Direct Radiation Exposure Research Articles

Study of Natural Radioactivity of Slovak Cements

Building materials belongs to the sources causing direct radiation exposure, therefore the natural radionuclide content of building materials is necessary to be still discussed over the world. Cements cause direct radiation exposure because of their radium (Ra), thorium (Th) and potassium (K) content. Like other construction materials, the natural level of radioactivity in cement gives rise to external and internal indoor exposure. This work is focused on the assessment of natural radioactivity of cements commonly used in the Slovak Republic. The cement samples of CEM I, CEM II, CEM III and CEM V types from the significant Slovak cement producers were analyzed in the experiment. The samples were tested for the radionuclides content by using gamma spectroscopic measurements. The radionuclides activity in the Portland cements ranged from 5.8 – 21.6 Bq kg, 16.0 – 38.23 Bq kg and 52.0 – 733.6 Bq kg for Ra, Th and K, respectively. The measured radionuclides content was compared to the specific requirements in relation to the Slovak eco-labelling process. The index of mass activity of natural radionuclides (gamma index) in cements was calculated in the range from 0.122 – 0.484.

Measurement of natural radioactivity in building materials used in Urumqi, China

Building materials contain natural radionuclides (226)Ra, (232)Th and (40)K, which cause direct radiation exposure of the public. The concentrations of (226)Ra, (232)Th and (40)K in commonly used building materials of Urumqi, China have been analysed using gamma-ray spectrometry. The concentrations of (226)Ra, (40)K and (232)Th in the studied building materials range from 19.8 to 87.4, from 273.3 to 981.2 and from 11.6 to 47.7 Bq kg(-1), respectively. The radium equivalent activity (Raeq), gamma index (Iγ) and alpha index (Iα) were calculated to assess the radiation hazards to people living in dwellings made of the materials studied. The calculated Raeq values of all the building materials are lower than the limit of 370 Bq kg(-1) for building materials. The values of Iγ and Iα of all the building materials are less than unity. The study shows that these materials may be safely used as construction materials and do not pose significant radiation hazards.

Dose and Time Dependence of Targeted and Untargeted Effects after Very Low doses of α-Particle Irradiation of Human Lung Cancer Cells

Understanding the effects to human health resulting from exposure to low doses of ionizing radiation is a persisting challenge. No one questions the deleterious consequences for humans following exposure to high radiation doses; however, in the low dose range, the complex and to some extent unknown cellular responses raise important misgivings about the resulting protective or potentially detrimental effects. Bystander effects are involved in low dose exposures, being characterized by the appearance in unirradiated cells of a cellular damage associated with direct radiation exposure. The purpose of our work was to assess, by using clonogenic and micronuclei assays, the dose and time dependence of the bystander response after cells exposure to very low doses of α-particles and to evaluate its importance in the overall induced damage. The study includes an irradiated cells culture, a medium transfer culture with non-irradiated cells and a culture with irradiated cells after centrifugation. We observed a non-negligible contribution of the bystander effects in the overall cellular damage. Low-dose hyper-sensitivity was observed for medium transfer and irradiated cells after centrifugation cultures. Delayed and earlier cellular damage were similar in almost all experiments, suggesting an effectiveness of irradiated medium to induce a bystander response soon after irradiation.

Re: The efficacy and safety of ureteroscopy for ureteral calculi in pregnancy: our experience in 32 patients

We read the retrospective study presenting the series on ureteroscopy (URS) using for urolithiasis in pregnant women with great interest [1]. Although many studies have published about the feasibility and safety of URS in pregnant women in recent years [2–5], this is the largest series. I applaud the authors for managing 32 pregnant patients who had obstructive symptoms related with ureter calculi (n: 27) and non-calculous conditions (n: 5). Although the safety of URS for ureteral stones in pregnant patients is not signiWcantly diVerent from the safety of that procedure in non-pregnant patients [5], in fact it causes anxiety to the each of patient and surgeon. Perioperative anesthesia management of pregnant women during obstetric or non-obstetric surgery is more stressful than non-pregnant women because of maternal physiological changes during pregnancy, diseases speciWc for pregnancy and taking care of both pregnant and fetus [6]. Endoscopic procedures on pregnant women are performed with no Xuoroscopic control to avoid the deleterious eVects of radiation exposure on her and the fetus. All of the endoscopic procedures performed on pregnant without Xuoroscopic imaging require advanced surgical skills, special care, and experience. The usage of inverted Xuoroscope’s C-arm and thyroid collars to shield the uterus was previously reported to protect the fetus from the direct radiation exposure [7]. Ultrasonography (US) or Doppler US is the safest and X-ray free imaging modality used as guidance for the diagnosis of ureteral calculi or endoscopic treatment [8]. In the study, the authors have performed all procedures with direct visualization. No information is added if they felt any diYculty during the manipulations such as ureteral balloon dilation or Double-J stent or guide-wire insertion.

