Using GafChromic film to estimate the effective dose from dental cone beam CT and panoramic radiography.

OBJECTIVES: To demonstrate the feasibility of GafChromic(®) XR-QA2 (ISP Corp., Wayne, NJ) as a dosemeter when performing measurements of the effective dose from three cone beam CT (CBCT) units and to compare the doses from examinations of three common dental clinical situations. A second aim was to compare the radiation doses for three digital panoramic units with the doses for the CBCT units. METHODS: The CBCT units used were Veraviewepocs 3De(®) (J Morita MFG Corp., Kyoto, Japan), ProMax(®) 3D (Planmeca, Helsinki, Finland) and NewTom VGi(®) (Quantitative Radiology, Verona, Italy). GafChromic XR-QA2 films were placed between the selected layers of the head and neck of a tissue-equivalent human skull (RANDO(®) phantom; The Phantom Laboratory, Salem, NY). The exposure parameters were set using the automatic exposure control function of the units. Depending on the availability, medium and smaller field of view (FOV) scanning modes were used. The effective dose was estimated using the 2007 International Commission on Radiological Protection formalism. RESULTS: The lowest effective dose of a CBCT unit was observed for ProMax 3D, FOV 4 × 5 cm (10 µSv), the highest for NewTom VGi, FOV 8 × 8 cm-high resolution (129 µSv). The range of effective doses for digital panoramic machines measured was 8-14 µSv. CONCLUSIONS: This study demonstrates the feasibility of using radiochromic films for dental CBCT and panoramic dosimetry.

Is it true that the radiation dose to which patients are exposed has decreased with modern radiographic films?

OBJECTIVES: To determine whether the radiation dose administered to patients has decreased with new radiographic films and digital imaging systems. METHODS: A total of 10 171 official reports on radiological practice in dental surgeries (covering the years 1996-2003) from 16 Spanish autonomous regions were studied, analysing the type of film used, the exposure times and the radiation doses administered in each dental clinic for four different teeth: upper molar, lower molar, upper incisor and lower incisor. RESULTS: The Agfa Dentus M2 radiographic film needed the longest exposure times for all of the teeth (0.6 s, 0.5 s, 0.4 s and 0.4 s, respectively) followed in decreasing order by Ultraspeed, Insight, Ektaspeed and the digital systems, the decrease with respect to the first reaching as much as 60%. Regarding the dose administered, Agfa Dentus M2 used the highest dose (3.1 mGy) followed by Ultraspeed (2.7 mGy), Insight (2.2 mGy), Ektaspeed (2.2 mGy) and, finally, the digital systems (1.1 mGy). Statistical analysis showed significant differences between the doses administered for the digital systems with respect to the radiographic films (P < 0.001) and with respect to manual or automatic processing (P < 0.001). However, there were no significant differences in dose between the different types of films themselves, or between the radiographic developing processes themselves (manual and automatic). CONCLUSION: Not even the use of the most sensitive of modern films has brought about a reduction of the dose administered to patients in Spain. Only digital systems, it seems, will bring about reduction in this dose.

Digital enhancement of radiographs for assessment of interproximal dental caries.

OBJECTIVES: Evaluation of a particular digital caries image-enhancing mode (filter) for its effect on the validity of measurements of caries lesion depth. METHODS: Standardized radiographs of 44 extracted teeth exhibiting interproximal caries lesions were obtained. Six radiographs were obtained of each tooth and digitized. Four radiographs were made using D-speed film with and without soft tissue scattering equivalent (STSE) at normal exposure time (0.32 s) and underexposed (0.16 s). Two were made using E-speed film with STSE normally (0.16 s) and underexposed (0.08 s). On each of the 264 radiographs, 4 independent examiners measured the central depth (CD) of 1 carious lesion per tooth both on the unchanged radiographic image and after use of the filter. Histometric CD assessments provided a gold standard for comparison with the radiographic measurements (validity). Repeated measures ANOVA was calculated for validity in relation to examiner, lesion type, filter, film type, exposure time and STSE. RESULTS: The lesion type was identified to statistically significantly influence the validity of CD measurements. Examiner in combination with defect type (P<0.001), filter (P = 0.017), exposure (P = 0.027) and film type (P = 0.044) had an additional albeit small effect. CONCLUSIONS: The lesion type significantly influenced the validity of CD measurements: enamel lesions were less underestimated than dentin lesions.

