• Progress in Medical Physics
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• v.15 no.1
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• pp.30-38
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• 2004

Purpose: To develop a whole body frame for the purpose of reducing patient motion and minimizing setup error for extra-cranial stereotactic radiotherapy, and to evaluate the repositioning setup error of a patient in the frame. Materials and Methods: The developed whole body frame is composed of a base plate, immobilizer, vacuum cushion, ruler and belts. The dimension of the base plate is 130 cm in length, 50 cm in width and 1 cm in thickness. The material used in the base plate of the frame was bakelite and the immobilizer was made of acetal. In addition, Radiopaque angio-catheter wires were engraved on the base plate for a coordinate system to determine the target localization. The measurement for radiation transmission and target localization is peformed in order to test the utilization of the frame. Also, a Matlab program analyzed the patients setup error by using the patient's setup images obtained from a CCTV camera and digital record recorder (DVR). Results: A frame that is useful for CT simulation and radiation treatment was fabricated. The frame structure was designed to minimize collisions from the changes in the rotation angle of the gantry and to maximize the transmission rate of the Incident radiation at the lateral or posterior oblique direction. The lightening belts may be used for the further reduction of the patient motion, and the belts can be adjusted so that they are not in the way of beam direction. The radiation transmission rates of this frame were measured as 95% and 96% at 10 and 21 MV, respectively. The position of a test target on the skin of a volunteer is accurately determined by CT simulation using the coordinate system in the frame. The estimated setup errors by Matlab program are shown 3.69$\pm$1.60, 2.14$\pm$0.78 mm at the lateral and central chest, and 7.11 $\pm$2.10, 6.54$\pm$2.22 mm at lateral and central abdomen, respectively. The setup error due to the lateral motion of breast is shown as 6.33$\pm$ 1.55 mm. Conclusion: The development and test of a whole body frame has proven very useful and practical in the radiosurgery for extra-cranial cancers. It may be used in determining target localization, and it can be used as a patient immobilization tool. More experimental data should be obtained in order to improve and confirm the results of the patient setup error.

• Journal of Chest Surgery
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• v.38 no.11 s.256
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• pp.761-772
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• 2005

Background: Following the implantation of heart valve prostheses, it is important to maintain therapeutic INR to reduce the risk of thromboembolism. The objective of this study was to suggest a practical dosing guideline for Korean outpatients with prosthetic heart valves managed by a pharmacist-run anticoagulation service (ACS). Material and Method: A retrospective chart review was completed for all patients enrolled in the ACS at Seoul National University Hospital from March, 1997 to September, 2000. Patients who were at least 6 months post-valve replacement and had nontherapeutic INR value (less than 2.0 or greater than 3.0) were included. The data on 688 patients (1,782 visits) requiring dosing adjustment without any known drug or food interaction with warfarin were analyzed. The amount of adjusted dose and INR changes based on the INR at the time of the event were calculated. Aortic valve replacements (AVR) patients and mitral or double valve replacement (MVR/DVR) patients were evaluated separately. Result: Two methods for the warfarin dosage adjustment were suggested: Guideline I (mg-based total weekly dose (TWD) adjustment), Guideline II (percentage-based TWD adjustment). The effectiveness of Guideline 1 was superior to Guideline II overall in patients with both AVR and MVR/DVR. Conclusion: The guideline suggested in this study could be useful when the dosage adjustment of wafarin is necessary in outpatients with mechanical heart valves.

