Coronary CT 검사시 SFOV 변화에 따른 환자선량 평가

남윤철(Yoon Chul Nam),김부환(Boo Hwan Kim),이민영(Min Young Lee),신설경(Seol Kyung Shin),김문찬(Moon Chan Kim),한동균(Dong Kyoon Han) 대한CT영상기술학회 2007 대한CT영상기술학회지 Vol.9 No.1

Purpose The radiation dose in coronary study is high compared with other CT examination. Patient dose in CT is usually expressed in terms of the organ dose and effective dose. The purpose of this study is to evaluate patient organ dose and effective dose vary with scan fiend of view in coronary CT examination. Materials and Methods Organ dose was actually measured by using anthropomorphic phantom and Rapido-Photo-Luminescent(RPL) Glass. Effective dose measured by using ion chamber system. Results The survey on a patient dose showed that the organ dose was 98mGy in the heart part and 93mGy in the Lt. lung part and 63mGy in the Rt. lung part and 98mGy in the Lt. breast part and 75mGy in the Rt. breast part. Effective dose was 16.1mSv. Organ dose was decreased from 32.3% to 40.9% in used SS, S, M(SFOV) examination, compared to used L, LL(SFOV) examination. Effective dose was decreased 39.5% in used SS, S, M(SFOV) examination, compared to used L, LL(SFOV) examination. Conclusion As a conclusion, the radiation dose was very high dose in coronary study. Future research should be directed to identify the least amount of radiation required in CT scans to ensure that diagnostic performance is not significantly compromised.

TLD법과 Monte Carlo Simulation에 의한 CT Organ Dose의 비교

남윤철(Yoon Chul Nam),조원홍(Won Hong Cho),김문찬(Moon Chan Kim),한동균(Dong Kyoon Han) 대한CT영상기술학회 2006 대한CT영상기술학회지 Vol.8 No.1

The TLD method, which is used in measuring organ dose in computed tomography, needs high-priced equipments and much time. On the other hand, Monte Carlo simulation makes it possible to measure organ dose with comparative ease. However, the problem is that it is doubtful whether the result estimated by the simulation is trusty. For this reason, the organ dose outputted from Monte Carlo simulation was compared with that of TLD method under the same condition. The organ dose actually measured by TLD method was compared under the condition samewith the organ dose outputted from Monte Carlo simulation, from two aspects. First, the organ dose of the lungs was measured under 4 slice MDCT, 8 slice MDCT and 16 slice MDCT, respectively, concerning the computed tomography on chest in order to compare the two organ doses as to the type of equipment. Second, the organ dose of liver was measured by varying beam collimation and beam pitch, concerning the computed tomography on abdomen under 16 slice MDCT so as to compare the organ dose outputted by various scan parameters. As the result, Monte Carlo simulation was lower between 16 and 18 percent than TLD method, in the organ dose of the lungs concerning the CT on chest. Likewise, the result of Monte Carlo simulation was lower between 34 and 38 percent than that of TLD method, under various conditions of scan parameter.

Spiral CT에서 Interpolation이 선량증가에 미치는 영향에 관한 연구

이대규(Dae kyoo Lee),남윤철(Yoon Chul Nam),김문찬(Moon Chan Kim),한동균(Dong Kyoon Han) 대한CT영상기술학회 2008 대한CT영상기술학회지 Vol.10 No.1

The purpose of this study is to recognize how much dose and scan length increased by interpolation in spiral scan and to understand about correlation with factors such as beam collimation and pitch. We measured dose and scan length changing pitch and beam collimation using the GE company equipments.

