Imaging Science in Dentistry

Korean Academy of Oral and Maxillofacial Radiology (대한영상치의학회)
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Contrast reference values in panoramic radiographic images using an arch-form phantom stand

  • Shin, Jae-Myung (Department of Oral and Maxillofacial Surgery, Ilsan Paik Hospital, Inje University College of Medicine) ;
  • Lee, Chena (Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University) ;
  • Kim, Jo-Eun (Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University) ;
  • Huh, Kyung-Hoe (Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University) ;
  • Yi, Won-Jin (Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University) ;
  • Heo, Min-Suk (Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University) ;
  • Choi, Soon-Chul (Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University) ;
  • Lee, Sam-Sun (Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University)
  • Received : 2016.02.14
  • Accepted : 2016.04.06
  • Published : 2016.09.30
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Abstract

Purpose: The purpose of this study was to investigate appropriate contrast reference values (CRVs) by comparing the contrast in phantom and clinical images. Materials and Methods: Phantom contrast was measured using two methods: (1) counting the number of visible pits of different depths in an aluminum plate, and (2) obtaining the contrast-to-noise ratio (CNR) for 5 tissue-equivalent materials (porcelain, aluminum, polytetrafluoroethylene [PTFE], polyoxymethylene [POM], and polymethylmethacrylate [PMMA]). Four panoramic radiographs of the contrast phantom, embedded in the 4 different regions of the arch-form stand, and 1 real skull phantom image were obtained, post-processed, and compared. The clinical image quality evaluation chart was used to obtain the cut-off values of the phantom CRV corresponding to the criterion of being adequate for diagnosis. Results: The CRVs were obtained using 4 aluminum pits in the incisor and premolar region, 5 aluminum pits in the molar region, and 2 aluminum pits in the temporomandibular joint (TMJ) region. The CRVs obtained based on the CNR measured in the anterior region were: porcelain, 13.95; aluminum, 9.68; PTFE, 6.71; and POM, 1.79. The corresponding values in the premolar region were: porcelain, 14.22; aluminum, 8.82; PTFE, 5.95; and POM, 2.30. In the molar region, the following values were obtained: porcelain, 7.40; aluminum, 3.68; PTFE, 1.27; and POM, - 0.18. The CRVs for the TMJ region were: porcelain, 3.60; aluminum, 2.04; PTFE, 0.48; and POM, - 0.43. Conclusion: CRVs were determined for each part of the jaw using the CNR value and the number of pits observed in phantom images.

Keywords

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