• 대한방사선기술학회지:방사선기술과학
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• 제46권6호
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• pp.509-517
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• 2023

This study analyzed imaging conditions and exposure index through clinical information collection and dose calculation programs in coronary angiography examinations. Through this, we aim to analyze the effective dose according to examination conditions and provide basic data for dose optimization. In this study, ALARA(As Low As Reasonably Achievable)-F(Fluoroscopy), a program for evaluating the radiation dose of patients and the collected clinical data, was used. First, analysis of imaging conditions and exposure index was performed based on the data of the dose report generated after coronary angiography. Second, after evaluating organ dose according to 9 imaging directions during coronary angiography, with the LAO fixed at 30°, dose evaluation was performed according to tube voltage, tube current, number of frames, focus-skin distance, and field size. Third, the effective dose for each organ was calculated according to the tissue weighting factors presented in ICRP(International Commission on Radiological Protection) recommendations. As a result, the average sum of air kerma during coronary angiography was evaluated as 234.0±112.1 mGy, the dose-area product was 25.9±13.0 Gy·cm², and the total fluoroscopy time was 2.5±2.0 min. Also, the organ dose tended to increase as the tube voltage, milliampere-second, number of frames, and irradiation range increased, whereas the organ dose decreased as the FSD increased. Therefore, medical radiation exposure to patients can be reduced by selecting the optimal tube voltage and field size during coronary angiography, maximizing the focal-skin distance, using the lowest tube current possible, and reducing the number of frames.

• Journal of Korean Neurosurgical Society
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• 제64권6호
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• pp.933-943
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• 2021

Objective : Percutaneous pedicle screw (PPS) fixation is a needle based procedure that requires fluoroscopic image guidance. Consequently, radiation exposure is inevitable for patients, surgeons, and operation room staff. We hypothesize that reducing the production of radiation emission will result in reduced radiation exposure for everyone in the operation room. Research was performed to evaluate reduction of radiation exposure by modifying imaging manner and mode of radiation source. Methods : A total of 170 patients (680 screws) who underwent fusion surgery with PPS fixation from September 2019 to March 2020 were analyzed in this study. Personal dosimeters (Polimaster Ltd.) were worn at the collar outside a lead apron to measure radiation exposure. Patients were assigned to four groups based on imaging manner of fluoroscopy and radiation modification (pulse mode with reduced dose) : continuous use without radiation modification (group 1, n=34), intermittent use without radiation modification (group 2, n=54), continuous use with radiation modification (group 3, n=26), and intermittent use with radiation modification (group 4, n=56). Post hoc Tukey Honest significant difference test was used for individual comparisons of radiation exposure/screw and fluoroscopic time/screw. Results : The average radiation exposure/screw was 71.45±45.75 µSv/screw for group 1, 18.77±11.51 µSv/screw for group 2, 19.58±7.00 µSv/screw for group 3, and 4.26±2.89 µSv/screw for group 4. By changing imaging manner from continuous multiple shot to intermittent single shot, 73.7% radiation reduction was achieved in the no radiation modification groups (groups 1, 2), and 78.2% radiation reduction was achieved in the radiation modification groups (groups 3, 4). Radiation source modification from continuous mode with standard dose to pulse mode with reduced dose resulted in 72.6% radiation reduction in continuous imaging groups (groups 1, 3) and 77.3% radiation reduction in intermittent imaging groups (groups 2, 4). The average radiation exposure/screw was reduced 94.1% by changing imaging manner and modifying radiation source from continuous imaging with standard fluoroscopy setting (group 1) to intermittent imaging with modified fluoroscopy setting (group 4). A total of 680 screws were reviewed postoperatively, and 99.3% (675) were evaluated as pedicle breach grade 0 (<2 mm). Conclusion : The average radiation exposure/screw for a spinal surgeon can be reduced 94.1% by changing imaging manner and modifying radiation source from real-time imaging with standard dose to intermittent imaging with modified dose. These modifications can be instantly applied to any procedure using fluoroscopic guidance and may reduce the overall radiation exposure of spine surgeons.

