Sources of noise in digital subtraction radiography

Wenzel, Ann; Sewerin, I

doi:10.1016/0030-4220(91)90441-e

Cited by 61 publications

(32 citation statements)

References 18 publications

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“…In both cases, the obtained error values are in good agreement with those calculated in previous works [11] . Another relevant observation is that OD and G ref interaction cannot be disregarded.…”

Section: Methodssupporting

confidence: 81%

“…The methodology proved to be effective in reducing the variability of measured grey levels on a uniform film, however the measured standard deviation of absolute grey levels (0.14 to 2.00) has resulted to be greater than the standard deviation due to acquisition noise (equal to 1.38 according to Table 1) [11] . A possible explanation may be that uniform OD films were not perfectly clean; besides, certain levels of optical density have been obtained overlaying more than one film, and a perfect adhesion was not easy to achieve.…”

Section: Resultsmentioning

confidence: 97%

“…Different acquisition systems can be used: camera based ones, flatbed scanner, x-ray digitisers; up to now, none seems to have definitively overcome the other ones [9,10] , and all are affected by noise produced by the non-uniformity of the back-lighting source: Wenzel and Sewerin well outlined out the main sources of noise related to radiograph digitisation process [11] , while Audenino et al demonstrated the importance of the non-uniformity of the back-lighting source to the end of results repeatability: it produces the dependency of measured grey levels on the position and orientation of the image on the back-lighting system [12] . This phenomenon has been seldom considered, but may not be insignificant:…”

Section: Introductionmentioning

confidence: 99%

“…Another algorithm, introduced in [14] , seems to be able to effectively filter out randomly introduced noise. However it is opinion of the authors that a significant portion of digitisation noise is not randomly distributed, being related to the non-uniformity of the back-lighting source; a proof is given by the peculiar pattern of subtraction images obtainable when performing repeatability tests [11] ; a further confirm was found by means of a rigorous statistical analysis [12] . More refined algorithms are summarized by Kim [15] ; they take into account spatial frequency distribution [16] or are based on segmentation [17,18] ; maximum likelihood estimators are employed [15] or a priori knowledge in relation to a given kind of images [18] .…”

Section: Introductionmentioning

confidence: 99%

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Compensation of the non-uniformity of back-lighting sources when digitising X-ray films for video-densitometric measures

Zanetti

Franceschini

2012

JBGC

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Background: computerised image analysis and the building of electronic archives require the digitisation of x-ray films performed in the past, when direct digitisation was not yet available. Different techniques can be used, based on laser scanning or camera acquisition; both can be heavily impaired by the non-uniformity of the backlighting source. This work wants to develop a methodology, able to reduce this noise source. Methods:The introduced algorithm is a step beyond the common compensation of backlighting non-uniformity through subtraction; in fact, each grey level is corrected taking into account not only its position on the back-lighting system and its raw value, but also the interaction between these two parameters.Results: Given a certain acquisition system, the introduced algorithm has allowed to reduce the maximum grey level standard deviation, read on uniform grey level films, from 9.15 to 2.00 (on a scale from 0 to 255) against traditional subtraction techniques that achieved a minimum standard deviation equal to 5.39. Conclusions:The employed algorithm has proved to be effective in order to obtain same measured grey levels, almost independent from the position of the radiograph on the back-lighting system, and therefore makes x ray image digitisation more accurate.

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Section: Methodssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Compensation of the non-uniformity of back-lighting sources when digitising X-ray films for video-densitometric measures

Zanetti

Franceschini

2012

JBGC

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“…Bu durumda çıkartma işlemi ideal şartlarda gerçekleştirilememekte/hatalı gerçekleşmekte dolayısı ile kemik kayıp ya da kazancından kaynaklanan değişiklikler ayırt edilememekte ya da yanlış yorumlanabilmektedir. 10,43 Gelişen teknoloji ile birlikte piyasaya sürülen yazılımlardan yararlanılarak DSR'de kullanılan radyografik görüntülerin densite değerlerinin eşleştirilmesi ya da geometrik hizalama işlemlerinin yapılabilmesi mümkündür. Densite ve kontrast eşleştirmeye yönelik problemler yazılımlar ile başarılı bir şekilde çözülebilirken, projeksiyon geometrisine yönelik farklılıkların düzeltilmesi daha komplike bir işlemdir ve bu konuda yapılan girişimler bulunmakla birlikte sorun tam olarak çözülememiştir.…”

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IMAGING SYSTEMS USED FOR DIAGNOSIS OF PERIODONTAL PATHOLOGY Part 2: Alternative Imaging Systems and Image Processing Methods

