CAVE TM-like 시스템에서 투명 패널 인터페이스를 이용한 가상객체 조작 및 탐색 기법

Immersion and interaction are the most important elements in Virtual Reality. Interaction, which facilitates user communication with the virtual environment, is an especially important element in Positive VR, moreso than in Negative VR. Therefore in Positive VR, the user should be able to communicate his purpose to the virtual world by using interaction techniques that don't obstruct the communication. Common user operations are the selection and manipulation of objects at a distance and navigation of a large-scale virtual world. In the CAVE^(TM)-like system, projection-based full-immersive virtual environment system, it is necessary that a user in a physically limited space be able to utilize efficient interaction techniques to communicate with a large-scale virtual world which appears as a 3D image. I propose a transparent panel interface which can be used for efficient 3D interaction in the CAVE^(TM)-like system. To make this panel interface, render the 3D virtual world to the frame buffer first and then map the texture which is made from the buffer to the 3d virtual panel object. Using this panel interface, the user can select and manipulate the virtual object easily. Moreover, mapping the small map for the virtual world to the virtual panel object gives support to the user as a navigation tool. And it can be the 2D system control tool for the virtual world application. In addition, the user can interact with the virtual world through the desktop metaphor interface. It contains the demonstration of the transparent panel interface for the virtual museum application in the CAVE^(TM)-like system. ;가상현실(Virtual Reality)에서 몰입감(immersion)과 상호작용(interaction)은 필요 불가결한 요소이다. 특히 단순한 시각적 디스플레이만 제공하는 수동적 가상현실이 아닌 사용자의 의도가 반영되는 능동적 가상현실에서는 가상공간상의 가상객체와의 의사소통 방법인 상호작용이 더욱 중요한 요소가 된다. 그러므로 능동적 가상현실에서는 사용자의 몰입감을 저해하지 않는 상호작용 기법을 사용하여 원거리 가상객체를 선택 및 조작하고 대규모 가상공간을 탐색하는 등의 사용자 의도가 가상세계에 효과적으로 전달될 수 있어야 한다. 특히 CAVE^(TM)-like 시스템과 같은 프로젝션 기반의 완전몰입형 가상환경에서는 물리적으로 한정된 공간 안에 있는 사용자가 삼차원 이미지로 구현된 대규모 가상세계와 효과적으로 상호작용 할 수 있는 기법이 필요하다. 본 논문에서는 CAVE^(TM)-like 시스템 상에서 효과적으로 삼차원 인터랙션을 수행하기 위한 투명 패널 인터페이스를 제안한다. 이를 이용하면 투명 아크릴패널에 사용자 시선방향의 삼차원 가상세계를 텍스처로 변환하여 가상 인터페이스에 투영함으로써 가상객체를 쉽고 효과적으로 선택하여 조작할 수 있다. 또한 전체 가상세계를 한 눈에 인식할 수 있도록 이차원 지도 텍스처를 가상 인터페이스에 매핑하고 사용자의 위치를 표시해줌으로써 탐색보조도구로써의 기능을 수행한다. 사용자의 의도에 맞는 적절한 텍스처를 패널 인터페이스 도구에 매핑함으로써 상호작용 기능 뿐만 아니라 시스템 제어기능을 함께 제공받을 수 있으며, 데스크탑 메타포를 적용하여 편리성이 증가된 인터페이스를 통해 가상공간과 상호작용 할 수 있다. 본 논문에서는 CAVE^(TM)-like 시스템에서의 대규모 가상공간을 표현하는 어플리케이션인 가상미술관에서 투명 패널 인터페이스를 적용하였다.논문개요 = v I. 서론 = 1 1.1 연구 배경 = 1 1.2 연구 목적 및 내용 = 2 II. 관련 연구 = 4 2.1 선택/조작/탐색 삼차원 상호작용 = 4 2.2 패널을 이용한 시스템 제어 기법 = 8 III. 데스크탑 메타포가 추가된 투명 패널 인터페이스 = 11 3.1 택타일 피드백이 적용된 삼차원 패널 인터페이스 = 11 3.2 랜더텍스쳐를 이용한 가상객체 선택 및 조작 기법 = 18 3.2.1 프레임버퍼를 이용한 가상환경의 텍스쳐화 = 19 3.2.2 선택 및 조작 기법 = 21 3.3 가상 맵을 이용한 탐색 기법 = 23 3.3.1 자유 회전 이동 = 23 3.3.2 목적지 지정 이동 = 26 IV. 구현 및 결과 = 30 4.1 구현 환경 및 구현 내용 = 30 4.2 구현 결과 = 33 V. 결론 = 41 5.1 연구 결과 및 의의 = 41 5.2 향후 연구 = 42 참고문헌 = 43 ABSTRACT = 4

