Dual Source CT와 Multi Detector CT에서 Coronary 검사의 방사선량 분석

권성옥(Seong Ohk Kwon),하동윤(Dong Yoon Ha),최준호(Joon Ho Choi),이상우(Sang Woo Lee),서동수(Dong Soo Suh) 대한CT영상기술학회 2007 대한CT영상기술학회지 Vol.9 No.1

Purpose This study compared an exposure dose of DSCT with MDCT in cardiac CT and we analyzed how much the radiation dose increased or decreased. Materials and Methods For an experiment, CT device for the human body was used by 16 channel MDCT(Multi Detecter CT) manufactured by siemens and DSCT(Dual Source CT) called by SIEMENS Somatom Definition CT. It is available for supplying two source with each different kVp and mAs, processing and gathering the data at the same time. we used ECG Simulator(Marquette Electronics. USA) for examining a change of Heart Rate. An experiment method compares CTDIvol and CTDIDLP of DSCT with MDCT and is to measure. it was performed by using ECG Simulator in DSCT Coronary study, giving Heart Rate with a variety of numerical value, such as 50bpm, 55bpm, 60bpm, 65bpm, 70bpm, 75bpm, 80bpm, 85bpm, 90bpm, 95bpm, 100bpm, 105bpm, 110bpm, according to high or low of each heart rate, comparing and measuring CTDIvol and CTDIDLP, we can know whether there is some differences. Results 1. The Coronary study protocol of MDCT is 120kVp, 600mAs, Rotation time 0.37sec, Scan Time 18~20sec. CTDIvol and CTDIDLP measured each 46.80mGy, 936mGy. The Coronary study protocol of DSCT is 120kVp, 300mAs, Rotation time 0.33sec, Scan Time 8~10sec. CTDIvol and CTDIDLP measured each 47.45mGy, 427.05mGy. As a result, CTDIDLP was reduced about 55% in DSCT compared with Multi Detecter CT though CTDIvol is similar. 2. Heat rate of Coronary Study used ECG Simulator in DSCT is 50bpm, 55bpm, 60bpm, 65bpm, 70bpm, 75bpm, 80bpm, 85bpm, 90bpm, 95bpm, 100bpm, 105bpm, 110bpm. according to high or low of each heart rate, CTDIvol is measured to 60.81mGy in 50bpm and 29.llmGy in 110bpm. 3. CTDIvol and CTDIDLP of MDCT used Coronary study protocol is measured to 46.80mGy and 936mGy. measured CTDIvol of DSCT is 29.11~60.81mGy in 50bpm ~110bpm heart rate and CTDIDLP is measured to 261.99~547.29mGy. Conclusion The Dual Source CT is increased 29.9%~0.1% of CTDIvol in 50bpm ~ 110bpm compared with the Multi Detecter CT. And the CTDIvol in 70bpm ~ 110bpm was reduced by 9%~37.8. In the Single Source the Table speed came to be late as a heart rate increase. On the other hand, The Table speed of DSCT did fast according to the increase of the Heart Rate and The Scan time is reduced. When heart rate is slow, CTDIDLP of Dual Source CT is reduced by 41.6 % compared with Multi Detecter CT and When heart rate is fast, CTDim.P of Dual Source CT is reduced by 72.1% compared with Multi Detecter CT.

CT검사시 소아환자의 적정 촬영조건에 관한 연구

권성옥(Seong Ohk Kwon),하동윤(Dong Yoon Ha),이희정(Hee Jeong Lee),김선기(Seon Ki Kim),서동수(Dong Soo Suh),장동수(Dong Soo Chang) 대한CT영상기술학회 2005 대한CT영상기술학회지 Vol.7 No.1

Purpose In this study, In order to decrease of exposure rate and attain better image quality for protect pediatric patients. We investigated to find the optimal exposure factors for pediatric patients in computed tomography. Materials and methods : We performed this study to assesment exposure rates from using the pencil type Ionization chamber. We are using the 16 channel multi detector computed tomography(16-MDCT) on General Electric Lightspeed ultra 16. In this Experimental phantom made of each brain and abdomen types to 5kg, 5~10kg, 10~20kg, 20~40kg, 40~60kg, more 60kg etc(Standard of korea child growth 표). Results The results obtained were as followed : 1) Optimal Exposure factor of brain Phantom is : 100kVp~120kVp, 160mA~200mA(Weighting steps) 2) Optimal Exposure factor for Abdomen Phantom is : 80kVp~100kVp, 60mA~180mA(Weighting steps) 3) Measured Exposure rates : 10%~180%,(using the adult Exposure factor) 4) Measured Exposure rates : -30%~110%,(decease of one steps Exposure factor) 5) Abdomen Phantom Exposure rates is more than brain Phantom caused of beam hardening artifact in brain. Conclusion From the results of these studies, It is suggested that which are using the optimal exposure factor to decrease exposure rate and attain better image quality for protect pediatric patients. We are need to standard official certification in order to avoid of radiation hazard.

