp when compares the eDQE at different tube voltage. Especially, the eDQE was considerably higher without the use of an anti-scatter grid on equivalent effective dose. This indicates that the reducing the scatter radiation did not compensate for the loss of absorbed effective photons in the grid. When the grid is not used the eDQE increased with increasing FDD because of the greater effective modulation transfer function (eMTF). However, most of major hospitals in Korea employed a short FDD of 100 cm with an anti-scatter grid for the chest radiological examination of a 15 month old infant. As a result, the entrance surface air kerma (ESAK) values for the hospitals of this survey exceeded the Korean DRL (diagnostic reference level) of $100{\mu}Gy$. Therefore, appropriate technical parameters should be established to perform pediatric chest examinations on children of different ages. The results of this study may serve as a baseline to establish detailed reference level of pediatric dose for different ages.