Influence of Body Composition Parameters on the Treatment Response and Long-term Oncologic Outcomes in Patients with Primary Rectal Cancer

Purpose : Body compositions can be obtained readily from CT images and are modifiable. Body composition parameters such as obesity and sarcopenia have been reported to be associated with morbidity and mortality in patients with cardiovascular disease, chronic obstructive pulmonary disease, and metabolic syndrome. Recently, sarcopenia has been demonstrated as a prognostic factor in cancer patients. We evaluated the association of body composition with the preoperative chemoradiotherapy (PCRT) response and long-term oncologic outcomes in non-metastatic rectal cancer patients. Methods : We enrolled 1,384 patients with stage(y)0-III rectal cancer who had been treated at Asan Medical Center between January 2005 and December 2012. The body composition at diagnosis was measured by abdomino-pelvic computed tomography (CT) using Asan-J software. Two consecutive axial CT images at the level of the L3 lumbar vertebra were processed and then averaged for each patient. Sarcopenia, visceral obesity (VO), and sarcopenic obesity (SO) were defined using CT-measured parameters such as the skeletal muscle index (total abdominal muscle area, TAMA), visceral fat area (VFA), and VFA/TAMA. SMI was calculated as TAMA/height2. We evaluated three types of criteria according to the SMI for sarcopenia. VO was defined as ≥ VFA of 100 cm2. A VFA/TAMA ratio of over 3.2 was defined as SO. An inflammatory status was defined as a neutrophil-lymphocyte ratio of ≥3. Obesity was categorized by a body mass index (≥ 25 kg/m2). Pathologic responses to PCRT were evaluated using the tumor regression grade (TRG) system according to the proportion of tumor cells as well as fibrosis. Results : Among the 1,384 study patients, 894 (64.6%) were at the localized stage, and 490 (35.4%) had regional lymph node metastasis. A total of 536 (38.7%) patients in this series had received preoperative chemoradiotherapy. According to Western, Japanese and Korean criteria, 943 (68.2%), 834 (60.3%) and 215 (25.4%) patients were categorized as having sarcopenia, respectively. The records indicated that 307 (22.2%) patients had SO and 670 (48.4%) had visceral obesity. We further found that 458 (33.1%) cases had a BMI of 25 or higher and 278(20.2%) were in an inflammatory state with an NLR≥3. The total regression rate after PCRT was significant low in patients with VO (20.1%, p=0.029) and SO (11.5%, p=0.038). The 5-year overall survival (OS) rate was significantly lower in SO patients (no SO vs. SO; 79.1% vs. 75.5%, p=0.02) but the 5-year recurrence-free survival (RFS) rate was not different (77.3% vs. 77.9% p=0.858). Sarcopenia, SO, VO, and obesity were not associated with RFS. However, obesity, SO, age, sex, inflammatory status, and tumor stage were confirmed as independent factors associated with poorer OS by multivariate analysis. In subgroup analysis based on the tumor stage or inflammatory markers, an association between SO and the OS rate was more prominent in patients with (y)p stage 0-2 and no inflammatory status. Conclusion : The presence of SO and a low body mass index at diagnosis are individually associated with poorer OS in non-metastatic rectal cancer patients. |연구목적 신체 구성비는 컴퓨터 단층촬영 영상을 통해 쉽게 얻을 수 있고 교정이 가능하다. 비만, 근육감소증과 같은 신체 구성비 변수들이 심혈관계질환, 만성 폐쇄성 호흡기질환 및 대사질환에서 이환율 또는 사망률과 관계가 있다는 내용들이 다수 보고되고 있고 최근 암 환자에서도 근육감소증이 중요한 예후 예측 인자임이 발표 되고 있다. 본 연구에서는 원격 전이를 동반하지 않은 직장암 환자에서 신체 구성비가 수술 전 항암화학요법 치료 반응에 영향을 미치는 지 여부와 장기적인 생존율에 미치는 영향에 대해 평가하였다. 연구 방법 서울아산병원에서 2005년 1월부터 2012년 12월까지 근치적 절제술을 받았던 0-III기 직장암 환자 1,384을 연구 대상으로 하였다. 진단 당시 시행한 컴퓨터 단층촬영 (CT) 영상에서 Asan-J software를 통해 신체 구성비를 측정하였다. L3 요추 위치에서 선택된 축상 이미지상의 모든 근육을 포함한 총 복부 근육 면적을 CT상의 HU에 대한 미리 결정된 임계 값 또는 신호 강도를 사용하여 경계를 정했다. CT 영상에서 측정된 변수 – 골격근 지수, 내장 지방 면적, 내장 지방 면적/총 복부 근육 면적 값에 따라 근육 감소증, 내장 비만 (VO), 근육 감소를 동반한 비만 (SO)을 정의하였다. 골격근지수는 총 복부 근육 면적/신장2 으로 계산하였다. 근육감소증은 골격근 지수 수치에 따라 3가지 기준을 각각 적용하여 분석하였다. 내장 비만은 내장 지방 면적이 100 cm2 이상인 경우로 정의하였고, 근육 감소를 동반한 비만은 내장 지방 면적/총 복부 근육 면적비가 3.2 이상인 경우로 정의하였다. 호중구-림프구 비가 3 이상인 경우는 전신적인 염증을 동반한 상태로 정의하였다. 체질량 지수가 25 kg/m2 이상인 환자는 비만으로 분류하였다. 수술 전 항암화학요법에 대한 병리조직학적 반응성은 암 세포와 섬유화의 비율에 따라 평가하였다. 연구 결과 1,384 명의 직장암 환자들 중 894 (64.6%) 명은 림프절 전이가 없었고 943 (68.2%) 명은 림프절 전이가 있다. 수술 전 항암화학요법을 받은 환자들은 536 (38.7%) 였다. 적용 기준에 따라 943 (68.2%), 834(60.3%), 215(25.4%) 명이 근육감소증으로 분류되었다. 307 (22.2%) 는 근육감소증을 동반한 비만이었고 670 (48.4%)는 내장 비만이 있었다. 458 (33.1%) 체질량 지수가 25 이상인 비만 이었다. 278 (20.2%) 는 호중구-림프구비가 3 이상인 염증이 있는 상태로 평가 되었다. VO가 있는 환자와 (20.1%, p=0.029) SO가 있는 환자에서 (11.5%, p=0.038) 수술 전 항암화학요법 치료 후 완치율이 통계적으로 유의하게 낮았다. 근육감소증을 동반한 비만 환자에서 5년 생존율이 유의하게 낮았으나 (84% vs. 78%, p=0.02) 5년 재발 없는 생존기간에는 차이가 없었다 (77.3% vs. 77.9% p=0.957). 근육감소증, 근육감소증이 동반된 비만, 내장 비만, 그리고 비만 모두 RFS과는 연관성이 없었다. 다변량 분석에서 비만, SO, 나이, 성별, 염증 상태, 그리고 병기는 전체 생존율에 영향을 미치는 독립적인 예후 예측인자로 나타났다. 병기 또는 염증상태에 따른 하위 그룹 분석에서 근육감소증을 동반한 비만과 전체 생존율의 연관성은 병기가 0-2기이고 염증이 없는 상태의 환자에서 더욱 뚜렷하게 나타났다. 결론 및 제언 원격 전이를 동반하지 않은 직장암 환자에서 SO와 낮은 체질량지수는 전체 생존율에 부정적인 영향을 미친다.Maste

