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ORIGINAL RESEARCH Table of Contents   
Year : 2009  |  Volume : 20  |  Issue : 1  |  Page : 21-25
The comparison of subjective image quality in conventional and digital panoramic radiography


1 Department of Oral Diagnosis and Radiology, Faculty of Dentistry, Gazi University, Ankara, Türkiye
2 Department of Statistics, Faculty of Arts and Sciences, Ankara, Türkiye

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Date of Submission02-Oct-2007
Date of Decision16-Mar-2008
Date of Acceptance16-Apr-2008
 

   Abstract 

Objective: The purpose of this study was to compare the subjective image quality of (1) regular intensifying screens with medium intensifying screens, (2) regular intensifying screens with digital radiography, and (3) medium intensifying screens with digital radiography for panoramic radiographs.
Materials and Methods: Forty-five patients participated and a total of 90 radiographs were obtained in the study. The patients were divided into three groups (regular-medium intensifying screen, regular intensifying screen-digital radiography, and medium intensifying screen-digital radiography) that consisted of 15 people each. All radiographs were assessed by three oral radiologists independently. The observers evaluated the images using a 3-point scale (1=well visible, 0=partly visible, -1=not or hardly visible) for anatomical structures and pathological findings that are commonly found on panoramic radiographs. Subjective image quality of the groups and comparison of the observers were assessed by using non parametric Kruskal Wallis and Mann-Whitney U tests.
Results: For all groups and observers, no statistically significant difference (p>0.05) was found for both anatomical structures and pathologies and between anatomical structures and pathologies according to the Mann Whitney U test. In comparison with observers, no statistically significant difference (p>0.05) was found for both anatomical structures and pathologies and between anatomical structures and pathologies for all groups according to the Kruskal Wallis test.
Conclusion: The subjective image quality of medium and regular intensifying screens and conventional and digital panoramic radiographs were found statistically equal in this study.

Keywords: Digital radiography, image quality, intensifying screens, panoramic radiography

How to cite this article:
Peker I, Toraman AM, Usalan G, Altunkaynak B. The comparison of subjective image quality in conventional and digital panoramic radiography. Indian J Dent Res 2009;20:21-5

How to cite this URL:
Peker I, Toraman AM, Usalan G, Altunkaynak B. The comparison of subjective image quality in conventional and digital panoramic radiography. Indian J Dent Res [serial online] 2009 [cited 2019 Sep 18];20:21-5. Available from: http://www.ijdr.in/text.asp?2009/20/1/21/49052
Panoramic radiographs are widely used to obtain a comprehensive survey of the maxillofacial complex. One of the advantages is reduction in radiation dose compared with a full-mouth intraoral survey. [1],[2]

Film-screen systems of medium intensifying screen (speed class 200) have been accepted in extraoral radiography. The problem up to now has been that a regular intensifying screen (speed class 400) has not been able to gain uniform acceptance in maxillofacial radiology. [3] The faster the screen, the lower the radiation dose to the patient but the less the detail of the final image. [4] However, most dental extraoral diagnostic tasks can be accomplished with screen-film combinations that have a speed of 400 or faster. [5]

In all aspects of radiography, digital images have become the new way of displaying radiographic data to the observer. [6] A growing number of dental practitioners prefer digital radiography instead of conventional film radiography. [7],[8] The advantages of digital techniques compared with film techniques are fast communication of images, the small storage space needed, and lower contamination of the environment. Digital radiographs can be obtained using storage phosphor plates or charge-coupled device (CCD) sensors. [6] Previous studies [9],[10],[11] demonstrated that digital panoramic radiographs are of satisfactory diagnostic value.

The purpose of this study was to compare the subjective image quality of (1) regular intensifying screens with medium intensifying screens, (2) regular intensifying screens with digital radiography, and (3) medium intensifying screens with digital radiography for panoramic radiographs.


   Materials and Methods Top


The study had been approved by the Ethical Committee of Gazi University, Faculty of Dentistry to fulfill the Helsinki Declaration.

