In conventional x-ray imaging, including CT, the peak tube voltage (kVp) is a variable setting that affects image contrast, especially that due to differences in attenuation of high molecular weight substances such as iodine and calcium. For example, attenuation due to iodine at 80 kVp is approximately double that at 120-140 kVp. However, if the tube current (mA) is not adjusted appropriately t...

PURPOSE Cerebral perfusion x-ray computed tomography (PCT) is a powerful tool for noninvasive imaging of hemodynamic information throughout the brain. Conventional PCT requires the brain to be imaged multiple times during the perfusion process, and hence radiation dose is a major concern. The authors propose a PCT reconstruction algorithm that allows for lowering the dose while maintaining a hi...

This paper considers a problem of absolute stabilization with a speci ed level of disturbance attenuation for a class of uncertain systems in which the uncertainty is structured and satis es a certain integral quadratic constraint. The paper shows that an uncertain system is absolutely stabilizable with a speci ed level of disturbance attenuation if and only if there exists a solution to a corr...

cell banking is long –term storing of cell stocks that requires intensive care and maintenance to ensure its adequate quality. the main goal of a biological bank is preparing a repository source of cell culture system in a global manner. on the other hand, cell culture is an invaluable tool for investigators in numerous fields. successful maintenance of cells requires knowledge and practice of ...

The object of this study was to compare organ dose and image quality effects of using bismuth and barium vinyl in-plane shields with standard and low tube current thoracic CT protocols. A RANDO phantom was scanned using a 64-slice CT scanner and three different thoracic protocols. Thermoluminescent dosemeters were positioned in six locations to record surface and absorbed breast and lung doses....

ABTRACT Background: In nuclear medicine, phantoms are mainly used to evaluate the overall performance of the imaging systems and practically there is no phantom exclusively designed for the evaluation of the software performance.  In this study the Hoffman brain phantom was used for quantitative evaluation of reconstruction techniques. The phantom is modified to acquire t...

The present neuroimaging study examines how repetition-related neural attenuation effects differ as a function of the perceptual similarity of the repetition and subsequent memory. One previous study (Turk-Browne et al., 2006) reported greater attenuation effects for subsequent hits than for misses. Another study (Wagner et al., 2000) found that neural attenuation is negatively correlated with ...

Water is naturally found in atmosphere in three major physical states as: liquid (rain, fog & clouds), solid (snow flakes, ice-crystals) & gaseous (water vapors). In any of the forms the occurrence of water causes hindrances in the path of radio waves in form of absorption & scattering leading to some loss in signal quality & quantity both which is quantified in terms of attenuation. Here we pr...

spect detects γ-rays from administered radiopharmaceutical within the patient body. γ-rays pass through different tissues before reaching detectors and are attenuated. attenuation can cause artifacts; therefore different methods are used to minimize attenuation effects. in our study efficacy of chang method was evaluated for attenuation purpose, using a custom made heart phantom. due to differe...