선량감소효과를 위한 저관전압 복부CT의 추적검사에의 적용

안수현(Su Hyeon Ahn),조인완(In Wan Cho),강성진(Seong Jin Kang),강래욱(Rae Wook Kang),유병헌(Byeong Heon Yoo),김승식(Seung Sik Kim) 대한CT영상기술학회 2006 대한CT영상기술학회지 Vol.8 No.1

Purpose To study the analyse radiation dose, CT number, contrast scale, image quality of the patient who needs periodic follow-up examination by applying abdominal CT using low tube voltage. Materials & Methods To evaluate the image quality of abdomen, radiation dose, CT number and contrast scale follows in change of tube voltage, subjects are divided into two groups. One group is the patients able to be applied in the clinical analysis and the other group vvere used phantom. Somatom Sensation 16(Siemens, Erlangen, Germany) was used. Twenty patient were selected at random in the group which was applied periodic follow-up examination by CT. In this clinical study, tube current was fixed in 150mA, tube voltage was adjusted according to appropriate value of each examinations and then we measured CTDI values. The measurement of CT number of each organs was performed by setting up a lcm diameter ROI at abdominal organs in the same height of first lumbar vertebra by using images of arterial phase. Quality of the abdominal images were graded into the 3 degrees by two radiologists in consensus. Abdominal shaped acrylic phantom was used in phantom study. Ion chamber was inserted into the holes located on the center and periphery of the phantom, and around there, then scaned, and radiation dose were automatically displayed by the reader which were 80kVp, 100kVp, 120kVp, 140kVp of tube voltage were applied to the phantom(diluted contrast medium with water 1:10 ratio), then the phantom was scanned and a 1cm diameter ROI in the center of the image was measured CT number. Results CTDI value was m decreased in 100kVp by 36%(11.70mGy vs 7.50mGy) in comparison with 120kVp. According to radiologist’ evaluation, there were 17 equivalent, 3 acceptable, 0 unacceptable in the group of 20 subjects. Radiation dose in the phantom study showed decreasing as tube voltage was lowered from 80kVp to 140kVp. Peripheral dose decreased by 38%, and central dose decreased by 41%. CT number showed 1365.9±4.4HU in 80kVp, 1046.1±3.7 in 100kVp, 862.8±3.2HU in 120kVp, 737.5±3.0 in 140kVp. Conclusion By applying the low tube voltage using abdominal CT to the patients who need periodical follow-up examination, the quality of the image is relatively high contrast scale without a lowering of image quality and we can decrease the effect of radiation dose.

경부 CT검사시 선속경화현상 감소를 위한 환자 자세 및 영상 평가

정우준(Woo Jun Jeong),신훈(Hoon Sin),오용운(Yong Woon Oh),김진배(Jin Bae Kim),조인완(In Wan Cho),구상진(Sang Jin Gu),유병헌(Byeong Heon Yoo) 대한CT영상기술학회 2009 대한CT영상기술학회지 Vol.11 No.1

Purpose The goals of this study was to examine the changes of beam hardening effect in shoulder and to evaluate the change of image quality which follows in positional change in patients with neck diseases. Materials and methods 30 patients with neck diseases were included in this study and 16-slice MDCT (Sensation 16, Siemens, Erlangen, Germany) was undergone. Positions of patients had changed with time such as neutral position with(group N), position with raising left arm (group S), and position with getting off everted both arms maximally(group P). ROI (1cm in area) located at supraclavicular fatty tissue for measuring CT noise was measured(3 times) and an average was recorded. For analysis of radiation exposure, parameters were fixed and scanned topograms of changed positions were compared with CTDIvol values measured at same position. Two investigators assessed image qualities, which were graded to unacceptable, suboptimal, adequate, good, excellent diagnostic quality. Results In CT noise, group S and group P showed 23% and 19% decrement rather than those of group N respectively. In radiation exposure, group S and group P showed 12% and 11% decrement rather than those of group N respectively. In 30 patients, image qualities of group N, group S, and group P were analyzed to unacceptable(n=0, 0, 0), suboptimal (n=0, 28, 2), adequate (n=24, 26, 3), good (N=28, 6, 22), and excellent diagnostic quality (n=8, 0, 33). Conclusion Appropriate positional change in neck CT scanning is useful method for obtaining images of improved quality and reducing beam hardening effect by shoulder.