• Journal of Chest Surgery
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• v.41 no.4
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• pp.430-438
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• 2008

Background: All the patients with mechanical valves require warfarin therapy in order to prevent them from developing thromboembolic complications. According to the ACC/AHA practice guidelines, after AVR with bileaflet mechanical prostheses in patients with no risk factors, warfarin is indicated to achieve an INR of 2.0 to 3.0. After MVR with any mechanical valve, warfarin is indicated to achieve an INR of 2.5 to 3.5. But in our clinical experience, bleeding complications (epistaxis, hematuria, uterine bleeding, intracerebral hemorrhage etc.) frequently developed in patients who maintained their INR within this value. So, we retrospectively reviewed the patients with bileaflet mechanical heart valve prosthesis and we determined the optimal anticoagulation value. Material and Method: From January 1984 to February 2007, 311 patients have been followed up at a national medical center. We classified the AVR patients (n=60) into three groups as follows: an INR from 1.5 to 2.0 in Group I, an INR from 2.0 to 2.5 in Group II and an INR from 2.5 to 3.0 in Group III. We classified the MVR (n=171) and DVR (n=80) patients into four groups as follows: an INR from 1.5 to 2.0 in Group I, an INR from 2.0 to 2.5 in Group II, an INR from 2.5 to 3.0 in Group III and an INR from 3.0 to 3.5 in Group III. We compared the groups for their thromboembolic and bleeding complications by means of the Kaplan Meier method. Result: In the AVR patients, 2 thromboembolic complications and 4 bleeding complications occurred and the log rank test failed to identify any statistical significance between the groups for thethromboembolic complication rate, but groups I and II had lower bleeding complication rates than did group III. Thirteen thromboembolic complication and 15 bleeding complication occurred in the MVR and DVR patients, and the log rank test also failed to identify statistical significance between the groups for the thromboembolic complication rate, but groups I and II had lower bleeding complication rates that did groups III and IV. Conclusion: The thromboembolic complication rate was not statistically different between groups I and II and groups III and IV, but the bleeding complication rates of groups I and II were lower than those of groups III and IV. So this outcome encouraged us to continue using our low intensive anticoagulation regime, that is, an INR of 1.5 to 2.5.

• Journal of Chest Surgery
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• v.29 no.9
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• pp.964-970
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• 1996

One hundred eight patients (Feb.'86, through Jan.'96) underwent 53 mitral(MVR), 20 aortic(AVR), )5 double(DVR) valve replacement with SJM prosthesis. There were 55 males and 53 females whose mean age was 36.3 $\pm$ 10.4 years. We used 143 valves in mitral(88), aortic(54), and tricuspid(1) sites. The size and number of valves were 31 mm(32). 33inm(23), 29mm(20), 27mm(10), 25mm(2), and 35mm(1) in mitral site; 2)mm(21), 21mm(1 S), 19mm(7), 25mm(5), 27mm(2), and 33mm(1) in aortic site; and Blmm(1) in tricuspid site. Preoperative NYHA functional classes were II(14), III(73) and IV(21), and which were improved into I(89) and II(16) postoperatively. Early postoperative complications occurred in 15 cases(13.9%) in which LOS was the most common one(5 cases; 4.6%). fatly hospital death occurred in 3 cases(2.8%) due to LOS(1) and sudden cardiac arrest(2) he cummulative total follow-up period was 437.6 pl-yr with a mean of 4.1$\pm$2.9 years. There were 5 events of valve related'complications (2 TE, 1 paravalvular leak, 1 TE+paravalvular leak, 1 PVE) with the occurrence rate as 1.14%/pt-yr. Reoperation was performed in 2 cases and there were 2 cases of valve related death due to one PVE and one paravalvlllar leak. The complication free rate was 91.4$\pm$ ).4% at 10 years. Actuarial survival rate was 93.6 $\pm$ 3.1 % at 10 years.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.59-59
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• 2003

