The imaging performance of a storage phosphor system for dental radiography

Brettle, D S; Workman, A; Ellwood, R.P.; Launders, Jason; Horner, Keith; Davies, Robin

doi:10.1259/0007-1285-69-819-256

Cited by 67 publications

(62 citation statements)

References 5 publications

(7 reference statements)

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“…A digitalization error (causing lack of reproducibility) of pixel values would be deleterious in these situations because it would attribute pixel values that differ from those corresponding to a true change that occurred in the patient. Apparently, photon noise originating from Xrays may be one factor that could contribute to the large digitalization error observed for photostimulable plates of the Digora system 4,6,17,18 . As observed in Table 2 through Table 5, the lower exposure times (0.3; 0.2; 0.1; 0.05 s) showed, in general, higher pixel variability.…”

Section: Discussionmentioning

confidence: 99%

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Reproducibility of pixel values for two photostimulable phosphor plates in consecutive standardized scannings

et al. 2006

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ABSTRACT:The objective of the present study was to determine the reproducibility of the pixel values obtained with the Digora system (Soredex, Finland). Exposures were standardized, with variation in exposure and scanning time of two photostimulable phosphor plates containing a stepwedge image. The smallest variation in pixel values ranged from 50 to 75%, with the widest variations being observed in less dense steps. A signifi cant difference in pixel values was observed in terms of X-ray exposure and scanning times and between the two plates themselves (ANOVA, p < 0.01). Using the present methodology, the reproducibility of pixel values was not satisfactory for the tested white photostimulable plates. This wide variation in digitalization might be infl uenced by the amount of X-rays that sensitized the plates. It may be important to establish the reproducibility of the pixel values in quantitative studies using digital image. DESCRIPTORS:Radiography, dental, digital; Reproducibility of results. RESUMO:O objetivo do presente trabalho foi determinar a reprodutibilidade dos valores de "pixels" obtidos com o sistema Digora (Soredex, Finlândia). As exposições foram padronizadas, com variação no tempo de exposição e leitura de duas placas de fósforo fotoestimuláveis contendo a imagem de um penetrômetro. A menor variação nos valores de "pixels" foi de 50 a 75%, sendo as maiores variações oriundas nas faixas mais claras. Uma diferença signifi cante nos valores de "pixels" foi observada em relação ao tempo de exposição e leitura das placas e entre as duas placas (ANOVA, p < 0,01). Utilizando a presente metodologia, a reprodutibilidade dos valores de "pixels" das placas testadas do sistema Digora não foi satisfatória. Essa grande variação na digitalização pode ter sido infl uenciada pela quantidade de Raios X que sensibilizou as placas. Isso pode ser importante para estabelecer a reprodutibilidade dos valores de "pixels" em estudos quantitativos usando imagem digital. DESCRITORES:Radiografi a dentária digital; Reprodutibilidade dos resultados.

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Section: Discussionmentioning

confidence: 99%

“…Finally, the image is obtained electronically, eliminating chemical processing, and the plates are also reutilizable 6,11 .…”

Section: Introductionmentioning

confidence: 99%

Reproducibility of pixel values for two photostimulable phosphor plates in consecutive standardized scannings

et al. 2006

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“…It is most often integrated with other metrics to assess image quality for specific tasks, 6 , 7 , 8 , 9 and has been commonly utilized in the development, characterization, optimization, and comparison of many new imaging technologies such as computed radiography, (10) digital mammography, 11 , 12 storage phosphors for dental X‐ray, (13) and other devices in a preclinical 14 , 15 and clinical 16 , 17 environment.…”

Section: Introductionmentioning

confidence: 99%

Practical considerations for noise power spectra estimation for clinical CT scanners