Urography검사 시 Dual Energy의 사용에 대한 유용성에 관한 연구

윤동민(Dong Min Yoon),김완욱(Wan Yuk Kim),남윤철(Yoon Chul Nam),김문찬(Moon Chan Kim) 대한CT영상기술학회 2011 대한CT영상기술학회지 Vol.13 No.1

Ⅰ. Purpose To evaluate the use of virtual non-contrast image(virtual nonenhanced image, VNC) replacing pre contrast image of Single Energy(S/E) by comparing Dual Energy(D/E) urography with single energy urography and to study the effects of dose reduction by this method. Ⅱ. Materials and Methods For evaluation the image quality of VNC and pre image, 50 patients images that underwent urography CT by Siemens Dual Source SOMATOM Definition Flash were used and for image evaluation, imagestransferred to the GE PACS were used. CT number and SNR of VNC and pre image measured at same location(L2 level) were compared and dose were measured by PLD at liver rt. lobe, lt. kidney, rt. kidney, aorta, L-spine body, anterior fat. To compare radiation dose of D/E and S/E, Female Alderson Radiation Therapy Phantom and optical glass dosimeter were used. For dosimetry, D/E methods and D/E method with exception of pre image, S/E method were used. Optical glass dosimeterwere located at rt. lobe of liver of L2level and both kidneys and dose were measured and compared. Ⅲ. Results In comparison of VNC and pre image, two images showed large differences at the spine. The CT number of pre image of spine that less affected by contrast effect was 65.91±16.8 higher than those of VNC. At abdominal main organs, CT number of VNC for rt. liver, rt. kidney, lt. kidney and aorta were found to be 15.01±2.8, 9.25±2.0, 13.61±2.3 and 2.36±1.1 higher than those of the pre image, so no significant differences were observed. The SNR of pre image at L-spine body(L2 level) was 1.16±1.2 higher than those of VNC. At abdominal main organs, SNR of VNC for rt. liver, rt. kidney, lt. kidney and aorta were found to be 2.43±1.5, 0.86±0.5, 0.88±0.5 and 0.48±0.3 higher than those of the pre image, so no significant differences were observed. In comparison of dose, by D/E method without pre image, mean value of dose of rt. liver, rt. kidney and lt kidney were 13.61, 12.00 and 12.00 mGy and were 33%, 35% and 32% lower than D/E method, and 21%, 23% and 25% lower than S/E method. The total DLP of D/E method without pre image(484 mGy) was 30% lower than D/E(687 mGy), 24% lower than S/E(636 mGy). Ⅳ. Conclusion By using the D/E for urography, pre image can be replaced by VNC and more information can be offered than the existing S/E method with dose reduction effect. 목 적 Dual energy(이하 D/E)를 이용한 urography 검사 시 기존 single energy(이하 S/E)의 pre contrast를 이용한 검사와 비교하여, pre contrast image를 대체하는 가상의 비 조영 영상(virtual non-contrast image, virtual nonenhanced image, 이하 VNC)의 사용에 대해 평가하고 이를 통한 선량감소의 효과에 대해 연구해보고자 한다. 대상 및 방법 VNC와 pre image의 영상평가를 위해 Siemens사의 Dual Source SOMATOM Definition Flash를 사용하여 urography를 검사한 50명의 영상을 이용하였으며, 영상 평가는 GE PACS에 전송된 영상을 사용하였다. VNC와 pre image의 동일한 위치에서 CT number와 SNR을 측정하여 비교하였고, 간 우엽과 좌측 신장, 우측 신장, 대동맥, L-spine body, anterior fat에서 측정하였다. D/E의 선량 비교를 위해 Female Alderson Radiation Therapy Phantom과 광학 유리 선량계를 사용하였다. 선량측정은 D/E를 이용한 방법과 D/E에서 pre image를 제외한 방법, S/E를 이용한 방법을 사용하였고 L1 위치의 간 우엽과 양측 신장에 유리 선량계를 위치하여 선량을 측정, 비교하였다. 결 과 VNC와 pre image의 영상평가에서 CT number는 조영 효과의 영향을 비교적 덜 받는 spine에서 pre image가 65.91±16.8 높게 나타나 두 영상이 큰 차이를 나타냈다. 복부의 주요장기에서 VNC가 각각, 간 우엽의 실질조직에서 15.01±2.8, 우측 신장에서 9.25±2.0, 좌측 신장에서는 13.61±2.3 높게 나타나 유의한 차이가 없었으며 조영제의 영향을 가장 많이 받는 혈관부위인 대동맥에서는 2.36±1.1 높게 나타나 유의한 차이가 없었다. SNR은 L-spine body에서만 pre image가 1.16±1.2 높았다. 복부의 주요장기에서 VNC가 각각, 간 우엽의 실질조직에서 2.43±1.5, 우측 신장에서 0.86±0.5, 좌측 신장에서 0.88±0.5 높게 나타나 유의한 차이가 없었으며 대동맥에서 0.48±0.3 높게 나타나 유의한 차이가 없었다. 선량의 비교 시 pre image를 제외한 D/E를 사용한 방법에서 간 우엽 실질조직의 평균값은 13.61 mGy, 우측 신장의 평균값은 12.00 mGy, 좌측 신장의 평균값은 12.00 mGy로 각각 D/E보다 33%, 35%, 32% 감소하였으며 S/E보다 21%, 23%, 25%의 선량감소를 나타내었다. 총 DLP는 pre를 제외한 D/E를 사용한 방법에서 484 mGy로 D/E검사 시 687 mGy 보다 30%, S/E 검사 시 636 mGy 보다 24%의 선량감소효과를 나타내었다. 결 론 Urography 검사 시 D/E를 사용하면 pre image에 대체할 수 있는 VNC를 만들 수 있고, 기존 S/E를 사용한 검사에 비해 더 많은 정보를 제공하면서 선량 감소를 가져올 수 있다.

