Showing papers in "Iranian Journal of Medical Physics in 2016"
TL;DR: A hierarchical classification method for breast cancer detection is developed by including two Adaptive Boosting classifiers, the first classifier is devoted to separate normal and tumorous cases and the second layer is designed to detect tumor type.
Abstract: Introduction Breast cancer is the second cause of mortality among women. Early detection of it can enhance the chance of survival. Screening systems such as mammography cannot perfectly differentiate between patients and healthy individuals. Computer-aided diagnosis can help physicians make a more accurate diagnosis. Materials and Methods Regarding the importance of separating normal and abnormal cases in screening systems, a hierarchical classification system is defined in this paper. The proposed system is including two Adaptive Boosting (AdaBoost) classifiers, the first classifier separates the candidate images into two groups of normal and abnormal. The second classifier is applied on the abnormal group of the previous stage and divides them into benign and malignant categories. The proposed algorithm is evaluated by applying it on publicly available Mammographic Image Analysis Society (MIAS) dataset. 288 images of the database are used, including 208 normal and 80 abnormal images. 47 images of the abnormal images showed benign lesion and 33 of them had malignant lesion. Results Applying the proposed algorithm on MIAS database indicates its advantage compared to previous methods. A major improvement occurred in the first classification stage. Specificity, sensitivity, and accuracy of the first classifier are obtained as 100%, 95.83%, and 97.91%, respectively. These values are calculated as 75% in the second stage Conclusion A hierarchical classification method for breast cancer detection is developed in this paper. Regarding the importance of separating normal and abnormal cases in screening systems, the first classifier is devoted to separate normal and tumorous cases. Experimental results on available database shown that the performance of this step is adequately high (100% specificity). The second layer is designed to detect tumor type. The accuracy in the second layer is obtained 75%.
21 citations
TL;DR: The results showed that the attenuation of high-energy photons is primarily administered by the atomic number and density of the concrete, which is dependent on density of concrete but also on atomic number of composing elements.
Abstract: Introduction: Globally, the need for radiotherapy as a part of cancer management increases every year. Thus, the shielding for megavoltage radiotherapy rooms is of great importance. Materials and Methods: In the present study, 14 types of developed high-density concrete with densities ranging from 2.45 to 5.11 were simulated by using Monte Carlo method. The linear attenuation coefficient and the tenth value layer were also calculated. These dosimetric parameters were investigated for megavoltage photon beam spectra for various energies (4, 6, 10, 15, and 18 MeV) of the Varian linac and 60Co gamma rays. The results of simulation were compared with the available published results. Results: The results showed that the attenuation of high-energy photons is primarily administered by the atomic number and density of the concrete. Moreover, the variation of attenuation coefficient with density was not completely linear. Conclusion: It was concluded that the attenuation of high-energy photons not only depends on the density of concrete, but also on the atomic number of its composing elements. dependent on density of concrete but also on atomic number of composing elements.
11 citations
TL;DR: As radiographic X-ray equipments in Kerman province are relatively old with a high workload, it is recommended that AEOI modify the current policies by changing the frequency of QC test implementation to at least once a year.
Abstract: Introduction Application of quality control (QC) programs at diagnostic radiology departments is of great significance for optimization of image quality and reduction of patient dose. The main objective of this study was to perform QC tests on stationary radiographic X-ray machines, installed in 14 hospitals of Kerman province, Iran. Materials and Methods In this cross-sectional study, QC tests were performed on 28 conventional radiographic X-ray units in Kerman governmental hospitals, based on the protocols and criteria recommended by the Atomic Energy Organization of Iran (AEOI), using a calibrated Gammex QC kit. Each section of the QC kit incorporated different models. Results Based on the findings, kVp accuracy, kVp reproducibility, timer accuracy, timer reproducibility, exposure reproducibility, mA/timer linearity, and half-value layer were not within the acceptable limits in 25%, 4%, 29%, 18%, 11%, 12%, and 7% of the evaluated units (n=28), respectively. Conclusion As radiographic X-ray equipments in Kerman province are relatively old with a high workload, it is recommended that AEOI modify the current policies by changing the frequency of QC test implementation to at least once a year.
10 citations
TL;DR: In this paper, the authors investigated specific activities of radionuclide and dose assessment of some species of mushrooms using a high-purity germanium (HPGe) detector with 30% relative efficiency.
Abstract: Introduction Artificial and natural radionuclides are found in diverse environmental compartments, such as water, soil, rocks, vegetables, animals, and human body tissues. As such, humans and environments are at constant exposure of these radiation types. In this research investigated specific activities of radionuclide and dose assessment of some species of mushrooms. Materials and Methods In this study, natural and artificial radioactivity concentrations were determined in Agaricus bispora (nourished mushrooms), Cantharellus cibarius, Coprinus micaceus (wild fungi species) and their composts through gamma-ray spectrometryusinga high-purity germanium (HPGe) detector with 30% relative efficiency. Results Radioactivity concentrations of 238U and 232Th in edible mushroom samples were lower than the minimum detectable activity (MDA). For 40K and 137Cs, these concentrations were within the ranges of 1895.24-1920.24and <0.45-0.72Bq/kg, respectively. Moreover, specific activities of 238U, 232Th, 40K, and 137Cs in the composts varied within the ranges of < 0.47 - 3.40, 6.59-7.82, 1166.12-1428.27, and 0.75-1.97±Bq/kg, respectively. Excess lifetime cancer risk due to the ingestion of nourished mushrooms was calculated as 1.28×10-4, which is lower than the maximum acceptable value. Conclusion Results of this study showed that the radioactivity concentrations of edible mushrooms are close to or lower than MDA. In addition, radioactivity concentrations of the composts were indicative of the low pollution of the studied regions by radiocesium. Annual consumption rate threshold was calculated as 26.7 kg in dry weight (fresh weight: 267 kg). Therefore, it could be concluded that consumption of these mushrooms is associated with no health consequences for consumers.
