11,056 research outputs found
Development of a synthetic phantom for the selection of optimal scanning parameters in CAD-CT colonography
Full text linkThe aim of this paper is to present the development of a synthetic phantom that can be used for the selection of optimal scanning parameters in computed tomography (CT) colonography. In this paper we attempt to evaluate the influence of the main scanning parameters including slice thickness, reconstruction interval, field of view, table speed and radiation dose on the overall performance of a computer aided detection (CAD)–CTC system. From these parameters the radiation dose received a special attention, as the major problem associated with CTC is the patient exposure to significant levels of ionising radiation. To examine the influence of the scanning parameters we performed 51 CT scans where the spread of scanning parameters was divided into seven different protocols. A large number of experimental tests were performed and the results analysed. The results show that automatic polyp detection is feasible even in cases when the CAD–CTC system was applied to low dose CT data acquired with the following protocol: 13 mAs/rotation with collimation of 1.5 mm × 16 mm, slice thickness of 3.0 mm, reconstruction interval of 1.5 mm, table speed of 30 mm per rotation. The CT phantom data acquired using this protocol was analysed by an automated CAD–CTC system and the experimental results indicate that our system identified all clinically significant polyps (i.e. larger than 5 mm)
Expression, purification and DNA-binding activity of tilapia muscle-specific transcription factor, MyoD, produced in Escherichia coli.
No full textApplication of CT in Diagnosing Carcinoma of the Maxillary Sinuses : PART 2: An Experimental Study of Pitfalls Encountered when Diagnosing Carcinoma of the Maxillary Sinuses with CT
Full text link1982-03A phantom simulating the transverse section of the maxillary sinuses was constructed for experimentation with various CT scanners to study the following: (1) the occasional inability to image the very thin posterior-lateral walls which have no real bone defects, and (2) to verify whether or not the bony walls surrounding the maxillary sinuses are actually as thick as they appear on CT. The phantom was made of an acrylic cylinder containing three cavities simulating the maxillary sinuses and the nasal cavity and filled with water. The walls, made of thin aluminum and acrylic plates and placed between water and air, disappeared in some CT images. The thickness of the walls calculated from CT values was greater than the true thickness imaged by each CT scanner. The author stresses that in CT images, either experimentally or clinically, thin bony walls placed between water and air or fat tend to disappear, and that bony walls tend to appear thicker than their true thickenss.departmental bulletin pape
Pore-scale freezing of a sandy saline soil visualized with micro-CT
No full textThere are three types of images:CT raw images obtained by micro-CT;Ice crystal segmentation results processed by ilastik and ImageJ from CT raw images;Water fraction distribution in specimens processed by Matlab and ImageJ from segmentation results.Figures 4(a) are ice crystal segmentation results in different quadrants processed from CT raw images via ImageJ and Matlab.Figures 5(a) are initial ice nuclei and final ice crystal segmentation results of the same sand specimen.Figures 7 and 8 are CT raw images of the specimen with different water content and salt content.Figures 11(a) and (d) are CT raw images of the specimen with different water content and salt content. (b) and (e) are water fraction distribution in different specimens processed by Matlab and ImageJ from CT image segmentation results. (c) and (f) are ice crystal segmentation results in different specimens segmented from CT raw images.</p
A Non-biotin Polymerized Horseradish-peroxidase Method for the Immunohistochemical Diagnosis of Canine Distemper
No full textCT-guided minimally-invasive penile fracture repair
No full textABSTRACT We present the case of a 28 year old patient with an incomplete tear of the tunica albuginea occurred after having sexual intercourse in the female superior position. The diagnostic assessment was performed first clinically, then with CT, owing to its high resolution, allowed to exactly detect the tear location leading to precise preoperative planning. After adequate diagnosis through imaging and proper planning, the patient was performed a selective minimally invasive surgical approach to repair the lesion. The patient had good erection with no angular deformity or plaque formation after a 3-month follow-up.</div