Coronary CT Angiography에서 Cardio ImageXact

김부환(Boo Hwan Kim),남윤철(Yoon Chul Nam),박건진(Kun Jin Park),김완역(Wan Yuk Kim),김문찬(Moon Chan Kim) 대한CT영상기술학회 2008 대한CT영상기술학회지 Vol.10 No.1

Purpose This research is that evaluate quality of reconstruction by Heart rate change in coronary arteries building CT examination about coronary artery disease patient who is being on the increase gradually and improve quality of reconstruction by searching for Cardiac reconstruction phase of most suitable in Heart rate that do using Cardio ImageXact that is TOSHIBA company’ s software. Materials and Methods From May, 2006 to July, 2007, Coronary CT Angiography did to 43 outpatients who examine and patient who undergo Coronary Artery Bypass Graft(CABG) surgical operation excepted. Patient does NPO during before examination and vital(BP, Heart rate) check and do 1/2T and carry on the head Metoprolol in case Heart rate more than 65, and in case is more than 75, effect conducted examination after 1 hour that is time that become maximum efficiency after did to take 1T(100mg). Reconstructed data using Cardio ImageXact that is TOSHIBA raw data reconstruction software by Auto(Best)phase, % method, ms(milli-second) method cardiac reconstruction raw data. Analysis method use Cardio ImageXact software acquires data as much as 0~99% to 1% space and 10ms space and R-R interval space to 10ms space in section of 2 level(aortic valve, mitral valve level)in raw data after examination and quality selects the best cardiac phase and acquire volume data in 3 method. Corona1y artery’ s quality in 3 cardiac recon mode analyzed comparison. Results Compared point through vessel analysis of target patient total 43 people on above 3 mode to use TOSHIBA company’ s cardiac phase recon software. 1. When Heart rate is 50~59 Average point becomes difference in segment No.2 and No.3, No.6, No.7 in 3 recon mode and difference did not become in other segment. 2. When Heart rate is 60~69 Could know that could acquire good image seeing that ms method acquires near point in 1 point in segment excepting segment No.10. 3. When Heart rate is 70~79 It is seldom difference of m.5 mode with % mode in each segment different 3 recon mode, showed near differentia in 1 point more with Auto(Best)phase mode, and % mode and ms mode could know that difference of average point is not great quality difference of image after recon in 0.1 point interior and exterior. 4. When Heart rate is over 80 Each segment different 3 recon mode could know in segment excepting segment No.9 that ms mode could get better image showing near point 1 point than Auto(Best) mode with % mode. Each segment different acquired point could make image that ms mode is better receiving near point in head of a family 1 point in Auto(Best) mode and % mode, ms mode to be 3 recon mode in each heart rate different each segment and % mode was some difference than ms mode, but did not show large difference. However, Auto(Best)recon mode to acquire good image missing near point in 1 point than above 2 mode difficulty know can. Also, Heart rate 3 recon mode did not show difference greatly in 50~59 but Heart rate is higher more than 60~69, 70~79, 80 difference of point that acquire could appear greatly and know qualitative difference of image. Conclusion By Auto(Best) and % mode or ms mode strongly in Heart rate that do stable very cardiac phase image that may not do reconstruction get. But, 75% and 45% cardiac phase are thought that this research is value more to supplement this to could not have gotten good image, and could not have good image in Auto(Best)phase usually in heart rate’ s case that do unstable. Reduce patient’ s re-procedure having gotten good image through this research, and expect to give large help diagnostic and treatment of heart vessel disease by supplying correct diagnostic information.