목적 : 환자의 호흡에 의한 움직임 및 부정확한 환자 자세 setup 때문에 3 차원 전신 정위 방사선치료,3 차원 입체조형 방사선치료 IMRT와 같은 방사선 치료기술에서 병소에 대한 정확한 표적 위치측정은 매우 어려운 실정이다. 그러므로 본 연구는 방사선 치료시 환자의 움직임을 최대한 고정시켜 줄 수 있으며 환자 자세에 대한 setup 오차를 감소시키고 환자 전신에 산재한 병소의 위치를 좌표화할 수 있는 전신 정위 프레임 제작과 제작한 프레임에 대한 고정효과 및 재현성을 나타내는 환자 자세의 setup 오차를 평가하는데 있다. 재료 및 방법 : 자체 제작한 전신 정위 프레임 구조는 CT 영상 촬영 가능성에 중점을 두고 병소 표적의 좌표실현 및 환자체형에 따른 다양성 그리고 프레임에 대한 견고성 및 안정성 확인에 초점화하여 제작하였다. 이렇게 제작된 전신 정위 프레임에 대한 방사선 투과율 측정 실험과 CCTV 카메라와 DVR(Digital Video Recorder)를 이용해 환자 자세 변화에 대한 영상을 획득하여 matlab으로 구현한 오차분석용 프로그램으로 환자 외부자세에 대한 오차 비교 평가하고 CT 촬영에 의한 가상표적 위치측정 실험을 수행하였다. 또 한 고정벨트 추가 사용으로 인한 환자의 고정효과 정도를 살펴보았다. 결과 : 제작된 전신 정위 프레임에 대한 방사선 투과율은 마그네트론 10, 21 MeV의 에너지에서 95, 96% 의 투과율이 측정되었고 30 $^{\circ}$. 60 。각도의 경사로 빔이 전달될 때는 90.3, 94.4% 가 측정되었다. CCTV 카메라를 이용하여 흉부 및 복부의 움직임을 촬영한 영상을 Matlab프로그램으로 구현한 오차분석 프로그램을 적용한 결과, 환자 자세에 대한 오차의 평균값은 흉부의 lateral 방향에서는 3.63$\pm$1.4 mm, AP 방향에서는 2.1$\pm$0.82 mm이었다. 그리고 복부의 later의 방향에서는 7.0$\pm$2.1 mm, AP 방향에서는 6.5$\pm$2.2 mm 이었다. 또한 표적 위치측정을 위해서 환자의 피부에 임의의 가상표적을 부착하고 CT 촬영한 영상결과, 프레임으로 가상표 적에 대한 위치를 정확히 파악할 수 있었다. 결론 : 제작된 프레임을 적용하여 방사선투과율 측정실험, 환자 외부자세에 대한 오차 측정실험, 가상표적 위치측정 실험 등을 수행하였다. 환자 외부자세에 대한 오차 측정실험 경우, 더 많은 Volunteer를 적용하여 보다 정확한 오차 측정실험이 수행되어야 할 것이며 정확한 표적 위치 측정실험을 위해서 내부 마커를 삽입한 환자를 적용한 임상실험이 수행되어야 할 것이다. 또한 위치결정에서 획득한 좌표값의 정확성을 알아보기 위해서 팬톰을 이용한 방사선조사 실험이 추후에 실행되어져야 할 것이다. 그리고 제작된 프레임에 Rotating X선 시스템과 내부 장기의 움직임을 계량화하고 PTV에서의 최적 여유폭을 설정함으로써 정위 방사선수술 및 3 차원 업체 방사선치료에 대한 병소 위치측정과 환자의 자세에 대한 setup 오차측정 결정에 도움이 될 수 있을 것이라고 사료된다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.1
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• pp.30-37
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• 2006

