Comparisons of physical imaging properties among three kinds of imaging plates used in photostimulable phosphor systems for dental radiography

Comparison of two digital intraoral radiography imaging systems as a function of contrast resolution and exposure time

BACKGROUND

To compare the image quality of two different digital imaging systems; one photostimulable phosphor plate system (PSP) and a direct digital radiography system with CMOS imaging sensor; via evaluating contrast resolution among four different exposure times.

METHODS

Endodontically treated incisor teeth embedded in paraffin blocks are aligned next to a 99.5% Al wedge and exposed for 0.8, 0.1,0.125 and 0.16 seconds using both the CMOS and PSP systems. Using ImageJ software, 5 isometric and isogridded ROI from each root filling area and isometric ROI from the Al stepwedge were calculated.

RESULTS

Evaluation of the total of 120 images displayed that PSP system produced significantly higher contrast resolution (P<0.05) in regard to pixel values than the CMOS. The CMOS system was non- responsive to increasing dose (P=0.000). Regarding the EqAl values, no significant difference was determined between groups (P>0.05).

CONCLUSIONS

The contrast resolution was higher using the PSP system. It can be estimated that, filling material will be more obvious under lower doses using PSP.

The missing link in image quality assessment in digital dental radiography

Digital radiography is gaining popularity among general dental practitioners. It includes digital intraoral radiography, digital panoramic radiography, digital cephalography, and cone-beam computed tomography. In this study, we focused on the methods to assess image quality of these techniques, except for digital cephalography, in the light of historical issues. We stressed on the importance of the development of a standardized phantom and quantitative analysis of diagnostic image quality using it, especially in the aspect of psychophysical properties of these digital systems. There is no missing link in the image quality assessment in digital intraoral radiography and cone-beam computed tomography in dental use. However, there are missing links between physical and diagnostic image qualities in panoramic radiography. The development of a semi-standardized phantom and the corresponding quantitative analysis method for image quality may be required in digital panoramic radiography. Quantitative image quality assessment using a standardized phantom will also be promising in the future artificial intelligence era.

Rating the extent of surface scratches on photostimulable storage phosphor plates in a dental school environment

OBJECTIVE

The aims of this study were (1) to subjectively quantify the degree of scratching and smudging that had taken place in the junior clinic in the 9 months following the implementation of digital radiology; (2) to compare the findings with a previously published report; and (3) to identify areas in the protocol and training that can be refined to minimize future scratching and smudging.

METHODS

Seven sets of blank clinical photostimulable storage phosphor (PSP) plates were scanned after exposing them at 65 kV and 7 mA for 0.80 s. Scanned plates were lightly wiped with a soft cloth and alcohol, repackaged in plastic sleeves, re-exposed and rescanned. The two sets of resulting images were subjectively rated independently by two investigators for artefacts and placed in five categories.

RESULTS

Of all the images, approximately 75% were rated in the top 3 categories (most readable), leaving 17% and 8% in the poor and unsatisfactory categories, respectively. Mean rated values of the two image sets (before and after wiping) were not statistically different, but ratings slightly improved after cleaning the plates.

CONCLUSIONS

Wiping all plates to remove surface contamination may not always be necessary or desirable. Systems that are designed to minimize handling of the plates may help minimize scratching of them.

Quality of film-based and digital panoramic radiography

OBJECTIVES

To compare the image quality of panoramic radiographs obtained with storage phosphor plate and screen-film systems.

METHODS

Panoramic radiographs were taken in 60 patients both with film and with a storage phosphor plate system (30 with DenOptix (Dentsply/Gendex) and 30 with Digora PCT). The images were obtained with either the Cranex Tome or the Scanora multimodal X-ray unit. The screen-film combination was Lanex medium/Curix Ortho HT-G. The digital images were displayed as 8-bit images with a 300 dpi resolution on a 19" monitor and the film images were placed on a light box adjacent to the screen. Ten observers evaluated diagnostic image quality by means of visual grading analysis of different anatomical structures. The structures were scored as being visualized much better (5), better (4), equal (3), worse (2) or much worse (1) in the digital images than in the film images. The mean number of patients receiving the different scores was calculated. Statistical methods used were Wilcoxon sign rank test and Mann-Whitney test.

RESULTS

On average, visualization was equal in 19 of the 30 patients imaged using Digora PCT; in 10 it was worse. The corresponding values for DenOptix were 20 and 9. The difference between the film-based and the digital images was small but statistically significant (P<0.0001). The difference between the two image plate systems was not statistically significant (P>/=0.17).

CONCLUSIONS

It was concluded that digital panoramic radiographs are equivalent to film-based images for most purposes.