Radiological Physics and Technology

, Volume 10, Issue 1, pp 91–94 | Cite as

Quantification of the accuracy limits of image registration using peak signal-to-noise ratio

  • Yoshinori TanabeEmail author
  • Takayuki Ishida


A new method was developed for quantifying the accuracy limits of image registration devices and the distortion of anatomical structures in verification images without image registration. A correlation was found between peak signal-to-noise ratio (PSNR) and the amount of parallel movement (1–10 mm at 1-mm intervals) of a rectangular parallelepiped phantom [correlation coefficient (CC) −0.91, contribution ratio (CR) 0.83]. Rotating the phantom from 1° to 10° at 1° intervals produced a similar correlation with PSNR (CC −0.91, CR 0.83). To allow for manual registration, the grid pattern of the Mylar top plate was extracted from 455 pelvic portal images of 21 patients using a band-pass filtering technique. This revealed a different correlation between the original data (CC −0.62, CR 0.38) and averaged data (CC −0.96, CR 0.92), but this is considered to have been caused by structural distortion and manual matching errors. Thus, PSNR can be used to evaluate the accuracy limits of image registration and provide a judgment index that can be used in re-planning or re-setup in adaptive radiotherapy.


Setup accuracy Peak signal-to-noise ratio Image registration Image-guided radiotherapy Geometric uncertainty Adaptive radiotherapy 


Compliance with ethical standards


This study was funded by a Kazuya Yamashita Grant of the Japanese Society of Radiological Technology (Grant Number 1).

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Japanese Society of Radiological Technology and Japan Society of Medical Physics 2016

Authors and Affiliations

  1. 1.Department of RadiologyYamaguchi University HospitalUbeJapan
  2. 2.Division of Health SciencesGraduate School of Medicine, Osaka UniversitySuitaJapan

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