The role of miRNA in the direct and indirect effects of ionizing radiation

This review focuses on a number of recent studies that have examined changes in microRNA (miRNA) expression profiles in response to ionizing radiation and other forms of oxidative stress. In both murine and human cells and tissues, a number of miRNAs display significant alterations in expression levels in response to both direct and indirect radiation exposure. In terms of direct irradiation, or exposure to agents that induce oxidative stress, miRNA array analyses indicate that a number of miRNAs are up- and down-regulated and, in particular, the let-7 family of miRNAs may well be critical in the cellular response to oxidative stress. In bystander cells that are not directly irradiated, but close to, or share media with directly irradiated cells or tissues, the miRNA expression profiles are also altered, but are somewhat distinct from the directly irradiated cells. Based on the results of these numerous studies, as well as our own data presented here, we conclude that miRNA regulation is a critical step in the cellular response to radiation and oxidative stress and that future studies should elucidate the mechanisms through which this altered regulation affects cell metabolism.

Pointers for Optimizing Radiation Dose in Chest CT Protocols

Chest CT represents the third most commonly performed CT examination [1]. Use of the appropriate radiation dose for chest CT is especially important because of direct radiation exposure of breasts, lungs, and other organs, such as the thyroid, which represent some of the most radiosensitive organs in the human body. In this article, we review practical strategies for reducing radiation dose associated with chest CT examinations.

Exposure From the Large C-Arm Versus the Mini C-Arm Using Hand/Wrist and Elbow Phantoms

This study tests the conventional wisdom that using fluoroscopy under identical geometrical conditions results in less radiation when using the mini C-arm relative to the large C-arm. We evaluated the radiation dose for both direct exposure and scatter 2.54 cm outside the intensifier. We used 3 mini and 3 large C-arms in a vertical orientation with the image intensifier below the specimen and the source above. We used 2 specimens: a cadaver hand/wrist and a cadaver elbow. Specimens were tested both directly on the intensifier and on a hand table placed on the intensifier. For the same setup, use of the mini C-arm resulted in direct patient radiation exposure greater than the exposure delivered by the large C-arm. Specifically, exposure using the mini C-arm was 53% to 70% greater than that using the large C-arm. In addition, use of the hand table resulted in exposure 80% to 94% greater compared with placing the specimen directly on the intensifier. In all cases, scatter at 2.54 cm from the intensifier resulted in an average exposure of 1.5% (SD, 0.24%) of the direct beam. Tube current, and therefore machine radiation output, was approximately 13 to 14 times greater for the large C-arm. Direct radiation exposure to the patient and scatter to the surgeon are minimized when the C-arm is positioned with the intensifier below and the extremity is placed directly on the intensifier. Under identical geometrical conditions with the intensifier below the specimen, the large C-arm with its greater source to image intensifier distance is associated with less radiation exposure than the mini C-arm.

High environmental temperatures affect reproduction in the cow

A critical review regarding the reproduction physiology of the cow, related to the main effects of high environmental temperatures, in order to point out the scientific and economic importance of its adaptation to tropical conditions, in contrast to those prevailing in temperate zones, is presented. Follicular development, estrus, embryonic implantation, gestation, parturition and return to estrus within the postpartum period are affected. However, economic losses due to heat stress have not been estimated for the Colombian cattle industry and the same appears to be true for other tropical countries. Bos taurus derived genotypes seem to be more susceptible to heat stress than the Bos indicus, given their higher metabolic rate and lesser capacity for heat dissipation. Nevertheless, alterations due to heat stress should depend on the degree of adaptation of individuals or genotypes. For instance, in Colombia there are some B. taurus derived breeds which are adapted to temperature ranges, deleterious to non adapted breeds. It is recommended to establish protected zones for cattle to avoid direct sun radiation exposure and protection from low temperatures, in order to avoid the correspondent effects of temperatures, above or below the range which does not affect animal physiology. It is necessary to reorient the systems of genetic selection in order to select bovines which can adapt better to different climatic conditions existing within the tropics. It should be noted that high environmental temperatures depress food consumption which then interferes in the reproductive efficiency.

