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This work aimed to research the efficiency of gamma irradiation and shielding characteristics on the lead oxide (PbO) doped the crosslinked polystyrene-b-polyethyleneglycol (PS-b-PEG) block copolymers and polystyrene-b-polyethyleneglycol-boron nitride (PS-b-PEG-BN) nanocomposites materials. The crosslinked PS-b-PEG block copolymers and PS-b-PEG-BN nanocomposites mixed with different percentage rates of PbO were used to research gamma-ray shielding characteristics. The synthesis of the copolymer was done by emulsion polymerization methods. The characterization and morphological analyses of irradiated samples were explored handling with the Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), and Scanning Electron Microscope (SEM) methods. The gamma-rays that were emitted from the E 152u source were observed with a High Purity Germanium (HPGe) detector system and examined with a GammaVision computer program. Our samples, including the different percentage rates of the PS-b-PEG (1000, 1500, 10,000), BN, and PbO, were irradiated in various gamma-ray photon energy regions (from 121.78 keV to 1408.01 keV). Then, Linear-Mass Attenuation Coefficients (LACs-MACs), Half-Tenth Value Layer (HVL), Mean Free Path (MFP), and Radiation Protection Efficiency (RPE) values of the samples were calculated. Via crosschecking the acquired data from samples with and without PbO and BN, it was observed that, if the different percentage rates by weight nano-powder of PbO and BN are added in the polymer mixture, it can be used as a convenient shielding material against gamma rays.

The aim of this study was to identify a rational strategy for the selection of multi-beam IMRT in patients with right breast cancer through the comparison of dosimetric parameters of the planning target volume (PTV) and organs at risk (OARs) using five different radiotherapy modalities. This was a retrospective study using computed tomography scans from ten patients with early-stage right breast cancer who had been treated previously. Three dimensional conformal radiotherapy (3DCRT), forward-planned IMRT (for-IMRT), inverse-planned IMRT (inv-IMRT), helical tomotherapy (HT), and volumetric-modulated arc therapy (VMAT) were planned for each patient. The plans were compared according to dose–volume histogram analysis. The most significant impact of inverse-planned multi-beam modalities for right breast cancer was the reduction of Dmax, Dmean, V53.5 and prescribed dose volume (cc) outside of the PTV (breast) (OB-V50) of the PTV. HT decreased the ipsilateral OAR volumes receiving higher doses. In exchange, HT also increased the volumes receiving low doses, which is known to lead to an increased rate of radiation-induced secondary malignancies. The heart, LAD, and contralateral doses for 3DCRT and for-IMRT were significantly lower than those for inv-IMRT, HT, and VMAT. In addition, inv-IMRT demonstrated an increase in exposed volume of heart, LAD, ipsilateral lung, and contralateral lung compared with those parameters for HT or VMAT. Although it is known to reduce cardiac toxicity with breath hold technique in left sided breast cancer, similarly it is possible for 3DCRT and for-IMRT techniques in right sided breast cancer even in free breathing.