CT검사로 인한 방사선 피폭이 혈액에 미치는 생물학적 변화에 관한 연구

권성옥(Seong Ohk Kwon),김선기(Seun Ki Kim),김강환(Kang Hwan Kim),하동윤(Dong Yoon Ha) 대한CT영상기술학회 2009 대한CT영상기술학회지 Vol.11 No.1

Purpose For this study we collected patients blood with performing CT exam before and after at our hospital and to research about radiation dose influence of blood cell count. Materials and methods The research object was implemented dynamic liver scan patient and blood analysis was performed with blood collected at CT exam before and after. In total 46 people(35 M, 11 Fe, mean age 57; range 30~77 years), weight ranged from 45kg to 112kg; mean 64kg, radiation dose ranged from 685mGy to 2,548mGy; mean 1,615mGy. The scan were performed with GE LightSpeed Ultra 16 Plus, Siemens Somatom Sensation 16, and blood analysis equipment using coulter counter theory, and sampling were used as EDTA tube. Blood examination value was compared with WBC, RBC, Hb, platelet, neutrophil, lymphocyte etc. Results WBC was decreased up to 46% compared to other cell. RBC cell was increased in 5 people and decreased in 41 people. Hb was increased up to 23% in 39 people and decreased in 7 people. Platelet was increased up to 13% in 35 people and decreased in 40 people. Neutrophil was increased up to 18.9% in 35 people and decreased in 40 people. Finally, lymphocyte was increased up to 6.6% but decreased 10.8% in 34 people. Conclusion Althougt we did not know the decrement or increase of the blood corpuscles whether radiation dose or not patient condition, but blood corpuscles count has varied in human body after CT examination. Further validation study is needed to know effect of radiation exposure to human body, because blood corpuscles is destroyed and newly born successively, and to understand about the precise process after radiation energy absorption.

High Dose Computed Tomography검사의 Exposure Dose 측정 및 평가

김주(Joo Kim),권성옥(Seong Ohk Kwon),김기홍(Ki Hong Kim),서동수(Dong Soo Suh),최준호(Joon Ho Choi) 대한CT영상기술학회 2007 대한CT영상기술학회지 Vol.9 No.1

Purpose Charge of patient decreased on account of National Health Insurance benefit in CT examination. Scan time is reduced by generalization of spinal CT and utility of MDCT technic. Accuracy of diagnosis has improved because of up-to-date software. As a result, coefficient of utilization on CT examination increased and exposure dose is reduced by improved performance of detector and CT unit. It was necessary to use Thin slice in other to acquire a quantity of data but radiation hazard of adapted Multi-phase study increased. This Study evaluates exposure dose in CT examination. Objects and Methods CT head arteriography protocol is 20kVp, 100~300mAs, tube rotation time 0.5 or 1sec, total scan time 53sec, neck arteriography protocol is 120kVp, 150~300mAs, tube rotation time 0.5, 0.75 or 1sec, total scan time 67sec. CT OMU protocol is 120kVp, 120mAs, tube rotation time 1sec, total scan time 30sec. CT perfusion protocol is 80kVp, 200mAs, tube rotation time 1sec, total scan time 40sec. CT coronary artery protocol is 120kVp, pre : 20mAs, coronary artery : 600mAs, tube rotation time 0.5, or 0.37sec, total scan time 32sec. CT 3D intestine protocol is 120kVp, 200mAs, tube rotation time 0.5sec, total scan time 88sec. We located Ionization chamber at the center brain and abdomen acrylic and measure exposure dose. Results Exposure dose of CT head arteriography is 12.6R, exposure dose of CT neck arteriography is 23.83R, exposure dose of CT OMU is 12.6R, exposure dose of CT coronary artery is 6.15R, exposure dose of CT 3D intestine is 9.68R. We measured 5 times multi-phase study of CT neck arteriography, CT 3D intestine : 5 times, CT OMU : 2 times, CT perfusion : 2 times, CT coronary artery : 3 times Conclusion Exposure dose of CT head arteriography is 12. 6R which is maximum value and exposure dose of CT OMU is 12.6R which is minimum value. there is not only benefit but also a loss

16 MDCT장비에서 Dose Modulation Program인 CareDose와 CareDose4D의 CTDIvol값 비교

이희정(Hee Jeong Lee),권성옥(Seong Ohk Kwon),김주(Joo Kim),서동수(Dong Soo Suh),정성민(Seong Min Chung),임청환(Cheong Hwan Lim) 대한전산화단층기술학회 2005 대한CT영상기술학회지 Vol.7 No.1