위암의 병변부위의 입체적 정보제공을 위한 Ray-sum 기법의 활용

조인완(In Wan CHO),강성진(Sung Jin KANG),안수현(Soo Hyun AHN),유병헌(Byung Hun YOO),김승식(Seung Sik KIM) 대한CT영상기술학회 2005 대한CT영상기술학회지 Vol.7 No.1

Purpose To Provide the three dimensional image of gastric cancer for pre operation planning of extent of resection margin by Ray-sum technique. Material & Method 34 cases(male 27, female 7) of pathologically proven stomach cancer are included in this examination during Oct. 2004~Jan. 2005. All patients were fasting state during 8 hours, and N injected buscopan 20min, before examination. On the table, they ingested 2 packs of gas forming agent and took the images on the supine position. Imaging examinations were performed with Somatom Sensation 16(Siemens, Erlangen, Germany) CT scanner with 0.75mm collimation, 5mm thickness, 9mm/sec table feed and the images were reconstructed with 1mm thickness and 0.7mm increments. Then we made Ray-sum images by using Wizard (Siemens, Erlangen, Germany) with -400~-1024 threshold, 30% of penetration and 85% brightness. Finally images were analysed by radiologist without knowledge about patients as 4grades(Excellent, Good, Fair, Poor). Result Among 34 cases, early gastric cancer is 17, advanced gastric cancer is 12 and others are 5 cases. 8cases of early gastric cancer and 11 cases of advanced gastric cancer are detected on the Ray-sum images and graded Excellent is 1, Good is 2, Fair is 4 and Poor is 1 case in early gastric cancer and Excellent is 7, Good is 3, Fair is 1 and Poor is 0 case in advanced gastric cancer. As result, the sensitivity of Ray-sum images is 47% of early gastric cancer and 91.6% of advanced gastric cancer. Conclusion CT Ray-sum technique is useful tool for surgical operation plan of gastric cancer patients. And this technique maybe replaced with U.G.I

Comparative Analysis and Usefulness by Quantitative Evaluation of Deep Learning Image Reconstruction and Adaptive Statistical Iterative Reconstruction-V in Aortic Vessels CT

고창수(Chang-Su Ko),조인완(In-Wan Cho),강지원(Ji-Won Kang),정우준(Woo-Jun Jeong),송훈(Hoon Song) 대한CT영상기술학회 2021 대한CT영상기술학회지 Vol.23 No.2

