Search

Substantial concentration has been associated to the monitoring of vital signs and human activity using wireless body area networks. However, one of the key technical challenges is to characterize an optimized transceiver geometry for desired isolation/bandwidth and specific absorption rate (SAR) characteristics, independent of transceiver chip on-body location. A microwave performance evaluation of monopole wearable transceiver was completed and results presented. A novel on-body antenna transceiver was designed, simulated and fabricated using an ultra-thin substrate RO 3010 (h = 250 µm) that ensures compactness and enhanced flexibility. The designed transceiver was evolved using very high value of dielectric constant using CST® Studio Suit and FEKO® numerical platforms. The on-body characterization for both fatty and bone tissues was experimentally verified for a bandwidth of 200 MHz. The fabricated configuration and real-time testing provides very promising microwave radiation parameters with a gain of 2.69 dBi, S 11  < - 13 dB at an operational frequency of 2.46 GHz. Multi-banding was achieved by introducing fractals in the design of the printed monopole. SAR calculations for feet, head and arm at microwave power levels ranging from 100 to 800 mW are incorporated. Furthermore, the real time data acquisition using developed transceiver and its experimental verification is illustrated.

The impact of occupational radiation exposures on oncology staff working in the disciplines of Nuclear Medicine (NM), Radiotherapy (RT), and Diagnostic Radiology (DR) is of significance to ensure a health risk free environment. In this study, occupationally received radiation doses amongst Pakistani oncology staff in NM, RT and DR during the period (2003-2012) were assessed. The Film Badge Dosimetry (FBD) technique has been utilized to process over 81,000 films (13,237 workers) concerning the occupationally exposed workers data (2003-2012) at a national scale. The annual effective doses were found to range between 0.30-0.97 mSv for NM, 0.44-1.02 mSv for RT and 0.31-1.09 mSv for DR. The annual effective doses averaged over a period of 10 years were assessed to be 0.63, 0.70 and 0.68 mSv for NM, RT and DR respectively. The exposure data were categorized into three exposure levels (≤0.99, 1-4.99 and 5-9.99 mSv) to establish the staff distribution in these categories. It was found that 89.8-96% in NM, 82-94.5% in RT and 76-96.8% staff workers in DR have received doses within the range from the Minimum Detectable Limit (MDL)--0.99 mSv. The annual effective doses, in all categories, were measured to be less than the recommended annual limit of 20 mSv.

Slot antennas are often considered as a suitable choice for microwave ablation due to design simplicity, low cost to manufacture and a highly confined temperature profile. In this paper, an iterative coupled thermal/microwave numerical formulation is presented to analyze and develop miniature slot antenna geometries for localized liver cancer treatment. The thermal solver determines the specific absorption rate (SAR) as a pre-processing step to determine the temperature distribution profile within malignant tissues. The microwave solver uses this computed thermal solution together with related boundary/sub-domain settings to determine complex propagation wave number as an Eigen value. The desired microwave response in terms of insertion loss <0.1 dB, VSWR 1:1.1, and return loss less than -22 dB was achieved at 2.45 GHz. The simulated results agree well with the measured response.

The data analysis of occupationally exposed medical workers in Nuclear Medicine (NM), Radiotherapy (RT) and Diagnostic Radiology (DR) at the Institute of Nuclear Medicine and Oncology (INMOL), Pakistan is presented for the time interval (2007-2011). The whole-body exposure doses of the workers were measured by using the Film Badge Dosimetry technique. The annual average effective doses in NM, RT and DR have been found well below the permissible annual limit of 20 mSv (averaged over a period of 5 consecutive years), with no over-exposure detected. This declining trend of annual average effective dose is the consequence of improved radiation protection practices at INMOL during the recent years.