관상동맥 CT혈관조영술에서의 운동 인공물에 대한 심전도 보정에 의한 영상재구성 기법

윤재혁(Jae Hyeok Yun),김홍석(Hong Seok Kim),구양수(Yang Su Ku),조영기(Young Ki Cho) 대한전산화단층기술학회 2009 대한CT영상기술학회지 Vol.11 No.1

Purpose This study was purposed to report cases to whom an image reconstruction technique based on ECG-pulsing editing was applied for artifacts in images caused by instable breathing when the cycle of heart rate is irregular or very fast. Materials and methods An image reconstruction technique based on ECG-pulsing editing was applied to 5 patients who were sampled from those who had ECG-synchronized CT angiography since September 2007 and in whose images artifacts occurred. Results Artifacts in the images could be removed through the movement, deletion and insertion of specific intervals of heart rate by the image reconstruction technique based on ECG-pulsing editing. Conclusion The image reconstruction technique based on ECG-pulsing editing is considered greatly helpful in reconstructing optimal 3D images from images with distortion, loss or stair-step artifacts in patients showing fast or irregular heart rate.

나선형 CT와 16 Slice MDCT의 Brain과 Abdome 검사 시 산란선에 관한 연구

윤재혁(Jae hyeok Yun),류병규(Byeong gyu Ryu),이관원(Gwang won Lee),김동수(Dong su Kim),장양선(Yang seon Jang),구양수(Yang su Ku) 대한CT영상기술학회 2008 대한CT영상기술학회지 Vol.10 No.1

Purpose The present study purposed to measure the degree of scattered ray of radiation in spiral CT and 16-Slice MDCT of brain and abdomen using Rando phantom and to examine the change in non-patients’ exposure to scattered ray according to distance between the central beam and the patient and the reduction of exposure according to the thickness of a protection outfit for shielding from radiation. Materials and methods We measured the change of scattered ray on non-patients according to distance between the brain beam of CT and the patient and the change of scattered ray according to the thickness of an apron for shielding from scattered ray, assuming a critically ill patient and an infant on Somatom Plus 4 and MDCT table at the present hospital using Rando phantom under the same setting of cerebral and abdominal CT scan parameters. In order to reduce errors in measurements, each factor was measured three times and the mean value was obtained. The height of the survey meter probe was 111.5cm, which is ordinary adults’ iliac crest level. Results A. In the result of brain test with Plus 4, the reduction rate of scattered ray at a distance of 50cm according to distance from the central beam without an apron (15.5mR) and with an apron on: 1. When Pb equivalent was 2.5mm, the reduction rate of scattered ray was 91.55% at 50cm, 94.82% at 100cm, 98.64% at 150cm, and 99.38% at 200cm. 2. When Pb equivalent was 5.0mm, the reduction rate of scattered ray was 98.50% at 50cm, 99.26% at 100cm, 99.58% at 150cm, and 99.70% at 200cm. 3. When Pb equivalent was 7.5mm, the reduction rate of scattered ray was 98.87% at 50cm, 99.37% at 100cm, 99.79% at 150cm, and 99.80% at 200cm. B. In the result of brain test with 16-Slice MDCT, the reduction rate of scattered ray at a distance of 50cm according to distance from the central beam without an apron (16.47mR) and with an apron on: 1. When Pb equivalent was 2.5mm, the reduction rate of scattered ray was 95.40% at 50cm, 97.69% at 100cm, 98.84% at 150cm, and 99.33% at 200cm. 2. When Pb equivalent was 5.0mm, the reduction rate of scattered ray was 98.54% at 50cm, 99.18% at 100cm, 98.54% at 150cm, and 99.66% at 200cm. 3. When Pb equivalent was 7.5mm, the reduction rate of scattered ray was 98.10% at 50cm, 99.55% at 100cm, 99.86% at 150cm, and 99.78% at 200cm. C. In the result of abdomen test with Plus 4, the reduction rate of scattered ray at a distance of 50cm according to distance from the central beam without an apron (61.47mR) and with an apron on: 1. When Pb equivalent was 2.5mm, the reduction rate of scattered ray was 91.52% at 50cm, 97.15% at 100cm, 98.74% at 150cm, and 99.40% at 200cm. 2. When Pb equivalent was 5.0mm, the reduction rate of scattered ray was 98.48% at 50cm, 99.19% at 100cm, 99.60% at 150cm, and 99.72% at 200cm. 3. When Pb equivalent was 7.5mm, the reduction rate of scattered ray was 98.81% at 50cm, 99.49% at 100cm, 99.71% at 150cm, and 99.82% at 200cm. D. In the result of abdomen test with 16-Slice MDCT, the reduction rate of scattered ray at a distance of 50cm according to distance from the central beam without an apron (79.47mR) and with an apron on: 1. When Pb equivalent was 2.5mm, the reduction rate of scattered ray was 96.56% at 50cm, 98.64% at 100cm, 99.34% at 150cm, and 99.69% at 200cm. 2. When Pb equivalent was 5.0mm, the reduction rate of scattered ray was 98.96% at 50cm, 99.45% at 100cm, 99.72% at 150cm, and 99.85% at 200cm. 3. When Pb equivalent was 7.5mm, the reduction rate of scattered ray was 99.56% at 50cm, 99.75% at 100cm, 99.86% at 150cm, and 99.94% at 200cm. Conclusion According to the results of this study, scattered ray decreased with the increase of distance. The scattered ray shielding effect was highest when the Pb equivalent of the radiation shielding outfit was 7.5mm. However, the reduction rate of scattered ray with a radiation shielding outfit at thickness of 5.0mm was higher (+4% on the average) than that with an outfit a