Conventional diagnostic nuclear medicine applications have been continuously increasing in most nuclear medicine departments in Turkey, but to our knowledge no one has studied the doses to technologists who perform nuclear medicine procedures. Most nuclear medicine laboratories do not have separate control rooms for technologists, who are quite close to the patient during data acquisition. Technologists must therefore stay behind lead shields while performing their task if they are to reduce the radiation dose received. The aim of this study was to determine external radiation doses to technologists during nuclear medicine procedures with and without a lead shield. Another aim was to investigate the occupational annual external radiation doses to Turkish technologists. Methods: This study used a Geiger-Mü ller detector to measure dose rates to technologists at various distances from patients (0.25, 0.50, 1, and 2 m and behind a lead shield) and determined the average time spent by technologists at these distances. Deep-dose equivalents to technologists were obtained. The following conventional nuclear medicine procedures were considered: thyroid scintigraphy performed using 99m Tc pertechnetate, whole-body bone scanning performed using 99m Tc-methylene diphosphonate, myocardial perfusion scanning performed using 99m Tcmethoxyisobutyl isonitrile, and 201 Tl (thallous chloride) and renal scanning performed using 99m Tc-dimercaptosuccinic acid. Results: The measured deep-dose equivalent to technologists per procedure was within the range of 0.13 6 0.05 to 0.43 6 0.17 mSv using a lead shield and 0.21 6 0.07 to 1.01 6 0.46 mSv without a lead shield. Also, the annual individual dose to a technologist performing only a particular scintigraphic procedure throughout a year was estimated. Conclusion: For a total of 95 clinical cases (71 patients), effective external radiation doses to technologists were found to be within the permissible levels. This study showed that a 2-mm lead shield markedly reduced the external dose to technologists. The doses to technologists varied significantly for different diagnostic applications. Consequently, the estimated annual dose to a technologist performing only a particular scintigraphic procedure is very different from one type of procedure to another. The results of this study should help in determining the rotation time of technologists in different procedures and differences in their individual techniques.

Summary The work which has been done on cement‐polymer composite based shielding materials was comprehensively described in the present article, the choice of the study presented here is based on the choice of the researches. The new Hyperbranched Poly Amino‐Ester‐block‐Poly Caprolactone‐Polyurathane Plaster‐concrete composites mixed with different percentage soft lead oxide and arsenic oxide is used to research gamma‐ray shielding and thermal conductivity characteristics. The synthesis of new Hyperbranched Poly Amino‐Ester‐block‐Poly Caprolactone‐Polyurathane copolymer was achieved by Atom Transfer Reaction and Condensation Polymerization methods. The characterization of Hyperbranched Poly Amino‐Ester‐block‐Poly Caprolactone‐Polyurathane Plaster was made with the Nuclear Magnetic Resonance, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry, Gel Permeation Chromatography, Thermogravimetric Analysis, Scanning Electron Microscope methods. The transmitted fluxes of gamma‐rays that were emitted from Eu152 source was detected by a High Purity Germanium (HPGe) detector system at Karadeniz Technical University‐Department of Physics in Trabzon and analyzed by a GammaVision (Version:6.07‐Ortec, Oak Ridge, TN) computer program. The composite phase change materials including 89, 87, 69, 67% Portland cement, 1% and 3% PU‐Plaster, 10% and 30% weight percent lead oxide and arsenic oxide was irradiated in the various gamma ray photon energy region (121.78, 344.28, 778.90, 964.08, 1085.87, 1112.07, and 1408.01 keV) for 3600 seconds. Then, linear attenuation coefficients, mass attenuation coefficients, half‐value layer, tenth value layer, mean free path, radiation protection efficiency, and gamma‐rays absorption of concrete‐the Hyperbranched Poly Amino‐Ester‐block‐Poly Caprolactone‐Polyurathane copolymers specimens were experimentally investigated. Thermal properties and morphological analysis of the irradiated substances were explored handling differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscope methods of the nano lead oxide and arsenic oxide including composite phase change material via gamma irradiation were submitted. Moreover, the effect of the Hyperbranched Poly Amino‐Ester‐block‐Poly Caprolactone‐Polyurathane amount on the radiation attenuation of the composite material was investigated. Gamma attenuation experiments have been performed to specify lead equivalent values for the improved composite material. The composite equivalent thickness values from 0.5 to 0.6 cm sample thickness and 0.665 cm radius were obtained. Via crosschecking the acquired data from concrete samples with and without lead and arsenic, it was observed that, if the powder of lead oxide and arsenic oxide to cement ratio of 10% and 30% by weight is added in the concrete mixture, the concrete‐the Hyperbranched Poly Amino‐Ester‐block‐Poly Caprolactone‐Polyurathane composite can be used as a suitable shield against gamma rays. Also, mass attenuation coefficients were calculated as theoret...