• Title, Summary, Keyword: Extra-Phase Image

Search Result 5, Processing Time 0.038 seconds

Extra-phase Image Generation for Its Potential Use in Dose Evaluation for a Broad Range of Respiratory Motion

  • Lee, Hyun Su;Choi, Chansoo;Kim, Chan Hyeong;Han, Min Cheol;Yeom, Yeon Soo;Nguyen, Thang Tat;Kim, Seonghoon;Choi, Sang Hyoun;Lee, Soon Sung;Kim, Jina;Hwang, JinHo;Kang, Youngnam
    • Journal of Radiation Protection and Research
    • /
    • v.44 no.3
    • /
    • pp.103-109
    • /
    • 2019
  • Background: Four-dimensional computed tomographic (4DCT) images are increasingly used in clinic with the growing need to account for the respiratory motion of the patient during radiation treatment. One of the reason s that makes the dose evaluation using 4DCT inaccurate is a change of the patient respiration during the treatment session, i.e., intrafractional uncertainty. Especially, when the amplitude of the patient respiration is greater than the respiration range during the 4DCT acquisition, such an organ motion from the larger respiration is difficult to be represented with the 4DCT. In this paper, the method to generate images expecting the organ motion from a respiration with extended amplitude was proposed and examined. Materials and Methods: We propose a method to generate extra-phase images from a given set of the 4DCT images using deformable image registration (DIR) and linear extrapolation. Deformation vector fields (DVF) are calculated from the given set of images, then extrapolated according to respiratory surrogate. The extra-phase images are generated by applying the extrapolated DVFs to the existing 4DCT images. The proposed method was tested with the 4DCT of a physical 4D phantom. Results and Discussion: The tumor position in the generated extra-phase image was in a good agreement with that in the gold-standard image which is separately acquired, using the same 4DCT machine, with a larger range of respiration. It was also found that we can generate the best quality extra-phase image by using the maximum inhalation phase (T0) and maximum exhalation phase (T50) images for extrapolation. Conclusion: In the present study, a method to construct extra-phase images that represent expanded respiratory motion of the patient has been proposed and tested. The movement of organs from a larger respiration amplitude can be predicted by the proposed method. We believe the method may be utilized for realistic simulation of radiation therapy.

Optical Encryption of a Binary Image by Phase Modulation of the Wavefront

  • Song, Jaehun;Moon, Inkyu;Lee, Yeonho
    • Journal of the Optical Society of Korea
    • /
    • v.20 no.3
    • /
    • pp.358-362
    • /
    • 2016
  • We present a new scheme for optical encryption of a binary image. In our method, the original binary data page is first divided into two identical pages. In each data page, the “on” and “off” pixels are represented by two discrete phases that are 90° apart. The first page corresponds to the phase conjugation of the second page, and vice versa. In addition, the wavefront of the two data pages is changed simultaneously from planar to spherical, for better encryption. The wavefront modification is represented by an extra phase shift, which is a function of position on the wavefront. In this way the two separate pages are both encrypted, and therefore the pages cannot be distinguished in a CCD. If the first page is used as an encrypted data page, then the second page is used as the decryption key, and vice versa. The decryption can be done by simply combining the two encrypted data pages. It is shown in our experiment that encryption and decryption can be fully accomplished in the optical domain.

Enhanced robust data embedding techniques (내성을 강화한 data embedding기법)

  • 정인식;권오진
    • Proceedings of the IEEK Conference
    • /
    • /
    • pp.247-250
    • /
    • 2002
  • Data embedding has recently become important for protecting authority. In this paper, we Propose a robust data embedding technique for images. Our techniques are based on the convolution between message image and a random phase carrier. We add extra bits with carrier image to improve precision of detecting rate, moreover, we use block by block based cyclic correlation for the compensation of distortion. In experiment, we show that the proposed a1gorithm is robust to Stirmark 3.1. attacks.

  • PDF

A Current Dynamic Analysis Based Open-Circuit Fault Diagnosis Method in Voltage-Source Inverter Fed Induction Motors

  • Tian, Lisi;Wu, Feng;Shi, Yi;Zhao, Jin
    • Journal of Power Electronics
    • /
    • v.17 no.3
    • /
    • pp.725-732
    • /
    • 2017
  • This paper proposed a real-time, low-cost, fast transistor open-circuit fault diagnosis method for voltage-source inverter fed induction motors. A transistor open-circuit changes the symmetry of the inverter topology, leading to different similarities among three phase load currents. In this paper, dynamic time warping is proposed to describe the similarities among load currents. The proposed diagnosis is independent of the system model and needs no extra sensors or electrical circuits. Both simulation and experimental results show the high efficiency of the proposed fault diagnosis method.

Implementation of Self-frequency Synchronizing Circuit using Single-sideband Up-converter and Image Rejection Mixer (단측파대 상향변환기와 이미지제거 혼합기를 이용한 자기동조회로의 구현)

  • Yeom, Seong-Hyeon;Kim, Tae-Young;Kim, Tae-Hyun;Park, Boem-June
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.13 no.6
    • /
    • pp.1058-1063
    • /
    • 2010
  • In this paper, we designed self-frequency synchronizing circuit using image rejection mixer(IRM) and single-sideband(SSB) up-converter which can effectively eliminate the image frequencies occurred in multi-channel super-heterodyne receivers and help us to match inter-channel phase. Also the self-frequency synchronizing circuit simplifies system because there need no extra devices for making intermediate frequency(IF) by creating the local signal within several nanoseconds by means of generating the same frequency of IF signal and modulating radio frequency(RF) signal. We adopt the limiting amplifier for the purpose of protecting the circuit from spurious signals which come from the front end side having wide instantaneous bandwidth characteristics and constantly injecting same level into the input local signal of IRM. The IRM we fabricated has image rejection ratio of 27dB, which is good over 7dB for foreign company's. Also, the SSB up-converter we fabricated has 1dB compression point of 18dBm, which is good over 16dB for foreign company's. And the size is compact about one-forth.