두개부와 흉부 CT 검사시 Bismuth 차폐재를 이용한 안구의 렌즈와 유방의 선량감소에 대한 평가

변정인(Jung in Byun),남윤철(Yoon chul Nam),이홍(Hong Lee),신상보(Sang bo Shin),한동균(Dong kyoon Han) 대한CT영상기술학회 2008 대한CT영상기술학회지 Vol.10 No.1

Purpose Bismuth shield can filter twice in that penetrates X-ray, which is essential in diagnosis, and it also partially decreases skin dose. Hence, it is necessary to study the effects in reduction of absorbed dose on highly sensitive organs, which are included in the regions of cranial and chest CT exams. Materials and methods All exams were proceeded on LlghtSpeed 16MDCT (GE Medical System, Milwaukee, U.S.A.), Rando phantom (Model RAN-110, Churchin associate LID., USA) and Glass dosimetry system(GD-351,8.5mm, FGD-1000) for the measurement of radiation dose. In addition, AttenuRad radiation protection devices of eyeballs & breast (F&L Medical Products Co.) are used for protection of sensitive organs. In cranial examination, the brain CT protocols was used for the examinations, and the summary of it is as followed: The glass radiation elements were put on left and right lens of phantom eyeballs, and the radiation before and after the use of Bismuth shield were measured twice when 120kVp of current were changed into 150mAs, 200mAs, and 200mAs, and when 250mAs were changed into 100kVp, 120kVp, and 140kVp. In chest examination, low-dose protocol and chest routine protocol are used for the examination. The conditions of low-dose protocol are as followed:120kVp, noise index 11.57(10~50mA), tube rotation time 0.8sec, pitch 1.375, and table speed 13.75mm/sec. Also, the conditions of chest routine CT protocol are 120kVp, noise index 15.86(160~250mA), tube rotation time 0.8sec, pitch 1.35, and table speed 13.5mm/sec. The glass elements were put on the both nipples of phantom and the radiation before and after the use of bismuth shield were measured twice. When the shield is used, rubber-made spacer(1cm) should be on the breasts, followed by bismuth shield, because it decreases not only the scattering ray absorption into breast wall caused by bismuth shield but image artifact potentially. Results The result of the measurement of orbit shielding during cranial examination. The results of measurements of the radiation(from 120kVp to 150, 200, 250 and 300mAs) before and after the use of bismuth shield are as followed: from 18.4±0.3mGy to 10.25±0.5rnGy(44.3% decrease) at 150mAs; from 23.9±0.9mGy to 13.9±0.1mGy(41.5% decrease) at 200mAs; from 37.3±0.3mGy to 19.8±0.9mGy(47.1% decrease) at 250mAs; and from 47.8±3.4mGy to 24.4±1.4mGy(46.8% decrease) at 300mAs. On the other hand, the measurements of radiation(from 250mAs to 100, 120, and 140 kVp) before and after the use of bismuth shield are as followed: from 22.9±0.2mGy to 22.9±0.2mGy(51.2% decrease) at 100kVp; from 34.4±0.9mGy to 19.5±0.2mGy(43.3% decrease) at 120kVp; and from 49.5 ±4.4mGy to 29±1.2mGy(41.4% decrease) at 140kVp. The result of the measurement of orbit shielding during breast examination. In low-dose protocol, the results of measurements of the radiation before and after the use of bismuth shield are 3.16±0.02mGy and 2.44±0.03mGy(22.78% decrease), respectively, and in chest routine protocol, the results were 14.45±1.08mGy and 11.93±0.21mGy(17.43% decrease), respectively. Conclusion In cranial examination, there was not much change in the radiation dose of eye lens with an application of bismuth shield, even increases of mAs with constant kVp. On the other hand, the rate of reduction of radiation dose by bismuth shield is seen with constant mAs and increase of kVp. Due to the use of bismuth shield, radiation dose has been decreased about 22.8%in low-dose study, and 17.4% in chest routine study. In our hospital, the use of bismuth shield of orbit is not applied to adults, but applied to some infants only when brain CT exam was operated to them. The breast shield is applied, as a test, to women under 50 years old. According to this study, the results show obviously that the use of the bismuth shield can reduce radiation dose of highly radiation-sensitive organs. As mentioned before, the amount of radiation that eye balls received at 250mAs(at

