• Title/Summary/Keyword: Linear Observer

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Bladder filling variations during concurrent chemotherapy and pelvic radiotherapy in rectal cancer patients: early experience of bladder volume assessment using ultrasound scanner

  • Chang, Jee Suk;Yoon, Hong In;Cha, Hye Jung;Chung, Yoonsun;Cho, Yeona;Keum, Ki Chang;Koom, Woong Sub
    • Radiation Oncology Journal
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    • v.31 no.1
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    • pp.41-47
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    • 2013
  • Purpose: To describe the early experience of analyzing variations and time trends in bladder volume of the rectal cancer patients who received bladder ultrasound scan. Materials and Methods: We identified 20 consecutive rectal cancer patients who received whole pelvic radiotherapy (RT) and bladder ultrasound scan between February and April 2012. Before simulation and during the entire course of treatment, patients were scanned with portable automated ultrasonic bladder scanner, 5 times consecutively, and the median value was reported. Then a radiation oncologist contoured the bladder inner wall shown on simulation computed tomography (CT) and calculated its volume. Results: Before simulation, the median bladder volume measured using simulation CT and bladder ultrasound scan was 427 mL (range, 74 to 1,172 mL) and 417 mL (range, 147 to 1,245 mL), respectively. There was strong linear correlation (R = 0.93, p < 0.001) between the two results. During the course of treatment, there were wide variations in the bladder volume and every time, measurements were below the baseline with statistical significance (12/16). At 6 weeks after RT, the median volume was reduced by 59.3% to 175 mL. Compared to the baseline, bladder volume was reduced by 38% or 161 mL on average every week for 6 weeks. Conclusion: To our knowledge, this study is the first to prove that there are bladder volume variations and a reduction in bladder volume in rectal cancer patients. Moreover, our results will serve as the basis for implementation of bladder training to patients receiving RT with full bladder.

Interobserver agreement for detecting Hill-Sachs lesions on magnetic resonance imaging

  • Alkaduhimi, Hassanin;Saarig, Aimane;Amajjar, Ihsan;van der Linde, Just A.;van Wier, Marieke F.;Willigenburg, Nienke W.;van den Bekerom, Michel P.J.
    • Clinics in Shoulder and Elbow
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    • v.24 no.2
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    • pp.98-105
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    • 2021
  • Background: Our aim is to determine the interobserver reliability for surgeons to detect Hill-Sachs lesions on magnetic resonance imaging (MRI), the certainty of judgement, and the effects of surgeon characteristics on agreement. Methods: Twenty-nine patients with Hill-Sachs lesions or other lesions with a similar appearance on MRIs were presented to 20 surgeons without any patient characteristics. The surgeons answered questions on the presence of Hill-Sachs lesions and the certainty of diagnosis. Interobserver agreement was assessed using the Fleiss' kappa (κ) and percentage of agreement. Agreement between surgeons was compared using a technique similar to the pairwise t-test for means, based on large-sample linear approximation of Fleiss' kappa, with Bonferroni correction. Results: The agreement between surgeons in detecting Hill-Sachs lesions on MRI was fair (69% agreement; κ, 0.304; p<0.001). In 84% of the cases, surgeons were certain or highly certain about the presence of a Hill-Sachs lesion. Conclusions: Although surgeons reported high levels of certainty for their ability to detect Hill-Sachs lesions, there was only a fair amount of agreement between surgeons in detecting Hill-Sachs lesions on MRI. This indicates that clear criteria for defining Hill-Sachs lesions are lacking, which hampers accurate diagnosis and can compromise treatment.

