scholarly journals Image Quality Differences In CT Scan Thorax By Using Slice Thickness Variation

2017 ◽  
Vol 8 (2) ◽  
pp. 87-91
Author(s):  
Samsun Samsun ◽  
Legia Prananto ◽  
Novita Wulandari
Keyword(s):  
Image Quality ◽  
Ct Scan ◽  
Spatial Resolution ◽  
Optimal Parameter ◽  
Thickness Variation ◽  
Slice Thickness ◽  
Picture Quality ◽  
Thorax Ct ◽  
Research Show ◽  
Selection Of

The picture quality get from CT Scan of Thorax which required optimal parameter selection that’s right, one of them the selection of slice thickness. The method taken from theses that have been publish in the year 2013. The results of the research show the percentage of the value of the average spatial resolution of 2.5 mm slice thickness is (33.3%), noise (17.8%), artefact (1%). On the thickness of the slices 5 mm spatial resolution is (17%), noise (8.9%), artefacts (0%). On the thickness of slices of 7.5 mm spatial resolution is (8.9%), noise (11.1%), artefacts (53.3%). While the thickness of the slices the spatial resolution is 10 mm (8.9%), noise (22.2%), artefacts (68.9%). Based on the research results obtained the conclusion that thickness 2.5 mm slices on Thorax CT-Scan images produce better picture quality than with the thickness of the slices 5 mm, 7.5 mm, 10 mm, because the spatial resolution is more clear so as to reduce noise and artifacts.

scholarly journals The Effects Of High Dose and Low Dose Protocols In Thorax’s CT Scan Image Quality

2021 ◽  
Vol 11 (2) ◽  
pp. 189
Author(s):  
Ni Larasati Kartika Sari ◽  
Deni Tiko Bahagia ◽  
Puji Hartoyo ◽  
Dewi Muliyati
Keyword(s):  
Computed Tomography ◽  
Image Quality ◽  
Ct Scan ◽  
Spatial Resolution ◽  
Low Dose ◽  
High Dose ◽  
Ct Number ◽  
Noise Ratio ◽  
Computed Tomography Dose Index ◽  
Dose Index

<p class="AbstractHeading">ABSTRACT</p><p class="AbstractText">The aim of this research was to evaluate the effects of two different dose protocols’ usage on image quality. This research was performed on three different CT Scanners using high dose and low dose protocols of thorax scan. Different exposure parameters were used, depending on each scanner’s setting. GE QA CT Scan phantom was used for image quality assessment.  Image quality measured were CT number accuracy, uniformity and linearity, noise uniformity, spatial resolution and Contrast To Noise Ratio (CNR). CT Scan’s dose index, CTDIvol (Volumetric Computed Tomography Dose Index), was also measured to evaluate how these two protocols work in reducing radiation dose. The result showed that the usage of low dose protocols reduce the CTDIvol value at 85-91% compared to the high dose protocols, meanwhile most of the image quality parameters obtained from both protocols were still considered good. The CT number accuracy, uniformity, linearity and noise uniformity for all CT Scans were all still inside BAPETEN’s (Indonesia National Regulator Agency) threshold. There were 20-23% difference on the spatial resolution value measured from both protocols. The most significant difference came from CNR. The CNR obtained from high dose protocols were 65-93% higher than the one from low dose protocols.   </p><p class="AbstractText">Keywords: contrast to noise ratio, CTDIvol, CT number, spatial resolution</p><p class="AbstractHeading">ABSTRAK</p><p>Penelitian ini mengevaluasi pengaruh penggunanaan protokol dosis tinggi dan protokol dosis rendah terhadap kualitias citra dan dosis khususnya pada pemeriksaan CT Scan thorax. Penelitian ini dilakukan pada 3 sampel CT Scan yang berbeda. Faktor eksposi yang digunakan berbeda untuk tiap scanner, bergantung pada setting yang terdapat pada scanner. Fantom yagdigunakan untuk menilai kualitas citra adalah fantom GE QA CT Scan. Adapun kualitas citra yang diukur adalah keseragaman, akurasi, dan linearitas CT number, keseragaman noise, resolusi spasial, serta <em>Contrast to Noise Ratio</em> (CNR). Sementara dosis radiasi yang diamati adalah CTDIvol (Volumetrik <em>Computed Tomography Dose Index</em>) yang tampil pada konsol. Hasil penelitian ini menunjukkan bahwa penggunaan protokol dosis rendah mampu mengurangi nilai CTDIvol sebesar 85-91% dibanding dengan protokol dosis tinggi, sementara sebagian besar parameter kualitas citra yang diukur masih dinilai baik. Nilai akurasi, keseragaman, dan linearitas CT number  serta keseragaman noise pada protokol dosis tinggi dan dosis rendah, keseluruhannya masih dalam batas ambang BAPETEN. Terdapat perbedaan sebesar 20-23% pada nilai resolusi spasial yang terukur dari  kedua protokol. Nilai CNR pada protokol dosis tinggi lebih baik dari pada protokol dosis rendah, dengan perbedaan yang cukup signifikan, yaitu 65-93%.</p><p class="AbstractText">Kata kunci: <em>contrast to noise ratio</em>, CTDIvol, <em>CT number</em>, resolusi spasial</p>

Modified algorithm for fast bandwidth selection for kernel estimates of multidimensional probability densities