In vitro comparison of four different dental X-ray films and direct digital radiography for proximal caries detection.

This study investigated the efficiency of different speeds of conventional intraoral films and a direct digital system for proximal caries detection. In this study, 48 extracted human posterior permanent teeth were used. Conventional bitewing radiographs and direct digital radiographs were obtained from the teeth. Three observers independently assessed 96 proximal surfaces, each observer had 10 years of experience. The presence or absence of caries was scored according to a five-point scale. True caries depth was determined by histological examination. The diagnostic accuracy of each radiographic system was assessed by means of a receiver operating characteristic (ROC) curve analysis. The mean of areas under the ROC curve (Az) was analyzed by pairwise comparison of ROC curve. The interobserver agreement was evaluated by using ANOVA analysis. The statistical analysis of Az scores exhibited no significant difference for the five imaging modalities (p > 0.05). There was no statistically significant difference between interobserver agreements (p > 0.05). The results of this study showed that the diagnostic performance of E- and F-speed films and direct digital radiography are similar for proximal caries detection.

Survey of dental radiological practice in Turkey.

OBJECTIVES: The aim of this study was to determine the dentist's knowledge about dose reduction techniques, radiographic equipment and quality of dental radiographic service in general dental practice in Turkey. METHODS: The survey was performed on 636 dentists who attended the 11th International Congress organized by the Turkish Dental Association. Information on the demographic characteristics of the dentists, radiographic equipment, techniques and processing they used and radiation protection was obtained with a 32 point questionnaire. RESULTS: The respondents' knowledge concerning the technical details of their equipment was limited, with 512 (86.9%) not knowing the kilovoltage peak (kVp) of their machine. Only 34 (5.5%) respondents reported having rectangular collimators. The dentists had little knowledge about the speed of film they used. D-speed film was the most preferred one with 21.6%. Fifty-eight (10.2%) dentists used E-speed film and the F-speed film was used only by 13 (2.3%) dentists. The most preferred technique (62%) for periapical radiography was the bisecting angle technique. Four hundred and eighty five (82.5%) of the dentists reported that they took the radiographs by themselves. CONCLUSIONS: In the present study, the results indicate that for minimizing any unnecessary radiation, attempts should be made to improve dentists' knowledge about radiation dose reduction techniques.

Psychophysical properties of a new F-speed intraoral film.

OBJECTIVES: To compare the psychophysical properties of the new Kodak InSight F-speed intraoral dental film with those for the E-speed Ektaspeed Plus film by means of the perceptibility curve (PC) test. METHODS: A specially designed test object was used. The test object was made of aluminium and was 10 mm thick. It contained ten holes, contrast details, with the same diameter of 1.5 mm but with different depths. The depths ranged from 0.03 mm to 0.30 mm in steps of 0.03 mm. The holes were placed randomly within a square area with a total of 16 possible positions. Radiographs of the test object were obtained over the full exposure ranges of the two films. A Combex DX-907 dental X-ray unit was used operating at 10 mA and two tube potentials, 70 kVp and 90 kVp. The focus-to-object distance was 50 cm. Ten observers evaluated the radiographs under uniform artificial lighting using a view box and stated the number of perceptible representations of contrast details. In order to construct perceptibility curves, absolute values of the reciprocal of the minimum perceptible logarithmic exposure differences, 1/(DeltalogE)min, were plotted as functions of the logarithm of exposures, logE, registered by the tested films. Comparisons between the two films were made separately for the two tube potentials, 70 kVp and 90 kVp. RESULTS: The results are presented graphically. PCs for the InSight film had higher peaks than those for the Ektaspeed Plus film. This indicates that the viewers were able to perceive smaller exposure differences in the former compared with the latter. PCs for the InSight film were shifted towards the left along the exposure axis relative to the PCs for the Ektaspeed Plus film indicating that the former film is more sensitive than the latter. The integrals of the PCs for InSight film were larger than those for Ektaspeed film indicating superior psychophysical properties of the InSight film. CONCLUSIONS: From the point of view of perception, the new InSight film has such psychophysical properties in comparison with Ektaspeed Plus film that it will be the more favourable of the two in clinical radiographic practice.

In vitro carious lesion detection on D-, E-, and F-speed radiographic films.