Scar formation after lower eyelid incision for reconstruction of the inferior orbital wall related to the lower eyelid crease or ridge in Asians

  • Oh, Seong Jin;Kim, Kwang Seog;Choi, Jun Ho;Hwang, Jae Ha;Lee, Sam Yong
    • Archives of Craniofacial Surgery
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    • v.22 no.6
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    • pp.310-318
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    • 2021
  • Background: Transcutaneous lower eyelid approaches are associated with a risk of postoperative scarring depending on the distance between the incision line and the lower eyelid margin. The lower eyelid crease of Caucasians corresponds to a ridge-shaped fold in young Asians. However, this relationship has not been sufficiently evaluated in the latter. The authors, therefore, investigated the location of the scar and the lower eyelid crease or ridge to find the optimal location for the incision line. Methods: This study included 60 out of 139 patients who underwent inferior orbital wall reconstruction through a lower eyelid skin incision between July 2019 and June 2020. According to the location of the scar, the patients were classified into three groups: group A (≥ 2 mm above the lower eyelid crease or ridge), group B (within the lower eyelid crease or ridge to 2 mm above the lower eyelid crease or ridge), and group C (within the lower eyelid crease or ridge to 2 mm below the lower eyelid crease or ridge). At 6 or 12 months after surgery, the Patient and Observer Scar Assessment Scale (POSAS) score was obtained, the distance between the lower eyelid margin and the scar (DMS) and the distance between the margins of the peripheral pupil and the lower eyelid (DMPE) were measured, and the occurrence of ectropion was evaluated. Results: Group B had the lowest POSAS score (A: 22.7 ± 8.0, B: 20.9 ± 2.4, C: 32.5 ± 4.1, p< 0.001). Linear regression analysis showed that the DMS was positively correlated with the POSAS score (p< 0.001) and that the risk of DMPE widening increased as the DMS decreased (p= 0.029). None of the patients had ectropion. Conclusion: When using the transcutaneous approach for inferior orbital wall reconstruction, the optimal incision site is within the lower eyelid crease or ridge to 2 mm above the lower eyelid crease or ridge.

Sex determination from lateral cephalometric radiographs using an automated deep learning convolutional neural network

  • Khazaei, Maryam;Mollabashi, Vahid;Khotanlou, Hassan;Farhadian, Maryam
    • Imaging Science in Dentistry
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    • v.52 no.3
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    • pp.239-244
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    • 2022
  • Purpose: Despite the proliferation of numerous morphometric and anthropometric methods for sex identification based on linear, angular, and regional measurements of various parts of the body, these methods are subject to error due to the observer's knowledge and expertise. This study aimed to explore the possibility of automated sex determination using convolutional neural networks(CNNs) based on lateral cephalometric radiographs. Materials and Methods: Lateral cephalometric radiographs of 1,476 Iranian subjects (794 women and 682 men) from 18 to 49 years of age were included. Lateral cephalometric radiographs were considered as a network input and output layer including 2 classes(male and female). Eighty percent of the data was used as a training set and the rest as a test set. Hyperparameter tuning of each network was done after preprocessing and data augmentation steps. The predictive performance of different architectures (DenseNet, ResNet, and VGG) was evaluated based on their accuracy in test sets. Results: The CNN based on the DenseNet121 architecture, with an overall accuracy of 90%, had the best predictive power in sex determination. The prediction accuracy of this model was almost equal for men and women. Furthermore, with all architectures, the use of transfer learning improved predictive performance. Conclusion: The results confirmed that a CNN could predict a person's sex with high accuracy. This prediction was independent of human bias because feature extraction was done automatically. However, for more accurate sex determination on a wider scale, further studies with larger sample sizes are desirable.

The Influence of Sensory Interference Arising from View-Height Differences on Visual Short-Term Memory Performance (조망 높이의 차이가 초래한 감각적 간섭이 시각단기기억 수행에 미치는 영향)

  • Ka, Yaguem;Hyun, Joo-Seok
    • Science of Emotion and Sensibility
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    • v.23 no.1
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    • pp.17-28
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    • 2020
  • Lowering observers' view-height may increase the amount of occlusion across objects in a visual scene and prevent the accurate identification of the objects in the scene. Based on this possibility, memory stimuli in relation to their expected views from different heights were displayed in this study. Thereafter, visual short-term memory (VSTM) performance for the stimuli was measured. In Experiment 1, the memory stimuli were presented on a grid-background drawn according to linear perspectives, which varied across observers' three different view-heights (high, middle, and low). This allowed the participants to remember both the color and position of each memory stimulus. The results revealed that testing participants' VSTM performance for the stimuli under a different memory load of two set-sizes (3 vs. 6) demonstrated an evident drop of performance in the lowest view-height condition. In Experiment 2, the performance for six stimuli with or without the grid-background was tested. A similar pattern of performance drop in the lowest condition as in Experiment 1 was found. These results indicated that different view-heights of an observer can change the amount of occlusion across objects in the visual field, and the sensory interference driven by the occlusion may further influence VSTM performance for those objects.