Forty-five patients (22 females and 23 males) who required panoramic radiography for diagnostic purposes participated in this study. The exclusion criteria were pregnancy, age below 17 years old, occupational x-ray exposure, and patients with previous extensive radiographic examinations. The patients were divided into three groups of 15 people each. Two panoramic images of each 45 patients (90 radiographs) were obtained on separate days.

Conventional panoramic radiographs were obtained with a Trophy OP100 (Instrumentarium, Tuusula, Finland) panoramic unit. Medium (Eastman Kodak Co, Rochester, NY) and regular (Dr. Goos Suprema GmbH, Heidelberg, Germany) intensifying screens (15x30 cm cassette) and Kodak T Mat G films (Eastman Kodak Co, Rochester, NY) were used in this study. Film radiographs were developed in an automatic film processor (Velopex, Extra-X, Medivance Instruments Ltd, London, UK and NW107A) with freshly prepared solutions. Digital panoramic images were obtained with a Orthoralix 9200 DDE (Gendex Co, Milan, Italy) panoramic unit and a CCD-based system used with VixWin 2000 software (Gendex Co, Milan, Italy). The combinations of screens and a digital system are listed in [Table 1]. Representative images of screen and digital system combinations compared in the study are shown in [Figure 1],[Figure 2],[Figure 3].

All radiographs were assessed by three observers who are oral radiologists with at least 10 years of experience, independently. The observers evaluated the images using a 3-point scale [3] (1=well visible, 0=partly visible, -1=not or hardly visible) for anatomical structures and pathological findings, which are commonly found on panoramic radiographs [Table 2]. The film radiographs were assessed using a x2 magnification X-viewer (Luminosa, CSN Industrie, Italy) in a quiet room with subdued ambient lighting. Images from the digital system were displayed directly on a 17-inch monitor screen with 8-bit resolution in the same ambient lighting. The observers were not allowed to change window (contrast) and level (brightness) features of the software. To avoid observer fatigue, an interval of at least 1 week separated each viewing session.

Data Analysis

Subjective image quality of the groups and comparison of the observers were assessed using non parametric Kruskal Wallis and Mann-Whitney U tests. The Mann Whitney U test was performed in comparison with the first and second exposures and anatomic structures and pathological findings for each group and observer. The Kruskal Wallis test was performed in comparison with observers for the first and second exposures and anatomic structures and pathological findings. The level of statistical significance was α=0.05.


   Results Top


A total of 45 patients with a mean age of 21.60 years old participated and a total of 90 radiographs were obtained in this study.

For all groups and observers, no statistically significant difference (p>0.05) was found for both anatomical structures and pathologies and between anatomical structures and pathologies according to the results of Mann Whitney U test [Table 3].

In comparison with observers, no statistically significant difference (p>0.05) was found for both anatomical structures and pathologies and between anatomical structures and pathologies for all groups according to the results of the Kruskal Wallis test [Table 4].


   Discussion Top


Subjective image quality of the medium and regular intensifying screens for conventional panoramic radiography and conventional and CCD based digital panoramic radiographs were compared in this study.

In the study by Dannewitz, et al., [9] the subjective image quality of anatomical structures and pathological findings were assessed on digital panoramic images and the image quality of anatomical structures was assessed on various film-screen combinations and digital panoramic systems by Kaeppler, et al. [3] In this study, the subjective image quality of both anatomical structures and pathological findings were assessed on two different screens for conventional panoramic radiography and a digital panoramic system based on a CCD receptor.

It was reported that the difference between exposure settings of the medium and regular intensifying screens had been small and the advantage of the regular intensifying screen had not yet been proved. [3] Fast screens have large phosphor crystals and efficiently convert X-ray photons to visible light but produce images with lower resolution. As the size of the crystals or the thickness of the screen decreases, the speed of the screen also declines but image sharpness increases. Fast screens also have a thicker phosphor layer and a reflective layer, but these properties also decrease sharpness. [5] Fuhrmann, et al.[12] give priority to medium intensifying screen for diagnosis. Kaeppler, et al.[3] reported that the regular intensifying screens at a low tube potential level can replace medium intensifying screens. In this study, subjective image quality of the medium and regular intensifying screens was evaluated and no statistically significant differences were found for either anatomical structures or pathological findings for all observers.

