Composite modulation transfer function evaluation of a cone beam computed tomography breast imaging system

2009 ◽  
Vol 48 (11) ◽  
pp. 117002 ◽  
Author(s):  
Ruola Ning
Keyword(s):  
Computed Tomography ◽  
Transfer Function ◽  
Cone Beam Computed Tomography ◽  
Modulation Transfer Function ◽  
Breast Imaging ◽  
Imaging System ◽  
Cone Beam ◽  
Function Evaluation ◽  
Modulation Transfer

Modulation Transfer Function Evaluation of a Hadamard Transform Photothermal Deflection Imaging System with Beam Condensing Optics

1988 ◽  
Vol 42 (8) ◽  
pp. 1487-1493 ◽  
Author(s):  
Patrick J. Treado ◽  
Michael D. Morris
Keyword(s):  
Transfer Function ◽  
Modulation Transfer Function ◽  
Imaging System ◽  
Function Evaluation ◽  
Hadamard Transform ◽  
Modulation Transfer ◽  
Photothermal Deflection

The modulation transfer function of a source-encoded Hadamard transform imaging system including beam condensing optics is derived. The effects of diffraction, convolution with the encoding apertures, mask motion, and focus errors are considered explicitly. The derived equations are shown to describe resolution of Hadamard transform photothermal deflection imagers with up to 30 × condensing optics.

scholarly journals Modulation transfer function evaluation of cone beam computed and microcomputed tomography by using slanted edge phantom

2019 ◽  
Author(s):  
Szabó TAMÁS BENCE
Keyword(s):  
Transfer Function ◽  
Spatial Resolution ◽  
Modulation Transfer Function ◽  
Imaging System ◽  
Ct Images ◽  
Function Evaluation ◽  
Strong Positive Correlation ◽  
Micro Ct ◽  
Modulation Transfer ◽  
Voxel Size

Modulation transfer function (MTF) is a well known and widely accepted method for evaluating the spatial resolution of a digital radiographic imaging system. In the present study our aim was to evaluate the MTF obtained from CBCT and micro-CT images. A cylinder shaped phantom designed for slanted-edge method was scanned by a CBCT device at a 100 µm isometric voxel size and by a micro-CT device at a 20 µm isometric voxel size, simultaneously. The MTF curves were calculated and the mean spatial resolutions at 10% MTF were 3.33 + 0.29 lp/mm in the case of CBCT images and 13.35 + 2.47 lp/mm in the case of micro-CT images. The values showed a strong positive correlation regarding the CBCT and the micro-CT spatial resolution values, respectively. Our results suggests that CBCT imaging devices with a voxel size of 100 µm or below might aid the validation of fine anatomical structures and allowing the opportunity for reliable micromorphometric examinations

Imaging

2019 ◽  
pp. 382-434
Author(s):  
B. D. Guenther
Keyword(s):  
Transfer Function ◽  
Modulation Transfer Function ◽  
Noise Intensity ◽  
Imaging System ◽  
Optical Transfer Function ◽  
Modulation Transfer ◽  
Optical Aperture ◽  
System Properties ◽  
Incoherent Imaging ◽  
Optical Transfer

Treating an imaging system as a linear system and use llinear system properties to d iscuss both coherent and incoherent imaging. Use a one dimensional pin hole camera to study the theory of incoherent imaging. Two different criteria, Rayleigh and Sparrow, are used to define the resolution limits of the camera. From the simple theory define the optical transfer function and the modulation transfer function as appropriate characterizations of complex imaging systems. A review of the human imaging system emphasizes tits idfferences with man made cameras. Coherent imaging is based on Abbe’s theory of microscopy. A simple 4f imaging system can be used to understand how spatial resolution is limited by the optical aperture and by controlling the aperture, we can enhance the edges of an image or remove noise intensity noise on a plane wave. Apodizing the aperture allows astronomers to locate planents orbiting distant stars.

Correction of Cupping Artifacts in Axial Cone-Beam Computed Tomography Images by Using Image Processing Algorithms

2019 ◽  
Vol 10 (2) ◽  
pp. 132-136
Author(s):  
Tahmineh Razi ◽  
Nader Vahdani Manaf ◽  
Morteza Yadekar ◽  
Sedigheh Razi ◽  
Shiva Gheibi
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Imaging System ◽  
Dental Materials ◽  
Cone Beam ◽  
Correction Coefficient ◽  
Gamma Correction ◽  
Cross Sectional ◽  
Computed Tomography Images ◽  
Cupping Artifacts

Objectives: One of the most important problems of cone-beam computed tomography (CBCT) imaging technique is the presence of dense objects, such as implants, amalgam fillings, and metal veneers, which result in beam-hardening artifacts. With an increase in the application of CBCT images and considering the problems in relation to cupping artifacts, some algorithms have been presented to reduce these artifacts. The aim was to present an algorithm to eliminate cupping artifacts from axial and other reconstructed CBCT images. Materials and Methods: We used CBCT images of NewTom VG imaging system (Verona, Italy, at Dentistry Faculty, Medical Sciences University, Tabriz, Iran) in which every image has a resolution of 366 × 320 in DICOM format. 50 images of patients with cupping artifacts were selected. Using Sobel edge detector and nonlinear gamma correction coefficient, the difference was calculated between the density of axial images in the main image and the image resulting from nonlinear gamma correction at the exact location of the radiopaque dental materials detected by Sobel. The points at which this density difference was out of a definite limit were treated as image artifacts and were eliminated from the main image by the inpainting method. Results: The resultant axial images, for producing reconstructed cross-sectional, panoramic images without cupping artifacts, were imported into NTT viewer V5.6 and utilized. Conclusions: With comparison, acquired images observed that the offering algorithm is practical and effective for reducing the cupping artifacts and preserving the quality of the reconstructed images. This algorithm does not need any additional equipment.

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