Effects of scanning resolution and digital image magnification on photostimulable phosphor imaging system
- 41 Downloads
To examine the effects of changes in scanning resolution and digital magnification on the image quality and diagnostic ability of the photostimulable phosphor imaging system.
Using a photostimulable phosphor imaging system, images of a human adult dried mandible phantom embedded in a 25 mm-thick epoxy resin block were made. The latent images on the photostimulable phosphor imaging plate were scanned using four different pixel sizes as follows: 25μm×25μm, 50μm×50μm, 100μm×100μm and 200μm×200μm. A primary image was produced for each pixel size. These images were also digitally magnified at powers of 2, 4 and 8 times. The gradient range, brightness and contrast of each image were adjusted to optimum levels on a cathode ray tube display, and hard copies were produced with a writing pixel size of 60μm×60μm. The granularity, sharpness and anatomical diagnostic ability of the images were assessed subjectively by eight dentists.
Increasing the scanning resolution tended to generally improve image quality and diagnostic ability. Visual image quality was maintained up to a pixel size of 50 μm, and diagnostic ability was maintained up to a pixel size of 100μm. Digital image magnification degrated image quality, and more than 2-times magnification degraded diagnostic ability.
Under the present experimental conditions, increasing the scanning resolution did not always lead to an improvement in image quality or diagnostic ability, and digital image magnification degraded image quality and diagnostic ability.
Key WordsPhotostimulable phosphor imaging system Scanning resolution Digital magnificatio
- 6).Sanderink, G.C.H., Huiskens, R., Van der Stelt, P.F., Welander, U.S. and Stheeman, S.E.: Image quality of direct digital intraoral X-ray sensors in assessing root canal length: The Radio Visio Graphy, Visualix/VIXA, Sens-A-Ray, and Flash Dent systems compared with Ektaspeed films.Oral Surg. Oral Med. Oral Pathol. 78: 125–132, 1994.PubMedCrossRefGoogle Scholar
- 7).Tsuchiya, T.: Visual recognition of spatial frequency information in diagnostic intraoral roentgenograms.Dent. Radiology. 28: 267–284, 1988 (in Japanese)Google Scholar
- 8).Sato, S.: A study on evaluation of dental films by digital image processing: analysis of alveolar trabecular by means of two-dimensional FFT.Dent. Radiology. 26: 242–253, 1986 (in Japanese)Google Scholar
- 10).Isu, T. and Sakurai, T.: Spatial frequency processing conditions on intraoral computed radiography.Oral Radiol. 12: 27–38, 1996Google Scholar
- 12).Svanaes, D.B., Moystad, A., Risnes, S., Larheim, T.A. and Gröndahl, H.G.: Intraoral storage phosphor radiography for approximal caries detection and effect of image magnification: Comparison with conventional radiography.Oral Surg. Oral Med. Oral Pathol. 82: 94–100, 1996.Google Scholar
- 17).Hayakawa, Y., Farman, A.G., Kelly, M.S. and Kuroyanagi, K.: Intraoral radiographic storage phosphor image mean pixel values and signal-to-noise ratio: effects of calibration.Oral Surg. Oral Med. Oral Pathol. 86: 601–605, 1998Google Scholar
- 20).Yoshiura, K., Kawazu, T., Chikui, T., Tatsumi, M., Tokumori, K., Tanaka, T. and Kanda, S.: Assessment of image quality in dental radiography, part 2: Optimum exposure conditions for detection of small mass changes in 6 intraoral radiography systems.Oral Surg. Oral Med. Oral Pathol. 87: 123–129, 1999Google Scholar