OBJECTIVES: To compare the accuracy in detection of interproximal natural carious lesions in vitro between Ultraspeed (D), Ektaspeed Plus (E), and Insight (F) radiographic films. STUDY DESIGN: Ten observers indicated on a 5-point scale their confidence in detecting an interproximal lesion in 240 surfaces (120 extracted teeth) with noncavitated carious lesions. Truth was assessed microscopically from hemisections. The areas (Az) beneath receiver operating characteristic (ROC) curves were pairwise compared and used for a 2-way analysis of variance. RESULTS: Az values were significantly correlated with observers (P=.002; Eta=0.671) and film type (P=.003; Eta=0.412). E differed significantly (mean Az: 0.624) from both D (mean Az: 0.591; P=.028) and F (mean Az: 0.594; P=.037), although the 95% confidence intervals clearly overlapped. CONCLUSION: The superior performance of Ektaspeed failed to prove clinical relevance.

Reliability of digital radiography of interproximal dental caries.

PURPOSE: To compare the effects of different image processing modes (filters) on the reproducibility and validity of the assessment of interproximal carious lesions viewed in digitized radiographic images. MATERIALS AND METHODS: Variables studied were film type, exposure time, and tissue scatter radiation. Images were assessed in relation to film type, exposure time and tissue scatter. Standardized radiographs of 50 extracted teeth were obtained and 44 areas of interproximal caries were detected. Six radiographs were obtained of each tooth and digitized using FRIACOM software. Four were made using D-type film with and without soft tissue scatter equivalent at normal exposure time (0.32 seconds) and underexposed (0.16 seconds). Two were made using E-type film with TSE normal (0.16 seconds) and underexposed (0.08 seconds). On each of the 300 radiographs, the central depth (CD) of each carious lesion was measured at 18x magnification both on the unchanged radiographic image and after use of two different filters. All measurements were repeated after 1 week to estimate reproducibility. RESULTS: Histometric CD assessments provided a gold standard for comparison with the radiographic measurements (validity). Whereas reproducibility was not influenced by one of the filters, filter "structure" improved the overall validity of CD measurements. In this study, digital manipulations of radiographic images resulted in statistically significant improvement of the validity of CD measurements.

The use of radiation dose-reduction techniques in the practices of dental faculty members.

X-ray exposure to dental patients has been significantly reduced by the introduction of speed group E intraoral film, rectangular beam limitation, long position indicating devices (PIDs), and rare-earth intensifying screens for extraoral radiography. Research indicates that many dentists do not use these techniques. However, schools of dentistry have implemented them to varying degrees for many years, so this investigation was conducted to determine the extent to which dental school faculty members use these materials and techniques in their own practices. Comparisons were made between full- and part-time instructors, those in practice for fifteen years or less and those in practice for more than fifteen years, and those with postgraduate education versus those with no formal education beyond dental school. The significance of differences was measured with chi-square analysis. The results indicate that dentists with faculty appointments utilize dose-reducing techniques to degrees that are comparable to or greater than reported usage by non-dental faculty practitioners. Faculty dentists in practice fifteen years or less are more likely than their older colleagues to use E-speed film (p = 0.001), whereas those in practice more than fifteen years are more likely to use longer PIDs (p = 0.049). Greater acceptance of these practices by faculty may lead to reinforcement of their use in the clinical education of dental students.

[Roentgenological materials on the Russian market]. / Rentgenograficheskie materialy na Rossiikom rynke.

The paper outlines the qualitative parameters of radiographic medical films and methods of their evaluation by Russian and foreign experts. A classification of their films is presented. The Russian methods and equipment for film examination do not satisfy the objective testing of up-to-date radiographic materials.

An in-vitro evaluation of Kodak Insight and Ektaspeed Plus film with a CMOS detector for natural proximal caries: ROC analysis.

This study compared the diagnostic efficacy of Kodak Ektaspeed Plus film, Kodak Insight film, a newly introduced E/F-speed film, and Schick CMOS-APS digital sensor, with respect to caries detection in 92 proximal surfaces of extracted unrestored teeth, 51 of which were carious. Ground truth was evaluated histologically and the lesions classified as enamel or dentinal. Eight observers read the radiographs using a five-point confidence rating scale to record their diagnoses. Analyses using receiver operating characteristic curves revealed the areas under each curve that indicated the diagnostic accuracy (Ektaspeed Plus - 0.760, Insight - 0.778 and CMOS-APS sensor - 0.732). ANOVA revealed significant differences with respect to caries depth (p<0.031) and observers (p<0.0001). Weighted kappa analyses indicated moderate to substantial inter- and intra-observer agreement (0.42 and 0.66, respectively). The results suggest that none of the imaging modalities evaluated in this study differed in their diagnostic capabilities with respect to proximal decay detection and that the Insight film which was used with 20% less radiation exposure than Ektaspeed Plus film was as good as the other two sensors for this purpose.

