Calculation of microdosimetric spectra for protons using Geant4-DNA and a µ-randomness sampling algorithm for the nanometric structures.

PURPOSE: Through introducing stochastic quantities that can be connected to the dimensions of the microscopic structures exposed to radiations, microdosimetry is concerned with the substantive specifications of radiation quality that could help gain insight into radiation effects. Utilizing the µ-randomness method and Geant4-DNA code, we calculated microdosimetry quantities for nanometric structures in a spherical body of water irradiated with protons. To gain more insight into the effects of radiation on microscopic structures and validate the code parameters, we made a comparison between our results obtained within Geant4-DNA and results from other simulations. MATERIALS AND METHODS: We calculated microdosimetric quantities through irradiating a spherical body of water of 6 µm diameter with 0.5-100 MeV protons. Microdosimetric quantities were derived for cylinders with diameter × height values of 23 × 23, 50 × 100, and 300 × 300 Å × Å, which would resemble the typical sizes of sub-cellular organisms such as the DNA, nucleosome, and chromatin fiber. We exploited the concept of µ-randomness to introduce convex bodies of random positions and directions for calculating microdosimetric quantities. We used the Geant4-DNA Monte Carlo simulation toolkit for transporting protons and secondary particles and calculating the frequency- and dose-mean lineal and specific energies in cylindrical volumes. Specifically, for same-sized cylindrical volumes, microdosimetric parameters obtained by Nikjoo et al. using the KURBUC code were used for evaluation. RESULTS: For the energy range investigated, the frequency-mean lineal energy, dose-mean lineal energy, frequency-mean specific energy, and dose-mean specific energy vary within [2.34,47.06] (keV/µm), [10.40,68.55] (keV/µm), [0.04,39.38] × 106 cGy, and [0.16,90.29] × 106 cGy, respectively. Regardless of the proton energy, our specific-energy results showed higher sensitivity to volume change, for smaller cylinder volumes rather than larger ones. Regardless of both proton energy and volume of the cylinder under study, we observed a generally better agreement between our frequency-mean, than dose-mean, specific energy results and the KURBUC results. CONCLUSION: Using Geant4-DNA to account for the stochastic nature of energy depositions due to physical interactions between radiation and matter, we calculated microdosimetry parameters concerning proton irradiation. By employing microdosimetry concepts in conjunction with simulation results of our previous work on radiation effects on the DNA, we pinpointed and quantified correlations between microdosimetry parameters and DNA damage. As such, for a volume with comparable mass and mean chord length to the DNA, we could observe the clear correspondence of the mean lineal and specific energy results with the double-strand-break yields of protons in Gy-1.Gbp-1.

Ultraviolet radiation rate in Mashhad, Iran.

Todays, Climate change can be effect on the intensity of ultraviolet (UV) radiation and cause of many human diseases. In this cross-sectional study, changes of the intensity of UV ray were associated with the changes in latitude and longitude, height, climatic conditions, natural and human-made artifacts. Given that the highest radiation intensity was at the beginning of the summer, the radiation rate of UV ray in Mashhad was measured in the summer using a Hagner radiometer, the UV-A model. The radiation rate of the UV ray was determined in 2000 stations, which were 5 km far from each other. Data were analyzed using SPSSv16 software, T-test, and ANOVA tests. The results of this study showed that the radiation rate of UV ray in Mashhad was 0.49±0.143 mSv per year. The findings showed that latitudinal and longitudinal changes did not have a significant effect on the intensity of UV radiation (P > 0.001). The changes in the height above the sea level influenced the irradiance rate of UV and increasing the height above the sea level raised UV radiation (P < 0.001). Human artifacts significantly changed the rate of UV radiation (P < 0.001). Cloudy, semi-cloudy and sunny conditions had the most effects on UV radiation (P < 0.001). The results revealed that the average rate of UV ray in Mashhad was below the global standard (10 W/m2 for UV ray), and traffic in open air could not be risky.

Microbial contamination data of keypad and touch screen of cell phones among hospital and non-hospital staffs - A case study: Iran.

