During operating of the X-ray machines, if the protection of X-ray rooms is insufficient, not only the patient but also clinical staffs as well as public are exposed to high X-ray dosage and they are affected from X-ray related to the dose level. In the present survey, by testing the radiological leakage and scatter from X-rays machines in radiology departments of 7 randomly selected hospitals in Duhok governorate, the effects dose of X-ray to the both control panel area and the patients waiting or visiting area who are located near the radiography room, were measured. The dose was recorded for a range of peak kilovoltage (kVp) and mAs values to find efficiency of shielding materials (barriers) of radiography rooms for different X-rays level. The measurements were performed at one meter above the ground surface which was the same height of X-rays tube by using Gamma Scout dosimeter. From the measurement results, it was seen that the most hospitals barriers (doors and walls) were not appropriate to the standards except 2 hospitals. The maximum effective doses were measured in uncontrolled area of Khazer hospital which was 82.48 ± 0.73 mSv·yr −1 that was much more than the reference dose limits and in controlled area of Haval Banda Zaroka hospital which was 12.98 ± 0.16 mSv·yr −1 . In result, the knowledge about the radiation dose affecting the radiologists and public in the selected hospitals was obtained, and by informing the radiologists and the hospitals managements, the necessary regulations would be planned.

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Plane waves with norm conserving pseudopotentials (PW-PP) method in conjunction with density functional theory (DFT) frame work have been used to investigate structural, electronic and optical properties of lead-halide cubic perovskite CsPbX3 (X=Br, Cl and I). The generalized gradient approximation (GGA), specifically Perdew-Burke-Ernzerhof (PBE) flavor, has been chosen to treat the exchange correlation term of Kohn-Sham equation. Structural parameters are comparable with other theoretical and experimental studies. In spite of good agreement of our band gap values  with other theoretical works, however, they were not comparable when compared to the experimental  values due to the well-known problem of Eg value underestimation of DFT. To update the  value, we have used GW method as a self-consistent quasiparticle method on energies and wave functions and indeed they have been improved. Optical properties have been calculated using density functional perturbation theory (DFPT). Our results show that CsPbX3 (X=Br, Cl, I) has maximum response to the electromagnetic spectrum at low energies (visible region) but minimum response at high energies.

In the recent years, caesium lead halides CsPbX 3 with the halogen elements Cl, Br and I have gained much attention of researchers owing to their attractive optical properties. In the present work we discuss the changes in their structure, bandgap and optical properties that occur under hydrostatic pressures 1-10 GPa. The density functional theory based on the generalized gradient approximation within the Perdew-Burke-Ernzerhof approach for exchange-correlation energy is used for calculations, in conjunction with the augmented plane-wave pseudopotential method. Since the generalized gradient approximation underestimates the bandgap, we employ the GW method to improve the bandgap values. The optical properties are computed in the photon-energy range 0.1-3.6 eV, using the density functional perturbation theory. As the pressure increases, the Pb-halogen bonds become contracted, whereas the volume of the unit cell shrinks uniformly, with no phase or structure-type transformations. The bandgap decreases with increasing pressure and the corresponding decrease rate for CsPbI 3 is less than that for CsPbBr 3. In general, the optical response of the caesium lead halides increases with increasing pressure, while the peaks of maximums of the response functions are red-shifted.