Soğur¹,

Baksı²

2014

EÜ Dişhek Fak Derg

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ÖzetRadyografiler, periodontal hastalıkların tanı ve tedavisinde kullanılan en önemli gereçlerdir. Periodontal dokuların değerlendirilmesinde rutinde kullanılan iki boyutlu görüntüleme sistemleri, alveoler kemikte ortaya çıkan erken dönem değişikliklerin saptanmasında yetersiz kalmaktadır. Her ne kadar, üç boyutlu görüntü oluşturan Bilgisayarlı Tomografi (BT) ve Konik Işınlı Bilgisayarlı Tomografi (CBCT) gibi görüntüleme sistemleri kemik defektlerinin 3 boyutlu olarak değerlendirme imkanını bize sunsa da, maliyetlerinin yüksek olması ve hastaya ulaşan radyasyon dozunun konvansiyonel filmlere oranla daha yüksek olması gibi önemli dezavantajları vardır. Tuned aperture computed tomography (TACT) görüntüleme sistemi ya da Optik Coherence Tomografi (OCT) gibi alternatif görüntüleme sistemlerinin periodontitise bağlı olarak kemikte meydana gelen değişikliklerin saptanmasına yönelik yapılan çalışmalar umut vaad etmektedir. Bunun yanı sıra, kemikte meydana gelen değişikliklerin saptanması aşamasında görüntü analiz yöntemlernn kullanımı, minör seviyedeki oluşan densite değişikliklerin bile kalitatif ve kantitatif olarak gözlemleyebilmemizi kolaylaştırmaktadır. Bu derlemenin amacı; periodontitise bağlı olarak alveoler kemikte meydana gelen değişikliklerin erken dönemde saptanmasında kullanılan alternatif görüntüleme ve analiz yöntemlerini değerlendirmektir.Anahtar Kelimeler: Dijital radyografi, dental, görüntü analiz yöntemleri, periodontoloji Abstract Radiographs are the most accurate diagnostic aid available in the diagnosis and treatment of periodontal disease. 2 dimensional (2-D) systems imaging systems used routinely in periodontology are not effective to detect the early bone changes according to the periodontal disease. Even though 3-D systems available such as Computed Tomography (CT) and Cone Beam Computed Tomography (CBCT ) has become a valuable imaging modality in periodontology to determine a three-dimensional (3D) architecture of osseous defects

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Clinical and histological findings in guided bone regeneration (GBR) around titanium dental implants with autogeneous bone chips using a new resorbable membrane

Schlegel

Sindet‐Pedersen

Hoepffner³

2000

J. Biomed. Mater. Res.

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The aim of this study was to test the value of a polydioxanon-membrane (PDS(R), Ethicon, Norderstedt, Germany) in combination with autogenous bone as a spacer for guided bone regeneration of denuded implant surfaces in comparison to simple augmentation. Altogether, in 8 Beagle dogs of 12 months, the three mandibular premolars were extracted on both sides and, after an uneventful healing of the extraction sockets in each mandibular site, two seize defined bone defects were produced. The defects were 7 mm long, had a vertical extension of 7 mm, and were 7 mm deep. These also included, therefore, the resection of the lingual cortical bone wall. In the center of all these 32 bone defects, Brânemark fixtures with a diameter of 3 mm and a length of 10 mm were implanted. Every implant was primarily stable due to the fixation in the native bone under the created defects. In each mandible site, one bone defect was filled with autologous bone resulting from the previous defect preparation. Half of the defects were covered with a PDS membrane, and the other half were covered only by the relocation of the mucoperiosteal flap. During the observation period of 90-180 days, continuous clinical and radiological controls were executed. Aside from the observed clinical healing problems in the test sites, such as exposure of the membranes and serious inflammatory reactions, the histological and radiological results of the control group regarding bone regeneration were superior to these of the test group, which were valid also for the subgroups with or without autologous bone fillings.

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Sources of noise in digital subtraction radiography

Cited by 61 publications

References 18 publications

Compensation of the non-uniformity of back-lighting sources when digitising X-ray films for video-densitometric measures

Compensation of the non-uniformity of back-lighting sources when digitising X-ray films for video-densitometric measures

IMAGING SYSTEMS USED FOR DIAGNOSIS OF PERIODONTAL PATHOLOGY Part 2: Alternative Imaging Systems and Image Processing Methods

Clinical and histological findings in guided bone regeneration (GBR) around titanium dental implants with autogeneous bone chips using a new resorbable membrane

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