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Publisher: Mashhad University of Medical Sciences   (Total: 15 journals)   [Sort by number of followers]

Showing 1 - 15 of 15 Journals sorted alphabetically
Archives of Bone and Joint Surgery     Open Access   (Followers: 7, SJR: 0.628, CiteScore: 1)
Avicenna J. of Phytomedicine     Open Access   (SJR: 0.535, CiteScore: 3)
Intl. J. of Pediatrics     Open Access   (Followers: 4)
Iranian J. of Basic Medical Sciences     Open Access   (SJR: 0.538, CiteScore: 2)
Iranian J. of Medical Physics     Open Access   (SJR: 0.239, CiteScore: 0)
Iranian J. of Neonatology     Open Access   (Followers: 4, SJR: 0.151, CiteScore: 0)
Iranian J. of Otorhinolaryngology     Open Access   (SJR: 0.269, CiteScore: 1)
J. of Cardio-Thoracic Medicine     Open Access   (Followers: 2)
J. of Evidence-based Care     Open Access   (Followers: 7, SJR: 0.152, CiteScore: 1)
J. of Fasting and Health     Open Access   (Followers: 1)
J. of Fundamentals of Mental Health     Open Access  
J. of Midwifery and Reproductive Health     Open Access   (Followers: 15)
J. of Paramedical Sciences & Rehabilitation     Open Access  
Nanomedicine J.     Open Access  
Reviews in Clinical Medicine     Open Access   (Followers: 2)
Journal Cover
Iranian Journal of Medical Physics
Journal Prestige (SJR): 0.239
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2345-3672
Published by Mashhad University of Medical Sciences Homepage  [15 journals]
  • Assessment of the Specific Activity of Radionuclides Emitters of Alpha and
           Beta in Ground Water ...

    • Abstract: Introduction: Since the episode of lead poisoning epidemic that occurred in Zamfara state of Nigeria, people living around the gold mines in the state are continuously worried about the safety of their environment, drinking water in particular. This study examined the gross activity concentrations of alpha and beta in groundwater of different locations in Anka Local Government Area (L.G.A) Zamfara state to estimate the possible radiation dose and its potential health effects. Materials and method: Thirty-two Samples of water were drawn from hand-dug wells and boreholes in the area by stratified random sampling method. ISO 9696 and ISO 9697 methods were adapted using Eurysis system- multiple channel gas-filled proportional counter for measuring gross alpha and gross beta activity concentration in the samples. Results: The results obtained showed that the range of alpha and beta activity concentration in the ground water of the area is 0.114 to 3.698 Bq/l and 0.071 – 4.823 Bq/l with a geometric mean of 0.961 Bq/l and 2.134 Bq/l respectively. The results obtained were found to be higher than the reference limits of 0.5 Bq/l and 1.0 Bq/l for gross alpha and beta activity concentration respectively, as well as the 0.1 mSv/y for effective dose equivalent, set by World Health Organization. Conclusion: The results show that the average concentrations of alpha and beta activity in the samples are above the WHO recommended limit. There is a possible negative consequence of these excessive radiations to the inhabitants of this environment.
      PubDate: Tue, 10 Apr 2018 19:30:00 +010
       
  • A Phantom Study for Optimization of Image Quality and Radiation Dose for
           Common Radiographic ...

    • Abstract: Introduction: In minimizing patient radiation dose to a minimum, radiation dose surveillance as a function of radiographic technical parameters can be carried out via phantom studies. The evidences afforded can then be used to evaluate technical parameters used in the radiographic procedures to reduce radiation dose without compromising on image quality. Materials and Methods: The experimental study was carried out using an anthropomorphic phantom and Leeds test object. Computed radiographic system was utilized and the images were printed for objective evaluation. DAP readings were obtained using a DAP meter for the technical parameters employed for the radiographic procedures. Results: The lowest radiation doses were obtained for all four radiographic procedures when using 0.2mm additional copper filtration. The highest tube potential appropriate to the body part being imaged, patient size, the image receptor response and the information required resulted in the minimum radiation dose to the patient without compromising on image quality. The focus to film distance utilized for the radiographic procedure must be in accordance to the focus to grid distance specified by the manufacturer when using the bucky to eliminate grid “cut-off.” Conclusion: Optimization of image quality and radiation dose can be carried out using a phantom and selecting the imaging parameters that yields an acceptable image quality with lowest entrance surface dose whilst taking into consideration adjustment for patient size.
      PubDate: Fri, 06 Apr 2018 19:30:00 +010
       
  • Effects of Occupational Exposure on Blood Cells of Radiographers Working
           in Diagnostic ...

