J Meikai Dent Med 46 1, 7 21, 2017 7 2 45 2 2 XY 45 2 1 2 1 2 2 2 XY 45 2 2 3 2 4 5 3 3 100 μm 50 μm 100 μm 3 3 MTF High Resolution Image of Panoramic Radiography by Applying 2-Dimensional Super-resolution Technique Yoshihiro SAITO, Maki IZAWA, Chihiro FUSHIMI, Tomonori OZAWA, Nobutoshi TAKAHASHI and Yasuhiko OKUMURA Division of Dental Radiology, Department of Diagnostic & Therapeutic Science, Meikai University School of Dentistry Abstract : Thetwo dimensional super resolution technology has been reported. A detector, which was set at a 45 degree angle, was moved in the diagonal direction of pixel to collect images. In this collection process, the images were synthesized to recon
8 46 2017 struct the super-resolved image in the two dimensional direction. It has been clarified that this technology is effective in the coordinate system created by rotating the conventional XY coordinates 45 degrees and that the resolution is twice as high as Nyquist frequency of detector. The objective of the study is to apply this technology to the panoramic X-ray system with the aim of its clinical application. In the experiment, the clinically used X-ray generator and detector were used to prepare the experimental panoramic X-ray equipment of single axis rotation. Then, the image reconstruction algorithm of curved cross-sectional images was developed to apply the twodimensional super resolution technology to panoramic radiography. The requirements for practical application of super-resolution technology to panoramic X-ray equipment were also examined. Consequently, the following conclusions were obtained. 1. The frequency response of panoramic image of one-dimensional super resolution showed a cutoff frequency twice as high as Nyquist frequency of image detector medium. 2. It was confirmed that the panoramic image of two-dimensional super resolution was formed in two dimensions created by rotating the conventional XY coordinates 45 degrees. The frequency response showed a cutoff frequency twice as high as Nyquist frequency of image selection recording medium. 3. Two-dimensional super resolution was clinically applied to take X-ray images of maxillary anterior teeth of dried human skull. The results demonstrated super-resolved images were better than panoramic images in terms of resolution. 4. When compared with images obtained by intraoral radiography, super-resolved images were equivalent to film images in terms of resolution. Super-resolved images were better than film images in terms of graininess. Key words : digital X-ray photography, super-resolution, modulation transfer function MTF, improvement of resolution 3 1, 2 1950 1963 Lukosz 3 2 2003 4 Lukosz 1.8 Lukosz 1 2 350-0283 1-1 2009 5 2 2 Detector Moving and Frame Additional TechniqueDEMOT 1 2014 6 1 2
2 9 1 2 1 2 45 2 2 XY 45 2 2 6 2 6 2 1 2 1 1 1 Fig 1 ω r 1 rω Fig 1 Algorithm of the panoramic image by the parallel beam Fig 2 Algorithm of the panoramic image by the fan beam R W r 1 rω RW 1 Fig 2 r 1 rω B/A 2 r rω B/ARW 2 2 2 1 2 5 Fig 3
10 46 2017 Fig 3 Image reconstruction algorithm of the super-resolution 10 1/10 Fig 3 P1 1 10 1/10 10 P1 P2 10 1 1 160 8cm 9 10 3 2 2 2 6 Fig 4 Fig 5 The head of dental cone beam CT X-ray image detector 2 1 1 CT E2 Fig 4 SXR-90-0.2 0.2 0.2 mm 60 kv 4.0 ma Cd-Te Cmos SCAN 300 FPY OyAFAT, ESPOO, FinlandFig 5 100 100 μm 60 1,300 300 fps CTN 120 G Fig 6 0.198 8cm1
2 11 160 80 cm 76 cm Fig 71.05 Fig 8 2 3 0.7 0.7 mm60 kv 1mA 0.1 Insight Film Kodak, NY DENT-X AFP imaging, NY RG-D RG-F 4 Type 6 MTF R-1 W 3 1 2 Fig 6 Turn table Fig 7 Geometric arrangement of the simulator Fig 8 Experimental apparatus
