Determination of early bone metastasis on Bone Scans Using the Gray Levels Histogram / Búsqueda de metástasis ósea temprana en gammagramas óseos usando el histograma de tonos de gris

ABSTRACT The aim of this paper is to show a technique to speed up the interpretation of bone scans in order to determine the presence of early bone metastasis. This is done using the gray levels histogram of the region of interest. The technique is intended to assist in the bone scans interpretation in order to provide a successful diagnosis. During the analysis, three types of histograms were observed on the regions of interest. If the histogram is narrow and shifted toward the origin, the bone scan is free of metastasis. If it is shifted to the right and slightly broadened, indicates the presence of a bone anomaly different from a metastasis. On the other hand, if the histogram is more broadened and shifted to the right, is suggests the presence of metastasis. This histogram is characterized by displaying small curls on the right side providing information about the metastatic disease stage, which could be low-amplitude peaks and have a short length, if the metastasis is in early stage, or high-amplitude peaks and a long length, if is advanced. Finally, the analyzed region is displayed in false color considering the minimum gray levels observed in the histogram.

Filter construction using Ronchi masks and Legendre polynomials to analyze the noise in aberrations by applying the irradiance transport equation.

We tested different optical elements placed in three different positions by applying the irradiance transport equation (ITE), obtaining the wavefront $[ W(x,y) ]$[W(x,y)] and aberration surface [$ \textit{AS}(r,\theta ) $AS(r,θ)]. The existing noise in the captures $ I $I as well as in the $ W $W and $ AS $AS were analyzed applying several filters: first a filter based on Legendre polynomials (LP), generating the most probable points increasing the data resolution; second, a filter based on a 50 deg 2D-LP was used as a multilineal fit (multiple linear regression); and third, an ideal bandpass filter in the Fourier space after inducing a periodicity using Ronchi simulated masks with periods in $ x,y,xy $x,y,xy was used to perform data scanning (similar to the four-step phase-shifting method). Signal-to-noise ratio values were obtained for each proposed filter along with the most probable image free from noise, determined from a linear combination of the original data and the applied filters.

Moiré-Ronchigram analysis applied in the characterization of aberration surfaces and optical surface parameters from 3D wavefronts.

In this work, we propose the construction of the Moiré-Ronchigram as a pattern obtained from simple Ronchigrams, superposed and with a slight degree of rotation, to obtain a 3D wavefront. The aberrations in the obtained wavefront are fitted to the aberration Zernike polynomial of degree 12 in order to obtain a polynomial expression of a high degree of efficiency, which is subsequently compared with the general equation of quadrics (considering the coefficients accordingly) to obtain essential parameters (as focus, eccentricity, or F number) that allow us to understand and manipulate the optical elements under test optimally. Finally, we compare our results analyzing optical surfaces to make a weak statistic of our proposed method.

Visualizando Gammagramas Óseos en Colores / Displaying Bone Scans in Color

Resumen En este trabajo se describe el uso de un software para detectar metástasis óseas en gammagramas cuyo funcionamiento está basado en un método cuantitativo. En la investigación se incluyeron cuarenta y tres gammagramas óseos de pacientes con cáncer de próstata, los cuales fueron previamente analizados visualmente por tres especialistas y su diagnóstico se tomó como referencia. Debido a que no todos los huesos de un paciente muestran los mismos tonos de gris, cada uno de los gammagramas se segmentó para su análisis en cuatro regiones: cráneo, hombros, tórax y pelvis. La segmentación se hizo con el fin de obtener intervalos de tonos de gris en cada una de las regiones empleando un proceso estadístico. Para ello se calcularon la media y la desviación estándar de cuatro muestras que contenían cada una cuarenta y tres regiones. Tomando en consideración los intervalos, siete colores fueron asignados a cada región. Mediante los colores fue posible diferenciar los casos sanos e infiltrados en cada región, lo que facilita el diagnóstico. Se muestran ejemplos de los resultados en cada una de las regiones.