• 한국방사선학회논문지
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• 제11권6호
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• pp.423-428
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• 2017

본 연구에서는 몬테카를로 전산해석법으로 K대학교 진료영상 촬영 실습실의 방사선 조사실과 발생장치 제어실 내부 공간 유효선량률 분포 계산을 수행하였다. 방사선 발생장치는 최대 관전압 150 kVp에 최대 관 전류 700 mA이다. 전산해석 결과를 이용하여 차폐문이 닫힌 경우와 열린 경우의 진료영상 촬영 실습실의 공간선량 분포를 비교 평가하였다. 결과적으로, 차폐문이 열린 경우에도 방사선 발생장치 제어실의 유효선량률은 학생(수시출입자)의 연간 유효선량률 한도(6 mSv/y)를 초과하지 않는다는 것을 알 수 있었다. 하지만, 차폐문이 열려있을 때의 유효선량률이 차폐문이 닫힌 경우에 비해 납유리 앞에서는 약 16배, 차폐문 앞에서는 약 3,000배 더 높기 때문에 실습 중에 차폐문을 닫는 것이 불필요한 방사선 피폭을 크게 줄인다는 것을 알 수 있었다.

• 대한방사선기술학회지:방사선기술과학
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• 제38권4호
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• pp.483-489
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• 2015

현대의 의료용 방사선 발생장치는 영상을 저장하고 전송하기 위해 의료영상 표준규격으로 Digital image communications in medicine(DICOM)을 채택하고 있다. DICOM 규격에서는 피폭선량 정보 표시를 위해 DICOM dose Structured Report(DICOM dose SR)를 표준으로 제정하여 사용하고 있다. 이와 더불어 DICOM Modality Performed Procedure Step(DIOCM MPPS) 정보와 DICOM tag 정보에서도 부분적인 피폭선량 정보를 표시하고 있다. 본 연구에서는 DICOM과 관련된 피폭선량정보 표시방법에 대해 고찰하고 의료정보 시스템간의 상호연동 테스트를 위한 Integrating the Healthcare Enterprise(IHE)의 Radiation Exposure Monitoring(REM) 프로파일에 대해 살펴보았다. 의료기관에서 의료방사선피폭선량정보에 대한 품질관리를 위해서는 DICOM 정보에서 표시되는 피폭선량 정보형식에 대한 이해가 반드시 수반되어야 하고 장비도입 단계에서 관련 규격에 대한 검토가 이루어져야 한다.

• Korean Journal of Radiology
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• 제23권9호
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• pp.854-865
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• 2022

Photon-counting detector (PCD) CT is a new CT technology utilizing a direct conversion X-ray detector, where incident X-ray photon energies are directly recorded as electronical signals. The design of the photon-counting detector itself facilitates improvements in spatial resolution (via smaller detector pixel design) and iodine signal (via count weighting) while still permitting multi-energy imaging. PCD-CT can eliminate electronic noise and reduce artifacts due to the use of energy thresholds. Improved dose efficiency is important for low dose CT and pediatric imaging. The ultra-high spatial resolution of PCD-CT design permits lower dose scanning for all body regions and is particularly helpful in identifying important imaging findings in thoracic and musculoskeletal CT. Improved iodine signal may be helpful for low contrast tasks in abdominal imaging. Virtual monoenergetic images and material classification will assist with numerous diagnostic tasks in abdominal, musculoskeletal, and cardiovascular imaging. Dual-source PCD-CT permits multi-energy CT images of the heart and coronary arteries at high temporal resolution. In this special review article, we review the clinical benefits of this technology across a wide variety of radiological subspecialties.

• 전기학회논문지
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• 제58권7호
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• pp.1450-1455
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• 2009

Assumed that an IPTV camera system is to be used as an ad-hoc sensor for the surveillance and diagnostics of safety-critical equipments installed in the in-containment building of the nuclear power plant, an major problem is the presence of high dose-rate gamma irradiation fields inside the one. In order to uses an IPTV camera in such intense gamma radiation environment of the in-containment building, the radiation-weakened devices including a CCD imaging sensor, FPGA, ASIC and microprocessors are to be properly shielded from high dose-rate gamma radiation using the high-density material, lead or tungsten. But the passive elements such as mirror, lens and window, which are placed in the optical path of the CCD imaging sensor, are exposed to a high dose-rate gamma ray source directly. So, the gamma-ray irradiation characteristics of the passive elements, is needed to test. A CCD camera lens, made of glass material, have been gamma irradiated at the dose rate of 4.2 kGy/h during an hour up to a total dose of 4 kGy. The radiation induced color-center in the glass lens is observed. The degradation performance of the gamma irradiated lens is explained using an color component analysis.