Optimal postoperative surveillance strategies for stage III colorectal cancer

BACKGROUND Optimal surveillance strategies for stage III colorectal cancer (CRC) are lacking, and intensive surveillance has not conferred a significant survival benefit. AIM To examine the association between surveillance intensity and recurrence and survival rates in patients with stage III CRC. METHODS Data from patients with pathologic stage III CRC who underwent radical surgery between January 2005 and December 2012 at Asan Medical Center, Seoul, Korea were retrospectively reviewed. Surveillance consisted of abdominopelvic computed tomography (CT) every 6 mo and chest CT annually during the 5 year follow-up period, resulting in an average of three imaging studies per year. Patients who underwent more than the average number of imaging studies annually were categorized as high intensity (HI), and those with less than the average were categorized as low intensity (LI). RESULTS Among 1888 patients, 864 (45.8%) were in HI group. Age, sex, and location were not different between groups. HI group had more advanced T and N stage (P = 0.002, 0.010, each). Perineural invasion (PNI) was more identified in the HI group (21.4% vs 30.3%, P < 0.001). The mean overall survival (OS) and recurrence-free interval (RFI) was longer in the LI group (P < 0.001, each). Multivariate analysis indicated that surveillance intensity [odds ratio (OR) = 1.999; 95% confidence interval (CI): 1.680-2.377; P < 0.001], pathologic T stage (OR = 1.596; 95%CI: 1.197-2.127; P = 0.001), PNI (OR = 1.431; 95%CI: 1.192-1.719; P < 0.001), and circumferential resection margin (OR = 1.565; 95%CI: 1.083-2.262; P = 0.017) in rectal cancer were significantly associated with RFI. The mean post-recurrence survival (PRS) was longer in patients who received curative resection (P < 0.001). Curative resection rate of recurrence was not different between HI (29.3%) and LI (23.8%) groups (P = 0.160). PRS did not differ according to surveillance intensity (P = 0.802). CONCLUSION Frequent surveillance with CT scan do not improve OS in stage III CRC patients. We need to evaluate role of other surveillance method rather than frequent CT scans to detect recurrence for which curative treatment was possible because curative resection is the important to improve post-recurrence survival

