Quality descriptors of optical beams based on centred reduced moments I: spot analysis

Castañeda, Román; Garcı́a-Sucerquia, Jorge; Brand, F.A.

doi:10.1016/j.optcom.2003.09.020

Cited by 11 publications

(4 citation statements)

References 21 publications

(23 reference statements)

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“…Thereafter, the threshold value will be subtracted from the unchanged image values to perform an offset reset. 10,17 The result is an image similar to that in Fig. 1͑c͒, whose gray-level histogram is shown in Fig.…”

Section: Comet Cell Images Preprocessingmentioning

confidence: 93%

“…It is customary to perform further analysis based on higher order moments if E 0 р0.8. 10,17,18 However, geometric descriptors based on higher order moments are not straightforwardly defined at all.…”

Section: Centered Reduced Moments and Associated Density Functionsmentioning

confidence: 99%

“…It is well known that all the odd order moments of V 0 (u,v) are equal to null if the image is symmetric with respect to the coordinates origin. 17,18 Therefore, the centers of mass of…”

Section: Centered Reduced Moments and Associated Density Functionsmentioning

confidence: 99%

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Centered reduced moments and associate density functions applied to alkaline comet assay

et al. 2005

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The single cell gel electrophoresis assay is a sensitive, rapid, and visual technique for deoxyribonucleic acid (DNA) strand-break detection in individual mammalian cells, whose application has significantly increased in the past few years. The cells are embedded in agarose on glass slides followed by lyses of the cell membrane. Thereafter, damaged DNA strands are electrophoresed away from the nucleus towards the anode giving the appearance of a comet tail. Nowadays, charge coupled device cameras are attached at optical microscopes for recording the images of the cells, and digital image processing is applied for obtaining quantitative descriptors. However, the conventional software is usually expensive, inflexible and, in many cases, can only provide low-order descriptors based in image segmentation, determination of centers of mass, and Euclidean distances. Associated density functions and centered reduced moments offer an effective and flexible alternative for quantitative analysis of the comet cells. We will show how the position of the center of mass, the lengths and orientation of the main semiaxes, and the eccentricity of such images can be accurately determined by this method.

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Section: Comet Cell Images Preprocessingmentioning

confidence: 93%

Section: Centered Reduced Moments and Associated Density Functionsmentioning

confidence: 99%

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Centered reduced moments and associate density functions applied to alkaline comet assay

et al. 2005

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“…To check the agreement between the planned and the actual spot position, a routine was implemented that allows to automatically obtain the beam spot's centroid coordinates. For this purpose, the method of centered reduced moments (Castaneda et al 2003) has been applied. This method takes into account all pixels in a certain area of interest around the spot, and is therefore more robust and unbiased against possible malfunctioning pixels or other irregularities compared to fitting methods or a simple maximum determination.…”

Section: Beam Spot Position Measurementsmentioning

confidence: 99%

Investigations of a flat-panel detector for quality assurance measurements in ion beam therapy

et al. 2011

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Increased accuracy in radiation delivery to a patient provided by scanning particle beams leads to high demands on quality assurance (QA). To meet the requirements, an extensive quality assurance programme has been implemented at the Heidelberg Ion Beam Therapy Center. Currently, high-resolution radiographic films are used for beam spot position measurements and homogeneity measurements for scanned fields. However, given that using this film type is time and equipment demanding, considerations have been made to replace the radiographic films in QA by another appropriate device. In this study, the suitability of the flat-panel detector RID 256 L based on amorphous silicon was investigated as an alternative method. The currently used radiographic films were taken as a reference. Investigations were carried out for proton and carbon ion beams. The detectors were irradiated simultaneously to allow for a direct comparison. The beam parameters (e.g. energy, focus, position) currently used in the daily QA procedures were applied. Evaluation of the measurements was performed using newly implemented automatic routines. The results for the flat-panel detector were compared to the standard radiographic films. Additionally, a field with intentionally decreased homogeneity was applied to test the detector's sensitivities toward possible incorrect scan parameters. For the beam position analyses, the flat-panel detector results showed good agreement with radiographic films. For both detector types, deviations between measured and planned spot distances were found to be below 1% (1 mm). In homogeneously irradiated fields, the flat-panel detector showed a better dose response homogeneity than the currently used radiographic film. Furthermore, the flat-panel detector is sensitive to field irregularities. The flat-panel detector was found to be an adequate replacement for the radiographic film in QA measurements. In addition, it saves time and equipment because no post-exposure treatment and no developer and darkroom facilities are needed.

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Image Quality Criteria

Groß¹,

Zügge²,

Peschka³

et al. 2006

Handbook of Optical Systems

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Quality descriptors of optical beams based on centred reduced moments I: spot analysis

Cited by 11 publications

References 21 publications

Centered reduced moments and associate density functions applied to alkaline comet assay

Centered reduced moments and associate density functions applied to alkaline comet assay

Investigations of a flat-panel detector for quality assurance measurements in ion beam therapy

Image Quality Criteria

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