기존의 ASIR-V 기법과 DLIR 기법을 이용하여 영상을 재구성한 후, 정량적 비교평가를 통한 DLIR 기법의 유용성에 대하여 확인해 보고자 한다. Phantom을 이용하여 구조적 유사지수(SSIM), 신호 대 잡음비(SNR)와 대조도 대 잡음비(CNR)을 비교분석하였다. 또한 대동맥 혈관 CT(AVCT) 검사를 진행한 환자들의 영상을 바탕으로 Phantom과 동일한 방법으로 SNR과 CNR을 비교분석 하였다. 측정된 SSIM 값은 두 기법간의 영상을 서로 비교한 평균 값에서 TF와 SSIM 값이 높게 측정 되었다. Phantom을 이용한 SNR 측정값을 토대로 한 두 기법 간의 통계적 유의성 검증 결과 모든 플러그에서 통계적으로 유의한 결과를 보였다.(p<0.05) CNR 측정값을 토대로 한 통계적 유의성 검증 결과에서는 TF-H와 ASIR-90%의 Brain 플러그에서는 통계적으로 유의한 수준을 나타내지 않았으며,(p>0.05) 그 외 다른 플러그에서는 통계적으로 유의한 결과를 보였다.(p<0.05) AVCT를 검사를 진행한 환자들의 조영 전과 조영 후 영상에서의 SNR값은 통계적으로 유의한 결과를 보였다.(p<0.05) CNR값의 통계적 유의성은 조영 전 영상에서는 하행 대동맥 측정영역에서만 통계적으로 유의한 결과를 보이지 않았으며,(p>0.05) 나머지 부위에서는 통계적으로 유의한 수준을 나타냈다.(p<0.05) 조영 후 영상에서는 모든 관심 부위에서 통계적으로 유의한 결과를 보였다.(p<0.05) DLIR 기법은 영상의학과 판독의와 임상의에게 정확한 진단을 결정하는데 많은 도움을 줄 수 있으며 AVCT검사에서 기존의 영상 재구성 기법에 비해 보다 나은 최적의 영상을 획득할 수 있는 재구성 기법으로 충분한 가치가 있다고 사료된다. We studied that how the Deep Learning Image Reconstruction(DLIR) technique was useful through comparative evaluation after reconstructing the images by conventional ASIR-V technique and DLIR technique. We measured SSIM with PBU-60 Phantom and compared SNR and CNR by the each tissue equivalent material, using Tomotherapy Cheese Phantom. Also SNR and CNR were compared in the same way with phantoms, using the patients’ aortic vessels CT images. As a result of comparing average of SSIM from the images reconstructed by ASIR-V technique and True-Fidelity(TF) images which were reconstructed by DLIR, the average of SSIM from TF was higher than the average of SSIM from ASIR-V. In the using Phantom the result that based on SNR between two techniques had statistical significance.(p<0.05) The result that based on CNR was significant statistically in all the plugs except for the case of CNR from TF-H and ASIR 90% at the plug of brain. SNR result, there was statistical significance between the two techniques(p<0.05) in both cases of pre and post enhanced AVCT images from the patients. At the pre-enhanced images, CNR from every part had significant result statistically except for the part of descending aorta from TF-H and ASIR-90%. However, there was statistical significance in the post-enhanced images of every ROI.(p<0.05) DLIR technique help the radiologist and the clinicians diagnose the diseases accurately. Compared to the conventional technique reconstructing the images in AVCT, it would be good enough to get much more high-quality images.

저관전압 흉부 CT검사 시 CT value의 변화에 따른 영상평가

김현주(Hyun Joo Kim),송훈(Hoon Song),조인완(In Wan Cho),안수현(Su Hyeon Ahn),신훈(Hoon Shin),유병헌(Byeong Heon Yoo),김승식(Seung Sik Kim) 대한CT영상기술학회 2007 대한CT영상기술학회지 Vol.9 No.1

Purpose Experiments carried out on the patients who visited this department for pulmonary disease and need CT scans for Follow-up to observe change of CT value, evaluation of image quality and decrease of radiation dose as change of tube voltage Materials and Methods Subjects were the patients of 20 persons visited this department for pulmonary disease and Somatom Sensation 16(Siemens, Erlangen, Germany) was used. Measurement of CT value as change cf tube voltage was done by setting up ROI diameter of 1cm at the height of thyroid, aortic arch, right pulmonary artery in arterial phase image using 100OkVp, measuring 3 times, and recorded the average. CT value of phantom was measured by scanning phantoms which means contrast media diluted by normal saline by various ratio with tube voltage of 80kVp, 100kVp, 120kVp, 140kVp and recorded the average of 3 CT values of center of phantom image. In analysing radiation dose, CTDIvol. values of the latest arterial phase image of 120kVp and as this research set that of 100kVp were analyzed comparatively. 2 observers graded quality of chest images by 5 degrees (UnaccepTable, Suboptimal, Adequate, Good, Excellent diagnostic quality). Results CT value of chest image increased at 100kVp by 14.06%~27.26% in each ROI than 120kVp. CT value of phantom increased as tube voltage lowered at various concentration of contrast media. CTDIbol. decreased at 100kVp(5.00mGy) by 36% than 120kVp(7.80mGy) in radiation dose analysis. here were 0 UnaccepTable, 1 Suboptimal, 3 Adequate, 10 Good, 6 Excellent diagnostic quality in totally 20 persons. Conclusion Chest CT scanning with low kilo-voltage for patients who need CT scan repeatedly can bring images valuable for diagnose, and decrease radiation dose against patients.