In digital systems, there are several advantages such as fast communication of images, the small storage space needed, and lower contamination of the environment. [6] Digital systems allow for recording of electronic patient files, saving of time and digital image analysis such as zooming and optimal window and level settings. [13] Several authors [14],[15],[16] reported a dose reduction of about 40-70% in digital panoramic radiography compared with the conventional panoramic system. Subjective image qualities of conventional and digital panoramic radiographs were investigated in previous studies [6],[17],[18],[19] and they found the digital images to be comparable with conventional panoramic images. On the other hand, Gijbels, et al. [13] reported that digital panoramic images had poorer image quality than conventional panoramic images. There was no statistically significant difference between conventional panoramic images that were obtained with medium and regular screens and digital images for all observers in this study. These results are in accordance with other studies.

In digital radiology, the diagnosis frequently depends on the correct adjustment of window and level because by altering these parameters, lesions can be produced or faded away. [15] However, it was reported that the functions of image enhancement were useful for image quality. [6] The observers were not allowed to change window and level features of the software. The assessments were carried out under standardized conditions of the software in order to eliminate possible diagnostic differences in this study.

Repeatability and reproducibility is essential in evaluating the precision of any technique. High precision is important in ensuring consistency of the diagnosis between observers in clinical practice. Furthermore, it is of importance in the follow-up of patients over a period of time. [20] Interobserver agreements for panoramic radiography were investigated in several studies and they reported that the results varied from fair to almost perfect. [21],[22] Other studies [23],[24] that evaluated accuracy of radiographic methods showed differences in diagnostic performance between individual observers and they emphasized that this condition might have been due to differences in experience, training, or visual perception. There was no statistically significant difference between three observers for all systems in this study. This may be due to all observers being oral radiologists with at least 10 years of experience.

In conclusion, the subjective image quality of medium and regular intensifying screens and conventional and digital panoramic radiographs were found statistically equal in this study. Regular intensifying screens and digital panoramic systems provide relatively lower radiation dose to the patient than medium intensifying screens. Additionally, the advantages of digital techniques compared with film techniques are fast communication of images, the small storage space needed, and lower contamination of the environment. Clinicians should consider these conditions in dental practice.