Purpose The aim of this study is to apply to clinic a proper technical factor by comparing the value of CTDIvol with dose modulation program of CareDose and CareDose4D in 16 MDCT. Material & Method The value of CTDIvol of constant and variable mA(140mA) was measured in Siemens somatom sensation 16 VB10B CT. The measurement of CTDIvol of CareDose and CareDose4D was performed with technical factor variation. With ART phantom of human shape, CareDose used the Siemens somatom sensation 16 VA70C, and CareDose4D done Siemens somatom sensation 16 VB10B. Result The value of CTDIvol of constant mA and variable mA of CareDose4D was 9.8mGy to 10.92mGy, and 4.13mGy to 5.58mGy, respectively. The value of CTDIvol by kVp variation was minimum 2.53mGy, 2.335mGy at 80kVp and maximum 11.34mGy to 10.18mGy at 140 kVp in the two mode. The value of CTDIvol by table pitch variation in CareDose didn’t vary with 8.14mGy, that by pitch variation of 1, 1.2, 1.5, 2 was 7.38, 7.36, 5.94, 4.60mGy, respectively. The value of CTDIvol by slice thickness variation in CareDose also didn’t vary with 8.14mGy, but CareDose4D increased from 7.26 to 7.35mGy according to increment of thickness. When the tube rotation time was 0.5, 0.75, 1, 1.5 second, the value of CTDivol was 8.14, 8.56, 8.14, 8.21mGy in CareDose and 7.27, 7.30, 7.29, 7.38mGy in CareDose4D, respectively. The value of CTDIvol by scan type was 17.16 and 17.97mGy in CareDose and CareDose4D with sequence mode, and 22.06 and 22.65mGy with spiral mode. Conlclusion The value of CTDivol was decreased by appling CT with dose modulation program for reduction of exposed dose. The value of CTDIvol excluding scan type of technical factor was decreased more in CareDose4D than in CareDose.

CT 검사 시 촬영조건에 따른 Image Quality와 Dose에 관한 연구

유흥준(Heung Joon Yoo),권성옥(Seong Ohk Kwon) 대한CT영상기술학회 2008 대한CT영상기술학회지 Vol.10 No.1

Purpose To provide an advice on the patient dosimetry quantities without obstructing the medical purposes through the decrease in kVp and the use of Dose modulation program, Care dose 4D for tube current with patient screening by weight in CT examination. Materials and Methods Each weight group(51kg~60kg, 61kg~70kg, 71kg~80kg, 81kg~90kg) consists of 5 patients from total 20 patients with follow-up abdomen CT examination. CT values and noise according to the tube ctuTent were measured, and exposure dose and image quality were compared. Somatom Sensation 16 equipment was used for measurement. Dose modulation program, Care dose 4D was used for tube current, and tube voltage was measured using 100kVp at Pre Enhancement phase on the abdomen. Examination range was compared and analyzed by applying same FOV with the recently examined tube potential of 120kVp. Results In case of 120 kVp and 100 kVp by using Dose modulation program, Care dose 4D, CT values were decreased on the whole. However, the tendency of CT values of adjacent abdominal organs were measured similarly. 1his means that the contrast resolution is not greatly influenced by the lowered tube voltage of 100 kVp. When we measured the noise of the liver, the spleen, and the descending aorta according to the weight of the patient in the image quality measurement, as the weight of the patient decreases the noise ratio was also reduced as follows : from 0.76:1 to 0.88:1 for the liver, from 0.75:1 to 0.87:1 for the descending aorta, and from 0.73:1 to 0.85:1 for the spleen. Therefore, we can conclude that high quality image can be obtained using 100 kVp in the patient having a weight of 60 kg and the height of at least 165~175 cm. If the tube voltage was reduced from 120 kVp to 100 kVp, no tube current change was observed, and the CTDIvol value was decreased over 30%. Conclusion It would be very helpful in reducing radiation exposure to perform CT examination using optimal shooting condition according to the patient’s weight and physical constitution presented by the clinical trial results. Once the standard protocol is presented at the conference or public agency, We think that the radiation exposure of a patient can be greatly decreased by using optimal shooting condition for each hospital based on the protocol.