Assessments of natural radioactivity and radiological hazards in construction materials used in Elazig, Turkey

Abstract Building materials contain natural radionuclides (238U, 232Th and 40K) and therefore cause direct radiation exposure to the public. The radioactivity content of samples obtained from building materials produced in Elazig city, East Anatolian of Turkey, have been analyzed by gamma-ray spectrometry. However, radium equivalent activities, total and annual effective dose rate and external (gamma), internal (alpha) hazard indexes were calculated and radon concentration, radon specific exhalation rate and effective radium content were measured. Also, indoor radon measurements carried out in each floor (uninhabited) of rough construction (newly construction). The specific concentrations of 238U, 232Th and 40K, from selected building materials, ranged from 3.5 to 114.1 Bq/kg, 1.6–20.7 Bq/kg and 201.4–4928.0 Bq/kg, respectively. The lowest of Raeq is 36.5 ± 1.8 Bq/kg calculated in bricks while the highest value is 405.2 ± 20.9 Bq/kg in gas concrete. The average indoor radon concentration is 364.3 Bqm−3, which is higher than the global mean value, in newly constructed floor.

Emerging role of radiation induced bystander effects: Cell communications and carcinogenesis

Ionizing radiation is an invaluable diagnostic and treatment tool used in various clinical applications. On the other hand, radiation is a known cytotoxic with a potential DNA damaging and carcinogenic effects. However, the biological effects of low and high linear energy transfer (LET) radiations are considerably more complex than previously thought. In the past decade, evidence has mounted for a novel biological phenomenon termed as "bystander effect" (BE), wherein directly irradiated cells transmit damaging signals to non-irradiated cells thereby inducing a response similar to that of irradiated cells. BE can also be induced in various cells irrespective of the type of radiation, and the BE may be more damaging in the longer term than direct radiation exposure. BE is mediated either through gap-junctions or via soluble factors released by irradiated cells. DNA damage response mechanisms represent a vital line of defense against exogenous and endogenous damage caused by radiation and promote two distinct outcomes: survival and the maintenance of genomic stability. The latter is critical for cancer avoidance. Therefore, efforts to understand and modulate the bystander responses will provide new approaches to cancer therapy and prevention. This review overviews the emerging role of BE of low and high LET radiations on the genomic instability of bystander cells and its possible implications for carcinogenesis.

Radioprotective Effect of Red Ginseng in Irradiated Mice with ${\gamma}$-ray

Recently, the incidents of direct or indirect radiation exposure due to increase of use of radiation or radioisotope are on the increase in medical and industrial circles. If are irradiated, free radicals are created through biological process, and are directly or indirectly damaged. This research intends to explore into the effect of at the level of cell (in vitro) and entity (in vivo), using red ginseng extract as radioprotective agent. In the experiment implemented at the level of cell (in vitro), degree of cell activity was measures by adding mouse mesenchymal stem cells into red ginseng extract saponin(0, 0.05, 0.2, and 0.4 g/L), and then the optimal concentration of influencing was calculated, in 24, 48, 72, and 96 hours after gamma irradiation at the optimal concentration of saponin, each cell survival rate was observed through XTT assay. The best time period of cultivation for the optimal activity of C3H/10T1/2 was as 48 hours, and the degree of optimal activity was shown at 0.05 g/L. In 48 hours after irradiation of 5 Gy to C3H/10T1/2 at 0.05 g/L, the degree of activity of increased by 10%. In the experiment implemented at the level of entity (in vivo), red ginseng extract saponin at a dose of 100 mg/kg/day was injected into the abdominal cavity of six-week immature mouse for two weeks. Right after the last abdominal injection, total body irradiation of gamma rays was carried out at a dose of 5 Gy and 10 Gy. And after irradiation, the blood sample was taken, and then the number of red corpuscles was counted. In result, the decrement of experimental group treated with red ginseng extract saponin was 2.3 times larger than that of control group. In view of the results so far achieved, it was revealed that red ginseng extract saponin has a radiation exposure protection effect in the experiment implemented at the level of cell (in vitro). In case of animal experiment, the decrement of number of red corpuscles decreased. Finally, it is necessary to carry out more various researches continuously.

Unilateral Myokymia of the Tongue After Radiation Therapy for Cervical Nodal Melanoma

Hypoglossal neuropathy with associated myokymia as a delayed effect of radiation is a rare occurrence, presumably due to the relative resistance of cranial nerves to injury from irradiation. The authors describe the first case of myokymia of the unilateral tongue with myokymic discharges on needle electromyography after hypofractionated radiation therapy for an extracranial melanoma of the neck. The earlier onset of myokymia than previous cases may represent more direct radiation exposure due to radiation site or the higher radiation dosage administered for treatment of melanomas.