Black rockfish and goldeye rockfish are commercially important fish species due to the increasing demand in Korea. When estimating the abundance of stocks for these species acoustically, it is of crucial importance to know the target strength(TS) to length dependence. In relation to these needs, TS measurement was conducted on black rockfish and goldeye rockfish in an acrylic salt water tank using 70kHz and 120kHz split beam echo sounders. The TS for these two species under the controlled condition was simultaneously measured with the swimming movement by DVR system and analyzed as a function of fish length(L). The results obtained are summarized as follows: The best fit regression of TS on fish length of black rockfish was TS=19.38 Log(L, cm)-70.46 ($r^2=0.71$) at 70kHz and TS=22.39 Log(L, cm)-70.40 ($r^2=0.64$) at 120kHz and in the standard form TS=20 Log(L, cm)-71.29 ($r^2 = 0.70$) at 70kHz and TS=20 Log(L, cm)-66.88 ($r^2=0.57$) at 120kHz. The best fit regression of TS on fish length of goldeye rockfish was TS=17.10 Log(L, cm)-68.28 ($r^2=0.37$) at 70kHz and TS=24.39 Log(L, cm)-73.74 ($r^2=0.59$) at 120kHz and in the standard form TS=20 Log(L, cm)-72.03 ($r^2=0.32$) at 70kHz and TS=20 Log(L, cm)-67.68 ($r^2=0.64$) at 120kHz. An empirical model for fish TS(dB) averaged over the dorsal aspect of 115 fishes of black rockfish and goldeye rockfish and which spans the fish length(L, m) to wavelength($\lambda$, m) ratio between 8 and 30 was derived : TS=34.12 Log(L)-14.12 Log($\lambda$)-23.83, ($r^2=0.90$).

• Journal of Chest Surgery
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• v.21 no.6
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• pp.1020-1029
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• 1988

The authors evaluated 153 patients who had undergone cardiac valve replacement between October 1979 and July 1988. The results are as follows: l. Out of 153 patients, there were 56 males and 97 females ranging from 15 to 62 years of age with a mean of 37 years. 2. Isolated mitral valve replacement took place in 82 patients, aortic valve replacement[AVR] in 16, double valve replacement[DVR] in 34, AVR combined with open mitral commissurotomy in 19, and tricuspid valve replacement[TVR] was done in 2 patients. 3. 153 patients had 187 prosthetic valves replaced with Ionescu-Shiley valves[16], Carpentier-Edwards[36], Bjork-Shiley[19], St. Jude Medical[108], and Duromedics[8]. 4. Our of 98 patients with atrial fibrillation[ 64% of a total 153 patients ] during the preoperative period, 22 patients recovered NSR[ 22/98, NSR recovery rate 22.4%] after valvular surgery and remaining 76 patients revealed persisting atrial fibrillation[76/153, 49.7% ]. 5. Preoperative episodes of systemic arterial embolization were attained in 9 patients[9/153, 6% ], and left atrial thrombi were confirmed in 22 patients intraoperatively[ 22/153, 14% ]. Of these, only one patient, however, demonstrated the correspondence of preoperative embolization and intraoperative existence of LA thrombi. 6. With mechanical prostheses, anticoagulant therapy was begun 48 hours after operation with sodium warfarin[2.5-5.0mg/day], maintaining the prothrombin time between 16 and 18 seconds or 30 to 50% of control values and continued for life. With tissue prostheses, sodium warfarin was continued for 3 to 6 months and converted into buffered ASA[ 325 mg/day ] for one year. 7. The mean follow-up for the survivors was 30.1 months, with a range from 3 months to 9 years. All suspected or confirmed thromboembolic episodes counted as events and occurred in 4 patients[ 1.04%/patient-year] with mechanical valve replacement. No persistent paralysis or death was noted. Late complications have not yet occurred in the patients with isolated MVR and AVR. 8. There were remarkable structural failures of tissue valves in 3 patients[ 1.9%/patient-year ], while no instance of failure of a mechanical valve. 9. There were 10 operative early deaths[10/153, 6.5%] and 5 late deaths[5/153, 3.3%]. Consequently, overall mortality was 9.8%[ 15/153] during follow-up period. 10. We currently favor using the St. Jude Medical valve in all patients requiring valve replacement except in those who can not take warfarin anticoagulation.