Noise Index 변화에 따른 환자 선량 최적화에 관한 연구

김진숙(Jin Sook Kim),이기백(Ki Baek Lee),권성옥(Seong Ohk Kwon) 대한CT영상기술학회 2016 대한CT영상기술학회지 Vol.18 No.1

목적 : 환자의 피폭선량을 감소하기 위한 목적으로 여러 기법들이 이용되고 있다. 본 연구에서는 복부 및 흉부 CT 검사 시 Noise Index 값을 상향조정 후 IR을 적용하여 환자의 선량을 최소화 하면서도 동일한 질의 영상을 얻을 수 있는지 알아보고자 하였다. 대상 및 방법 : 본원에 내원한 환자 중 GE사의 64 MDCT(Optima 660, GE Healthcare, USA, 이하 Optima660)로 흉부 및 복부 CT 검사를 시행한 환자를 대상으로 하였다. 기존 프로토콜을 적용한 환자들을 대조군으로 하였고 70kg을 기준으로 NI값을 1단계, 2단계로 나누어 적용한 프로토콜을 실험군 으로 지정하였다. 검사 환자를 각 검사 및 단계별로 35명씩 선별하여 검사 시 얻은 선량을 몸무게별 평균값으로 계산하여 비교평가 하였다. 이때 새로운 프로토콜 적용 시 ASiR 30%를 적용하였고 획득한 환자 데이터를 바탕으로 동일 ROI측정으로 얻은 HU, SD값으로 영상평가를 시행하였다. 결과 : 복부검사에서 70kg 미만 환자의 경우 선량이 12.79mGy, 10.23mGy, 8.53mGy 로 기존 프로토콜과 비교 시 각 단계별 20%, 33%의 선량 감소를 보였고 SNR값은 83.1, 98.3, 87.7 로 나타났다. 70kg 이상 환자의 경우 선량은 17.3mGy, 17.21mGy, 15.81mGy로 기존 프로토콜과 비교 시각 단계별 0.5%, 8.6%의 선량 감소를 보였고 SNR값은 78.7, 108.01, 81.8로 나타났다. 흉부검사에서 70kg 미만 환자의 경우 선량이 8.59mGy, 6.8mGy, 6.26mGy로 기존 프로토콜과 비교 시 각 단계별 20%, 27%의 선량 감소를 보였고 SNR값은 91.4, 97.1, 96.6로 나타났다. 70kg 이상 환자의 경우 선량은 12.6mGy, 12.28mGy, 11.41mGy로 기존 프로토콜과 비교 시 각 단계별 2.5%, 9.4%의 선량 감소를 보였고 SNR값은 90.3, 112.1, 100.6으로 나타났다. 결론 : 기존 프로토콜보다 70kg 기준으로 NI값을 단계별로 상향조정하여 ASiR 30%를 적용한 프로토콜 검사 시 영상의 질 저하 없이 선량감소 효과를 볼 수 있었으며 더욱 세분화된 프로토콜과 여러 선량 감소 조절인자를 이용한다면 최적화된 선량으로 높은 질의 영상을 얻을 수 있을 것으로 사료된다. Purpose : There are many techniques for reduction of patient dose from CT scan. In this study, we researched feasibility that can minimize patient dose preserving image quality by selecting Noise index according to weight of patients unlike former CT scans. Materials and method : We classified patients into 4 groups using weight and NI steps in each chest and abdomen & pelvis CT subjects. Classification standards are whether weight of patient is above 70kg or not, how many NI steps were raised(1 or 2 steps). Control group is patients whose scans were performed with routine protocols for chest and AP part. Patients of each group are 35 and their average of patient dose was compared. IR 30% was applied to experimental groups. Image quality assessments were performed in same location using ROI. CNR and SNR were used as criteria of Image quality. Result : In abdomen & pelvis CT less than 70kg, exposure dose, volume CT dose index (CTDIvol) was 12.79mGy, 10.23mGy, 8.53mGy and the variation of dose compared with routine protocol was decreased to 20% and 33%. The mean value of SNR was 83.1, 98.3, 87.7. Above 70kg, exposure dose was 17.3mGy, 17.21mGy, 15.81mGy and the variation of dose compared with routine protocol was decreased to 0.5% and 8.6%. The mean value of SNR was 78.7, 108.01, 81.8. In Chest CT less than 70kg, exposure dose was 8.59mGy, 6.8mGy, 6.26mGy and the variation of dose compared with routine protocol was decreased to 20% and 27%. The mean value of SNR was 91.4, 97.1, 96.6. Above 70kg, exposure dose was 12.6mGy, 12.28mGy, 11.41mGy and the variation of dose compared with routine protocol was decreased to 2.5% and 9.4%. The mean value of SNR was 90.3, 112.1, 100.6. Conclusion : We could have dose reduction without loss of image quality by adjusting NI and applying IR. In this reason, if we adopt more subspecialized protocols and use dose reducing techniques, we can obtain high-quality image with optimized radiation dose.