CT Quantitation and Prediction of the Risk of Type 2 Diabetes Mellitus in Non-Obese Patients with Pancreatic Fatty Infiltration
Full text linkYi Tang,1,* Zemin Wei,1,* Ning Li,2 Chao Jiang,2 Chen Liang,1 Lulu Sun,2 Lufeng Tian,3 Zhengyu Jin,4 Zhe Wu,2,* Hao Sun4,* 1Department of Endocrinology, Fushun Central Hospital, Fushun, Liaoning Province, People’s Republic of China; 2Department of Radiology, Fushun Central Hospital, Fushun, Liaoning Province, People’s Republic of China; 3Department of Internal Medicine, Fushun Central Hospital, Fushun, Liaoning Province, People’s Republic of China; 4Department of Radiology, State Key Laboratory of Complex Severe and Rare Disease, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Hao Sun, No. 1 Shuaifuyuan, Wangfujing Street, Dongcheng District, Beijing, 100730, People’s Republic of China, Tel +86-10-69159537, Email [email protected] Zhe Wu, Fushun Central Hospital, Xincheng Road, Shuncheng District, Fushun, Liaoning Province, 113006, People’s Republic of China, Tel +86-156-42018778, Email [email protected]: To examine the risk of type 2 diabetes mellitus in non-obese patients with pancreatic fatty infiltration through abdominal computed tomography (CT) quantitation.Patients and Methods: We carried out a retrospective analysis of abdominal CT and inpatient medical records of 238 inpatients from July 2019 to April 2021. The patients were divided into a normal non-obese group (BMI < 25, n = 135) and diabetic non-obese group (BMI < 25, n = 103). Abdominal CT-related parameters included body width; mean CT values of the pancreas, liver, and spleen; difference between pancreas and spleen CT values (P−S); pancreas-to-spleen attenuation ratio (P/S); and liver-to-spleen attenuation ratio (L/S). Logistic regression was used to estimate the risk factors for comorbid diabetes in a non-obese population.Results: The P-values of the pancreas CT value, P−S, P/S, body width, and L/S were all < 0.05 and correlated to comorbid diabetes in non-obese patients. Worsening pancreatic fatty infiltration increased the risk of developing diabetes. Using a P/S of 1.0 as reference, every successive decrease in this ratio by 0.1 increases patient risk by 3.981, 4.452, 6.037, and 12.937 times.Conclusion: The risk of developing type 2 diabetes mellitus in non-obese patients increases with the degree of pancreatic fatty infiltration as assessed by CT.Keywords: computed tomography, non-obese patients, pancreatic fatty infiltration, type 2 diabetes mellitu
Effective potential calculation in a two-dimensional electron gas containing quasi one-dimensional AlAs submonolayer
No full textWe report low-field magnetoresistance measurements of a two-dimensional electron gas in which half a monolayer of AlAs has been inserted into the centre of the GaAs quantum well. In these devices we observe a low file positive magnetoresistance on GaAs (001) substrates deliberately misoriented by 0.09 degrees toward. the [110] direction in which a critical field causes magnetic breakdown. A large anisotropy is observed in both the mobility and the low field magnetoresistance in the orthogonal [(1) over bar 10] and [110] directions. It is suggested that these effects arise from the quasi periodic effective one-dimensional potentials caused by the insertion of the AlAs submonolayer. We describe a method of using the anisotropic low field magnetoresistance to calculate the magnitude of the effective potential of the AlAs sub-monolayer at the GaAs/AlGaAs heterointerface
An approach to increasing the resolution of industrial CT images based on an aperture collimator
No full textThe spatial resolution of CT images is dominated by the focal spot size when it is large relative to the detector cells. We propose an approach to increase the spatial resolution by utilizing an aperture collimator. The aperture collimator is specially designed and placed in front of the X-ray source so that the rays penetrating the collimator form a set of narrow fan beams. Then an iterative algorithm is introduced to reconstruct CT images from the data obtained by scanning the narrow fan beams. Numerical experiments show that the proposed approach could significantly increase the resolution of the CT images. Furthermore, this approach is also robust against some challenging cases, such as the examination of low contrast object, reconstruction based on multi-energy data and perturbation of geometric errors in CT systems. (C) 2013 Optical Society of AmericaOpticsSCI(E)EI1ARTICLE2327946-279632
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