8 citations
TL;DR: Services provided by modern cell phones, along with the extensive use of these devices, could be considered as potential threats to public health, especially adolescents’ sleep quality.
Abstract: Introduction The negative health effects of electromagnetic radiation and psychological dependence are among the major consequences of widespread cell phone use in the general population, especially among adolescents. In this study, the relationship between cell phone use and sleep quality parameters was evaluated. Materials and Methods The study sample consisted of 820 students (305 males and 515 females), recruited from Arak University of Medical Sciences, Arak, Iran. The participants completed Pittsburgh Sleep Quality Index (PSQI) and Cell-phone Overuse Scale (COS); the validity of these questionnaires had been previously confirmed in the Iranian population. Information on demographic characteristics and variables associated with cell phone exposure, such as the frequency and duration of phone calls and number of messages was collected in a separate questionnaire. Results Data analysis showed that cell phone overuse was significantly correlated with sleep quality and its components. Moreover, the results indicated that the global PSQI score and some sleep components were significantly correlated with several variables related to cell phone use. Based on the findings, the mean PSQI score was significantly different among heavy and light cell phone users (P<0.01). Moreover, among heavy cell phone users, females had a higher global PSQI score, compared to males (P<0.01). Conclusion According to the literature and the present study, services provided by modern cell phones, along with the extensive use of these devices, could be considered as potential threats to public health, especially adolescents’ sleep quality. In order to reach a definitive conclusion, further systematic and laboratory studies are required.
8 citations
TL;DR: The animal experiment results showed that the MIPS decreased significantly as a function of injection volume in the experimental group and the changes of ICP and MIPS of rabbits from experimental group presented a negative correlation.
Abstract: Introduction Measuring magnetic induction phase shift (MIPS) changes as a function of cerebral hemorrhage volume has the potential for being a simple method for primary and non-contact detection of the occurrence and progress of cerebral hemorrhage. Our previous MIPS study showed that the intracranial pressure (ICP) was used as a contrast index and found the primary correlation between MIPS and ICP. Materials and Methods In this study，we theoretically deduced the approximate relationship between MIPS and ICP and carried out a comparison study between MIPS and ICP on cerebral hemorrhage in rabbits in this study. Acute cerebral hemorrhage was induced by injecting autologous blood (3 to 6mL) into the brain of rabbits in the experimental group (n=7). Results The animal experiment results showed that the MIPS decreased significantly as a function of injection volume in the experimental group and the changes of ICP and MIPS of rabbits from experimental group presented a negative correlation. We also found that the MIPS slopes of all experimental samples had a change trend from fastness to slowness with a reverse of the change of ICP. Conclusion These observations suggested that the non-contact MIPS method might be valuable and potential for monitoring acute cerebral hemorrhage and obtaining the ICP information.
7 citations
TL;DR: Non-negligible doses are absorbed from contaminant electrons by the skin, which is associated with an excess risk of cancer induction, according to the results of this study.
Abstract: Introduction Accurate estimation of the skin-absorbed dose in external radiation therapy is essential to estimating the probability of secondary carcinogenesis induction Materials and Methods Electron contamination in prostate radiotherapy was investigated using the Monte Carlo (MC) code calculation. In addition, field size dependence of the skin dose was assessed. Excess cancer risk induced by electron contamination was determined for the skin, surface dose, and prostate dose-volume histogram (DVH) using MC calculation and analytical methods. Results MC calculations indicated that up to 80% of total electron contamination fluence was produced in the linear accelerator. At 5 mm below the skin surface, surface dose was estimated at 6%, 13%, 27%, and 38% for 5×5 cm2, 10×10 cm2, 20×20 cm2, and 40×40 cm2 field sizes, respectively. Relative dose at Dmax was calculated at 0.92% and 5.42% of the maximum dose for 5×5 cm2 and 40×40 cm2 field sizes, respectively. Excess absolute skin cancer risk was obtained at 2.96×10-4 (PY) -1 for total 72 Gy. Differences in prostate and skin DVHs were 1.01% and 1.38%, respectively. Conclusion According to the results of this study, non-negligible doses are absorbed from contaminant electrons by the skin, which is associated with an excess risk of cancer induction.
7 citations
TL;DR: In this paper, the authors validated the influence of relative humidity and temperature as the major components of discomfort index (DI) and found that the mean annual absorbed and effective dose of radon in evaluated parking lots were found below the permissible limits.
Abstract: Introduction Recent studies of public underground parking lots showed the influence of radon concentration and the probable discomfort caused by parking cars. Materials and Methods Radon concentration was measured in semi-closed public parking lots in the six governorates of Kuwait, using Durridge RAD7radon detector (USA). Results The peak radon concentration in the parking lots of Kuwait governorates was relatively higher during winter (63.15Bq/m3) compared to summer (41.73 Bq/m3). Radon in the evaluated parking lots revealed a mean annual absorbed dose (DRn: 0.02mSv/y) and annual effective dose (HE: 0.06mSv/y). Conclusion This study validated the influence of relative humidity and temperature as the major components of discomfort index (DI). The mean annual absorbed and effective dose of radon in the evaluated parking lots were found below the permissible limits. However, high radon DRn and HE were reported when the assessment included the parking lots, the surrounding residential apartments, and office premises. Furthermore, the time-series analysis indicated significant variations of the seasonal and site-wise distribution of radon concentrations in the indoor evaluated parking lots of the six Kuwait governorates
6 citations
TL;DR: The dose calculation accuracy of TiGRT TPS for physical wedged fields in the central axis, build-up, and off-axis regions is adequate, while it is insufficient for out-of-field regions.