 
   References Top

1.van Aken J, van der Linden L. The integral absorbed dose in conventional and panoramic complete-mouth examinations. Oral Surg Oral Med Oral Pathol 1966;22:603-16.  Back to cited text no. 1    
2.Freeman JP, Brand JW. Radiation doses of commonly used dental radiographic surveys. Oral Surg Oral Med Oral Pathol 1994;77:285-9.  Back to cited text no. 2    
3.Kaeppler G, Dietz K, Reinert S. The effect of dose reduction on the detection of anatomical structures on panoramic radiographs. Dentomaxillofac Radiol 2006;35:271-7.  Back to cited text no. 3    
4.Whaites E. Essentials of dental radiography and radiology. 3 rd ed. London: Mosby; 2002.  Back to cited text no. 4    
5.White SC, Pharoah MJ. Oral radiology: Principles and interpretation. 5 th ed. St. Louis: Mosby; 2004. p. 71-85.   Back to cited text no. 5    
6.Molander B, Grφndahl HG, Ekestubbe A. Quality of film-based and digital panoramic radiography. Dentomaxillofac Radiol 2004;33:32-6.  Back to cited text no. 6    
7.Whaites E, Brown J. An update on dental imaging. Br Dent J 1998;185:166-72.  Back to cited text no. 7    
8.Parks ET, Williamson GF. Digital radiography: An overview. J Contemp Dent Pract 2002;3:23-39.  Back to cited text no. 8    
9.Dannewitz B, Hassfeld S, Eickholz P, Mühling J. Effect of dose reduction in digital dental panoramic radiography on image quality. Dentomaxillofac Radiol 2002;31:50-5.  Back to cited text no. 9    
10.Schulze R, Krummenauer F, Schalldach F, d'Hoedt B. Precision and accuracy of measurements in digital panoramic radiography. Dentomaxillofac Radiol 2000;29:52-6.  Back to cited text no. 10    
11.Benediktsdottir IS, Hintze H, Petersen JK, Wenzel A. Accuracy of digital and film radiographs for assessment of position and morphology of mandibular third molars and prevalence of dental anomalies and pathologies. Dentomaxillofac Radiol 2003;32:109-15.  Back to cited text no. 11    
12.Fuhrmann A, Rother U, Tietke M, Schulze D. Folienlose intraorale Filme und Film-Folien-Kombinationen in der bildgebenden Diagnostik der Zahneikunde. ZWR 2001;110:140-4.   Back to cited text no. 12    
13.Gijbels F, De Meyer AM, Bou Serhal C, Van den Bossche C, Declerck J, Persoons M. The subjective image quality of direct digital and conventional panoramic radiography. Clin Oral Investig 2000;4:162-7.  Back to cited text no. 13    
14.Haβfeld S, Ziegler C, Mühling J. Kann die digitale Panoramaschichtrφntgentechnik das filmbasierte Verfahren ersetzten? Zahnδrztl Welt 1997;106:510-4.   Back to cited text no. 14    
15.Dula K, Sanderink G, van der Stelt PF, Mini R, Buser D. Effects of dose reduction on the detectability of standardized radiolucent lesions in digital panoramic radiography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;86:227-33.   Back to cited text no. 15    
16.Hildebolt CF, Fletcher G, Yokoyama-Crothers N, Conover GL, Vannier MW. A comparison of the response of storage phosphor and film radiography to small variations in X-ray exposure. Dentomaxillofac Radiol 1997;26:147-51.  Back to cited text no. 16    
17.Farman TT, Farman AG. Clinical trial of panoramic dental radiography using a CCD receptor. J Digit Imag 1998;11:169-71.  Back to cited text no. 17    
18.Kaeppler G, Axmann-Krcmar D, Reuter I, Meyle J, Gomez-Roman G. A clinical evaluation of some factors affecting image quality in panoramic radiography. Dentomaxillofac Radiol 2000;29:81-4.   Back to cited text no. 18    
19.Mastoris M, Li G, Welander U, McDavid WD. Determination of resolution of a digital system for panoramic radiography based on CCD technology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004;97:408-14.   Back to cited text no. 19    
20.Ledgerton D, Horner K, Devlin H, Worthington H. Panoramic mandibular index as a radiomorphometric tool: An assessment of precision. Dentomaxillofac Radiol 1997;26:95-100.   Back to cited text no. 20    
21.Ledgerton D, Horner K, Devlin H, Worthington H. Radiomorphometric indices of the mandible in a British female population. Dentomaxillofac Radiol 1999;28:173-81.   Back to cited text no. 21    
22.Lee K, Taguchi A, Ishii K, Suei Y, Fujita M, Nakamoto T, et al . Visual assessment of the mandibular cortex on panoramic radiographs to identify postmenopausal women with low bone mineral densities. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:226-31.  Back to cited text no. 22    
23.Syriopoulos K, Sanderink GC, Velders XL, van der Stelt PF. Radiographic detection of approximal caries: A comparison of dental films and digital imaging systems. Dentomaxillofac Radiol 2000;29:312-8.  Back to cited text no. 23    
24.Syriopoulos K, Velders XL, Sanderink GC, van Ginkel FC, van Amerongen JP, van der Stelt PF. The effect of developer age on the detection of approximal caries using three dental films. Dentomaxillofac Radiol 1999;28:208-13.  Back to cited text no. 24    

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Correspondence Address:
Ilkay Peker
Department of Oral Diagnosis and Radiology, Faculty of Dentistry, Gazi University, Ankara, Türkiye

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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-9290.49052

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    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]

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