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Change in Image Quality According to the 3D Locations of a CBCT Phantom.

Hwang JJ, Park H, Jeong HG, Han SS - PLoS ONE (2016)

Bottom Line: We evaluated and compared the voxel size, homogeneity, contrast to noise ratio (CNR), and the 10% point of the modulation transfer function (MTF10%) of the center and periphery.Because the CNR, homogeneity, and MTF10% were significantly affected by positional changes of the phantom, an object's position can influence the interpretation of follow up CBCT images.Therefore, efforts to locate the object in the same position are important.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul, Korea.

ABSTRACT
A patient's position changes in every CBCT scan despite patient alignment protocols. However, there have been studies to determine image quality differences when an object is located at the center of the field of view (FOV). To evaluate changes in the image quality of the CBCT scan according to different object positions, the image quality indexes of the Alphard 3030 (Alphard Roentgen Ind., Ltd., Kyoto, Japan) and the Rayscan Symphony (RAY Ind., Ltd., Suwon, Korea) were measured using the Quart DVT_AP phantom at the center of the FOV and 6 peripheral positions under four types of exposure conditions. Anterior, posterior, right, left, upper, and lower positions 1 cm offset from the center of the FOV were used for the peripheral positions. We evaluated and compared the voxel size, homogeneity, contrast to noise ratio (CNR), and the 10% point of the modulation transfer function (MTF10%) of the center and periphery. Because the voxel size, which is determined by the Nyquist frequency, was within tolerance, other image quality indexes were not influenced by the voxel size. For the CNR, homogeneity, and MTF10%, there were peripheral positions which showed considerable differences with statistical significance. The average difference between the center and periphery was up to 31.27% (CNR), 70.49% (homogeneity), and 13.64% (MTF10%). Homogeneity was under tolerance at some of the peripheral locations. Because the CNR, homogeneity, and MTF10% were significantly affected by positional changes of the phantom, an object's position can influence the interpretation of follow up CBCT images. Therefore, efforts to locate the object in the same position are important.

No MeSH data available.


Related in: MedlinePlus

Statistical analysis of image quality index values.(A) Voxel size. (B) Contrast to Noise Ratio (CNR). (C) Homogeneity. (D) 10% point of the modulation transfer function (MTF10%). C, P, and I represent cephalo, panorama, and implant modes of the Alphard 3030 CBCT, respectively. Ray is the Ray Symphony CBCT. Gray columns represent the center position, large nodes represent the values with statistically significant difference compared with the center, and black dotted lines represent the tolerance levels.
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pone.0153884.g004: Statistical analysis of image quality index values.(A) Voxel size. (B) Contrast to Noise Ratio (CNR). (C) Homogeneity. (D) 10% point of the modulation transfer function (MTF10%). C, P, and I represent cephalo, panorama, and implant modes of the Alphard 3030 CBCT, respectively. Ray is the Ray Symphony CBCT. Gray columns represent the center position, large nodes represent the values with statistically significant difference compared with the center, and black dotted lines represent the tolerance levels.

Mentions: The ICC of the image quality indexes were all above 0.96. Image quality indexes among the five repeated images taken from the same location showed different means and standard deviations. These values were varied according to the exposure protocols and the phantom’s location (Table 3). Four image quality indexes showed statistically significant differences at some of the peripheral locations. Moreover, those locations were different for each image quality index (Table 4, Fig 4).


Change in Image Quality According to the 3D Locations of a CBCT Phantom.

Hwang JJ, Park H, Jeong HG, Han SS - PLoS ONE (2016)

Statistical analysis of image quality index values.(A) Voxel size. (B) Contrast to Noise Ratio (CNR). (C) Homogeneity. (D) 10% point of the modulation transfer function (MTF10%). C, P, and I represent cephalo, panorama, and implant modes of the Alphard 3030 CBCT, respectively. Ray is the Ray Symphony CBCT. Gray columns represent the center position, large nodes represent the values with statistically significant difference compared with the center, and black dotted lines represent the tolerance levels.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4836729&req=5

pone.0153884.g004: Statistical analysis of image quality index values.(A) Voxel size. (B) Contrast to Noise Ratio (CNR). (C) Homogeneity. (D) 10% point of the modulation transfer function (MTF10%). C, P, and I represent cephalo, panorama, and implant modes of the Alphard 3030 CBCT, respectively. Ray is the Ray Symphony CBCT. Gray columns represent the center position, large nodes represent the values with statistically significant difference compared with the center, and black dotted lines represent the tolerance levels.
Mentions: The ICC of the image quality indexes were all above 0.96. Image quality indexes among the five repeated images taken from the same location showed different means and standard deviations. These values were varied according to the exposure protocols and the phantom’s location (Table 3). Four image quality indexes showed statistically significant differences at some of the peripheral locations. Moreover, those locations were different for each image quality index (Table 4, Fig 4).

Bottom Line: We evaluated and compared the voxel size, homogeneity, contrast to noise ratio (CNR), and the 10% point of the modulation transfer function (MTF10%) of the center and periphery.Because the CNR, homogeneity, and MTF10% were significantly affected by positional changes of the phantom, an object's position can influence the interpretation of follow up CBCT images.Therefore, efforts to locate the object in the same position are important.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul, Korea.

ABSTRACT
A patient's position changes in every CBCT scan despite patient alignment protocols. However, there have been studies to determine image quality differences when an object is located at the center of the field of view (FOV). To evaluate changes in the image quality of the CBCT scan according to different object positions, the image quality indexes of the Alphard 3030 (Alphard Roentgen Ind., Ltd., Kyoto, Japan) and the Rayscan Symphony (RAY Ind., Ltd., Suwon, Korea) were measured using the Quart DVT_AP phantom at the center of the FOV and 6 peripheral positions under four types of exposure conditions. Anterior, posterior, right, left, upper, and lower positions 1 cm offset from the center of the FOV were used for the peripheral positions. We evaluated and compared the voxel size, homogeneity, contrast to noise ratio (CNR), and the 10% point of the modulation transfer function (MTF10%) of the center and periphery. Because the voxel size, which is determined by the Nyquist frequency, was within tolerance, other image quality indexes were not influenced by the voxel size. For the CNR, homogeneity, and MTF10%, there were peripheral positions which showed considerable differences with statistical significance. The average difference between the center and periphery was up to 31.27% (CNR), 70.49% (homogeneity), and 13.64% (MTF10%). Homogeneity was under tolerance at some of the peripheral locations. Because the CNR, homogeneity, and MTF10% were significantly affected by positional changes of the phantom, an object's position can influence the interpretation of follow up CBCT images. Therefore, efforts to locate the object in the same position are important.

No MeSH data available.


Related in: MedlinePlus