Abstract: Introduction Wedge modifiers are commonly applied in external beam radiotherapy to change the dose distribution corresponding to the body contour and to obtain a uniform dose distribution within the target volume. Since the radiation dose delivered to the target must be within ±5% of the prescribed dose, accurate dose calculation by a treatment planning system (TPS) is important. The objective of the present study was to quantify the dose calculation accuracy of TiGRT TPS for physical wedged fields in radiotherapy. Materials and Methods A Semiflex™ ionization chamber was used for dose measurements in a water phantom; TiGRT TPS was also applied for dose calculations. The central axis (i.e., high dose-small dose gradient), build-up (i.e., high dose-large dose gradient), off-axis (i.e., high dose-small dose gradient), and out-of-field (i.e., low dose-small dose gradient) regions were evaluated in this study. Finally, the confidence limit values were obtained to quantify the dose calculation accuracy of TPS in these regions. Results The confidence limit values for the central axis, build-up, off-axis, and out-of-field regions were 1.01, 8.62, 1.79, and 55.24, respectively. Furthermore, the results showed that TiGRT TPS underestimated the dose of build-up and out-of-field regions for most points. Conclusion According to the results of the present study, it can be concluded that the dose calculation accuracy of TiGRT TPS for physical wedged fields in the central axis, build-up, and off-axis regions is adequate, while it is insufficient for out-of-field regions.
6 citations
TL;DR: In this paper, the gamma ray spectrometer was used to detect the specific activities of 226Ra, 232Th, 40K, and 137Cs in drinking water samples from Arak, Mobarak Abad, and Taramazd wells.
Abstract: Introduction Natural and artificial radionuclides are the main sources of human radiation exposure. These radionuclides, which are present in the environment, can be dissolved into water. Evidence suggests that radionuclides being entered the human body through drinking or hot spring water can be harmful for human health. Materials and Methods In this study,10 samples were collected from ground water resources of Arak, one sample from the surface water of Kamal-Saleh Dam, and four samples from the hot springs of Mahallat region. The specific activities of 226Ra, 232Th, 40K, and 137Cs were determined in the samples, using gamma ray spectrometry and a high-purity germanium (HPGe) detector. Results Specific activities of 226Ra, 232Th, 40K, and 137Cs were determined in the water samples. The mean 226Ra activity concentrations in drinking water samples from Aman Abad, Mobarak Abad, and Taramazd wells were 7.65±1.64, 1.56±1.04, and 1.45±1.39 Bq/l, while the corresponding values for 232Th were 2.70±0.18, 0.41±0.16, and 1.27±0.44 Bq/l, respectively. The annual effective dose due to drinking water varied from 0.01 to 0.78 mSv/y. Moreover, the specific activity of 226Ra in the water samples from the orifice of Donbe, Shafa, Soleymani, and Souda hot springs varied from 0.47±0.16 to 1.90±0.21. Conclusion The calculated annual effective dose due to water consumption by Iranians was within the average annual global range. Therefore, based on the present results, radionuclide intake due to water consumption had no consequences for public health; however, it is recommended that hot spring baths use air conditioning devices.
5 citations
TL;DR: In this article, the gamma-ray spectrometric analysis showed that the specific activities of natural radionuclides in samples, except for limonite ore, were within the worldwide range.
Abstract: Introduction Iron ore is one of the most important natural raw materials that is widely used for manufacturing iron and steel. This type of ore contains various amounts of radionuclides; thus, exposing workers handling their extraction, transportation, and processing to radiation. Materials and Methods In this study, 12 ore samples (each mass weighing about 2 kg) were collected from the iron ore mining areas of Arak region, Iran. The specific activities of 226Ra, 232Th, and 40K were determined usinggamma-ray spectrometry method employing high-purity germanium (HPGe) detector. Results The specific activities of 226Ra, 232Th, and 40K in samples were 9.39-271.70 Bq/kg, -3 Sv/y) suggested in International Commission of Radiological Protection (ICRP) Publication 82. Conclusion The gamma ray spectrometric analysis showed that the specific activities of natural radionuclides in samples, except for limonite ore, were within the worldwide range. The effective dose received by workers was much lower than the maximum acceptable value (1000 μSv/y); therefore, the level of radiations in this mine had no adverse consequences for public health.
TL;DR: This study aimed to examine the effectiveness of fusion techniques in emotion recognition using musical stimuli using Electrocardiogram and galvanic skin responses of 11 healthy female students to describe emotions.
Abstract: Introduction To extract and combine information from different modalities, fusion techniques are commonly applied to promote system performance. In this study, we aimed to examine the effectiveness of fusion techniques in emotion recognition. Materials and Methods Electrocardiogram (ECG) and galvanic skin responses (GSR) of 11 healthy female students (mean age: 22.73±1.68 years) were collected while the subjects were listening to emotional music clips. For multi-resolution analysis of signals, wavelet transform (Coiflets 5 at level 14) was used. Moreover, a novel feature-level fusion method was employed, in which low-frequency sub-band coefficients of GSR signals and high-frequency sub-band coefficients of ECG signals were fused to reconstruct a new feature. To reduce the dimensionality of the feature vector, the absolute value of some statistical indices was calculated and considered as input of PNN classifier. To describe emotions, two-dimensional models (four quadrants of valence and arousal dimensions), valence-based emotional states, and emotional arousal were applied. Results The highest recognition rates were obtained from sigma=0.01. Mean classification rate of 100% was achieved through applying the proposed fusion methodology. However, the accuracy rates of 97.90% and 97.20% were attained for GSR and ECG signals, respectively. Conclusion Compared to the previously published articles in the field of emotion recognition using musical stimuli, promising results were obtained through application of the proposed methodology.