• Journal of Korean Neurosurgical Society
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• 제65권5호
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• pp.633-639
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• 2022

Accurate diagnosis of trigeminal neuralgia (TN) is the starting point for optimal treatment. Gamma knife radiosurgery (GKRS) is currently regarded as one of the first-line treatment options for medically refractory TN. GKRS is a less invasive treatment with a low risk of complications than other surgical procedures that provides a favorable pain control Barrow Neurological Institute (BNI) I-IIIb rate of >75% at short-term follow-up. Drawbacks of GKRS include the latency period before pain relief and higher recurrence rate compared with microvascular decompression. Therefore, repeat treatment is necessary if the initial GKRS was effective but followed by recurrence. The concept of dose rate and the biologically effective dose of radiation has been actively studied in radiation oncology and is also applied in GKRS for TN to achieve high safety and efficacy by prescribing the optimal dose. Recent progress in functional imaging, such as diffusion tensor imaging, enables us to understand the pathophysiology of TN and predict the clinical outcome after GKRS. Here, we review TN, GKRS, and recent updates, especially in the concepts of radiation dose, diffusion tensor imaging studies, and repeat treatment in GKRS for TN.

• Radiation Oncology Journal
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• 제27권1호
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• pp.42-48
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• 2009

목적: 영상유도방사선치료(IGRT)와 호흡동조방사선치료(4DRT)의 도입은 치료계획 및 치료부위 확인에서 환자에게 방사선 조사량을 증가시킬 가능성이 있다. 따라서 IGRT/4DRT용 영상장비와 기존 장비에서 영상선량을 측정 및 비교하였다. 대상 및 방법: IGRT 및 4DRT를 위해 새로이 도입된 4DCT (GE, Ultra Light Speed 16)와 모의치료기(Varian Acuity), 그리고 치료기(Varian IX)에 장착된 kVp (OBI)의 영상장비 및 EPID (aSi 1000)를 대상으로, RANDO 팬톰의 표면 선량을 측정하여 기존의 장비들(single slice CT (GE, Light Speed), 모의치료기(Varian, Ximatron), L-gram (Varian 2100C))과 비교하였다. 측정은 열형광선량계를 이용하여 두뇌부, 눈, 갑상선, 흉부, 복부 및 골반부의 표면에서 측정하였다. 결과: 기존 CT와 비교하여 4DCT모드에서는 흉부와 복부에서 10배 이상의 선량증가를 보였다($1.74{\pm}0.34$ vs $23.23{\pm}3.67$ cGy). Acuity에서의 선량은 모든 측정부위에서 Ximatron보다 감소하였다($0.91{\pm}0.89$ vs $6.77{\pm}3.56$ cGy). EPID는 기존 L-gram 선량의 약 50% ($1.83{\pm}0.36$ vs $3.80{\pm}1.67$ cGy)였다. OBI의 투시영상선량은 $0.97{\pm}0.34$ cGy며, CBCT 선량은 $2.3{\pm}0.67$ cGy였다. 결론: 4DCT가 선량증가의 가장 큰 원인이며, OBI와 CBCT에 의한 선량은 적으나 매번 치료에 적용 시 총 선량 증가에 대한 고려가 필요하다.

• 대한디지털의료영상학회논문지
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• 제13권1호
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• pp.1-6
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• 2011

The purpose of our study was to determine the entrance surface dose and absorbed dose in ovary when using the metal speculum and plastic speculum in hysterosalpingography respectively. The examinations was performed in anthropomorphic phantom into which calibrated photoluminescence glass dosimeter were placed on symphysis pubis level surface and ovary area. We checked average fluoroscopy time and spot expose times during the hysterosalpingography. It was average fluoroscopy time 58 sec, spot expose 5 times. We divided the subjects into two different groups to used metal and plastic speculum. We measured 10 times of absorbed dose in the same condition of the anthropomorphic phantom. We compared two groups adsorbed dose on ovary with speculum material-related. The entrance surface dose on of plastic Speculum using group was average 17.23 mGy, absorbed dose on ovary was average 3.51 mGy. The entrance surface dose on ovary of metal Speculum using group was average 19.95 mGy, absorbed dose on ovary was average 4.14 mGy. Plastic speculum using group shows a decrease absorbed dose(17.9%) as compared with metal speculum using group. The method of plastic speculum using in hysterosalpingography. might provide us with lower radiation dose, especially in patients with childbearing stage.

• 대한디지털의료영상학회논문지
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• 제12권1호
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• pp.65-69
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• 2010

High energy electron beams were to concentrically dose inside a tumor and more energy is a shape decreased of dose. Therefore, it is useful to radiation therapy of a tumor. Also high energy electron beams ionized into collision with a atom in structure material of tissue and it has big changes to dose distribution by multiple scattering. The study had to establish characteristic of electron beams from interaction of electron beams and materials. Experiment method was to measure dependence of electron beam central axis for depth dose curve, field flatness and symmetry and field size dependence. The results were able to evaluate data for a datum pint of electron beam. Also radiotherapy has to be considered for not only energy pencil of lines but characteristic, electron guide and isodose curves distribution.