Reporting Diagnostic Reference Levels for Paediatric Patients Undergoing Brain Computed Tomography

Brain computed tomography (CT) is a diagnostic imaging tool routinely used to assess all paediatric neurologic disorders and other head injuries. Despite the continuous development of paediatric CT imaging, radiation exposure remains a concern. Using diagnostic reference levels (DRLs) helps to manage the radiation dose delivered to patients, allowing one to identify an unusually high dose. In this paper, we propose DRLs for paediatric brain CT examinations in Saudi clinical practices and compare the findings with those of other reported DRL studies. Data including patient and scanning protocols were collected retrospectively from three medical cities for a total of 225 paediatric patients. DRLs were derived for four different age groupings. The resulting DRL values for the dose-length product (DLP) for the age groups of newborns (0-1 year), 1-y-old (1-5 years), 5-y-old (5-10 years) and 10-y-old (10-15 years) were 404 mGy cm, 560 mGy cm, 548 mGy cm, and 742 mGy cm, respectively. The DRLs for paediatric brain CT imaging are comparable to or slightly lower than other DRLs due to the current use of dose optimisation strategies. This study emphasises the need for an international standardisation for the use of weight group categories in DRL establishment for paediatric care in order to provide a more comparable measurement of dose quantities across different hospitals globally.

Game Theory Based Construction Efficient Topology in Wireless Sensor Networks

Topology control is one of the most important techniques used in wireless sensor networks; to some extent it can reduce energy consumption in which each node is capable of minimizing its transmission power level while preserving network connectivity. Reducing energy consumption has been addressed through different aspects till now. In this paper, we present a minimum spanning tree- (MST-) based algorithm, called noncooperative minimum spanning tree (NMST), for topology control in wireless multihop networks. In this algorithm, each node constructs its minimum power-cost spanning tree which is a tree and can connect the node with one hop away from its neighbor node in constructed topology. In addition we address the power-cost allocation problem when node acts selfishly. A class of strategies is proposed which construct minimum power-cost spanning tree such that the sum of the power-cost (as proxy of weight), at the same time, is a strong Nash equilibrium for a noncooperative game associated with the problem of efficient topology construction. Simulation results show that NMST can maximize the sensor network lifetimes.

Generation and transmission of 3 × 3 W-Band multi-input multi-output orthogonal frequency division multiplexing-radio-over-fiber signals using micro-ring resonators

Using the micro-ring resonator (MRR) system, the single and multi-carriers at frequencies of f(1)=192.898, f(2)=192.990, f(3)=193.1, f(4)=193.315, and f(5)=193.537  THz with a free spectral range (FSR) of 92, 110, 215, and 222 GHz, respectively, are generated to be suitable for a radio-over-fiber (RoF) system based on multi-input multi-output (MIMO) with orthogonal frequency division multiplexing (OFDM). Demonstrated are the concepts of all-optical MIMO signal generation and its transmission over a 50 km single mode fiber (SMF) optical link and an up to 3 m wireless link. Sixty-four multi-carriers are used in the all-optical generation of three MIMO W-Band RF signals, where the single carriers (f(3)-f(5)) transport the signals over the RoF link. The bit error rate (BER) of the overall system performance is discussed; thus, the transmission of MIMO signals is feasible for up to an SMF path 50 km long and a wireless distance of 3 m.