TL;DR: It can be concluded that the reduction ratio of creatinine and uric acid (dialysis efficiency) could be continuously monitored by UV spectroscopy during hemodialysis by using iterative measurements throughout the dialysis session.
Abstract: Introduction The concentration of substances, including urea, creatinine, and uric acid, can be used as an index to measure toxic uremic solutes in the blood during dialysis and interdialytic intervals. The on-line monitoring of toxin concentration allows for the clearance measurement of some low-molecular-weight solutes at any time during hemodialysis.The aim of this study was to determine the optimal wavelength for estimating the changes in urea, creatinine, and uric acid in dialysate, using ultraviolet (UV) spectroscopy. Materials and Methods In this study, nine uremic patients were investigated, using on-line spectrophotometry. The on-line absorption measurements (UV radiation) were performed with a spectrophotometer module, connected to the fluid outlet of the dialysis machine. Dialysate samples were obtained and analyzed, using standard biochemical methods. Optimal wavelengths for both creatinine and uric acid were selected by using a combination of genetic algorithms (GAs), i.e., GA-partial least squares (GA-PLS) and interval partial least squares (iPLS). Results The Artifitial Neural Network (ANN) sensitivity analysis determined the wavelengths of the UV band most suitable for estimating the concentration of creatinine and uric acid. The two optimal wavelengths were 242 and 252 nm for creatinine and 295 and 298 nm for uric acid. Conclusion It can be concluded that the reduction ratio of creatinine and uric acid (dialysis efficiency) could be continuously monitored during hemodialysis by UV spectroscopy.Compared to the conventional method, which is particularly sensitive to the sampling technique and involves post-dialysis blood sampling, iterative measurements throughout the dialysis session can yield more reliable data.
TL;DR: In this paper, the authors determined the activity concentrations of radionuclides and calculated the average annual committed effective dose (AACED) due to the ingestion of some medicinal and edible plants from Shazand, Markazi Province, Iran.
Abstract: Introduction Natural and artificial radionuclides are the main sources of human radiation exposure, which enter the food chain from the environment. Radionuclides can affect human health by transferring from soil to plants and entering the human body. In this research study, we aimed to determine the activity concentrations of radionuclides and calculate the average annual committed effective dose (AACED) due to the ingestion of some medicinal and edible plants from Shazand, Markazi Province, Iran. Materials and Methods The specific activities of 226Ra, 232Th, 40K, and 137Cs in eight medicinal and edible plant species and their surrounding soils were determined, using gamma-ray spectrometry and a high-purity germanium (HPGe) detector. The samples were collected from Shazand, situated in Markazi Province, Iran. Results The maximum soil-to-plant transfer factor (TF)for 226Ra, 232Th, 40K, and 137Cswas estimated at 0.13, 0.13, 3.17, and 0.09, respectively. Based on the findings, the AACED for 1kg of edible plants varied from 0.63±0.16 to 13.71±0.14μSv/y. The annual gonadal dose Equivalent (AGDE) varied from 556 to 717 µSv/y for the soil samples (mean: 642µSv/y). The threshold consumption rate for edible plants ranged between21.86and 82.63 kg/y. Conclusion In this study, AACED due to the ingestion of radionuclides was lower than the global average (0.3 mSv/y). Therefore, the present results indicated no radiation health risks, associated with the use of these medicinal plants for disease treatment. However, it should be noted that all soil samples and some plants were polluted by radiocesium.
TL;DR: It can be concluded that microwaves have significant effects on the blood of mice and it is suggested that further studies be conducted in this area to confirm the findings.
Abstract: Introduction The continuous and rapid growth of telecommunication industries, along with the common application of cell phones, hasraised debates on the associated risks for humanhealth due to exposure to radiofrequency fields, caused bycell phonesorother sources, and industrial and medical applications. Accordingly, in this study, we aimed to investigate the effects of cell phone radiation on BALB/c mice blood factors. Materials and Methods In this study, 48 BALB/c mice were divided into six groups, each consisting of eight animals. Fourexposure groups were exposed to radiation waves twice a day for 30 min, 1 h, 2 h, and 4 h, respectivelyover one month. On the other hand,one exposure group wasexposed to 900 and 1800 MHz radiations (2 W)for 4 h once a day. Afterwards, the blood samples were taken from the heart, and blood factors including white blood cell count, red blood cell count, platelet count, hemoglobin level, hematocrit level, MCH, MCHC,neutrophil count, and lymphocyte count weremeasured and analyzed by SPSS version 15. Results Based on the findings, MCHC in the exposure groupreceiving 0.5 h of radiation and MCH in the exposure groupsreceiving 0.5, 2, and 4 h of radiationwere significantlydifferentfromthe control group (P<0.05). Conclusion According to the results of the present study, it can be concluded that microwaves have significant effects on the blood of mice. Therefore, it is suggested that further studies be conducted in this area to confirm the findings.
TL;DR: The MCNPX calculation outcomes showed acceptable results in a low-energy X-ray beam range (10-35 keV), and the obtained spectra for different anode/filter combinations were in good conformity with the finding of previous research.