관상동맥 CT조영 검사시 선량감소 프로토콜에 관한 연구

윤영준(Yung Joon Yoon),김문찬(Moon Chan Kim),남윤철(Yoon Chul Nam) 대한CT영상기술학회 2009 대한CT영상기술학회지 Vol.11 No.1

Purpose To evaluate the feasibility of using relative low tube voltage scan protocols for low-dose about prospective and retrospective ECG gating scan on coronary image quality evaluation with 64-row MDCT. Materials and methods A female ART 300 phantom was used to simulate coronary artery of size(5mm in diameter) with four stenosis degrees(0%, 25%, 50% and 75%) at 55bpm heart rate. Cardiac scans were performed on a 64-row MDCT scanner(GE LightSpeed VCT) with rotation time of 350msec, 350mm scan length with proximal-middle coronary artery and two scan methods of prospective scan(axial) and retrospective scan(helical) of 0.2 pitch under each tens different scan protocols. Tube voltage and current were 100kVp/300~600mA, 120kVp/300~600mA, 140kVp/300~400mA. The simulative coronary arteries were filled with contrast media to reach an approximate value 400HU in the lumen. Background noise was measured to describe the basic image quality accordingly. CNR, SNR and contour sharpness represented in slope of CT density curve was calculated as well. Measured stenosis area and rates, described by the percentage area of stenosis on the cross-section images were also calculated. Comparative analysis standard stenosis rate with measured stenosis rate and the error are measured. Results Dose(CTDIvol) were 7.4~22.3mGy of prospective scan and 24.3~73.1mGy of retrospective scan by the protocols. Prospective scan method was measured less 30.5% radiation dose than retrospective scan. The corresponding image noise levels described in standard deviation of background signals varied with radiation dose, CNR and SNR mainly varied with tube current. The contour sharpness, which can reflect actual spatial resolution, is affected mainly by tube voltage. When comparing the groups with similar radiation dose of prospective(protocol 10) and retrospective(protocol 1) scans, prospective scan was measured obviously steeper mean slope value than retrospective scan. Significant difference stenosis rate error presented between two groups, which is low dose and high dose. Low dose group was overestimated on stenosis rate. When comparing the groups with similar radiation dose in same scan method protocol, protocols with lower tube voltage gained more accuracy in representing stenosis area and rate. Conclusion Prospective scan was estimated similar or higher results than retrospective scan in image quality evaluation as well as lower dose. Dose level and corresponding image quality is relevant to the accuracy of stenosis evaluation on simulated coronary arteries with 64-row MDCT. In this study, we find relative low-dose protocols with acceptable image quality showed a tendency of overestimating stenosis. Furthermore, prospective scan method take an effect reduced dose in condition keep stabile heart rate and using a lower tube voltage and higher tube current to gain accurate imaging result is more applicable than other protocols with the same radiation dose level.

