مجله فیزیک پزشکی ایران
سال:1396 | دوره: | شماره: |تعداد مقالات:8

Introduction Quality control (QC) techniques are used in monitoring and maintenance of the components of an x-ray system. QC of radiology devices plays a significant role in reduction of medication dose and optimization of image quality. This study aimed to conduct QC tests on randomly selected radiology devices, installed in diagnostic imaging departments of Iran. Materials and Methods In total, quality control tests were conducted on 51 conventional radiology devices installed in 20 cities of Iran in order to assess the accuracy of peak kilovoltage (kVp), exposure time, exposure linearity and reciprocity, reproducibility of exposure and determination of half-value layer (HVL) using a calibrated Mult-O-Meter. Results In this study, 38. 6% of devices had intolerable variance of kVp accuracy. The results of 34. 5% of devices were out of the acceptable limits in exposure time accuracy test. In 46. 7% and 53. 1% of devices, variance was greater than the acceptable range for exposure linearity and exposure reciprocity, respectively. In terms of reproducibility of exposure test, the reproducibility variance and percentage of tube output variations in 19. 4% of devices exceeded the limits. Moreover, the thickness of first HVL was lower than the acceptable limit in 14. 7% of devices. Conclusion According to the results of this study, there were wide variations in QC test results, perhaps mainly due to the fact that it is not an obligation to implement QC programs in Iran. The most important problems were non-reciprocity of exposure, nonlinearity of exposure with milliampere-second (mAs), kVp and timer inaccuracy. Involvement of medical physicists, radiologists and radiographers in the implementation of QC programs at various stages of development, installation and use of equipment should enable the gradual improvement in equipment performance.

Introduction There is a growing interest in determining the concentration of various elements in food spices. In the present study, the instrumental neutron activation analysis (INAA) was employed to measure the trace elements in 11 commonly food spices consumed in Tehran, Iran. Materials and Methods The levels of K, Mn, Na, Cl, V, Br, Al, and As were determined and their effects on human health were discussed. The results were compared with the values reported in the literature. The accuracy and precision of the analytical procedure was estimated by analyzing the Lichen (IAEA-336) reference material. Results The concentrations of the measured elements in the spices were 3850-29157, 10-335, 153-2849, 186-3063, 0. 2-2. 8, 2. 1-58. 7, and 72-2102 ppm for K, Mn, Na, Cl, V, Br, and Al, respectively. As was only detected in thyme (0. 8 ppm) and plantain (0. 42 ppm). Conclusion As the findings of the present study indicated, the concentrations of K and Na in the black pepper, garlic, and ginger were significantly higher than the values reported in other countries. The Mn levels in the black pepper and garlic consumed in Tehran were comparable with those in Poland. Furthermore, the concentration of As in these spices were lower than the maximum permissible limit.

Introduction High intensity focused ultrasound (HIFU) is considered a noninvasive and effective technique for tumor ablation. Frequency and acoustic power are the most effective parameters for temperature distribution and the extent of tissue damage. The aim of this study was to optimize the operating transducer parameters such as frequency and input power in order to acquire suitable temperature and thermal dose distribution in the course of a numerical assessment. Materials and Methods To model the sound propagation, the Khokhlov-Zabolotskava-Kuznetsov (KZK) nonlinear wave equation was used and simulation was carried out using MATLAB HIFU toolbox. Bioheat equation was applied to calculate the transient temperature in the liver tissue. Frequency ranges of 2, 3, 4, and 5 MHz and power levels of 50 and 100 W were applied using an extracorporeal transducer. Results Using a frequency of 2 MHz, the maximum temperatures reached 53° C and 90° C in the focal point for power levels of 50 W and 100 W, respectively. With the same powers and using a frequency of 3 MHz, the temperature reached to 71° C and 170° C, respectively. In addition, for these power levels at the frequency of 4 MHz, the temperature reached to 72° C and 145° C, respectively. However, at the 5 MHz frequency, the temperature in the focal spot was either 57° C or 79° C. Conclusion Use of frequency of 2 MHz and power of 100 W led to higher thermal dose distribution, and subsequently, reduction of the treatment duration and complications at the same exposure time in ablation of large tumors.

Introduction Radioactive materials naturally exist in the world. Indeed, approximately 82% of human-absorbed radiation doses, which are out of human control, arise from natural sources of radiation including cosmic, terrestrial, and exposure through inhalation or ingestion. Thus, the aim of the present study was to estimate health risk, as well as the effective and organ doses from naturally occurring background radiation in residents living in the vicinity of Khorramabad, Iran. Materials and Methods This cross-sectional study was carried out in Khorramabad, Iran. The measurements were performed using Geiger-Muller detector (RDS-110) during daylight from April to June, 2015. The natural gamma radiation measurements were made both indoor and outdoor across five regions of Khorramabad (north, south, west, east, and center). Results The estimated mean absorbed dose rate in outdoor and indoor zones were 0. 09± 0. 024 and 0. 117± 0. 032 mSvy-1, respectively. Additionally, the mean annual effective dose was calculated as 0. 69± 0. 19 mSvy-1, while the estimated health risk probability was 0. 0345%. Conclusion The average annual effective dose arising from gamma background radiation was higher than global values. Therefore, more studies are required to examine the relationship between radiation-induced effects and the natural background radiation level in Khorramabad.