Polarimetry of solar system small bodies using the Seoul National University 61cm telescope and TRIPOL

  • Jin, Sunho;Ishiguro, Masateru;Kwon, Yuna Grace;Geem, Jooyeon;Bach, Yoonsoo P.;Seo, Jinguk;Sasago, Hiroshi;Sato, Shuji
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.64.2-64.2
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    • 2019
  • It is known that lights scattered by comets and asteroids are partially polarized. From polarimetric observations of those objects, we can investigate physical properties, such as albedos, sizes of cometary dust particles and regolith of asteroids. Since the polarization degrees of those objects highly depend on their phase angles (Sun-object-observer's angles), long-term monitoring observations are required. Moreover, comets show unforeseeable activations (i.e., outbursts) which need follow-up observations to understand the mechanism. In order to realize such monitoring and transient observations, we installed the Triple-Range Imager and POLarimeter (TRIPOL) on the 61cm telescope of Seoul National University (Hereafter, SNU) Gwanak campus. With this combination, we can obtain g', r', i' bands photopolarimetric images simultaneously with $8.0^{\prime}{\times}8.0^{\prime}$ field of view and pixel resolution of 0.94" pixel-1. Here, we make a presentation regarding the photometric and polarimetric performances of TRIPOL on the SNU 61cm telescope. In addition, we introduce initial polarimetric results of asteroid and comets with the instruments. First, we determine the limiting magnitudes (defined as magnitudes for S/N=5) of $15.17{\pm}0.06$ (g'-band), $15.68{\pm}0.01$ (r'-band), $16.24{\pm}0.03$ (I'-band), respectively, with total 240-seconds exposure (four 60-seconds exposure images, each was taken at different rotation angle for the half-wave plate). Second, we found that the instrumental polarization is negligibly small, ($-0.32{\pm}0.04%$ in the g', $-0.36{\pm}0.05%$ in the r' and $-0.21{\pm}0.04%$ in the i'-bands), while the polarization efficiencies are large enough to maximize the performance (i.e., $97.52{\pm}0.03%$ in the g', $98.83{\pm}0.02%$ in the r' and $99.15{\pm}0.02%$ in the i'-bands). With the instruments, we made observations of three Jupiter-family comets, 21P/Giacobini-Zinner, 38P/Stephan-Oterma, and 46P/Wirtanen and plan to observe one near-Earth asteroid, (433) Eros, on a trial basis. Especially for comets, we discriminate signals from dust and gas to eliminate gas contamination, which are known to change observed degree of linear polarization, using multi-band images. We confirm that the phase angle dependency of these comets are consistent with previous observations, probably because polarimetric property of Jupiter-family comets are broadly homogeneous unlike asteroids. We will also describe future observation plans using TRIPOL and SNU 61cm telescope.

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Development of Unfolding Energy Spectrum with Clinical Linear Accelerator based on Transmission Data (물질투과율 측정정보 기반 의료용 선형가속기의 에너지스펙트럼 유도기술 개발)