Sensitometric comparison of speed group E and F dental radiographic films.

OBJECTIVE: To evaluate the sensitometric characteristics of Insight, (Eastman Kodak, Rochester, NY, USA) a new F-speed film, in fresh and depleted processing solutions and compare them with Ektaspeed Plus. METHODS: Two sets each of Insight (IP) and Ektaspeed Plus (EP) films were exposed to radiation levels ranging from 10.7 to 685.2 microGy. One set of films was processed in fresh chemicals while the other set was processed in solutions that had been used for 5 days to process over 500 radiographs. Unexposed films of both types were processed in both solutions to determine base-plus-fog density. Speed and contrast were measured according to ISO definitions and at other levels of density. RESULTS: IP was in speed group F as measured at optical density 1 above base-plus-fog when processed under both conditions. It was 25% faster than EP when both were processed in new solutions and 35% faster in the old solutions, permitting a 20-24% reduction in exposure time. The speeds of both film types decreased when processed in used solutions, but the decrease was smaller for IP than for EP. Speeds at other density levels were greater for IP than EP. Contrast as defined by ISO, and over other density ranges, was similar for both films. CONCLUSIONS: Insight is an F-speed film with a speed at least 25% greater than Ektaspeed Plus. IP is more resistant than Ektaspeed Plus to decreases in speed when processed in used chemicals. Contrast of IP and EP is comparable over several density ranges.

Sensitometric properties of Agfa Dentus OrthoLux, Agfa Dentus ST8G, and Kodak Ektavision panoramic radiographic film.

OBJECTIVES: The purpose of this study was to compare the sensitometric properties of and visualization of anatomical structures with Agfa OrthoLux green-sensitive panoramic radiographic film, Agfa ST8G green sensitive panoramic radiographic film, and Kodak Ektavision green-sensitive panoramic radiographic film used in combination with an Agfa Ortho Regular 400 imaging screen, Kodak Ektavision imaging screen, and Kodak Lanex Regular imaging screen. METHODS: The density response and resolution of panoramic radiographic film/intensifying screen combinations was evaluated by means of Hunter and Driffield curves, modulation transfer functions, and noise-equivalent number of quanta. Image clarity of selected anatomical structures was rated independently by 6 oral and maxillofacial radiologists. RESULTS: The ISO speed for the Agfa OrthoLux panoramic radiographic film combinations was the fastest, and the ISO speed for the Kodak Ektavision green-sensitive panoramic radiographic film combinations was the slowest. The average gradient for the Agfa ST8G systems was relatively steep in comparison with those for the other film/screen combinations. The modulation transfer functions for the Kodak Ektavision film were higher than those for the other films, irrespective of the screen combination used, and those for Agfa OrthoLux film were slightly higher than those for Agfa ST8G film. The noise-equivalent number of quanta for the Agfa ST8G film/screen combinations was lower than those for the other film/screen combinations. The noise-equivalent number of quanta for the Kodak Ektavision film/screen combinations was well within the high-frequency range, whereas Agfa OrthoLux combined with either the Kodak Ektavision imaging screen or the Kodak Lanex Regular imaging screen produced a noise-equivalent number of quanta similar to those of the Kodak Ektavision film/screen combinations in the low-frequency range. Agfa OrthoLux was perceived to provide clearer images of the selected anatomical details than Agfa ST8G, and the Agfa OrthoLux/Agfa Ortho Regular 400 combination was not significantly different from the Kodak Ektavision/Kodak Lanex Regular combination in terms of perceived image quality. CONCLUSION: Agfa OrthoLux is an improvement over Agfa ST8G in film speed, spatial resolution, granularity, and perceived diagnostic image quality. The Agfa OrthoLux/Agfa Ortho Regular 400 combination did not exceed the Kodak Ektavision film/Kodak Ektavision imaging screen combination in resolution, granularity, or perceived image quality.