Introduction The aim of this study was to investigate the sterilization potential of atmospheric pressure plasma jet (APPJ) and interactions of this technology with double-stranded DNA using the polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) techniques. Materials and Methods The plasma jet was produced through a high voltage sinusoidal power supply using a mixture of argon and oxygen gases with the flow rate of 1 L/min. Escherichia coli cells and double-stranded DNA (dsDNA) fragments were amplified by T7 universal primer through the PCR technique and treated with argon/oxygen APPJ at different exposure times. The data were analyzed by the agarose and polyacrylamide gel electrophoresis, SSCP and renewed PCR techniques. Results According to the results of the study, the APPJ could serve as an effective instrument for sterilization at > 30 sec discharge. The destruction of DNA was detectable by different techniques after 120 sec from APPJ discharge. Conclusion Our findings revealed that the active species of plasma can lead to cell death. These species may break or nick the dsDNA, exchange DNA nucleotides, and lead to transition and transversion mutations. These mutagenesis effects of APPJ might be the reason of microorganism cell death after the treatment in addition to other destructive effects of APPJ on macromolecules.

Introduction Exposure to chronic levels of ionizing radiation could be detrimental to health even at very low doses. Calabar free trade zone (CFTZ) was established to promote export business in Nigeria and it is yet to produce exposure data of the Zone. Materials and Methods The Zone was divided into three categories depending on the type of business. Category A had facilities with manufacturing businesses, Category B was service providers while Category C was oil and gas businesses. Exposure levels within the CFTZ were measured with exposure meter and results obtained were converted to annual effective dose in mSv/yr. The evaluated doses were used to estimate health risks to workers in the Zone in terms of lifetime cancer incidence and mortality for persons aged between 18 – 65 years using the conversion factors in BEIR VII. Results Category B facilities had dose values between 0. 21 – 0. 31 mSv/yr followed by Category A with dose values between 0. 23 – 0. 35 mSv/yr. Category C facilities had the highest dose values between 0. 33 – 0. 40 mSv/yr. The evaluated cancer incidence and mortality rates were generally less than 2 persons in 1, 000 persons for both male and female workers. Conclusion The study shows that the exposure levels in business facilities within the CFTZ were higher than the background radiation level. The effective doses were not uniform for the different categories. The estimated cancer incidence and mortality were low, and simple linear equations were generated to relate cancer incidence to mortality.

Introduction This study was conducted to evaluate the radiographers’ awareness of radiation protection principles in the radiology centers of the hospitals of Bandar Abbas, Iran. Materials and Methods This analytical cross-sectional study was conducted on 50 radiographers of three hospitals affiliated with Hormozgan University of Medical Sciences in 2015. The data were collected using a two-part questionnaire. The first part was related to the demographic information of the radiographers (i. e. age, gender, work experience, workplace, and passing related training courses). The second part consisted of questions related to the radiographers’ awareness in three fields of radiology physics, radiation protection, and hazards of radiation. Results According to the results of the present study, the mean total scores of the radiographers’ awareness about the radiology physics, radiation protection, and hazards of radiation was 18. 41± 1. 14 out of 22. However, the radiographers’ awareness of the three investigated fields had no statistically significant relationships with the work experience (P=0. 244) and gender (P=0. 386). However, there was a significant relationship between the radiographers’ awareness about the radiation protection and their education level (P=0. 034). Moreover, a significant association was found between the radiographers’ awareness and their workplace (P=0. 009). Additionally, the participation in the radiation training courses was significantly correlated with the radiographers’ awareness regarding the radiation hazards (P=0. 022). Conclusion According to the findings of the present study, the awareness level of the radiographers about the radiation protection principles was relatively good. However, it seems that the education level of the staff should be enhanced through holding regular short-term radiation training courses.

Introduction It has long been known that ionizing radiation can lead to detrimental effects in normal cells. In this light, Radioprotective chemicals have been used to decrease morbidity or mortality caused by ionizing irradiation. This study aimed to evaluate the radio-protective effect of N-acetylcysteine against radiation-induced mortality in male mice. Materials and Methods 52 healthy male mice were divided into four groups including NAC before irradiation (1), irradiation (2), NAC after irradiation (3) NAC before irradiation (4) and control. Three groups were treated orally with 100 mg/ kg of NAC. Gamma irradiation was performed at 8 Gy using a Co-60 machine. Kaplan-Meier method and the log-rank test were performed, using SPSS version 16. The significance level was considered to be 0. 05. Results The statistical analysis revealed a significant difference between the test and control groups (P>0. 05). The percentage of survival after 30 days was 46. 2% for the irradiation group (1). In addition, the percentage of decreased lifespan was calculated at 5. 90%, 23. 60% and 17. 93% for the first-third groups, respectively. Conclusion Results revealed lack of effectiveness of treatment with NAC after lethal dose. These results suggested that application of NAC for mice before irradiation protected them from the lethal effects of whole-body irradiation.