Dolly

Chen

Anastasio

et al. 2016

J Applied Clin Med Phys

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Local noise power spectra (NPS) have been commonly calculated to represent the noise properties of CT imaging systems, but their properties are significantly affected by the utilized calculation schemes. In this study, the effects of varied calculation parameters on the local NPS were analyzed, and practical suggestions were provided regarding the estimation of local NPS for clinical CT scanners. The uniformity module of a Catphan phantom was scanned with a Philips Brilliance 64 slice CT simulator with varied scanning protocols. Images were reconstructed using FBP and iDose4 iterative reconstruction with noise reduction levels 1, 3, and 6. Local NPS were calculated and compared for varied region of interest (ROI) locations and sizes, image background removal methods, and window functions. Additionally, with a predetermined NPS as a ground truth, local NPS calculation accuracy was compared for computer simulated ROIs, varying the aforementioned parameters in addition to ROI number. An analysis of the effects of these varied calculation parameters on the magnitude and shape of the NPS was conducted. The local NPS varied depending on calculation parameters, particularly at low spatial frequencies below ∼0.15 mm−1. For the simulation study, NPS calculation error decreased exponentially as ROI number increased. For the Catphan study the NPS magnitude varied as a function of ROI location, which was better observed when using smaller ROI sizes. The image subtraction method for background removal was the most effective at reducing low‐frequency background noise, and produced similar results no matter which ROI size or window function was used. The PCA background removal method with a Hann window function produced the closest match to image subtraction, with an average percent difference of 17.5%. Image noise should be analyzed locally by calculating the NPS for small ROI sizes. A minimum ROI size is recommended based on the chosen radial bin size and image pixel dimensions. As the ROI size decreases, the NPS becomes more dependent on the choice of background removal method and window function. The image subtraction method is most accurate, but other methods can achieve similar accuracy if certain window functions are applied. All dependencies should be analyzed and taken into account when considering the interpretation of the NPS for task‐based image quality assessment.PACS number(s): 87.57.C‐, 87.57.Q‐

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“…This is especially true for intra-oral radiography, where a significant reduction of radiation dose has been reported. [1][2][3][4][5] For extraoral digital radiography however, a smaller reduction can be expected because of the already low dose thanks to the use of intensifying screens and fast film-screen combinations in conventional radiography. For digital panoramic radiography, different amounts of dose reduction have been reported.…”

Section: Introductionmentioning

confidence: 99%

Radiation doses of indirect and direct digital cephalometric radiography

et al. 2004

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AimThe aim of this study was to measure organ doses and calculate the effective dose for indirect and direct digital cephalometric exposures. Material and methods Indirect digital cephalometric exposures were made of a Rando® phantom head using a Cranex Tome® multipurpose unit with storage phosphor plates from Agfa and the direct digital (Charge Coupled Device, CCD) exposures were made with a Proline Ceph CM® unit. Exposure settings were 70 kV and 4 mAs for indirect digital exposures. Direct digital exposures were made with 70 kV, 10 mA and a total scanning time of 23 s. TLD700® dosemeters were used to measure organ doses, and the effective doses were calculated with (effective dose sal ) and without inclusion of the salivary glands. A pilot study was carried out to compare diagnostic image quality of both imaging modalities. Results Effective doses were 1.7 µSv for direct digital and 1.6 µSv for indirect digital cephalometric imaging. When salivary glands were included in the calculation, effective doses sal were 3.4 µSv and 2.2 µSv respectively. Organ doses were higher for direct digital imaging, except for the thyroid gland, where the organ doses were comparable. Diagnostic image quality of indirect and direct digital cephalometric images seemed comparable. Conclusion Effective dose and effective dose sal were higher for direct digital cephalometric exposure compared with indirect digital exposure. Organ doses were higher for direct digital cephalography. From preliminary data, it may be presumed that diagnostic image quality of indirect and direct digital cephalometric images are comparable.

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The imaging performance of a storage phosphor system for dental radiography

Cited by 67 publications

References 5 publications

Reproducibility of pixel values for two photostimulable phosphor plates in consecutive standardized scannings

Reproducibility of pixel values for two photostimulable phosphor plates in consecutive standardized scannings

Practical considerations for noise power spectra estimation for clinical CT scanners

Radiation doses of indirect and direct digital cephalometric radiography

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