2020 ◽  
pp. 9-13
Author(s):  
A. V. Lapko ◽  
V. A. Lapko
Keyword(s):  
Probability Density ◽  
Optimal Parameter ◽  
Random Variables ◽  
Kernel Functions ◽  
Independent Random Variables ◽  
Functional Dependencies ◽  
Approximation Properties ◽  
Probability Density Estimation ◽  
Multidimensional Probability ◽  
Selection Of

An original technique has been justified for the fast bandwidths selection of kernel functions in a nonparametric estimate of the multidimensional probability density of the Rosenblatt–Parzen type. The proposed method makes it possible to significantly increase the computational efficiency of the optimization procedure for kernel probability density estimates in the conditions of large-volume statistical data in comparison with traditional approaches. The basis of the proposed approach is the analysis of the optimal parameter formula for the bandwidths of a multidimensional kernel probability density estimate. Dependencies between the nonlinear functional on the probability density and its derivatives up to the second order inclusive of the antikurtosis coefficients of random variables are found. The bandwidths for each random variable are represented as the product of an undefined parameter and their mean square deviation. The influence of the error in restoring the established functional dependencies on the approximation properties of the kernel probability density estimation is determined. The obtained results are implemented as a method of synthesis and analysis of a fast bandwidths selection of the kernel estimation of the two-dimensional probability density of independent random variables. This method uses data on the quantitative characteristics of a family of lognormal distribution laws.

Feature-Based Registration of Thorax CT Scan Slices

Informatica ◽  
2017 ◽  
Vol 28 (3) ◽  
pp. 439-452
Author(s):  
Mykolas J. Bilinskas ◽  
Gintautas Dzemyda ◽  
Mantas Trakymas
Keyword(s):  
Ct Scan ◽  
Feature Based ◽  
Thorax Ct

scholarly journals Optimisation of T2 and T2* sequences in MRI for better quantification of iron on transfused dependent sickle cell patients

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Azza Ahmed ◽  
Amani Baldo ◽  
A. Sulieman ◽  
Hind Mirghani ◽  
Fouad A. Abolaban ◽  
...  
Keyword(s):  
Sickle Cell ◽  
Acquisition Time ◽  
Thickness Variation ◽  
Slice Thickness ◽  
Pixel Size ◽  
Significant Difference ◽  
Repetition Time

AbstractThis work aimed to investigate the effect of different shim techniques, voxel sizes, and repetition time (TR) on using theT2 and T2* sequences to determine their optimum settings to investigate the quantification of iron in transfused dependent sickle cell patients. The effect of each of these parameters was investigated on phantoms of different Gadolinium (Gd) concentrations, on 10 volunteers and 25 patients using a1 5T MRI Philips scanner. No significant difference between the three shim techniques was noticed in either T2 or T2* sequence measurements. Pixel sizes of 1 × 1 and 2 × 2 mm provided optimum results for T2 measurements. At 1 × 1 mm pixel size the T2* measurements experienced less error in measurements than the size of 2.5 × 2.5 mm used in the literature. Even though the slice thickness variation did not provide any changes in T2 measurements, the 12 mm provided optimum T2* measurements. TR variation did not yield significant changes on either T2 or T2* measurements. These results indicate that both T2 and T2* sequences can be further improved by providing more reliable measurements and reducing acquisition time.

A study on the change in image quality before and after an attenuation correction with the use of a CT image in a SPECT/CT scan

2012 ◽  
Vol 61 (12) ◽  
pp. 2060-2067
Author(s):  
Yong-Soon Park ◽  
Woo-Hyun Kim ◽  
Dong-Oh Shim ◽  
Ho-Sung Kim ◽  
Woon-Kwan Chung ◽  
...  
Keyword(s):  
Image Quality ◽  
Ct Scan ◽  
Attenuation Correction ◽  
Ct Image ◽  
Before And After

scholarly journals Synthetic Aperture Imaging Using High-Frequency Convex Array for Ophthalmic Ultrasound Applications

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2275
Author(s):  
Hae Gyun Lim ◽  
Hyung Ham Kim ◽  
Changhan Yoon
Keyword(s):  
Image Quality ◽  
Penetration Depth ◽  
Spatial Resolution ◽  
High Frequency ◽  
Imaging System ◽  
Ex Vivo ◽  
Synthetic Aperture ◽  
Single Element ◽  
High Frequency Ultrasound ◽  
Synthetic Aperture Imaging

High-frequency ultrasound (HFUS) imaging has emerged as an essential tool for pre-clinical studies and clinical applications such as ophthalmic and dermatologic imaging. HFUS imaging systems based on array transducers capable of dynamic receive focusing have considerably improved the image quality in terms of spatial resolution and signal-to-noise ratio (SNR) compared to those by the single-element transducer-based one. However, the array system still suffers from low spatial resolution and SNR in out-of-focus regions, resulting in a blurred image and a limited penetration depth. In this paper, we present synthetic aperture imaging with a virtual source (SA-VS) for an ophthalmic application using a high-frequency convex array transducer. The performances of the SA-VS were evaluated with phantom and ex vivo experiments in comparison with the conventional dynamic receive focusing method. Pre-beamformed radio-frequency (RF) data from phantoms and excised bovine eye were acquired using a custom-built 64-channel imaging system. In the phantom experiments, the SA-VS method showed improved lateral resolution (>10%) and sidelobe level (>4.4 dB) compared to those by the conventional method. The SNR was also improved, resulting in an increased penetration depth: 16 mm and 23 mm for the conventional and SA-VS methods, respectively. Ex vivo images with the SA-VS showed improved image quality at the entire depth and visualized structures that were obscured by noise in conventional imaging.

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