    • Abstract:   Introduction: Because radiology technologists are exposed to protracted low-dose ionizing radiation and considering the possible effects of low-dose radiation on blood factors, we aimed to investigate the effects of occupational exposure on blood factors of radiographers working in radiology departments of Khuzestan Province, Iran.   Materials and Methods: This case-control study was conducted in Khuzestan Province, Iran, during 2015. Blood samples were obtained from 95 radiology technologists and 85 matched, nonradiated controls. The participants were chosen using the cluster sampling method.The data were collected by performing complete blood count (CBC) assay with aSysmexcell counter. To analyze the data, t-test and Pearson correlation coefficient were run in SPSS, version 16.   Results: T-test demonstrated that the mean values of blood factors were not significantly different between the two groups (P>0.05), and there was no significant difference between the two groups (radiographer and non-radiographer) by gender   Conclusion: In this study, occupational exposure did not have any deleterious effects on radiographers’ blood factor levels,but with increasing age and work experience in radiographers,  number of white blood cell decreased. uction: Because radiologyIntroduction: Because radiology technologists are exposed to protracted low-dose ionizing radiation and considering the possible effects of low-dose radiation on blood factors, we aimed to investigate the effects of occupational exposure on blood factors of radiographers working in radiology departments of Khuzestan Province, Iran.Materials and Methods: This case-control study was conducted in Khuzestan Province, Iran, during 2015. Blood samples were obtained from 95 radiology technologists and 85 matched, nonradiated controls. The participants were chosen using the cluster sampling method. The data were collected by performing complete blood count (CBC) assay with a Sysmex cell counter. To analyze the data, t-test and Pearson correlation coefficient were run in SPSS, version 16.Results: T-test demonstrated that the mean values of blood factors were not significantly different between the two groups (P>0.05), and there was no significant difference between the two groups (radiographer and non-radiographer) by genderConclusion: In this study, occupational exposure did not have any deleterious effects on radiographers’ blood factor levels, but with increasing age and work experience in radiographers, number of white blood cell decreased. technologists are exposed to protracted low-dose ionizing radiation and considering the possible effects of low-dose radiation on blood factors, we aimed to investigate the effects of occupational exposure on blood factors of radiographers working in radiology departments of Khuzestan Province, Iran. Materials and Methods: This case-control study was conducted in Khuzestan Province, Iran, during 2015. Blood samples were obtained from 95 radiology technologists and 85 matched, nonradiated controls. The participants were chosen using the cluster sampling method.The data were collected by performing complete blood count (CBC) assay with aSysmexcell counter. To analyze the data, t-test and Pearson correlation coefficient were run in SPSS, version 16. Results: T-test demonstrated that the mean values of blood factors were not significantly different between the two groups (P>0.05), and there was no significant difference between the two groups (radiographer and non-radiographer) by gender Conclusion: In this study, occupational exposure did not have any deleterious effects on radiographers’ blood factor levels,but with increasing age and work experience in radiographers,  number of white blood cell decreased.
      PubDate: Sat, 31 Mar 2018 19:30:00 +010
       
  • A study on slab-wooden dust-slab phantom for the development of thorax
           phantom

