Automatic exposure compensation in intraoral digital radiography: effect on the gray values of dental tissues (original) (raw)
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The purpose of this paper is to present a comparison of doses delivered to the patients when dealing with intra-oral, panoramic and CT dental examinations. The technology progress will be discussed from a dose and an image quality point of view. DAP values were measured for two intra-oral systems using speed D and E/F dental films, and a digital system in two different acquisition modes (CCD technology). For each system the DQE was also assessed. DWP and DAP were measured on three panoramic systems of various generations of units. Finally, CTDI w and DLP were measured using a standard CT (Dentascan) and a new tomographic system (NewTom) in order to assess the dose delivered when planning dental implants. The use of an E/F system instead of the D system allowed to reduce the DAP by a factor of 2 (respectively 56 and 24 mGy⋅cm 2) without significant loss of image quality. A further dose reduction by a factor of four was possible with digital systems but with a significant loss of spat...
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.
1993
Typical 35-mm slide scanners use a photodiode array and software that allows for digital and analog controls that are manually adjustable. The digital controls provide brightness and contrast adjustments, whereas corresponding analog controls adjust the exposure time and black level that determines the clamping level of the charge-coupled device for the maximum black in the image. The objective of this study was to determine the effects of these controls on the radiometric data of intraoral dental radiograph images, to establish recommended settings, and to set specific standard guidelines for the digitization process, Three approaches were used. The results of this study demonstrate that brightness and contrast control alterations on the digitizer produces different optical densities and modulation transfer function values, The impact of these results is unresolved yet must be considered in analysis on quantitative radiometric studies. (ORAL SURC ORAL MED ORAL PATHOL 1993;76:510-8)
Dentomaxillofacial Radiology, 2009
The aim of this study was to evaluate the performance of a quantitative method, based on pixel grey value measurements, for monitoring caries remineralization. Methods: Proximal radiographs of 11 patients (61 enamel caries lesions) were taken both before and after a 2 month remineralization protocol. Radiographs were digitized and for each area a follow-up image was subtracted from a baseline image. A quantitative analysis was undertaken using ImageTool software
Image analysis of endodontic radiographs: digital subtraction and quantitative densitometry
Dental Traumatology, 1990
In this study computerized image analysis procedures were applied to endodontic radiographs. Kontron IBAS 2000 is a commercially available image analysis system with processing routines applicable to radiograph digitizing and transformations. The system was evaluated for: its ability to harmonize blackening and contrast in endodontie radiographs; its ability to compensate for angulation distortion of sequential exposures of individual teeth; its potential for applieation of digital subtraction methods; and its use in automated gray-level analyses of diseased and healthy bone areas in endodontic radiographs. The Kontron IBAS 2000 system proved suitable for all applieations. However, the speciflcity of the subtraction procedure was limited by some inherent problems in the harmonization of blackening and in the subtraction process itself. On the other hand, automated gray level measurements proved to be a robust method for unbiased and quantitative assessment of healing of apical periodontitis.
Influence of cone beam CT scanning parameters on grey value measurements at an implant site
Dentomaxillofacial Radiology, 2013
Objectives: The aim of this study was to determine the grey value variation at the implant site with different scan settings, including field of view, spatial resolution, number of projections, exposure time and dose selections in two cone beam CT (CBCT) systems and to compare the results with those obtained from a multislice CT system. Methods: A partially edentulous human mandibular cadaver was scanned by three CT modalities: multislice CT (MSCT) (Philips, Best, the Netherlands), and two CBCT systems: (Accuitomo 170, Morita, Japan) and (NewTom 5G, QR, Verona, Italy). Using different scan settings 36 and 24 scans were obtained from the Accuitomo and the NewTom, respectively. The scans were converted to digital imaging and communications in medicine 3 format. The analysis of the data was performed using 3Diagnosys software (ver.3.1, 3diemme, Cantù, Italy) and Geomagic (studioH 2012, Morrisville, NC). On the MSCT scan, one probe designating the site for pre-operative implant placement was inserted. The inserted probe on MSCT was transformed to the same region on each CBCT scan using a volume-based threedimensional registration algorithm. The mean voxel grey value of the region around the probe was derived separately for each CBCT. The influence of scanning parameters on the measured mean voxel grey values was assessed. Results: Grey values in both CBCT systems significantly deviated from HU values measured with MSCT (p50.0001). In both CBCT systems, scan field of view (FOV) and spatial resolution selections had a statistically significant influence on grey value measurements (p50001). The number of projections selection had a statistically significant influence in the Accuitomo system (p50.0001) while exposure time and dose selections had no statistically significant influence on grey value measurements in the NewTom (p50.43 and p50.37, respectively). Conclusions: Grey level values from CBCT images are influenced by device and scanning settings.
Exposure reduction and image quality in orthodontic radiology: A review of the literature
American Journal of Orthodontics and Dentofacial Orthopedics, 1988
This article summarizes the use of rare earth screen technology to achieve high-quality panoramic and cephalometric radiographs with sizable reductions in patient radiation dosage. Collimation, shielding, quality control, and darkroom procedures are reviewed to further reduce patient risk and improve image quality.