Intracranial CT Angiography에서 3D 영상의 재현성 평가

윤동민(Dong Min Yoon),신상보(Sang Bo Shin),신철경(Sul Kyung Shin),남윤철(Yoon Chul Nam),김문찬(Moon Chan Kim) 대한CT영상기술학회 2012 대한CT영상기술학회지 Vol.14 No.1

목적 두개 내 동맥의 CT검사 후 3D processing을 하는 경우 사용되는 각 장비들을 비교하여 특징을 알아보고 3D processing시 유용한 방법에 대하여 고찰해 보고자 한다. 대상 및 방법 3D processing을 하기 위한 영상을 얻기 위해 Toshiba사의 64 channel MDCT(Aquilion TSX-101A, Toshiba, Japan)를 사용하여 Intracranial artery를 검사한 30명의 영상을 이용하였으며, 동일한 검사 부위의 조영제 주입 전 영상인 non-contrast image(이하 pre image)와 조영제 주입 후 영상인 post contrast image(이하 post image)를 이용하였다. Pre image와 post image를 3D Processing 장비 ADW(GE, version 4.4), Tera-Recon(Aquarius, version 3.7.0.13), Rapidia(Infinitt, version 2.8), Aquilion workstation(Toshiba, version TSX-101A), Intuition(Aquarius, version 4,4)에 각각 전송하고 자체 기능을 이용하여 bone을 제거하여 혈관부위만 남긴 영상을 만들어 ICA(internal carotid artery), BA(basilar artery), ACA(anterior cerebral artery), MCA(middle cerebral artery), PCA(posterior cerebral artery) 부위를 비교하였다. 결과 Rapidia와 Aquilion workstation에서는 CT number값을 이용하여 pre image와 post image를 적용하는 subtraction을 이용하고 있다. Rapidia와 Aquilion workstation에서 bone의 제거가 용이했고 혈관소실이 거의 없었다. Intuition은 display된 pre image와 post image의 pixel을 이용하여 A-B의 형식으로 계산하여 나타내고 이후 auto bone remove기능을 이용하여 혈관과 bone을 구분한다. Intuition은 bone의 제거가 특정부위에서 어려웠고 혈관소실도 있었다. ADW도 display된 pre image와 post image의 pixel을 이용하여 A-B의 형식으로 계산하여 나타내고 이후 auto bone remove기능을 이용하여 혈관과 bone을 구분한다. ADW는 bone의 제거는 용이했지만 특정부위의 혈관소실이 있었다. Tera-recon은 auto bone remove 기능을 이용하여 혈관에서 bone을 제거한다. Tera-recon에서는 bone의 제거가 특정부위에서 어려웠고 혈관소실도 있었다. 결론 CT검사 후 데이터를 이용하여 3D processing을 함에 있어 CT number값을 이용하여 pre image와 post image를 적용하는 subtraction의 기능을 이용하는 Rapidia와 Aquilion workstation의 사용이 보다 유용한 영상을 표현해내며 이는 원본 데이터의 왜곡을 최소화 하고 보다 실제에 가까운 3D 영상을 만든다. I. Purpose When using the 3D processing after the CT scan of intracranial arteries, study of best way to 3D processing and knowing the characteristics of each workstation. II. Material and methods For gain to the 3D image, 30 patients images that underwent CT Angiography, Intracranial Arteries by Toshiba 64 channel MDCT(Aquilion TSX-101A, Toshiba, Japan), images transferred to each 3D processing equipments. Pre and pat image was using the same location, and this images transfer to ADW(GE, version 4.4), Tera-Recon(Aquarius, version 3.7.0.13), Rapidia(Infinitt, version 2.8), Aquilion workstation(Toshiba, version TSX-101A), Intuition(Aquarius, version 4.4). Each workstation makes a 3D artery image without foreign object such as bone, vein, peripheral vessel, it using the self function at that time. Then, conμire the ICA(internal carotid artery), BA(basilar artery), ACA(anterior cerebral artery), MCA(middle cerebral artery), PCA (posterior cerebral artery). III. Result Rapidia and Aquilion workstation was using the CT number, then it takes a subtraction by pre and past image. Rapidia and Aquilion workstation was so useful equipments fee remove the bone and there was little or no loss of vessel. Intuition is using the display pixel of pre and past image, then appear to image such as A-B and compare vessel with bone by auto bone remove function. Intuition is hard to remove the bone and loss of vessel. ADW is also using the display pixel of pre and past image, then appear to image such as A-B and compare vessel with bone by auto bone remove function. ADW is useful equipments for remove the bone but it has loss of vessel. Tera-Recon takes a auto bone remove function and remove the bone from the vessel. Tera-Recon is hard hard to remove the bone and loss of vessel. IV. conclusion When using the 3D processing workstation for 3D image, Rapidia and Aquilion workstation subtraction function that apply to CT number of pre and post image is minimize distortion and so useful to mike a realistic 3D image.