• Journal of Chest Surgery
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• v.31 no.11
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• pp.1031-1036
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• 1998

Background: Medtronic-Hall mechanical valve is a world widely using prosthesis. But, in Korea, the clinical result from Medtronic-Hall valve replacement is not frequenthy available. Materials and methods: From March 1986 to May 1990, 50 patients underwent valve replacement surgery with Medtronic-Hall valve at Pusan National University Hospital. Seventeen were male and thirty three were female and ra nging in age from 16 to 70 years of age(mean=35 years). Results: The causes of valvular lesion were rheumatic in 43 patients, bicuspid aortic valve in 3 patients, degenerative lesion in three patients and bacterial endocarditis in one patient. The operative procedures were mitral valve replacement(MVR) in 38, aortic valve replacement(AVR) in 5 and double valve replacement(DVR) in 7. The most commonly used valve size was 21mm in AVR, 29mm in MVR. Concomitant surgical procedures were performed in 15 patients; left atrial thrombectomy in 9, left atrial auricle obliteration in 6 and tricuspid annuloplasty in 5(Kay: 2, DeVega: 3). New York Heart Association functional class was mostly Class Ⅲ or Ⅳ(91.5%) preoperatively and ClassⅠor Ⅱ(87.2%) after operation. The findings of postoperative echocardiogram of LAD, LVESD, LVEDD were reduced compared with preoperative period and ejection fraction was increased compared with preoperative period. Postoperative complications were massive bleeding in three, low cardiac output syndrome in two, thromboembolism in one and fulminant hepatitis in one patient. There were three hospital deaths and their causes were low cardiac output syndrome in two and rupture of left ventricle in one patient. The 5 year survival rate was 93.65±0.71% and 10 year actuarial survival rate was 88.27±6.42%. Conclusions: Medtronic-Hall mechanical valve has low valve related complication rate. It's durability and hemodynamic performance is comparable to other mechanical valves.

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.256-263
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• 2007

High NA objective design by using SELFOC materials was studied, and two kinds of objective for optical pick-up were designed. The SELFOC materials have radial gradient index distribution, and it gives additional degree of freedom in optical design. Therefore, we expect that optical design of high NA objective without aspheric surface will be possible. In this study, the variation of ms spot diameter was investigated as a function of quadratic constant and refractive index on axis for various combinations of axial thickness and entrance pupil diameter. For the survey, Code V was used for optimization and evaluation of the objective lenses. The result suggested that larger quadratic constant and higher refractive index on axis could give us better imaging performance for all combinations of axial thickness and pupil diameter. Based on the survey, we designed high NA objectives for DVR. There were two kinds of design solution consisting two spherical SELFOC lenses. The solution I had positive-positive lens configuration with short over-all-length, but it had poor off-axial performance compared with the solution II. The solution II had negative-positive lens configuration with good off-axial imaging performance. But the solution II had some disadvantages, long over-all-length and large diameter of the second lens.

• Journal of Chest Surgery
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• v.27 no.4
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• pp.272-280
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• 1994

Total 400 St.Jude Medical Bileaflet Valves were implanted in 336 pts from January 1983 to June 1993; 64 were aortic, 205 were mitral, 64 were double valve and 3 were tricuspid position. The follow up period extended from 6 months to 10 years[mean 24.3 months]. Male to female ratio was 1:1.7. There were total 27 deaths[cardiac related 20, cardiac non-related 7]. Overall mortality was 2.9%/pt-yr. There were 10 early deaths[3.0%] and 10 late cardiac related deaths [3.0%]. Prosthetic valve related complications occurred in 19 patients[5.7%] and among them, seven died; four died of thromboembolic events, two died of anticoagulants therapy related hemorrhagic complications and one died of bacterial endocarditis. NYHA class improved significantly especially in aortic valve replacement and double valve replacement. In AVR cases, the mean NYHA was 2.8 preoperatively and 1.3 postoperatively. And in DVR cases, 3.3 preoperatively and 2.2 postoperatively. The decision to employ a particular prosthesis was made according to the anticipated or known complications of the valve. The St.Jude Medical Valve retains all the hazards of other mechanical valves, most notably, thromboembolism. But the hemodynamic performance of St.Jude Medical Valve compared most favorably with other substitute valves in many reports. 0ur experience didn`t show any differences compared other authors in terms of valve related complication. So we concluded St. Jude Medical Valve can be primarily considered in the selection of artificial valve except in the patients when the usage of anticoagulant therapy is contraindicated.