Browsing by Author "Farrag, S. I."

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Effective Dose Calculations and Dose Rate Distribution Around Z-Portal Passenger Security Screening
(SPRINGER, 2016) Farrag, S. I.
Due to the increased concern over terrorist attacks, new technologies have been developed to improve the efficiency of security screening of passengers. The Z - portal is an inspection system designed to scan vehicles and large trucks, buses, and cargo containers. It has been installed in many sites in Egypt. The passenger should be screened before allowing to pass from a land to another. This technology uses ionizing radiation (X-rays). As the hazards related to ionizing radiation include the well-known carcinogenic risk, as well as other health effects, assessment of public exposure to these new types of security screening of a great importance we are presenting an assessment and distribution mapping of dose rate around two portals, then effective dose calculations and statistical analysis was performed. Methods: Two Z-portal systems are used for screening passenger by vehicles and trucks; Measurement of radiation dose rate was performed using dose rate survey meter, exposed with the two units during ten consecutive exposures each the organ effective doses was calculated. Results: Effective radiation doses ranged between 0.41 mu Sv and 6.66 mu Sv for one exposure. Thyroid, bone marrow, colon, lung, stomach, breast absorbed the most radiation for both screening systems with p <0.001. Conclusions: Effective doses of organ screened by the transmission system is significantly higher than the backscatter system however both systems are exceeding the dose limit of the general public per scan, as per ANSI standards of 0.1 mu Sv per scan for individual, cumulative effect is not considered, both systems should be reevaluated based on the general principles of justification, optimization and dose limitation versus new screening technology like passive millimeter - wave with no radiation emission.
A new approach of shielding technique due to a leakage of radiation exposure outside a 10 MEV Linac room in a facility designed for 6 MEV
(IEEE, 2015) Farrag, S. I.
At the national cancer institute - Cairo - Egypt. A decision of upgrading a linear accelerator of 6 MeV, Elekta machine, to high energy 10 MeV is taken. Because of advances in radiation sources and techniques, shielding and room design considerations for radiation oncology and such upgrade, are not covered by the NCRP reports. A problem has arises due to limited room size that was previously shielded based upon the 6 MeV energy, there was no other spaces for additional shielding in the treatment room which creates a problem of radiation leakage. This work presents an appraisal of radiation leakage and calculations of doses which vary from 65 mu Sv/hr to 7.5 mSv/hr. We discuss the particular shielding problems related to high energy machines. Finally a new shielding methodology is presented merging more than two materials shows to be effective and reduce shielding cost.
Numerical Computation of Specific Absorption Rate and Induced Current for Workers Exposed to Static Magnetic Fields of MRI Scanners
(IEEE, 2014) Farrag, S. I.
Currently-used Magnetic Resonance Imaging (MRI) scanners in Cairo City possess static magnetic field (SMF) that varies from 0.25 up to 3T. More than half of them possess SMF of 1.5T. Workers in MRI environments are exposed to static magnetic fields. This research paper presents a novel approach for numerical computation of induced current density and Specific Absorption Rate (SAR) values by estimation of fringe static magnetic fields. Iso-gauss line of MR was mapped and a polynomial function of the 7th degree was generated and tested. Induced current due to worker motion in the SMF and SAR values for organs and tissues have been calculated. Results illustrate that the computation tool used permits quick accurate MRI iso-gauss mapping and calculation of induced current and SAR values which can then be used for assessment of occupational exposure profile of MRI operators.