in this paper we study properties of symbols such that these belong to class of symbols sitting insidesm ρ,φ that we shall introduce as the following. so for because hypoelliptic pseudodifferential operatorsplays a key role in quantum mechanics we will investigate some properties of m−hypoelliptic pseudodifferential operators for which define base on this class of symbols. also we consider maxi...

Background: Gonad shielding has been recommended during pelvic x-rays since the 1950s. The popular method of gonad shielding is placement a lead shield in the midline of the pelvis. The aim of this study was to evaluate the prevalence and utility of gonad shielding in pediatrics undergoing pelvic x-rays.Materials and MethodsFollowing study approval, we retrospectively retrieved data from the di...

Introduction: Recently, the use of nanoparticles has increased for many purpose in medicine. One of these is using the nano particles in shields structure to protect sensitive organs such as breast which placed inside the field of chest CT scan and receives high dose. The aim of this study was the use of nano Bi2O3 to making shield for protection breast in chest CT examination ...

ion and Integration For the Nominal Modeling Case in the TSPA analysis, DOE implemented the model abstractionfor general corrosion of the drip shield in the Waste Package and Drip Shield DegradationSubmodel, as described in SNL (2008ag, Section 6.3.5.1), in which the drip shields weredistributed in the five percolation subregions. The Waste Package and Drip Shield DegradationSub...

A compensation method is proposed by which the uniformly shielded area of the axial magnetic field in a relatively short, open-structure axial magnetic shield can be extended. An open-ended cylindrical magnetic shield of 120 cm in length, 52 cm inner diameter, and a ;0.5 mm total thickness of the shielding material is used to demonstrate the idea. The shield axis is oriented along the horizonta...

Background: Epidemiological studies show that computed tomography (CT) is one of the main sources of ionizing radiations. Shielding of radiosensitive organs is one of the dose reduction methods. This study aimed to assess the eye lens dose reduction and image quality resulting from the use of radio-protective bismuth shield in brain CT imaging. Methods: Bismut...

PURPOSE To compare the dose and image quality of three methods for reducing the radiation dose to the eye at head computed tomography (CT): bismuth shielding, organ-based tube current modulation (TCM), and global reduction of the tube current. MATERIALS AND METHODS An anthropomorphic head phantom was scanned under six conditions: (a) without any dose reduction techniques (reference scanning);...