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1

Hazards of electromagnetic radiation

Jeleński Andrzej

Materiały Elektroniczne

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2020

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T. 48, nr 1-4

3--14

EN

After a brief overview of the nature of electromagnetic (EM) radiation and its sources, the article presents selected findings concerning the risks caused by low-frequency EM fields emitted by 50 Hz high-voltage power lines and home appliances. These sources of radiation affect mainly the nervous system and may contribute to the development of cancer. On the other hand, the impact of high frequency EM fields emitted by radio and television transmitters, and mobile phones originate mainly from dielectric losses leading to body heating (thermal hazards) as well as from some non-thermal hazards, which have been less extensively investigated. The remote consequences include: auditory and behavioural effects, blood-brain barrier disruption and cancer. The examples of the recommendations and standards developed by the international and national organizations are also presented.

PL

Po krótkim omówieniu źródeł i charakteru promieniowania elektromagnetycznego przedstawiono wybrane wyniki badań zagrożeń powodowanych przez pola EM niskiej częstotliwości emitowane przez linie energetyczne wysokiego napięcia 50 Hz i sprzęt AGD. Ich głównym efektem jest oddziaływanie na układ nerwowy i wpływ na choroby nowotworowe. Z kolei efektem pól EM wysokich częstotliwości emitowanych przez nadajniki radiowe, telewizyjne, telefony komórkowe są głównie straty dielektryczne prowadzące do nagrzewania ciała (zagrożenia termiczne) oraz słabiej zbadane zagrożenia nietermiczne. Do tych ostatnich należą: efekty słuchowe, behawioralne, zakłócenia działania bariery krew-mózg, choroby nowotworowe. Przedstawiono również przykłady zaleceń i norm opracowanych przez międzynarodowe i krajowe organizacje.

2

Trace elements in scalp hair of leukaemia patients

Khuder A., Bakir M. A., Hasan R., Mohammad A., Habil K.

Nukleonika

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2014

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Vol. 59, No. 3

111--120

EN

The aim of this study was to determine the concentration of Fe, Ni, Cu, Zn and Pb in scalp hair of leukaemia patients and healthy volunteers, using the optimised XRF method. Leukaemia hair samples were classifi ed corresponding to type, growth and age of the participants. The results showed that the studied trace elements (TEs) in both of leukaemia and control groups were positively skewed. In comparison with the control group, lower Fe, Cu, Zn and Pb and higher of Ni medians were found in all studied leukaemia patients. The median rank obtained by Mann–Whitney U-test revealed insignifi cant differences between the leukaemia patients subgroups and the controls. An exact probability (α < 0.05) associated with the U-test showed signifi cant differences between medians in leukaemia patients and controls groups for Pb (lymphatic/control, acute/control), Cu (lymphatic/control, chronic/control), Ni (lymphatic/control, chronic/control) and Fe (chronic/control). Very strong positive and negative correlations (r > 0.70) in the scalp hair of control group were observed between Ni/Fe-Ni, Cu/Fe-Cu, Zn/Fe-Zn, Pb/Fe-Pb, Cu/Ni-Zn/Ni, Cu/Ni-Pb/Ni, Zn/Ni-Pb/Ni, Zn/Fe-Zn/Cu, Pb/Ni-Ni and Ni/Fe-Pb/Ni, whereas only very strong positive ratios in the scalp hair of leukaemia patients group were observed between Ni/Fe-Ni, Cu/Fe-Cu, Zn/Fe-Zn and Pb/Fe-Pb, all correlations were signifi cant at p < 0.05. Other strong and signifi cant correlations were also observed in scalp hair of both groups. Signifi cant differences between grouping of studied TEs in all classifi ed leukaemia groups and controls were found using principal component analysis (PCA). The results of PCA confi rmed that the type and the growth of leukaemia factors were more important in element loading than the age factor.

3

Effect of scattered radiation in the total body irradiation technique: evaluation of the spoiler and wall dose component in the depthdose distribution

Piotrowski T., Adamska K., Malicki J.

Nukleonika

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2007

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Vol. 52, nr 4

153-158

EN

To determine the additional dose in layers of the body close to the skin during total body irradiation (TBI), due to radiation scattered off the treatment room walls and behind plexiglass spoilers applied to improve dose uniformity within the irradiated body. Large-field 6, 15 and 25 MV photon beams were generated by a Saturn 43 medical accelerator. A solid 30 ´ 30 ´ 30 cm3 PMMA (polymethylmethacrylate) phantom was used to represent radiation scattered from the body of the patient. Dose distributions were measured by a Farmer ionization chamber. The dose component arising from the spoiler was measured 5 mm below the phantom surface, over distances of 5-100 cm between the spoiler and the phantom surface. To measure the contribution of backscattered radiation from the walls, a small lead block was placed between the source and detector. Measurements were carried out in air with the PMMA phantom removed, to eliminate radiation backscattered from the phantom. As measured behind the spoiler, attenuation of the primary photon beam by the spoiler itself was by 8, 5 and 3% for 6, 15 and 25 MV beams, respectively. The highest dose contribution from the spoiler arose at 10 cm separation between the phantom surface and the spoiler. Assessed at a depth of 5 mm in the phantom, at spoiler-phantom separation of 10 cm, relative to case without spoiler and with wall backscatter subtracted, the dose enhancement due to the spoiler was by 8, 13 and 20% at beam energies 6, 15 and 25 MV, respectively. In these measurements, the distance between the source and the phantom surface was 300 cm and that between the source and the spoiler - 290 cm. The dose contributions due to radiation backscattered from the walls, relative to the case without any wall backscatter, estimated over the distal side of the phantom at a distance of 20 cm between the wall and that side of the phantom, were 5, 6 and 8% at beam energies 6, 15 and 25 MV, respectively. The use of a spoiler enhanced the dose in regions close to the phantom surface, compensating for the dose decrease over that area due to build-up effect. Radiation backscattered from the wall enhanced the dose in regions close to the phantom surface facing the wall.

4

Application bootstrapping Kaplan - Meier estimate for survival curve smoothing

Michalak M., Powidzki M., Moczko J. A.

Computational Methods in Science and Technology

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2002

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Vol. 8, nr 2

58--64

EN

In this article we wish to present and encourage the other to use bootstrap methods in statistical analysis. We show how to bootstrap Kaplan-Meier estimator and pay attention to its advantage opposite to classical analysis. Then we present simulation study and survival time of second remission of patients suffering for acute leukaemia.