Computerized method for measurement of displacement vectors of target positions on EPID cine images in stereotactic radiotherapy

Hidetaka Arimura, Shigeo Anai, Satoshi Yoshidome, Katsumasa Nakamura, Yoshiyuki Shioyama, Satoshi Nomoto, Hiroshi Honda, Yoshihiko Onizuka, Hiromi Terashima

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)


The purpose of this study was to develop a computerized method for measurement of displacement vectors of target position on electronic portal imaging device (EPID) cine images in a treatment without implanted markers. Our proposed method was based on a template matching technique with cross-correlation coefficient between a reference portal (RP) image and each consecutive portal (CP) image acquired by the EPID. EPID images with 512×384 pixels (pixel size:0.56 mm) were acquired in a cine mode at a sampling rate of 0.5 frame/sec by using an energy of 4, 6, or 10MV on linear accelerators. The displacement vector of the target on each cine image was determined from the position in which took the maximum cross-correlation value between the RP image and each CP image. We applied our method to EPID cine images of a lung phantom with a tumor model simulating respiratory motion, and 5 cases with a non-small cell lung cancer and one case of metastasis. For validation of our proposed method, displacement vectors of a target position calculated by our method were compared with those determined manually by two radiation oncologists. As a result, for lung phantom images, target displacements by our method correlated well with those by the oncologists (r=0.972 - 0.994). Correlation values for 4 cases ranged from 0.854 to 0.991, but the values for the other two cases were 0.609 and 0.644. This preliminary result suggested that our method may be useful for monitoring of displacement vectors of target positions without implanted markers in stereotactic radiotherapy.

Original languageEnglish
Title of host publicationMedical Imaging 2007
Subtitle of host publicationImage Processing
EditionPART 2
Publication statusPublished - 2007
EventMedical Imaging 2007: Image Processing - San Diego, CA, United States
Duration: Feb 18 2007Feb 20 2007

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
NumberPART 2
ISSN (Print)1605-7422


OtherMedical Imaging 2007: Image Processing
Country/TerritoryUnited States
CitySan Diego, CA

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Biomaterials
  • Radiology Nuclear Medicine and imaging


Dive into the research topics of 'Computerized method for measurement of displacement vectors of target positions on EPID cine images in stereotactic radiotherapy'. Together they form a unique fingerprint.

Cite this