Effects of Scatter Radiation on ICD and CRT Function

Effects of direct radiation on implantable cardiac devices have been well studied. However, the effects of scatter radiation are not as clear. Recommendations on management of patients with implantable cardiac devices undergoing radiotherapy are based on limited studies mostly involving pacemakers. We sought to elucidate the effects of scatter radiation on implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT)-ICDs. We exposed 12 ICDs and eight CRT-ICDs to 400 cGy of scatter radiation from a 6-MV photon beam. Devices were programmed with nominal parameters and interrogated prior to radiation, after each fraction, upon completion of the radiation course and again 1 week later. A retrospective review of patients undergoing radiotherapy at the Mayo Clinic-Rochester between 2002 and 2007 in whom the device was outside the radiation field was also performed. There were 13 patients with devices undergoing radiotherapy during this time period, 12 of whom were interrogated prior to and after radiation. Interrogation reports were reviewed for device reset or parameter changes. There was no evidence of reset or malfunction during or after radiation. Also, no episodes of device reset, inappropriate sensing or therapy, or changes in programmed parameters were found in our review of patients undergoing radiotherapy. Device reset or malfunction associated with scatter radiation likely represents an unpredictable, rare occurrence. While we see no clear contraindication to radiotherapy in patients with ICDs or CRT-ICDs, precautions should be taken to avoid direct radiation exposure and to closely evaluate patient outcomes before and after the radiation course.

The 'Cosmic silence' experiment: on the potential adaptive role of environmental background radiation

In low dose radiobiology, there is a strong interest in phenomena that could imply a deviation from the linear-no-threshold (LNT) model, which is currently used to estimate the excess relative cancer risk at low doses of ionizing radiation (IR) via a linear extrapolation from high- and intermediate-dose epidemiology risk data. Such phenomena include the adaptive response as well as bystander effects , occurring in cells which do not experience direct radiation exposure. These phenomena suggest that biological response to harmful agents such as ionising radiation may be more complex than that assumed by the LNT model. In particular, environmental background radiation represents a source of chronic low dose-rate exposure which may condition the response of living systems to acute exposure to genotoxic agents, also including IR itself, via an adaptive response. To clarify this aspect is essential not only to better evaluate the risk of chronic occupational exposure, but also to understand the role of environmental background radiation on biological evolution. Reduction of background environmental IR dose rate exposure is achieved at the National Laboratories at Gran Sasso (LNGS) of the Italian Institute for Nuclear Physics (INFN). Located underneath the Gran Sasso mountain range in central Italy, these laboratories offer an excellent opportunity to continuously maintain cell cultures at extremely reduced levels of environmental background radiation. The Cosmic Silence experiment represents the natural extension, to a human cell culture model (TK6 lymphoblastoid cells), of earlier experimental studies on S. Cerevisiae (L. Satta et. al. Mut Res 1995) and V79 Chinese hamster fibroblasts (L. Satta et. al. Radiat Environ Biophys 2002), which indicated a progressive disappearance of an adaptive response in cells kept under reduced environmental background IR conditions. For the Cosmic Silence experiment, TK6 parallel cultures were set up in the underground LNGS laboratories and in Rome and planned to be maintained and assayed for 12 months. Starting at 6 months of continuous, parallel cultures, measurements of DNA damage (micronuclei) or oxidative metabolism (antioxidant enzymatic activities of SOD, GPx, and Catalase) indicate that significant deprivation of environmental background IR renders cells less tolerant to an acute X-ray exposure of 1-2 Gy. These results are compatible with the concept that environmental background IR is behaving as an adaptive agent.

Evidence for a protective response by the gill proteome of rainbow trout exposed to X‐ray induced bystander signals

The bystander effect occurs when cells which are not directly exposed to radiation, but which receive signals from irradiated cells, respond as though they were irradiated. An X-ray induced bystander effect has been demonstrated in rainbow trout gills. Therefore, a proteomic comparison was made of gills from X-ray treated trout and trout exposed to X-ray induced bystander signals. 2-D gel analysis revealed X-ray exposure increased the expression of the cancer related protein annexin II. The proteomic changes associated with the bystander effect differed from those associated with direct radiation exposure. Expression of a hemopexin-like protein, Rho GDP dissociation inhibitor (RhoGDI) and pyruvate dehydrogenase (PDH) were increased. These proteins possess protective properties against reactive oxygen damage (a component of the bystander signal), regulate epithelial polarity and prevent lactate acidosis, respectively. There was also evidence for an increase in chromosome 1 SR-like CTD-associated factor (SCAF) protein turnover, which could suggest the protective response is transcriptionally regulated. The freshwater fish gill is a polarised barrier, separating against an external hypotonic environment. Since the maintenance of epithelial polarity is vital to gill function, these bystander effect proteomic changes could collectively protect the structural, functional and intracellular integrity of gill epithelia.