12 46 2017 2 1 1 80 rps 8cm 6 moduration transfer functionmtf 1.05 edge spread function ESF line spread functionlsf LSF MTF 3 2 1 2 Fig 9 45 rotate of detector Fig 9 45 2 2 1 20 cm 3cm 2 2 MTF MTF 45 XY 4 2 2 2 2 1 Fig 10 5 cycles/mm 3 cycles/mm
2 13 Fig 10 Test chart image A : Test chart reconstruction image at simulator B : Test chart image by conventional method panoramic tomography Fig 11 1-dimensional super-resolution image of test chart A : Test chart image by conventional method panoramic tomography B : Test chart image by One-dimensional super-resolution technique 2 1 Fig 11 1 X Fig 12 JISz 4704, 2005 8 5 LP/mm 8 LP/mm Fig 13 MTF 10 cycles/mm 5 cycles/mm 2
14 46 2017 Fig 12 Test chart by 1-dimensional super-resolution image and conventional method panoramic tomography enlarged image A : Conventional method panoramic image B : One-dimensional super-resolution image Fig 13 MTF of 1-dimensional super-resolution image and conventional method panoramic image A : Conventional method panoramic image B : 1-dimensional super-resolution image 2 3 2 Fig 14 2 XY 45 Fig 14 XY 2 45 2 Fig 15 2 Fig 16 2 Fig 17 45 XY XY 9 10 cycles/mm Fig 13 1 45 2 2 1 2
2 15 Fig 14 2-dimensional super-resolution image enlarged image comparison due to the inclination of the test chart A : Reconstructed image of the test chart grid was the vertical and horizontal to the floor B : Reconstructed image of the test chart grid was 45 rotated Fig 15 Comparison of the 2-dimensional super-resolution image and the conventional method panoramic image A : Conventional method panoramic image B : 2-dimensional super-resolution image 4 2 Fig 18 2 Fig 19 A Fig 20-A Fig 20-B 2 Fig 21 Fig 21-A Fig 22
16 46 2017 Fig 16 Comparison of the 2-dimensional super-resolution image and the intraoral radiography image enlarged image A : Intraoral radiography image B : 2-dimensional super-resolution image Fig 17 XY-axis direction MTF of the 2-dimensional superresolution image at 45 detector arrangement A : X-axis direction B : Y-axis direction 1960 7-12 2000 13-15 2 16-18 1 ASA 1,000 1 100 100 μm 13 15, 16, 19-21
2 17 Fig 18 Comparison of the 2-dimensional super-resolution image and the conventional method panoramic image on dry maxillary anterior bone A : Conventional method panoramic image B : 2-dimensional super-resolution image Fig 19 Comparison of the 2-dimensional super-resolution image and the conventional method panoramic image on dry maxillary anterior bone low-enlarged image at apical part A : Conventional method panoramic image B : 2-dimensional super-resolution image 1 Fig 10 Fig 10 1.05 0.2 mm 1.2 1.3 0.5 mm 10 μm 100 150 μm
18 46 2017 Fig 20 Comparison of the 2-dimensional super-resolution image and the conventional method panoramic image on dry maxillary anterior bone high-enlarged image at apical part A : Conventional method panoramic image B : 2-dimensional super-resolution image Fig 21 Comparison of the 2-dimensional super-resolution image and the intraoral radiography image on dry maxillary anterior bone magnification A : Intraoral radiography image B : 2-dimensional super-resolution image 22 2 1 1 1 10 cycles/mm 5 cycles/mm 2 5 6
2 19 Fig 22 Comparison of the 2-dimensional super-resolution image and the intraoral radiography image on dry maxillary anterior bone low-enlarged image at apical part A : Intraoral radiography image B : 2-dimensional super-resolution image Fig 23 Image established theory on XY coordinate system of the 45 detector 3 2 Fig 14 2 Y X Fig 14 45 XY 2 Fig 23 2 XY 45 6 5 2 1 2 Fig 16 20 cycles/mm 7 0.7 0.7 mm 1.15 105 μm 100 μm 10 μm
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