Abstract: Introduction One of the best methods in the diagnosis and control of breast cancer is mammography. The importance of mammography is directly related to its value in the detection of breast cancer in the early stages, which leads to a more effective treatment. The purpose of this article was to calculate the X-ray spectrum in a mammography system with Monte Carlo codes, including MCNPX and MCNP5. Materials and Methods The device, simulated using the MCNP code, was Planmed Nuance digital mammography device (Planmed Oy, Finland), equipped with an amorphous selenium detector. Different anode/filter materials, such as molybdenum-rhodium (Mo-Rh), molybdenum-molybdenum (Mo-Mo), tungsten-tin (W-Sn), tungsten-silver (W-Ag), tungsten-palladium (W-Pd), tungsten-aluminum (W-Al), tungsten-molybdenum (W-Mo), molybdenum-aluminum (Mo-Al), tungsten-rhodium (W-Rh), rhodium-aluminum (Rh-Al), and rhodium-rhodium (Rh-Rh), were simulated in this study. The voltage range of the X-ray tube was between 24 and 34 kV with a 2 kV interval. Results The charts of changing photon flux versus energy were plotted for different types of anode-filter combinations. The comparison with the findings reported by others indicated acceptable consistency. Also, the X-ray spectra, obtained from MCNP5 and MCNPX codes for W-Ag and W-Rh combinations, were compared. We compared the present results with the reported data of MCNP4C and IPEM report No. 78 for Mo-Mo, Mo-Rh, and W-Al combinations. Conclusion The MCNPX calculation outcomes showed acceptable results in a low-energy X-ray beam range (10-35 keV). The obtained simulated spectra for different anode/filter combinations were in good conformity with the finding of previous research.
TL;DR: A modified version of the ICRP reference phantom was developed by inserting a realistic eye phantom into the voxelized phantom and incorporated into the Adult Male (AM) reference and UF-ORNL phantoms, which were used for the dosimetric calculations during eyelid cancer therapy.
Abstract: Introduction Accurate estimation of the absorbed dose in radiosensitive organs, located away from the target volume during radiotherapy, is one of the main reasons for the development of reference phantoms. The International Commission on Radiological Protection (ICRP) reference phantoms can provide a more realistic view of the human anatomy in comparison with the previously used mathematical phantoms. However, the ICRP reference phantoms seem to have certain limitations, resulting in the inaccurate eye simulation due to the absence of super-high-resolution CT scan images. Materials and Methods In this study, we developed a modified version of the ICRP reference phantom by inserting a realistic eye phantom into the voxelized phantom. In addition, by using the developed model, the absorbed dose received by sensitive organs (e.g., thyroid, brain, and different parts of the eye) during radiotherapy of a common ocular surface tumor was determined. The results were compared with those obtained by the modified phantom developed by the University of Florida-Oak Ridge National Laboratory (UF-ORNL). Results Based on the results, the relative difference between the equivalent doses calculated by the developed phantom and UF-ORNL phantom was nearly 75-95% and 3% for thyroid and eye substructures, respectively. Conclusion Despite of many advantageous of voxel phantoms, they have considerable limitation in providing accurate model of the eye. In the present study, a detailed stylized model was developed and incorporated into the Adult Male (AM) reference and UF-ORNL phantoms. These phantoms were then used for the dosimetric calculations during eyelid cancer therapy.
TL;DR: This method allows evaluation of photochemical and aphakic retinal hazard only by comparing the calculated threshold temperature by a computer code with the temperature of the radiant source, which may be beneficial for hygienist and ophthalmic clinicians.
Abstract: Introduction
Blue light is a part of the spectrum with the highest energy content, which can reach the retina. The damage that it can cause to the retina is called photochemical or blue-light retinal injury. For the retinal injury assessment of the photochemical and aphakic retinal hazards in the wavelength range of 300-700 nm, use of effective spectral radiance limits (W.m-2.sr-1) seems to be slightly perplexing for ophthalmologists. However, in this study, the temperature (OC) that can emit the same effective spectral radiance limit was detected using a computer code; this method could help prevent blue-light retinal injury.
Materials and Methods
The limits proposed by International Commission on Non-Ionizing Radiation Protection for blue-light induced photochemical and aphakic eye hazards were expressed in terms of temperature by a computer code for 13 Planckian sources that produce the same radiance. The calculated temperature by the computer code, here known as threshold temperature, is the maximum source temperature that for a specified viewing distance and source diameter does not cause the exposure at the receptor position to exceed the exposure limit.
Results
In terms of threshold temperature, the exposure limits for aphakia or infant retinal injury are much lower than retinal photochemical damage. For light sources with more effective radiances, these differences reach 800 K.
Conclusion
This method allows evaluation of photochemical and aphakic retinal hazard only by comparing the calculated threshold temperature by a computer code with the temperature of the radiant source, which may be beneficial for hygienist and ophthalmic clinicians.
TL;DR: A new method based on neural network to estimate patient geometrical setup using 4-dimensional (4D) XCAT anthropomorphic phantom using an artificial neural network (ANN) could estimate true patient position with less error and indicated that patient geometric set-up is highly depended on the comprehensiveness of training set.