Targeted and Nontargeted Effects of Low-Dose Ionizing Radiation on Delayed Genomic Instability in Human Cells

All humans receive some radiation exposure and the risk for radiation-induced cancer at low doses is based on the assumption that there is a linear non-threshold relationship between dose and subsequent effect. Consequently, risk is extrapolated linearly from high radiation doses to very low doses. However, adaptive responses, bystander effects, and death-inducing effect may influence health effects associated with low-dose radiation exposure. Adaptive response is the phenomenon by which cells irradiated with a sublethal radiation dose can become less susceptible to subsequent high-dose radiation exposure. Bystander effects are nontargeted effects observed in cells that were not irradiated but were either in contact with or received soluble signals from irradiated cells. These non-hit bystander cells can exhibit damage typically associated with direct radiation exposure. Death-inducing effect is a phenomenon whereby medium from human-hamster hybrid cells displaying radiation-induced chromosomal instability is toxic to unirradiated parental cells. In this study, we show that human RKO cells do not exhibit adaptive response, bystander effect, or death-inducing effect, as measured by cell killing, or delayed genomic instability in a stably transfected plasmid-based green fluorescent protein assay measuring homologous recombination and delayed mutation/deletion events. However, growth medium conditioned by some chromosomally unstable RKO derivatives induced genomic instability, indicating that these cells can secrete factor(s) that elicit responses in nonirradiated cells. Furthermore, low radiation doses suppressed the induction of delayed genomic instability by a subsequent high dose, indicative of an adaptive response for radiation-induced genomic instability. These results highlight the inherent variability in cellular responses to low-dose radiation exposure and add to the uncertainties associated with evaluating potential hazards at these low doses.

Cell Cycle-Related Bystander Responses are not Increased with LET after Heavy-Ion Irradiation

Evidence has accumulated that irradiated cells affect their unirradiated neighbors, so that they in turn display cellular responses typically associated with direct radiation exposure. These responses are generally known as bystander effects. In this study, cell cycle-related bystander responses were investigated in three strains of human fibroblasts after exposure to densely ionizing radiation. Varying the linear energy transfer (LET) from 11 to 15,000 keV microm(-1) allowed a study of the impact of the complexity of DNA damage in the inducing cells on the responses of bystander cells. Using both broad-beam and microbeam irradiation, transient bystander responses were obtained for the induction of CDKN1A (p21). The latter was also observed when the transmission of bystander signals was limited to soluble factors. Targeted irradiation of single cells in confluent cell monolayers revealed no correlation between the amount of CDKN1A protein in the bystander cells and the radial distance to the targeted cells. In line with the induction of CDKN1A in bystander cells after irradiation with different LETs, a transient delay in the first G1 phase after irradiation of G0/G1 cells was observed. However, the CDKN1A induction revealed no significant effect on premature terminal differentiation considered to underlie fibrosis in irradiated tissue. Thus the unchanged differentiation pattern in bystander cells does not indicate pronounced, long-lasting effects.

