title: Quantification of the accuracy limits of image registration using peak signal-to-noise ratio.
abstract: 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.
authors.affiliation: Department of Radiology, Yamaguchi University Hospital, 1-1-1, Minamikogushi, Ube, Yamaguchi, Japan. tanabey@yamaguchi-u.ac.jp.|Division of Health Sciences, Graduate School of Medicine, Osaka University, 1-7, Yamadaoka, Suita, 565-0871, Japan. tanabey@yamaguchi-u.ac.jp.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Tanabe
authors.affiliation: Division of Health Sciences, Graduate School of Medicine, Osaka University, 1-7, Yamadaoka, Suita, 565-0871, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ishida
mesh_terms: D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009038:Motion; D019047:Phantoms, Imaging; D061089:Radiotherapy, Image-Guided; D059629:Signal-To-Noise Ratio; D014867:Water
chemical_list: D014867:Water
keywords: Adaptive radiotherapy; Geometric uncertainty; Image registration; Image-guided radiotherapy; Peak signal-to-noise ratio; Setup accuracy