Two commercially available (EP, Z) and eight new elastomeric composites (M1–M4, G1–G4, of thickness ≈1 mm) containing mixtures of differing proportions of heavy metal additives (Bi, W, Gd and Sb) have been synthesised and examined as protective shields. The intensity of the X-ray fluorescence radiation generated in the typical elastomeric shields for CT, containing Bi and other heavy metal additives influence on the practical shielding properties. A method for assessing the radiation shielding properties of elastomeric composites used in CT examination procedures via X-ray spectrometry has been proposed. To measure the radiation reduction ability of the protective shields, the dose reduction factor (DRF) has been determined. The lead equivalents for the examined composites were within the ranges of 0.046–0.128 and 0.048–0.130 mm for 122.1 and 136.5 keV photons, respectively. The proposed method, unlike to the common approach, includes a dose contribution from the induced X-ray fluorescence radiation of the heavy metal elements in the protective shields. The results clearly indicate that among the examined compositions, the highest values DRF have been achieved with preparations containing Bi+W, Bi+W+Gd and Bi+W+Sb mixtures with gradually decreasing content of heavy metal additives in the following order: Bi, W, Gd and Sb. The respective values of DRF obtained for the investigated composites were 21, 28 and 27 % dose reduction for a 1 mm thick shield and 39 and ~50 % for a 2 mm thick layer (M1–M4).

Eight elastomeric composites (NRU, GR1-GR4, NRBG08-NRBG24) containing mixtures of different proportions of heavy metal additives (Bi, W, Gd and Sb) have been synthesized and examined as protective shields. The NRU sample was a pure rubber matrix and served as a reference sample for heavy metal modified composites. Experimental procedure used for evaluation of the composite shields and their attenuation properties was based on the utilization of HPGe spectrometry and analysis of X-ray fluorescence radiation intensity of the heavy metal additives in the following energy ranges for: Sb (20-35 keV), Gd (35-55 keV), W (55-70 keV) and Bi (70-90 keV). The main contributor to the induced X-ray fluorescence radiation within the shield is Bi additive and the intensity of the X-ray radiation generated within the energy range of 70-90 keV strongly depends on its concentration. It was found that decreasing concentration of the Bi fraction from 0.35 (GR samples) to 0.15 (NRBG samples) results in significant lowering Bi X-ray fluorescence radiation within the 70-90 keV energy range. Secondary effect of decreasing Bi concentration was efficient diminishing excitation processes for lower Z heavy metal additives (W, Gd and Sb, GR vs. NRBG samples). As the final quality parameter of the shielding properties for the examined elastomers, dose reduction factor (DRF) coefficients were calculated for each shield. It was found, that the best shielding properties are observed for composites with lower Bi concentration (0.15 vs. 0.35 Bi mass fraction) with only slight further improvement of their parameters (DRF) with increasing of Gd concentration (Gd mass fraction 0.08, 0.16 and 0.24). The most efficient dose reduction composite was found to be NRBG24 elastomer with DRF value 0.47 (53 % dose reduction) for ca. 2 mm and 0.44 g/cm 2 layer thickness.

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Conducting safe coaching is essential for training police officers, who very often face a variety of unexpected and dangerous incidents. Their reaction to situations must be rapid and appropriate. To prepare officers for dangerous situations, but those that cannot be practiced in real life due to high costs, danger, time, or effort, virtual training seems to be the obvious choice. This article deals with the development of a calculation algorithm to assess the risk of actions taken on the site of a traffic incident, which was implemented into the training version of a virtual reality (VR) simulation. It includes a number of factors and elements that form a scenario of simulations that affect the degree of its difficulty and the assessment of the performance of each exercise. The different components of the algorithm that make it possible to assess the skills of the students of police specialist courses are presented. The acceptance criterion for the developed algorithm shall be the correct assessment of the student’s skills during the course of the training.

Os³ony elastomerowe redukuj¹ce dawki promieniowania X w technikach tomografii komputerowej **)Streszczenie -Opracowano bezo³owiowe os³ony redukuj¹ce dawki promieniowania w diagnostyce technikami tomografii komputerowej. Podstawê stanowi³a matryca z kauczuku naturalnego nape³nionego tlenkami: bizmutu, wolframu lub gadolinu. Ze wzglêdu na generowanie przez bizmut wtórnego promieniowania fluorescencyjnego rozszerzono pierwotne sk³ady kompozytów. Stwierdzono, ¿e otrzymane kompozyty kauczuku naturalnego zawieraj¹ce kombinacje tlenków metali charakteryzowa³y siê du¿ymi wartooeciami masowych wspó³czynników poch³aniania, wp³ywa³y na redukcjê natê¿enia promieniowania padaj¹cego o energii: E g = 60 keV o ok. 50 % a o energii E g = 122 keV o ok. 20 %. Jednoczeoenie prawie wszystkie próbki wulkanizatów wykazywa³y korzystne w³aoeciwooeci wytrzyma³ooeciowe. S³owa kluczowe: kauczuk naturalny, tlenek bizmutu, tlenek wolframu, tlenek gadolinu, tlenek antymonu, promieniowanie X. ELASTOMER SHIELDS REDUCING X-RADIATION DOSES IN COMPUTED TOMOGRAPHY TECHNIQUESSummary -We have developed lead-free shields reducing the radiation doses in the diagnostic computed tomography techniques. They are based on natural rubber matrix with oxides of bismuth, tungsten and gadolinium as fillers. Due to the generation of secondary fluorescence radiation by bismuth, the study was extended to other compositions. The obtained natural rubber composites containing the combinations of metal oxides were characterized by high values of the mass absorption coefficient, which effected in the reduction in the intensity of incident radiation with an energy E g = 60 keV by about 50 % and for E g = 122 keV by about 20 %. It should be noted that virtually all vulcanizates showed good strength properties.