Abstract The use of software based on a quantitative method for detecting skeletal metastasis in bone scans is presented. Forty-three bone scans of patients with prostate cancer were previously analyzed visually by three specialists and their diagnosis were taken as a reference. Later, these scans were analyzed by segmenting them into four regions: skull, shoulders, chest, and pelvis. The segmentation was made to obtain intervals of gray levels for each of the regions using a statistical process. Tríese values were found by calculating the mean and standard deviation of four samples containing each forty-three regions. Using these intervals, seven colors were assigned to each region. By means of the colors it is possible to differentiate healthy and infiltrated cases in each region, which may facilitate the diagnosis. Examples of results in each region are shown.

Noticeable Bone Degradation on a Plain Radiography: a Case / Degradación Ósea Observable en una Radiografía Simple: un Caso

Abstract: In this paper, an image of the humeral head obtained from a plain radiography was analyzed. The radiograph was obtained from a forty year-old female with diagnosed breast cancer and discomfort on the right shoulder. The aim of the study was to determine whether it is possible to observe early bone metastasis with plane radiography using the so called scanning method. Plotting the intensity distribution along the rows of the image is a fast, qualitative way to know if the bone has some abnormality. If the curves are "smooth" then the bone is healthy, but if they are discontinuous then it is sick. To obtain quantitative results, the rows intensities were analyzed around discontinuous zones. Using this technique it was possible to observe bone degradations of the order of 11%.

Resumen: En este trabajo se analiza una imagen de una cabeza humeral obtenida de una radiografía simple. La radiografía se obtuvo de una mujer de cuarenta años de edad diagnosticada con cáncer de mama y molestias en el hombro derecho. El objetivo del estudio fue determinar si es posible observar metástasis ósea temprana en una radiografía plana utilizando el método de escaneo. Graficar la distribución de intensidad de las filas de la imagen es una manera rápida y cualitativa de saber si el hueso tiene alguna anormalidad. Si las curvas son "suaves" entonces el hueso está sano, pero si son discontinuas entonces está enfermo. Para obtener resultados cuantitativos, se debe analizar la intensidad de las filas alrededor de las zonas discontinuas. Utilizando esta técnica fue posible observar una degradación ósea del orden del 11%.

Ronchi and Moiré patterns for testing spherical and aspherical surfaces using deflectometry.

The aim of this paper is to compare the Ronchi test and the Moiré deflectometry applied to a new pattern. To do so, we used two Ronchi patterns (typical Ronchigrams) produced by two identical Ronchi rulings angularly displaced and placed close to the curvature radius of a mirror. The result obtained by superposing both Ronchigrams is our new pattern, a Moiré pattern of the Ronchigram (Moiré-Ronchigram). The Zernike aberration polynomial coefficients of the tridimensional wavefront for both mirrors are obtained as a result. We also compared the Zernike coefficients obtained for each of the mentioned techniques and we found that the results with less dispersion are those where Moiré deflectometry was applied. Finally, as a confidence test for applying and testing the Moiré-Ronchigram, we compare our results with Open Fringe, FringeXP, and APEX, using the root-mean-square and standard deviation values.

Dynamic point shifting with null screens using three LCDs as targets for corneal topography.

In this paper, the use of three liquid crystal displays (LCDs) as targets for an experimental corneal topographer is proposed. The main advantage is that the geometrical pattern in the target can be modified without moving any mechanical part to apply the dynamic point shifting (DyPoS) method. Some results on the capabilities of the LCDs, obtained with photo frames, for measuring a 6.37 mm radius of curvature calibration sphere, and applying the DyPoS method, are presented. It is shown that the error in measuring the radius of curvature with DyPoS is reduced to 3% of the real value and the RMS in elevation or sagitta differences is around 15 µm, 30% or 66% of the values obtained without DyPoS, respectively.

Aberration extraction in the hartmann test by use of spatial filters.

Using a computer, we generated a set of filters to aid in the retrieval of aberration functions from Hartmanngrams. These filters consist of discrete two-dimensional data points, like the Hartmanngrams themselves, and are orthogonalized by the Gram-Schmidt procedure. The aberration coefficients are obtained by calculation of the scalar product of the Hartmanngram and each orthogonal filter.