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  1. The effectiveness of bismuth breast shielding with protocol optimization in CT Thorax examination
    Karim MKA, Rahim NA, Matsubara K, Hashim S, Mhareb MHA, Musa Y
    J Xray Sci Technol, 2019;27(1):139-147.
    PMID: 30584178 DOI: 10.3233/XST-180397
    BACKGROUND: Numerous techniques had been proposed to reduce radiation exposure in computed tomography (CT) including the use of radiation shielding.

    OBJECTIVE: This study aims to evaluate efficacy of using a bismuth breast shield and optimized scanning parameter to reduce breast absorbed doses from CT thorax examination.

    METHODS: Five protocols comprising the standard CT thorax clinical protocol (CP1) and four modified protocols (CP2 to CP5) were applied in anthropomorphic phantom scans. The phantom was configured as a female by placing a breast component on the chest. The breast component was divided into four quadrants, where 2 thermoluminescence dosimeters (TLD-100) were inserted into each quadrant to measure the absorbed dose. The bismuth shield was placed over the breast component during CP4 and CP5 scans.

    RESULTS: The pattern of absorbed doses in each breast and quadrant were approximately the same for all protocols, where the 4th quadrant > 3rd quadrant > 2nd quadrant > 1st quadrant. The mean absorbed dose value in CP3 was reduced to almost 34% of CP1's mean absorbed dose. It was reduced even lower to 15% of CP1's mean absorbed dose when the breast shield was used in CP5.

    CONCLUSION: This study showed that CT radiation exposure on the breast could be reduced by using a bismuth shield and low tube potential protocol without compromising the image quality.

  2. Dosimetric features and kinetic parameters of a glass system dosimeter
    Mhareb MHA, Alajerami YSM, Alqahtani M, Alshahri F, Saleh N, Alonizan N, et al.
    Luminescence, 2020 Jun;35(4):525-533.
    PMID: 31883298 DOI: 10.1002/bio.3761
    Lithium borate (LB) glasses doped with dysprosium oxide (Dy2 O3 ) have been prepared by utilizing the conventional melt-quench technique. The prepared glass samples were exposed to 60 Co to check their dosimetric features and kinetic parameters. These features involve glow curves, annealing, fading, reproducibility, minimum detectable dose (MDD), and effective atomic number (Zeff ). Kinetic parameters including the frequency factors and activation energy were also determined using three methods (glow curve analysis, initial rise, and peak shape method) and were thoroughly interpreted. In addition, the incorporation of Dy impurities into LB enhanced the thermoluminescence sensitivity ~170 times. The glow from LB:Dy appeared as a single prominent peak at 190°C. The best annealing proceeding was obtained at 300°C for 30 min. Signal stability was reported for a period of 1 and 3 months with a reduction of 26% and 31%, respectively. The proposed glass samples showed promising dosimeter properties that can be recommended for personal radiation monitoring.
  3. Exploring the properties of Dy2O3-Y2O3 Co-activated telluro-borate glass: Structural, physical, optical, thermal, and mechanical properties
    Thabit HA, Ismail AK, Mhareb MHA, Abdulmalik DA, I A, Al-Fakih AM, et al.
    Heliyon, 2023 Jul;9(7):e18309.
    PMID: 37539187 DOI: 10.1016/j.heliyon.2023.e18309
    The successful application of glass-based materials in a wide range of scientific fields depends on the associated physical, optical, thermal, and mechanical properties. This article investigate the structural, Physical, thermal, optical, and mechanical properties of Dy2O3, Y2O3 co-activated telluro-borate glass developed using the melt-quenching method. The glassy quality and the elements component of the specimens were observed using XRD and EDX analyses. The addition of Y2O3 rise the glass density from 2.956 to 3.303 g/cm3 the refractive index from 2.5 to 2.7. These changes are due to the increase in polarizability and non-bridging oxygen (NBO). The photoluminescence (PL) spectra revealed a broad peak at 550 nm and additional weak emission peaks at 573 and 664 nm, respectively. While the observed broader peak can be linked to the convolution of Bi3+ ions transitions corresponding to the non-centrosymmetric site respectively, the weak emission bands are due to 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2 Dy3+ transitions. Hence, the low symmetrical features of both Bi3+ and Dy3+ ions were confirmed. The increase in the Vickers hardness of the glass from 536.7 to 1366.9 indicates the influence of Y2O3 addition on the mechanical properties of the glasses. The findings help to improve our understanding of the behaviour of the glass composition and its prospective applications in disciplines such as photonic, and laser optics.
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