Abstract: Introduction Patient set-up optimization is required in radiotherapy to fill the accuracy gap between personalized treatment planning and uncertainties in the irradiation set-up. In this study, we aimed to develop a new method based on neural network to estimate patient geometrical setup using 4-dimensional (4D) XCAT anthropomorphic phantom. Materials and Methods To access 4D modeling of motion of dynamic organs, a phantom employs non-uniform rational B-splines (NURBS)-based Cardiac-Torso method with spline-based model to generate 4D computed tomography (CT) images. First, to generate all the possible roto-translation positions, the 4D CT images were imported to Medical Image Data Examiner (AMIDE). Then, for automatic, real time verification of geometrical setup, an artificial neural network (ANN) was proposed to estimate patient displacement, using training sets. Moreover, three external motion markers were synchronized with a patient couch position as reference points. In addition, the technique was validated through simulated activities by using reference 4D CT data acquired from five patients. Results The results indicated that patient geometrical set-up is highly depended on the comprehensiveness of training set. By using ANN model, the average patient setup error in XCAT phantom was reduced from 17.26 mm to 0.50 mm. In addition, in the five real patients, these average errors were decreased from 18.26 mm to 1.48 mm various breathing phases ranging from inhalation to exhalation were taken into account for patient setup. Uncertainty error assessment and different setup errors were obtained from each respiration phase. Conclusion This study proposed a new method for alignment of patient setup error using ANN model. Additionally, our correlation model (ANN) could estimate true patient position with less error.
TL;DR: The external dose rates of both genders rapidly decreased with time according to bi-exponential equations, which could be attributed to the additional factors associated with iodine excretion, as well as the physiology of the body in terms of 131I uptake.
Abstract: Introduction In order to discharge the patients receiving treatment with large radiation doses of 131I for thyroid cancer, it is necessary to measure and evaluate the external dose rates of these patients. The aim of the study was to assess a new method of external dose rate measurement, and to analyze the obtained results as a function of time. Materials and Methods In this study, a telescopic radiation survey meter was utilized to measure the external dose rates of a sample population of 192 patients receiving treatment with high-dose 131I at one, 24, and 48 hours after dose administration. Results The proposed technique could reduce the occupational radiation exposure of the physicist by a factor of 1/16. Moreover, the external dose rates of both genders rapidly decreased with time according to bi-exponential equations, which could be attributed to the additional factors associated with iodine excretion, as well as the physiology of the body in terms of 131I uptake. Conclusion According to the results of this study, telescopic radiation survey meter could be used to measure the external dose rates of patients receiving treatment with 131I. Furthermore, the average difference in the radiation exposure between female and male patients was calculated to be less than 17%.
TL;DR: Scattering from leg region had a significant effect on doses to testes, sigmoid colon contents, and sigmoids colon wall in the pelvic region, and prostate and the other organs were unaffected.
Abstract: Introduction Dose calculation of tumor and surrounding tissues is essential during prostate brachytherapy. Three radioisotopes, namely, 125I, 103Pd, and 131Cs, are extensively used in this method. In this study, we aimed to calculate the received doses by the prostate and critical organs using the aforementioned radioactive seeds and to investigate the effect of scattering contribution for the legs on dose calculations. Materials and Methods The doses to organs of interest were calculated using MCNPX code and ORNL (Oak Ridge National Laboratory) phantom. Results Doses to the prostate as a source of radiation for 125I, 103Pd, and 131Cs were approximately 108.9, 97.7, and 81.5 Gy, respectively. Bladder, sigmoid colon, and testes received higher doses than other organs due to proximity to the prostate. Differences between the doses when tallying with the legs intact and with the legs voided were significant for testes, sigmoid colon contents, and sigmoid colon wall because of their proximity to the prostate. There was also a good consistency between our results and the data published by Montefiore Medical Center and Albert Einstein College of Medicine for the prostate. Conclusion Scattering from leg region had a significant effect on doses to testes, sigmoid colon contents, and sigmoid colon wall in the pelvic region, and prostate and the other organs were unaffected. Brachytherapy treatment plans using 131Cs seeds allow for better sparing of critical tissues, with a comparable number of, or fewer, seeds required, compared to 125I seeds.
TL;DR: This method allows evaluation of photochemical and aphakic retinal hazard only by comparing the calculated threshold temperature by a computer code with the temperature of the radiant source, which may be beneficial for hygienist and ophthalmic clinicians.
Abstract: Introduction Blue light is a part of the spectrum with the highest energy content, which can reach the retina. The damage that it can cause to the retina is called photochemical or blue-light retinal injury. For the retinal injury assessment of the photochemical and aphakic retinal hazards in the wavelength range of 300-700 nm, use of effective spectral radiance limits (W.m-2.sr-1) seems to be slightly perplexing for ophthalmologists. However, in this study, the temperature (OC) that can emit the same effective spectral radiance limit was detected using a computer code; this method could help prevent blue-light retinal injury. Materials and Methods The limits proposed by International Commission on Non-Ionizing Radiation Protection for blue-light induced photochemical and aphakic eye hazards were expressed in terms of temperature by a computer code for 13 Planckian sources that produce the same radiance. The calculated temperature by the computer code, here known as threshold temperature, is the maximum source temperature that for a specified viewing distance and source diameter does not cause the exposure at the receptor position to exceed the exposure limit. Results In terms of threshold temperature, the exposure limits for aphakia or infant retinal injury are much lower than retinal photochemical damage. For light sources with more effective radiances, these differences reach 800 K. Conclusion This method allows evaluation of photochemical and aphakic retinal hazard only by comparing the calculated threshold temperature by a computer code with the temperature of the radiant source, which may be beneficial for hygienist and ophthalmic clinicians.
TL;DR: It is demonstrated that the MOI of different frequency bands might be used as a feature for some patients who are different from healthy subjects in terms of high-frequency bands or performance of two hemispheres in electroencephalography (EEG).
