[en] In this paper, the results of ambient dose equivalent rate measurements at different locations are presented. At every location measurements were performed twice a day, in the morning and afternoon. One of the aim of this study was to determine the impact of weather conditions on the ambient dose equivalent rate. Correlation between ambient dose equivalent rate values and the meteorological parameters such as temperature, pressure and relative humidity are analyzed. A moderate positive correlation was found between the ambient dose rate and pressure in the morning measurements. The average annual effective dose is calculated to be 0.105 mSv. (author)

[en] The evaluation of the risk of a terrorist attack has been made frequently by multiplying the probability of occurrence of a terrorist attempt by the probability of its success and a quantity which represents the consequences of a successful attack. In the case of a radiological attack the consequences will vary in case the action will be active or passive. Thirteen radionuclides were examined for their potential uses in credible threats or terrorist attacks based on their availability from laboratories and hospitals. Taking into account the dose conversion coefficients published by the International Atomic Energy Agency, those radionuclides with higher dose effectiveness for ingestion are the following: "2"1"0Po; "2"2"6Ra and "2"4"1Am. Other radionuclides which can be used in threats and terror attacks, like "1"3"7Cs for example have also been examined. The risks associated with the selected radionuclides have been tentatively ranked as high, medium, or low. The probability used to evaluate risks depends on the motivation of the terrorist and the capacity, which implies availability or the actual possibility of obtaining a particular radionuclide. On the other hand, whenever a list of radionuclides to be used in a malevolent action is available to a terrorist, the choice of the most adequate will depend also on the action to be undertaken. This work ranks risks associated with radiological terror based on physical, chemical, radio-toxicological and other relevant data on radionuclides, which were either already used in terror attacks, or were pointed out as adequate to be used in such malevolent actions. (author)

[en] The main task of this study is to calculate the radiological hazards due to gamma rays emitted from naturally occurring radionuclides (²²⁶Ra, ²³²Th, ²³⁵U and ⁴⁰K) in soil samples from some areas in Egypt. The mean activity concentration of ²³²Th, ²²⁶Ra, ²³⁵U and ⁴⁰K are 26.7, 31.1, 11 and 320.1 Bq/kg, respectively. The parameters which are used to assess the radiological hazard from exposure to these soil samples are estimated. The average absorbed dose rate of the radionuclides of interest for all measured samples is 43.5 nGy/h, while the average annual effective dose in air outdoors and indoors due to gamma radioactivity are calculated to be 53.6 and 213.9 µSv/h, respectively. The data obtained by this study will offer a base for ecologists, geophysicists and soil scientists to explain and solve easier some radio-ecological problems related to the areas under investigation. The results are intended to be further used in order to develop a data base for building a radio-ecological atlas for Egypt, in the near future. (author).

[en] All elements effect to absorption dose inside object irradiated on UELR-10-15S2 electron beam accelerator at VINAGAMMA were researched. These were: depth-dose profile, beam-size, surface-dose vs distance scanning-horn to object, limitation of conveyor speed. Base on the received results, a computer program for operator to calculate the DUR and determine the set-up values of power, the speed of conveyor, and the scanning frequency of UELR-10-15S2 (operator-parameter) in a specific irradiation case were built. Outputs of the program are good appropriate with perform case. (author)

[en] Among plant species, coniferous plants are particularly sensitive to ionizing radiation. We examined the effects of X-ray irradiation on cultured cells of Japanese cedar. Cell death in the cultured cells was increased drastically by X-ray irradiation at 5 Gy, which is as low as the dose inducing radiosensitive programmed cell death, i.e. apoptosis, in mammalian cells. The advancement of cell death in the Japanese cedar cells was accompanied by nuclear DNA fragmentation, which is typically observed both in apoptosis of mammalian cells and in hypersensitive programmed cell death observed in plant cells exposed to various environmental stresses. The results suggested that radiosensitive cell death should be involved in the susceptibility of coniferous plants to ionizing irradiation, and furthermore, this death should be a kind of programmed cell death which has a similarity to apoptosis in mammalian cells. (author)

[en] Long delays in renewal of calibration of secondary standards radiation dosimeters in radiation oncology centers due to the COVID19 pandemic have aroused concerns regarding accuracy in dose delivery to patients. The concerns are mainly due to the uncertainty in the absorbed dose to water calibration factor (N_DW) over a period of time. In this study, the N_DW factor for two ion chambers, thimble type (Farmer) and parallel plate type (Markus), used in most of the radiotherapy centers, were retrospectively reviewed for 20 years. The calibration on all occasions except once was carried out at the Secondary Standards Dosimetry Laboratory, Bhabha Atomic Research Centre, Mumbai. The change in the N_DW factor over this period was < ±3%. We, therefore, believe that a dosimeter with no history of repairs showed reasonable stability in the NDW factor over a long period. (author)

[en] This Regulation refers to the requirements of the Regulation CNEN-NN.3.01. 'Basic Act of Radiological Protection', as expressed in the section 5.9, and its application to the effective dose calculation for individual occupationally exposed. from the internal and external individual monitoring data

[en] Purpose: The aim of this study was to develop a method to derive the midplane dose [i.e., the two-dimensional (2D) dose distribution in the middle of a patient irradiated with high-energy photon beams] from transmission dose data measured with an electronic portal imaging device (EPID). A prerequisite for this method was that it could be used without additional patient information (i.e., independent of a treatment-planning system). Second, we compared the new method with several existing (conventional) methods that derive the midline dose from entrance and exit dose measurements. Methods and Materials: The proposed method first calculates the 2D contribution of the primary and scattered dose component at the exit side of the patient or phantom from the measured transmission dose. Then, a correction is applied for the difference in contribution for both dose components between exit side and midplane, yielding the midplane dose. To test the method, we performed EPID transmission dose measurements and entrance, midplane, and exit dose measurements using an ionization chamber in homogeneous and symmetrical inhomogeneous phantoms. The various methods to derive the midplane dose were also tested for asymmetrical inhomogeneous phantoms applying two opposing fields. A number of combinations of inhomogeneities (air, cork, and aluminum), phantom thicknesses, field sizes, and a few irregularly shaped fields were investigated, while each experiment was performed in 4-, 8-, and 18-MV open and wedged beams. Results: Our new method can be used to assess the midplane dose for most clinical situations within 2% relative to ionization chamber measurements. Similar results were found with other methods. In the presence of large asymmetrical inhomogeneities (e.g., lungs), discrepancies of about 8% have been found (for small field sizes) using our transmission dose method, owing to the absence of lateral electron equilibrium. Applying the other methods, differences between predicted and measured midplane doses were even larger, up to 10%. For large field sizes, the agreement between measured and predicted midplane dose was within 3% using our transmission dose method. Conclusions: Using our new method, midplane doses were estimated with a similar or higher accuracy compared with existing conventional methods for in vivo dosimetry. The advantage of our new method is that the midplane dose can be determined in the entire (2D) field. With our method, portal in vivo dosimetry is an accurate alternative for conventional in vivo dosimetry

[en] A brief overview is given of the basic principles of radiation protection: ALARA (as low as reasonably achievable) and its relation with the linear non-threshold (LNT) model for the induction of cancer by ionizing radiation

[en] Presentation is devoted to the determination of radiation doses necessary for proper sterilization effects. Different experimental methods are described and compared. Doses for sterilization of medical implants, physiological fluids, medical dressings and different tubes are discussed