  • Choi, Hyun Joon;Park, Hyo Jun;Yoo, Do Hyeon;Kim, Byoung-Chul;Yi, Chul-Young;Min, Chul Hee
    • Journal of Radiation Protection and Research
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    • v.41 no.1
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    • pp.41-47
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    • 2016
  • Background: For the accurate dose assessment in radiation therapy, energy spectrum of the photon beam generated from the linac head is essential. The aim of this study is to develop the technique to accurately unfolding the energy spectrum with the transmission analysis method. Materials and Methods: Clinical linear accelerator and Monet Carlo method was employed to evaluate the transmission signals according to the thickness of the observer material, and then the response function of the ion chamber response was determined with the mono energy beam. Finally the energy spectrum was unfolded with HEPROW program. Elekta Synergy Flatform and Geant4 tool kits was used in this study. Results and Discussion: In the comparison between calculated and measured transmission signals using aluminum alloy as an attenuator, root mean squared error was 0.43%. In the comparison between unfolded spectrum using HEPROW program and calculated spectrum using Geant4, the difference of peak and mean energy were 0.066 and 0.03 MeV, respectively. However, for the accurate prediction of the energy spectrum, additional experiment with various type of material and improvement of the unfolding program is required. Conclusion: In this research, it is demonstrated that unfolding spectra technique could be used in megavoltage photon beam with aluminum alloy and HEPROW program.

Video Camera Characterization with White Balance (기준 백색 선택에 따른 비디오 카메라의 전달 특성)

  • 김은수;박종선;장수욱;한찬호;송규익
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.41 no.2
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    • pp.23-34
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    • 2004
  • Video camera can be a useful tool to capture images for use in colorimeter. However the RGB signals generated by different video camera are not equal for the same scene. The video camera for use in colorimeter is characterized based on the CIE standard colorimetric observer. One method of deriving a colorimetric characterization matrix between camera RGB output signals and CIE XYZ tristimulus values is least squares polynomial modeling. However it needs tedious experiments to obtain camera transfer matrix under various white balance point for the same camera. In this paper, a new method to obtain camera transfer matrix under different white balance by using 3${\times}$3 camera transfer matrix under a certain white balance point is proposed. According to the proposed method camera transfer matrix under any other white balance could be obtained by using colorimetric coordinates of phosphor derived from 3${\times}$3 linear transfer matrix under the certain white balance point. In experimental results, it is demonstrated that proposed method allow 3${\times}$3 linear transfer matrix under any other white balance having a reasonable degree of accuracy compared with the transfer matrix obtained by experiments.

Geographical Structure of View Point in the Landscape Experience on Mountain in Yangsan City (경관체함이 발생하는 조망점의 지리구조에 관한 연구;양산시 소재 산지를 대상으로)

  • Kang, Young-Jo;Cha, Young-Chae;Cha, Myeong-Sook
    • Journal of the Korean Institute of Landscape Architecture
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    • v.36 no.3
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    • pp.75-84
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    • 2008
  • The purpose of this research is to find the visual characteristics and geographic structure in a landscape of mountains in Yangsan City. In order to carry out this study, 40 view points of 6 mountains in Yangsan City were selected to experience the mountainscape. The results are as follows. The mountainscape of Yangsan City was confirmed from the view point to the object of view as ranging in middle distance reverse, the angle of elevation 11${\sim}13^{\circ}$ which give the impression of confronted to the mountain, and the horizontal angle 50${\sim}90^{\circ}$ which gives the impression of vastness. This shows that mountainscapes are perceived impressively when seeing the mountain with the meaning to feel the texture of the mountain as a confrontational relationship rather than a pictorial relationship. The geographic structure of the view point which occurs in scenes of impressive experience is classified into eight types and its characteristics are investigated. The first type is corridor, and it emerges in a long narrow linear structure made from the surrounding environment with buildings or street trees. The second is tunnel in which a vision and light hidden while passing underneath a bridge, high-level road, or inside a tunnel can be seen. Third, the maze is formed by the mountain shape. The hill spur emerges when the direction of traffic changes after turning the coner of a building or mountain edge. The hill ground emerges at the top of a hill slope. Next, parallel emerges when the observer and the mountain are in the same direction of process. Confrontation occurs when confronting an isolated mountain. Finally, the view point emerges when passing through major points such as a bridge or square and the boundary of a village or city. This research arranged visual conditions that create impressive mountainscapes. Geographic characteristics in terms of Types that make possible to experience mountainscapes were described. The results of this research will be basic data collected for the management and preservation of mountainscapes and for landscape effect evaluation. Furthermore, this research suggests theoretical evidence to preserve and manage geographic structures that create view experiences as well as to preserve the landscape in terms of view points.