Radiographic detection of approximal caries: a comparison of dental films and digital imaging systems.

OBJECTIVES: To compare the diagnostic accuracy for the detection of approximal caries of two dental X-ray films, two CCD-based digital systems and two storage phosphor (SP) digital systems. METHODS: Fifty-six surfaces in 56 extracted unrestored premolars were radiographed under standardised conditions using two E-speed dental film, Ektaspeed Plus (Eastman Kodak Co, Rochester, NY, USA) and Dentus M2 Comfort (Agfa-Gevaert, Mortsel, Belgium), two CCD systems, Sidexis (Sirona, Bensheim, Germany) and Visualix (Gendex, Milan, Italy) and two SP systems, Digora (Soredex, Helsinki, Finland) and DenOptix (Gendex, Milano, Italy). The images were assessed by eight observers (four radiologists and four general practitioners). True caries depth was determined by histological examination. True caries depth was subtracted from the values given by the observers and an analysis of variance was performed. The null hypothesis was rejected when P < 0.05. RESULTS: No significant differences were found in diagnostic accuracy with the two dental films and the Sidexis and Digora systems. The depth of the lesion significantly affected observer performance. Caries depth was underestimated. Radiologists performed significantly better than general practitioners whatever the recording system. CONCLUSION: The diagnostic accuracy of digital systems is comparable with that of dental films. The ability of dentists to recognise caries correctly is the main factor contributing to variation in radiographic diagnosis and not the imaging modality.

Avaliaçäo da soluçäo Kodak no que se refere às densidades ótica e radiográfica, analisadas pelo fotodensitômetro MRA e pelo sistema digital Digora, no filme Kodak DF-58 / Kodak solution evaluation as far as optical and radiographic densities are concerned, analysed by MRA photodensitometer and Digora digital system, in the film Kodak DF-58

Analisou-se a utilizaçäo da densidade radiográfica (D.R.) como substituto da densidade ótica (D.O.) no controle de processamento radiográfico de filmes periapicais DF-58 que foram sensibilizados pelo aparelho de raios X GE 100. Os filmes foram divididos em cinco faixas, sendo que uma näo foi exposta, servindo para avaliaçäo da densidade base e velamento e as outras quatro faixas foram expostas com 1, 10, 60 e 300 impulsos, os quais foram processados manualmente em soluçäo Kodak em grupos de três nas temperaturas de 20º, 25ºC e 30ºC, com diferentes tempos. Para se avaliar a densidade ótica utilizou-se o fotodensitômetro MRA e para a avaliaçäo das densidades radiográficas escanearam-se as radiografias e utilizou-se o programa Digora for Windows 1.51 que forneceu dados, que puderam ser comparados com aqueles obtidos pelo método tradicional. Os resultados mostraram que a densidade ótica medida pelo fotodensitômetro, apresentou uma variaçäo correspondente aos níveis de cinza e variou conforme o número de impulsos nas faixas. Concluiu-se que as imagens das radiografias digitalizadas nas diferentes combinaçöes de temperatura/tempo nos fornecem uma grande precisäo de resultados e rapidez no controle de qualidade e podem substituir o fotodensitômetro na avaliaçäo das imagens de filmes radiográficos processados manualmente

Comparison of sensitometric and diagnostic performance of two films.

The sensitometric properties of Kodak Ektaspeed Plus and Flow E-speed film as well as their diagnostic efficacy for detecting proximal surface caries were compared. Flow and Kodak E-speed films were exposed and processed according to American National Standards Institute and American Dental Association (ADA) specifications, and film speed, contrast, and density of base plus fog were measured. Additionally, 80 premolar and molar teeth were imaged and their proximal surfaces scored by 12 dentists for the presence of caries. The actual depth of the caries was determined by microscopic examination of the teeth after sectioning. Kodak Ektaspeed Plus and Flow E-speed films, although labeled E-speed by the manufacturers, are both slow F-speed films. They have comparable base plus fog densities and comparable contrast curves. Dentists detected carious lesions equally well using both film types. The sensitivity, specificity, accuracy, and receiver operating characteristic area for detecting enamel and dentinal caries were not significantly different between the two films. Kodak Ektaspeed Plus and Flow E-speed films both meet or exceed the ADA performance specifications in terms of sensitometric properties. Both offer equal diagnostic utility for detecting caries.