Optimal Postoperative Surveillance Strategies for Colorectal Cancer: A Retrospective Observational Study

Simple Summary Optimal surveillance strategies for colorectal cancer remain undetermined, with intensive surveillance not conferring significant survival benefits. This study aimed to assess whether surveillance intensity is associated with recurrence and survival in patients with colorectal cancer. This retrospective observational study showed that, although frequent postoperative surveillance did not improve overall survival or recurrence-free survival, surveillance improved post-recurrence survival. Analysis using a recurrence risk-prediction model showed that intensive surveillance improved both post-recurrence survival and overall survival in patients who were at high risk of recurrence. Thus, intensive surveillance does not improve overall survival and recurrence-free survival but can help improve post-recurrence survival by detecting early-stage recurrence or increasing the curative resection rate. This study aimed to assess whether surveillance intensity is associated with recurrence and survival in colorectal cancer (CRC) patients. Overall, 3794 patients with pathologic stage I-III CRC who underwent radical surgery between January 2012 and December 2014 were examined. Surveillance comprised abdominopelvic computed tomography (CT) every 6 months and chest CT annually for 5 years. Patients who underwent more than and less than an average of three imaging examinations annually were assigned to the high-intensity (HI) and low-intensity (LI) groups, respectively. Demographics were similar in both groups. T and N stages were higher and perineural and lymphovascular invasion were more frequent in the HI group (p < 0.001 each). The mean overall survival (OS) was similar for both groups; however, recurrence-free survival (RFS) was longer (p < 0.001) and post-recurrence survival (PRS) was shorter (p = 0.024) in the LI group. In the multivariate analysis, surveillance intensity was associated with RFS (p < 0.001) in contrast to PRS (p = 0.731). In patients with high recurrence risk predicted using the nomogram, OS was longer in the HI group (p < 0.001). A higher imaging frequency in patients at high risk of recurrence could be expected to lead to a slight increase in PRS but does not improve OS. Therefore, rather than increasing the number of CT scans in high-risk patients, other imaging modalities or innovative approaches, such as liquid biopsy, are required

Intraoperative perfusion assessment of the proximal colon by a visual grading system for safe anastomosis after resection in left-sided colorectal cancer patients

We aimed to evaluate the clinical feasibility of a new visual grading system. We included 50 patients who underwent resection of primary colorectal cancer. Before anastomosis, the marginal vessel was cut and the perfusion status was assessed by a visual grading system. The visual grading system is comprised of five grades according to the bleeding from the marginal vessel and is categorized into 4 groups: good (grade A and B), moderate (grade C), poor (grade D) and none (grade E). Colorectal anastomosis was performed only in the good and moderate groups. We compared postoperative outcomes between the good and moderate groups and analysed the factors affecting the perfusion grade. Among the patients, 48% were grade A, 12% were grade B, and 40% were grade C. There was no anastomotic leakage. Only one patient with grade C showed ischemic colitis and needed reoperation. Age was the only factor correlated with perfusion grade in multivariate analysis (OR 1.080, 95% CI 1.006-1.159, p=0.034). The perfusion grades were significantly different between >65 and <65 year-old patients (>65, A 29.2% B 12.5% C 58.3% vs. <65, A 65.4% B 11.5% C 23.1%, p=0.006). Our intraoperative perfusion assessment that uses a cutting method and a visual grading system is simple and useful for performing a safe anastomosis after colorectal resection. If the perfusion grade is better than grade C, an anastomosis can be performed safely. Age was found to be an important factor affecting the perfusion grade