Abstract: Introduction Many features, emerging from mathematical techniques, have been used in the analysis of brain signals. In this study, the physical quantity of “moment of inertia” (MOI) was introduced as a feature to enhance high-frequency waves (HFWs) in electroencephalography (EEG). Materials and Methods In this research, the recorded EEGs from F3, F4, and Cz points in 20 males were used. A total of 30 noiseless epochs (4 sec with a 1 sec overlap) were selected for each eyes-open and eyes-closed state from each brain signal. After averaging the relative power spectrum (RPS) of 30 epochs and obtaining an RPS with low fluctuation, the MOIs of the power spectrum and each EEG band were calculated. Results The MOI enhanced the HFWs of brain signals; therefore, HFW fluctuations in the power spectrum of MOI were more evaluable and observable than those of RPS. Paired t-test showed no significant difference in the asymmetry of MOI between the eyes-open and eyes-closed states (P=0.227), while the MOIs of alpha and beta bands between these two states were significantly different [F(1, 38)=11.8; P=0.001 and F(1, 38)=12.9; P=0.001, respectively]. Conclusion This study demonstrated that the MOI of different frequency bands might be used as a feature for some patients who are different from healthy subjects in terms of high-frequency bands or performance of two hemispheres. Therefore, in order to ensure the applicability of the obtained results, evaluation of MOI for EEG of some disorders, such as attention-deficit hyperactivity disorder, alcoholism, and autism is suggested in future studies.
TL;DR: Optimize procedures are suggested for obtaining high-quality images, with a reasonably low dose imposed to the animals, depending on the animal thickness, focal spot to surface distance, imaging technique, and animal type.
Abstract: Introduction According to the International Commission on Radiological Protection publication numbers 60 and 21, the environmental control standards should ensure human and other species protection to a desirable degree. Since application of radiographic procedures in Veterinary Medicine has increased significantly, in this study, we aimed to evaluate the entrance skin dose to the animals (e.g., dogs, cats, horses, and birds) undergoing diagnostic radiology. Materials and Methods The entrance skin dose to the animals in different radiology procedures were estimated through a) indirect estimation using the output of X-ray tubes and b) direct measurement using LiF:Mg, Ti (TLD-100) thermoluminescence dosimeter. Regression analysis was performed for comparison of the two methods. The animals included in this study were cats, dogs, small birds, horses, parrots, and chough. Results The dose received by the animals varied from 20 mGy to 1189.2 mGy, depending on the animal thickness, focal spot to surface distance, imaging technique, and animal type. Conclusion Optimized procedures are suggested for obtaining high-quality images, with a reasonably low dose imposed to the animals.
TL;DR: A modified eye model was developed by considering the effects of accommodation on the lens shape and pupil size and it was demonstrated that the accommodation causes up to 40% discrepancy for fluence-to-dose conversion coefficients of electrons in the range of 600 to 800 keV.
Abstract: Introduction International Commission on Radiological Protection (ICRP) has provided a comprehensive discussion on threshold dose for radiation-induced cataract in ICRP publication 116. Accordingly, various parts of the eye lens have different radio-sensitivities. Recently, some studies have been performed to develop a realistic eye model with the aim of providing accurate estimation of fluence-to-dose conversion coefficients for different parts of the eye. However, the effect of accommodation, which changes the lens shape and pupil size, on dose conversion coefficients has not been considered yet. In this study, we purport to develop an accommodation-dependent eye model and to study the effects of accommodation on the electron and proton fluence-to-dose conversion coefficients. Materials and Methods Herein, a modified eye model was developed by considering the effects of accommodation on the lens shape and pupil size. In addition, MCNPX 2.6 Monte Carlo transport code was used to calculate the effects of eye lens accommodation on electron and proton fluence-to-dose conversion coefficients. Results Calculation of dose conversion coefficients demonstrated that the accommodation causes up to 40% discrepancy for fluence-to-dose conversion coefficients of electrons in the range of 600 to 800 keV, which is due to the change of eye lens shape during the accommodation of the eye. Conclusion Since the accommodation of the eye change the lens shape and pupil size, it has considerable effect on fluence-to-dose conversion coefficients of electrons at some ranges of incident particle energies that should be considered in simulation. However, the fluctuation of dose conversion coefficients of protons is negligible.
TL;DR: The calculation of the real phantom showed that water and polystyrene could function similarly, while evaluating dosimetry parameters in the Gamma Knife system; thus, water andpolystyrene are not appropriate phantom matters for this purpose.
Abstract: Introduction
The Gamma Knife system is designed solely for non-invasive treatment of brain disorders, and it benefits from stereotactic surgical techniques. Dose calculations required in the system are performed by GammaPlan code; in this code, brain tissue is considered uniform. In the present study, we evaluated the effect of Gamma Knife system on the obtained dose through simulating a real human brain phantom.
Materials and Methods
In this study, a Monte Carlo simulation code (MCNPX2.7) was employed to simulate Gamma Knife system. Brain tissue equivalent Snyder phantom and combinations were considered according to International Commission on Radiological Units (ICRU)-44 report.
Results
To ensure accuracy of the simulations, patient’s head was modeled by a spherical water phantom. At this point, the dosimetry parameters were compared with those obtained by the Monte Carlo code EGS4 and good consistency was observed (less than 7% difference). At the next stage, the above dosimetry parameters were compared with those obtained experimentally by polystyrene phantom and EDR2 dosimetry film and improved consistency was detected (less than 0.5% difference). Finally, the Snyder phantom, as the human brain, was simulated. The Full Width at Half Maximum (FWHM) and penumbra decreased by 4.7% and 18%, respectively. Moreover, an isocenter dose reduction of 30-40%, compared to the water phantom, was noted.
Conclusion
The calculation of the real phantom showed that water and polystyrene could function similarly, while evaluating dosimetry parameters in the Gamma Knife system; thus, water and polystyrene are not appropriate phantom matters for this purpose.
TL;DR: The proposed algorithm could discriminate the affective states with sensitivity, specificity, and correct classification rate of 99.01%, 100%, and 99.09%, respectively.