Microorganisms live almost everywhere, they are even present on inanimate objects such as Mobile phones, as a result contaminates our body. The main purpose of this study was tantamount to compare microbial contamination of keypad and touch screen mobile cell phones between hospital and non-hospital staffs. Samples were collected from 456 cell phones of hospital and non-hospital. Microbial swab samples were taken from 1 cm2 of surface from each cell phone, and incubated on Brain Heart Infusion agar media at 37.5 °C for 24 h. Isolated microorganisms were grown aerobically on 55% defibrinated Sheep Blood and eosin methylene blue agar media at 37.5 °C for 48 h. In present study the antibiotic microorganism-resistant could not be observed. Overall, 456 cell phones were collected: 240 (52.63%) from hospital staff (nurses), 216 (47.36%) from non-hospital staff (health care worker outside the hospital). The result indicates that the bacterial contamination of phones used by all of different investigated groups was lower in touch screen devices than keypad devices and the contamination was found more in hospital staff cellphone than non-hospital staff׳s cell device. Woman׳s cell also has a few colonies rather than man׳s cell phones. The dominant microorganisms in the hospital staff were, Enterobacteriaceae, Bacillus species, especially Gram-positive bacteria sporulated and staphylococcal negative coagulase, respectively. Cell phones could be a serious threat to the spread of cross-infection in hospitals, therefore development of hand hygiene and cell phone cleaning guidelines is needed regarding public cell phone use.

Social risk factors and outcome analysis of poisoning in an Iranian referral medical center: A toxico-epidemiological approach.

OBJECTIVE: Suicide is the second major reason of death in the age range of 15-24 and is the eighth reason for overall death of adults. Because of high accessibility of people to different medications in our society, one of the easiest ways for suicide is intentional self-poisoning with medications. Therefore, the aim of this study was to determine the rate of suicide with respect to influencing social factors on patients with intentional self-poisoning. METHODS: This was an analytic-descriptive prospective study. All study data were collected through a checklist in patients with intentional self-poisoning who had been referred to referral hospital within 2011-2012. FINDINGS: A total of 400 patients (60% female) were evaluated. Age average ± standard deviation of participants was 22.57 ± 9.20 years. About 78.2% had high school degree or less. Nearly 27.8% of all happened suicides take place as a result of family disputes, marital problems (21%) and poverty (11.5%). Love issues with a rate of 10.3% were set in the next step. About 23.2% had a history of a past psychological disorder. Around 97.5% of the patients survived. The shorter the time of hospitalization is for each patient, the better survival rate is obtained through post-suicidal medical care. A statistically meaningful relationship was observed between self-poisoning to commit suicide and absence of academic education (P = 0.02). CONCLUSION: Suicide attempt through self-poisoning is more common in female, married individuals, people without academic education and those with a poor socio-economic status. Furthermore, results announce family disputes as the most pre-disposing factor for suicide.

Comparison of Pap smear quality with anatomical spatula and convenience (spatula-cytobrush) methods: a single blind clinical trial.

OBJECTIVES: The Papanicolaou smear is a standard test for cervical cancer screening; however, the most important challenge is high false negative results. Several factors contribute to this problem and one the most important is inappropriate sampling. The aim of this study was to compare the quality of smears obtained by either an anatomical spatula or a spatula-cyto brush. METHODS: One hundred married women participated in this single blind clinical trial. After all participants were interviewed, two samples were obtained from each: one with a spatula-cytobrush and another with an anatomical spatula. Slides were prepared and assessed by two pathologists for kappa coefficient analysis. RESULTS: Cell adequacy was 96.1 % in anatomical spatula method and 91.2 % in spatula-cyto brush method (p= 0.016). The rates for endocervical cells and metaplasia cells were 70.6%and 24.5%, respectively, with the anatomical spatula method and 69.6% and 24.5% using a spatula-cytobrush (p<0.001). No one reported pain and the amount of bleeding was 38.2% in both methods (p>0.05). In addition, there were no statistically significant differences regarding infection and inflammatory reactions (p>0.05). CONCLUSION: Based on the findings of this study, the results of sampling with anatomical spatula were more acceptable and better than those of spatula-cytobrush sampling.