subpixel resolution
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2018 ◽  
Vol 103 ◽  
pp. 232-243 ◽  
Author(s):  
Mohamed Elsayed Eldib ◽  
Mohamed A.A. Hegazy ◽  
Myung Hye Cho ◽  
Min Hyoung Cho ◽  
Soo Yeol Lee

2018 ◽  
Vol 25 (6) ◽  
pp. 1650-1657 ◽  
Author(s):  
Mohamad Khalil ◽  
Erik Schou Dreier ◽  
Jan Kehres ◽  
Jan Jakubek ◽  
Ulrik Lund Olsen

Timepix3 (256 × 256 pixels with a pitch of 55 µm) is a hybrid-pixel-detector readout chip that implements a data-driven architecture and is capable of simultaneous time-of-arrival (ToA) and energy (ToT: time-over-threshold) measurements. The ToA information allows the unambiguous identification of pixel clusters belonging to the same X-ray interaction, which allows for full one-by-one detection of photons. The weighted mean of the pixel clusters can be used to measure the subpixel position of an X-ray interaction. An experiment was performed at the European Synchrotron Radiation Facility in Grenoble, France, using a 5 µm × 5 µm pencil beam to scan a CdTe-ADVAPIX-Timepix3 pixel (55 µm × 55 µm) at 8 × 8 matrix positions with a step size of 5 µm. The head-on scan was carried out at four monochromatic energies: 24, 35, 70 and 120 keV. The subpixel position of every single photon in the beam was constructed using the weighted average of the charge spread of single interactions. Then the subpixel position of the total beam was found by calculating the mean position of all photons. This was carried out for all points in the 8 × 8 matrix of beam positions within a single pixel. The optimum conditions for the subpixel measurements are presented with regards to the cluster sizes and beam subpixel position, and the improvement of this technique is evaluated (using the charge sharing of each individual photon to achieve subpixel resolution) versus alternative techniques which compare the intensity ratio between pixels. The best result is achieved at 120 keV, where a beam step of 4.4 µm ± 0.86 µm was measured.


2018 ◽  
Vol 43 (8) ◽  
pp. 1654 ◽  
Author(s):  
Manon Rostykus ◽  
Mattia Rossi ◽  
Christophe Moser

2017 ◽  
Vol 7 ◽  
pp. 197-217 ◽  
Author(s):  
Adina Ciomaga ◽  
Pascal Monasse ◽  
Jean-Michel Morel

Author(s):  
Luis A. Ocampo Giraldo ◽  
Aleksey E. Bolotnikov ◽  
Giuseppe S. Camarda ◽  
Yonggang Cui ◽  
Gianluigi De Geronimo ◽  
...  

2017 ◽  
Vol 88 ◽  
pp. 89-99 ◽  
Author(s):  
Jaka Javh ◽  
Janko Slavič ◽  
Miha Boltežar

2016 ◽  
Vol 4 ◽  
pp. 56
Author(s):  
Václav Olšanský ◽  
Carlos Granja ◽  
Pavel Krist ◽  
Radek Mařík ◽  
Jiří Bíla ◽  
...  

This article presents the processing of radiographic data acquired using the position-sensitive hybrid semiconductor pixel detector Timepix. Measurements were made on thin samples at the medical ion-synchrotron HIT [1] in Heidelberg (Germany) with a 221 MeV proton beam. The charge is energy by the particles crossing the sample is registered for generation of image contrast. Experimental data from the detector were processed for derivation of the energy loss of each proton using calibration matrices. The interaction point of the protons on the detector were determined with subpixel resolution by model fitting of the individual signals in the pixelated matrix. Three methods were used for calculation of these coordinates: Hough transformation, 2D Gaussian fitting and estimate the 2D mean. Parameters of calculation accuracy and calculation time are compared for each method. The final image was created by method with best parameters.


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