Abstract: Introduction Automatic human emotion recognition is one of the most interesting topics in the field of affective computing. However, development of a reliable approach with a reasonable recognition rate is a challenging task. The main objective of the present study was to propose a robust method for discrimination of emotional responses thorough examination of heart rate variability (HRV). In the present study, considering the non-stationary and non-linear characteristics of HRV, empirical mode decomposition technique was utilized as a feature extraction approach. Materials and Methods In order to induce the emotional states, images indicating four emotional states, i.e., happiness, peacefulness, sadness, and fearfulness were presented. Simultaneously, HRV was recorded in 47 college students. The signals were decomposed into some intrinsic mode functions (IMFs). For each IMF and different IMF combinations, 17 standard and non-linear parameters were extracted. Wilcoxon test was conducted to assess the difference between IMF parameters in different emotional states. Afterwards, a probabilistic neural network was used to classify the features into emotional classes. Results Based on the findings, maximum classification rates were achieved when all IMFs were fed into the classifier. Under such circumstances, the proposed algorithm could discriminate the affective states with sensitivity, specificity, and correct classification rate of 99.01%, 100%, and 99.09%, respectively. In contrast, the lowest discrimination rates were attained by IMF1 frequency and its combinations. Conclusion The high performance of the present approach indicated that the proposed method is applicable for automatic emotion recognition.
TL;DR: To identify specific brain regions, such as deep brain nuclei, a QSM contrast would be more beneficial than the conventional MRI contrasts, and results showed that the MEDI method resulted in higher-quality images.
Abstract: Introduction Quantitative susceptibility mapping (QSM) is a new contrast mechanism in magnetic resonance imaging (MRI). The images produced by the QSM enable researchers and clinicians to easily localize specific structures of the brain, such as deep brain nuclei. These nuclei are targets in many clinical applications and therefore their easy localization is a must. In this study, we aimed to implement two QSM estimation algorithms, threshold-based k-space division (TKD) and morphology enabled dipole inversion (MEDI) in presurgical planning. Materials and Methods In this study, susceptibility weighted imaging (SWI) was performed on six patients referred to our center for presurgical planning purposes. The susceptibility values, as well as the contrast-to-noise ratio of few brain regions were estimated. To identify the algorithm, which was best applicable to clinics, a comparison of the two methods was performed. Results QSM images were produced; however, the results did not show any significant differences between the susceptibility values of the two methods. The contrast-to-noise ratio for the susceptibility values of the subthalamic nucleus and substantia nigra brain regions were significantly superior using the MEDI approach over TKD, suggesting improved localization of brain regions using the former method. Conclusion This study suggests that to identify specific brain regions, such as deep brain nuclei, a QSM contrast would be more beneficial than the conventional MRI contrasts. This study compared MEDI and TKD methods for quantification of brain susceptibility maps, and results showed that the MEDI method resulted in higher-quality images.
TL;DR: There are significant differences between the cancer risks for some organs even in the phantoms of the same age, and using the reference data for all children with anatomical discrepancies would lead to under- or overestimation of the risk values.
Abstract: Introduction One of the central questions in radiological protection is the magnitude of the risks from low doses of radiation, related to the justification and optimization of the diagnostic medical exposures. Therefore, the aim of this study was to estimate the cancer incidence and mortality risks in children of different ages, sizes, and ethnicities undergoing computed tomography examinations. Materials and Methods In this study, the risk estimations were performed, using the organ dose data of 16 pediatric voxel phantoms obtained in our previous publications. In addition, we employed the risk models recommended by the committee of biological effects of ionizing radiation for all solid cancers, leukemia, and cancers of several specific sites. Linear interpolation was also applied for the risk estimations of different ages. Results According to the results of this study, there are significant differences between the cancer risks for some organs even in the phantoms of the same age. Therefore, it was concluded that using the reference data for all children with anatomical discrepancies would lead to under- or overestimation of the risk values. In addition, only the amount of dose cannot be the appropriate representative of the risk, and parameters like size, age, and gender might have direct impacts on cancer incidence and mortality risks. Conclusion The findings of the current study are useful to update the information about the individual and the long-term collective public health risks.
TL;DR: Investigating the effect of environmental 50 Hz magnetic fields at intensities of 3, 6, 15, 46, 110 and 207 mT on human umbilical vein endothelial cells (HUVECs) as a significant component of angiogenesis process confirmed the theory of "biological window" for magnetic fields.
Abstract: Introduction Over the last decades, considerable levels of electromagnetic fields (EMFs) have been characterized in the living environment. Recent epidemiological studies on occupational and residential exposure to EMF have shown that 50/60 Hz fields, known as extremely low frequencies (ELF), have various biological effects, such as angiogenesis. This study aimed to investigate the effect of environmental 50 Hz magnetic fields at intensities of 3, 6, 15, 46, 110 and 207 mT on human umbilical vein endothelial cells (HUVECs) as a significant component of angiogenesis process. Materials and Methods In this study, 43 experimental groups were evaluated, including a control group, 6 sham exposure groups, 18 acute, and 18 chronic exposure groups with different exposure intensities and durations of exposure. Proliferation and viability of HUVECs were examined via cell counting and MTT methods, respectively. Results No significant changes were observed in the proliferation of HUVECs by 50 Hz magnetic field, while the viability of some acute groups was found to increase. These findings confirmed the theory of "biological window" for magnetic fields. Conclusion According to the results of this study, since the 50 Hz magnetic field can effect on viability of HUVECs and these cells play a key role in angiogenesis, 50 Hz magnetic fields at the mentioned intensities probably could be effective in the improvement of angiogenesis process.