Electrical impedance tomography system: an open access circuit design

BACKGROUND: This paper reports a simple 2-D system for electrical impedance tomography EIT, which works efficiently and is low cost. The system has been developed in the Sharif University of Technology Tehran-Iran (for the author's MSc Project). METHODS: The EIT system consists of a PC in which an I/O card is installed with an external current generator, a multiplexer, a power supply and a phantom with an array of electrodes. The measurement system provides 12-bit accuracy and hence, suitable data acquisition software has been prepared accordingly. The synchronous phase detection method has been implemented for voltage measurement. Different methods of image reconstruction have been used with this instrument to generate electrical conductivity images. RESULTS: The results of simulation and real measurement of the system are presented. The reconstruction programs were written in MATLAB and the data acquisition software in C++. The system has been tested with both static and dynamic mode in a 2-D domain. Better results have been produced in the dynamic mode of operation, due to the cancellation of errors. CONCLUSION: In the spirit of open access publication the design details of this simple EIT system are made available here

Magnetohydrodynamic Flow Imaging Using Spin-Echo Pulse Sequence

In this study, magnetohydrodynamic (MHD) flow of conductive liquids due to injection of electrical current during magnetic resonance imaging (MRI) is investigated. A spin-echo based MRI pulse sequence is proposed to image the MHD flow. Magnetic resonance (MR) phase effects of the MHD flow is related to the MRI pulse parameters and injected current. Average velocity distributions of the MHD flow are reconstructed using the MR phase images. The method is validated by numerical simulations. The reconstruction error is 29 \% for 1 mA injected current with 20 ms duration when signal to noise ratio of the MHD phase measurements is 35. It is possible to obtain information about the MHD flow and determine viscosity inhomogeneities inside the imaged medium by using the MHD phase and velocity distributions. Design of a pulse sequence that generates an MHD flow with constant velocity at each data acquisition period may reduce the reconstruction error. By this way, the method may be utilized in imaging of liquid media, such as blood or cerebrospinal fluid surrounded by excitable tissue

Lack of evidence that obesity is a cause of pilonidal sinus disease

Objective: To find out whether pilonidal sinus is more common among obese people

The effect of three different sealers on the radiopacity of root fillings in simulated canals

WOS: 000243300400023PubMed ID: 17178508Objective. The aim of this study was to investigate the effect of 3 root canal sealers on radiopacity of root fillings in simulated canals by means of direct digital radiography. Study design. Thirty simulated root canals in transparent acrylic blocks were prepared with a 4% tapered, size 25 instrument. A single 4% tapered, size 25 gutta-percha cone was inserted into each canal. Standardized images of the blocks with an aluminum step-wedge were obtained by using Digora storage phosphor plates. Then, 3 root canal sealers (Roeko, Diaket, Pulpdent) were mixed according to the manufacturers' instructions. The gutta-percha cones were completely coated with one of the sealers and placed in the identical canal to the full working length. The images of the blocks were reobtained after sealer application. The mean gray values (MGVs) of root fillings were measured with or without the sealer at 3 different levels 0 mm, 6 mm, and 11 mm from apex) by using the Image Tool program. Each MGV measurement was then converted to its aluminum equivalent by means of the step-wedge values. A paired t test was used for statistical analysis. Results. RoekoSeal caused a significant decrease in the radiopacity of the root fillings at the 1-mm level (P 0.05). Conclusion. The type and the thickness of root canal sealers can influence the radiopacity of the root fillings