심혈관 CT 검사 시 적응식 통계적 반복 재구성법(ASIR)에 대한 유용성

장현철(Hyun Chul Jang),조용근(Yong Geun Cho),오용운(Yong Woon OH),김진배(Jin Bae Kim),조인완(In Wan Cho),구상진(Sang Jin Gu),유병헌(Byeong Heon Yoo) 대한CT영상기술학회 2010 대한CT영상기술학회지 Vol.12 No.2

Purpose The goals of this study was to evaluate effect of reduced radiation dose, change of CT noise, and proper amount of ASIR under assessing image quality with different ASIR amounts during cardiovascular CT examinations. Materials and methods 15 patients who had undergone routine cardiac CT for evaluation of bean problem were enrolled and all examinations were performed on a 64-MDCT scanner (Light-Speed VCT XTe, GE Healthcare, Milwaukee, USA). The GE performance evaluation phantom was scanned triple and noise were measured at center(directions of 6 o’clock) and periphery (directions of 9, 12, 3 o’clock) of phantom image under fixed 100 kVp and during changing of ASIR 0~100%. The two radiologists estimated me subjective image qualities of right coronary artery(RCA), left circumflex artery(LCX), left anterior descending artery(LAD) in reconstructed four chamber images. To assess radiation dose, CTDIvols recorded from applied ASIR man non-applied ASIR were compared and analyzed. Results In applied ASIR to image in 10 % increments (0~100%), CT noise of center(directions of 6 o’clock) and periphery(directions of 9, 12, 3 o’clock) of phantom decreased in 9.7%~49.5%, 9.8%~52.1%, 9.6%~48.9%, 9.7%~51.1%. Observer A and B estimated image quality respectively as follows: 15 and 15 patients until 60% ASIR, 13 and 13 patients until 70% ASIR, 12 and 8 patients until 80% ASIR, 8 and 6 patients until 90% ASIR, 7 and 6 patients at 100% ASIR In assessing radiation dose, CIDIvol recorded from 60% ASIR decreased in 46.9% (21.11 mGy) than non-applied ASIR(39.73 mGy) Conclusion 60% ASIR helps reduce radiation dose and acquire consistent image quality without spoiling quality.

CT Mammography검사 시 자세변화에 따른 영상평가 및 적정선량에 관한 연구

송훈(Hoon Song),김현주(Hyeon Ju Kim),신훈(Hoon Shin),조인완(In Wan Cho),오용운(Yong Woon OH),유병헌(Byeong Heon Yoo),김승식(Seung Sik Kim) 대한CT영상기술학회 2008 대한CT영상기술학회지 Vol.10 No.1

Purpose The subject of this study is female breast cancer patient who had. CT mammography before and after surgery. The study covers effects on exposure dose and image quality by change of exposure condition are observed, and makes comparative, analytic study of difference between a breast image taken with supine position and the other one with prone position. Materials & Methods Qualities of supine position image were compared with those of prone position image and difference between two of the images were analyzed with change of kVp and mAs by 3grades(Equivalent, Acceptable, Unacceptable). A special equipment was used for prone position image so as to breast of the subjects don’t be squeezed. CTDIvol was recorded scanning by 120kVp/100mAs during usual scanning and 100kVp/70mAs for this study. 20 female breast cancer patients were subjects, and Somatom Sensation16(Siemens, Erlagen, Germany) was used by 2 observers in this study. Two studies were conducted on phantom. First, ion chambers were put into holes around and center of a phantom, and exposure dose on reader was recorded after scanning the phantom with change of kVp and mAs. Second, CTDIvol that was changing by exposed area differ by position of the breast phantom was measured with change of kVp and mAs, Results According to the 20 scanned images based on change of position and image quality, It gives 1 case on Equivalent, 19 cases on Acceptable and 0 case on Unacceptable. CTDIvol is measured as 7.8mGy at 120kVp/100mAs and 3.5mGy at 100kVp/70mAs. but there was no relation with position. Surface dose decreased by mean 59% and deep dose decreased by 63% at 100kVp/70mAs compared at 120kVp/100mAs in phantom study while dose is measured as 1.11mGy at 100kVp/70mAs with straighten up position for maximum exposed area which is reduced by 10% compared with a lateral position in the same condition. Conclusion It’s impossible for exposure dose to be less than a certain value in order to satisfy a proper condition, 100kVpn/70mAs, at which the image quality is not effected. In this study, it results that prone position makes fine image especially for diagnosing patients before surgery rather than supine position does. consequently, this study shows that prone position have decisive role for the accurate examination of breast cancer