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CSI with photons may result in ovarian dysfunction and infertility due to radiation beam divergence into the true pelvis. However, reports of dosimetric analyses of the radiation received by the ovaries in such cases are lacking. The use of adjuvant chemotherapy may further increase the risk of ovarian failure. Laparoscopic ovarian transposition removes the ovaries from direct radiation exposure and, therefore, provides an option to preserve ovarian function. In this study, we report the radiation dosimetry of the ovaries before and after transposition in a female patient with medulloblastoma who underwent CSI. A 31 year-old nulliparous woman underwent complete surgical resection for a standard risk medulloblastoma of the left medial cerebellum and was offered CSI followed by chemotherapy. Computed tomography (CT) simulation was used for treatment planning and dose-volume histograms were generated. Before transposition, MRI of the pelvis demonstrated that both ovaries were within the spinal radiation field. Via laparoscopic transposition, the left ovary was placed adjacent to the lower pole of the left kidney while the right ovary was placed at the lower edge of the liver. Surgical clips at the most cephalad and caudal aspect of the ovaries permitted their localization on CT-simulation. The prescribed dose to the craniospinal axis was 2340 cGy with a posterior fossa boost of 3060 cGy delivered at 180 cGy per fraction using 6 MV photons. The mean, median and maximum doses for both ovaries before and after transposition are shown in Table 1. Before transposition, the mean and maximum doses to the ovaries corresponded to 42% and 69.4% of the prescribed dose of 2340 cGy for the left and to 7.1% and 30.9% of the prescribed dose for the right ovary, respectively. Ovarian transposition decreased the mean and maximum doses to 2.9% and 3.6% of the prescribed dose for the left and to 3.7% and 4.4% of the prescribed dose for the right ovary, respectively.Table 1Mean Total Dose (cGy)Median Total Dose (cGy)Maximum Total Dose (cGy)Left Ovary98310531624Left Transposed Ovary687084Right Ovary166129723Right Transposed Ovary8787103 Open table in a new tab This is the first report of three-dimensional dosimetric analysis of radiation dose delivered to the ovaries from CSI before and after lateral ovarian transposition. Given the significant reduction in ovarian dose following transposition, we recommend obtaining an MRI of the pelvis for ovarian localization in females who require CSI with photons. Ovarian transposition should also be considered as an option to maintain hormonal ovarian function and fertility in those cases where ovarian irradiation is otherwise unavoidable.

RADIATION EXPOSURE AND THE UROLOGIST: WHAT ARE THE RISKS?

Endourology is established in urology practice with routine use of fluoroscopic guidance. Medical personnel are rarely exposed to direct radiation exposure but secondary exposure occurs via radiation scatter. There are few reports on scatter radiation exposure and the subsequent risk to medical personnel involved in urological fluoroscopic procedures. We review the risks of scatter radiation exposure to medical personnel with reference to the routine use of fluoroscopic imaging in urological practice. We measured staff radiation exposure during a series of ureteral endourological procedures using LiF:Mg,Ti thermoluminescent dosimeters placed at the extremities of the operating surgeon, the assistant and the scrub nurse. Doses for percutaneous nephrolithotomy (PCNL) procedures were calculated by extrapolating from the ureteral procedure thermoluminescent dosimeter data. Theoretical scattered radiation dose rates were also calculated. The average ureteral procedure fluoroscopy time was 78 seconds with an exposure rate of 71 kV, 2.4 mA. The surgeon received the highest radiation exposure with the lower leg (11.6 +/- 2.7 microGy) and foot (6.4 +/- 1.8 microGy) receiving more radiation than the eyes (1.9 +/- 0.5 microGy) and hands (2.7 +/- 0.7 microGy). For a predicted annual caseload of 50 ureteral cases, the dose received does not exceed 0.12% of the Ionising Radiations Regulations 1999 annual dose limit for adult workers. Radiation exposure during PCNLs is higher but does not exceed 2% of the annual dose limits even if 50 PCNLs are performed annually. Fluoroscopic screening results in radiation exposure of medical personnel. The estimate of maximum scatter radiation exposure to the surgeon for 50 PCNL procedures a year did not exceed 10 mGy. This amount is less than 2% of permissible annual limits of equivalent dose to the extremities. Medical personnel should be aware of scatter radiation risks and minimize radiation exposure when involved in fluoroscopic screening procedures.

Measurement of natural radioactivity in building materials in Qena city, Upper Egypt

Building materials cause direct radiation exposure because of their radium, thorium and potassium content. In this paper, samples of commonly used building materials (bricks, cement, gypsum, ceramics, marble, limestone and granite) in Qena city, Upper Egypt have been collected randomly over the city. The samples were tested for their radioactivity contents by using gamma spectroscopic measurements. The results show that the highest mean value of 226Ra activity is 205 ± 83 Bq kg −1 measured in marble. The corresponding value of 232Th is 118 ± 14 Bq kg −1 measured in granite. For 40K this value is (8.7 ± 3.9) × 10 2 Bq kg −1 measured in marble. The average concentrations of the three radionuclides in the different building materials are 116 ± 54, 64 ± 34 and (4.8 ± 2.2) × 10 2 Bq kg −1 for 226Ra, 232Th and 40K, respectively. Radium equivalent activities and various hazard indices were also calculated to assess the radiation hazard. The maximum mean of radium equivalent activity Ra eq is 436 ± 199 Bq kg −1 calculated in marble. The highest radioactivity level and dose rate in air from these materials were calculated in marble.