Effective mAs 적용 CT에서 Pitch Factor 변화에 따른 Image Quality의 비교

김민찬(Min Chan Kim),남윤철(Yoon Chul Nam),방성호(Sung Ho Bang),한동균(Dong Kyoon Han) 대한CT영상기술학회 2008 대한CT영상기술학회지 Vol.10 No.1

In high version MDCT, is applying effective mAs that is different from constant mAs that is existent one time rotation mAs concept. By concept that consider pitch effect in dose that apply effective mAs in CT equipment and with image quality pitch to do increase to compensate image Quality’s decrease mA automatically increase. Even if increase pitch, whole dose by equal dose scan progress do. Therefore, in effective mAs pitch’s increase patient exposure dose effect that shorten scan duration without doing decrease appear. By Pitch’s increase, image quality decrease in case problem is or applies to pediatric patient that there are much actions in breath because fast scan consists by equal dose if is not done diagnosis value big.

흉부 CT검사시 AEC Program 적용에 의한 선량감소효과에 관한 연구

이대규(Dae kyoo Lee),남윤철(Yoon Chul Nam),김문찬(Moon Chan Kim) 대한CT영상기술학회 2006 대한CT영상기술학회지 Vol.8 No.1

Purpose The purpose of this study is to check how much a radiation dose of the thoraxis reduced when using AEC technique in CT examination, and to apply the program properly to clinical cases. Materials and Methods We measured organ doses of thyroid, upper chest, mid chest, lower chest, breast, liver when conducting a test by using Brilliance CT made by Philips, instead of AEC program, and compared the radiation dose reduction effect of each organ by measuring the effect shown when using D-DOM (a method of controlling a tube current according to the thickness of a subject for photography toward X-Y axis of a revolving angle of a tube) among AEC programs, and Z-DOM(a method of controlling a tube current according to the thickness of Z-axis position). Results The comparison between dose with AEC program and dose without AEC program in chest routine CT were as follows, 1. The thyroid dose using D-DOM and Z-DOM wasreduced 23.9% and 49.5% respectively rather than dose of non-AEC program. 2. The upper chest dose using D-DOM and Z-DOM was reduced 18.3% and 17.8% respectively rather than dose of non-AEC program. and The mid. chestdose using D-DOM and Z-DOM was reduced 15.2% and 12.7% respectively rather than dose of non-AEC program. and The lower chest dose using D-DOM and Z-DOM was reduced 5.8% and 22.4% respectively rather than dose of non-AEC program. 3. The breast dose using D-DOM and Z-DOM was reduced 10.7% and 7.5% respectively rather than dose of non-AEC program. 4. The liver dose using D-DOM and Z-DOM was reduced 20.3% and 26.4% respectively rather than dose of non-AEC program. 5. It was proven that as for the radiation dose reduction effect by D-DOM, the control of a tube current was mostly performed in the asymmetrical part such as shoulder when comparing upper chest (18.3%), mid. Chest(15.2%), and lower chest(5.8%). 6. Thyroid, Lower chest showed a greater radiation dose reduction effect when using Z-DOM rather than D-DOM. Conclusion The radiation dose reduction effect in each organ was proven higher by far when using AEC program. In particular, D-DOM demonstrated an excellent radiation dose reduction effect in the part that showed a great difference of thickness between AP and Lateral(ex. shoulder). Z-DOM displayed an outstanding effect in the neck part.