·Table of Contents ·General | Digital Autoradiography: possibilities and applicationsDelara S.GAFITULLINAInstitute of Nuclear Physics of Uzbek Academy of Sciences Ulugbek, Tashkent, 702132, Uzbekistan Contact |
Fig 1: Initial image of scandium distribution autoradiogram | Fig 2: The image after linearization |
The smoothing represents an outcome of a convolution with a matrix 3x3 coefficients of which:
1/4 in center, 1/8 above, below, from the right, 1/16 in four comers (fig. 3 ).
Fig 3: Reconstruction by filtration with different coefficients: a)T=16 b)T=16 c)T=12 p=30 p=28 p=0 |
a(l) | b(2) | c(l) |
d(2) | e(4) | f(2) |
g(l) | h(2) | i(l) |
The fluctuations of a hum noise of the gauge of the image decrease after smoothing, filtering upper highfrequencies. For exception of selected points with very small value of brightness filtering the structural unit will be carried out. This operation consists of processing by a matrix 3x3, enclosing a processed point, and finding among nine points of this matrix of a point, value of which as much as possible, with the consequent record of this content in a central point.
A | B | C |
0 | -1 | 0 |
D | E | F |
-1 | 4 | -2 |
G | H | I |
0 | -1 | 0 |
The value, opposite, among nine points of this matrix discovers a point with minimum value. Its content is written in a central point. In an outcome of these processings the gray scale image becomes brighter in zones of transition.
The decrease of noise in the resulting image is possible to achieve by filtering - convolution of the image with a matrix of coefficients 3x3. A principle of this filtering: a content of each point and eight points is at first read out which it enclose. Nine read out values are multiplied on nine weight coefficients, marked from A up to J, which can be positive or negative.
The filtering by a Laplacian, being a flexon on space coordinates, underlines all transitions ((( fig-4)
Laplacian
Fig 4: Reconstruction by a laplacian coefficients:p=1 ,T=128 |
Fig 5: Reconstruction by "windows": a)Initial image b) After a treatment | Fig 6: Reconstructed image of scandium distribution autoradiogram | Fig 7: Initial image of copper distribtuin autoradiogram |
Fig 8: The image after linearization |
Filtering underline of transitions consists of toting of the initial image with the Laplacian with appropriate weight. The treated thus image gives effect of a contour. The strong underline is received at P =1 and T = 128 ( fig.4 ). After processing the initial array of numbers the circumscribed programs will derivate the new numerical arrays, used for image reconstruction ( fig.6).
For to determine of resolution of autoradiographic method with DIP the following experiment was spent. On the neutron generator were irradiated of a copper plate by irregular flow of nuclear particles. Nonuniformity optical density of autoradiographic feature was inspected under the histogram of change of optical density ( fig.7 ). Then through a middle of a copper plate a slice of width 2mm was cut out and is divided on 20 specimens by the sizes 2x2 mm. On measured the gamma spectra of each specimens was constructed a curve of change of a content of a radionuclide ^Cu. Autoradiographic feature of allocation radioactive ^Cu was treated by DIP ( fig. 7 - 9 ). After DIP of autoradiographic feature from the treated image along the same bar a curve of density change is also constructed.
The resolution of method was determined as product by the first derivative from the required function and bound of an error (dI/dx) DI.
The resolution of a autoradiography method at minimum contrast in case photometry is equalled 2,7 arb.units, at use DIP- 32 arb.units.
Fig 9: Reconstructed image of copper distribution autoradiogram | Fig 10: The Histrograms:
1. of radioactivity change of "Cu by measured the gamma radiation; 2. of optical density change by means of photometry; 3. of optical density change after reconstruction of autoradiographic image. |
© AIPnD , created by NDT.net | |Home| |Top| |