두경부(Head & Neck) CT 검사 시 장기의 유효선량 측정

윤재혁(Jae-Hyeok Yun),이광원(Kwang-Weon Lee),조영기(Young-Ki Cho),최지원(Ji-Won Choi),이준일(Joon Il Lee) 대한방사선과학회(구 대한방사선기술학회) 2011 방사선기술과학 Vol.34 No.2

두경부(Head & Neck) CT(Computed Tomography)검사에서 환자가 받는 피폭선량 측정을 위하여 인체등가물질로 만든 Rando phantom과 유리선량계를 이용하여 두경부 검사에 따른 환자의 흡수선량의 변화를 실험을 통하여 연구하였다. 인체두부모형을 안와신경(optic nerve), 교뇌(pons), 소뇌(cerebellum), 갑상선(thyroid)으로 나누어, 두경부(Head & Neck) 부위의 검사를 단독검사(Brain, 3D Facial, Temporal, Brain Angiography, 3D Cervical Spine)와 복합검사(Brain+Brain Angiography, Brain+3D Facial, Brain+Temporal, Brain+3D Cervical spine, Brain+3D Facial+Temporal, Brain+3D Cervical Spin+Angiography)로 구분하여 유효선량의 변화를 실험한 후 결과를 측정하였다. 단순 Brain검사와 Brain Angio검사에는 optic nerve에 유효 선량이 높게 분석되었으며, 또한 Temporal검사에는 Pons에, 3D facial 검사와 3D Cervical Spin검사에는 thyroid의 유효선량 값이 높게 나타났다. 복합적으로 이루어는 검사 중 두경부의 Brain+Brain Angio의 검사는 cerebellum의 부위, Brain+3D facial 검사와 Brain+3D Cervical Spin의 복합검사는 thyroid의 부위, Brain+Temporal의 검사에는 pon’s 부위 유효 선량 값이 높게 나타났다. Brain +3D facial +Temporal의 복합검사와 Brain+3D Cervical Spin+Angio의 복합검사는 thyroid의 부위에 유효 선량 값이 높게 분석 되었다. 본 연구 결과 Brain+3D Cervical Spin+Brain Angio 복합검사인 경우의 유효 선량은 2.51858 mSv로 일반인의 연간 유효선량한도 1 mSv의 피폭을 초과하는 결과가 나왔다. 또한, Brain 단순 검사 시 optic nerve는 0.31312 mSv의 유효선량으로 향후 방사선학 검사가 이루어질 경우, 두경부의 일반인의 연간 유효선량을 훨씬 초과할 것이라 사료된다. 따라서 진료의 필요성에 의해서 시행되는 CT검사일지라도 질환 병변의 특성에 맞게 CT촬영조건 변화를 주면서 환자의 피폭선량을 최소한으로 할 수 있는 다양한 검사방법의 연구가 필요하다고 사료된다. In this study, we present the measurements of effective dose from CT of head & neck region. A series of dose measurements in anthropomorphic Rando phantom was conducted using a radio photoluminescent glass rod dosimeter to evaluate effective doses of organs of head and neck region from the patient. The experiments were performed with respect to four anatomic regions of head & neck: optic nerve, pons, cerebellum, and thyroid gland. The head & neck CT protocol was used in the single scan (Brain, 3D Facial, Temporal, Brain Angiography and 3D Cervical Spine) and the multiple scan (Brain+Brain Angiography, Brain+3D Facial, Brain+Temporal, Brain+3D Cervical spine, Brain+3D Facial+Temporal, Brain+3D Cervical Spine+Brain Angiography). The largest effective dose was measured at optic nerve in Brain CT and Brain Angiography. The largest effective dose was delivered to the thyroid grand in 3D faical CT and 3D cervical spine, and to the pons in Temporal CT. In multiple scans, the higher effective dose was measured in the thyroid grand in Brain+3D Facial, Brain+3D Cervical Spine, Brain+3D Facial+Temporal and Brain+3D Cervical Spine+Brain Angiography. In addition, the largest effective dose was delivered to the cerebellum in Brain CT+Brain Angiography CT and higher effective dose was delivered to the pons in Brain+Temporal CT. The results indicate that in multiple scan of Brain+3D Cervical Spine+Brain Angiography, effective dose was 2.52 mSv. This is significantly higher dose than the limitation of annual effective dose of 1 mSv. The effective dose to the optic nerve was 0.31 mSv in Brain CT, which shows a possibility of surpassing the limitation of 1 mSv by furthre examination. Therefore, special efforts should be made in clinical practice to reduce dose to the patients.