    • Abstract: Introduction: The determination of accurate dose distribution is an issue of fundamental importance in radiotherapy, especially with regard to the fact that the human body is a heterogeneous medium. Therefore, the present study aimed to analyze the density and isodose depth profiles of 6 MV beam in a SP34 slab-wooden dust (pine)-SP34 slab (SWS) heterogeneous phantom. Materials and Methods: The density of SP34 slab, wooden dust of pine, and thoracic region of 10 patients were calculated using computed tomography (CT) images. The depths of isodose lines were measured for 6 MV beam on the CT images of the chest, SP34 slab phantom, and SWS phantom. Dose calculation was performed at the depths of 2, 13, and 21 cm in both phantoms. Furthermore, patient-specific quality assurance (QA) was implemented using both phantoms.Results: The mean densities of the lung, SP34 slabs, and wooden dust were 0.29, 0.99, and 0.27 gm/cc respectively. The mean depths of different isodose lines in the SWS phantom were found to be equivalent to those in actual patients. Furthermore, the percentage variation between the planned and measured doses was higher in the SWS phantom as compared to that in the SP34 phantom. Furthermore, the percentage variation between the planned and measured doses in patient-specific QA was higher in the SWS phantom as compared to that in the SP34 phantom.Conclusion: As the findings indicated, the density and isodose depth profiles of the SWS phantom were equivalent to those of the actual thoracic region of human.
      PubDate: Sat, 31 Mar 2018 19:30:00 +010
       
  • Dynamic Modeling of the Electromyographic and Masticatory Force Relation
           Through Adaptive ...

    • Abstract: Introduction: Researchers have employed surface electromyography (EMG) to study the human masticatory system and the relationship between the activity of masticatory muscles and the mechanical features of mastication. This relationship has several applications in food texture analysis, control of prosthetic limbs, rehabilitation, and teleoperated robots.Materials and Methods: In this paper, we proposed a model by combining the concept of fuzzy interface systems and principal dynamic mode analysis (PDM). We hypothesized that the proposed approach would provide nonlinear and dynamic characteristics improving the estimation results compared to those obtained by the classical PDM analysis and still having the benefits of a PDM model including the sparse presentation of the system dynamics. After developing PDM, the nonlinear polynomial function of the PDM model was replaced with adaptive neuro-fuzzy inference system (ANFIS) network architecture. After training, the relevant fuzzy rules were extracted and used for creating the fuzzy block (as the nonlinear function block) and predicting the output signal. The proposed approach was later employed to predict bite force using EMG of the temporalis and masseter muscles.Results: Our proposed method outperformed the classical PDM analysis (in terms of our evaluation criteria) in predicting masticatory force . The inter-subject evaluation of the model performance proved that the model created using the data of one subject could be used for predicting masticatory force in other subjects.Conclusion: The proposed model can be helpful in food analysis to predict masticatory force based on the electrical activity of the masseter and temporalis muscles.
      PubDate: Sat, 31 Mar 2018 19:30:00 +010
       
  • Verification of Monitor unit calculations for eclipse Treatment Planning
           System by in- house ...

    • Abstract: Introduction: Computerized treatment planning is a rapidly evolving modality that depends on hardware and software efficiency. Despite ICRU recommendations suggesting 5% deviation in dose delivery the overall uncertainty shall be less than 3.5% as suggested by B.J. Minjnheer. J. In house spreadsheets are developed by the medical physicists to cross-verify the dose calculated by the Treatment Planning System (TPS).Materials and Methods: The monitor unit verification calculation (MUVC) verification was tested for pre-approved and executed treatment plans taken from the TPS. A total of 108 square fields and 120 multileaf-collimators (MLC) shaped fields for Head & Neck cancers, cervical and esophageal cancers were taken for evaluation. In house developed spreadsheet based on Microsoft Excel was developed. The dose calculation parameters such as Output Factor (O.F), Percentage Depth Dose (PDD) and off axis ratio (OAR) data were taken from the TPS. Results: The overall MU ratio fell within the range of 0.999 to 1.02 for square field geometries showing deviation of 1% between the TPS calculation and the spread sheet calculation. The MU ratios were 0.995 for Head & Neck plans & 1.012 for cervix plans with the standard deviation of 0.024 & 0.029 respectively. However we observed the mean MU ratio for Esophagus plan was 1.026 with the standard deviation of 0.040.Conclusion: The spreadsheet was tested for most of the routine treatment sites and geometries. It has good agreement with the Eclipse TPS version 13.8 for homogenous treatment sites such as head &and neck and carcinoma cervix.
      PubDate: Sat, 31 Mar 2018 19:30:00 +010
       
  • The Practice of Chest Radiography Using Different Digital Imaging Systems:
           Dose and Image Quality

    • Abstract: Introduction: The study was undertaken to evaluate the practice of chest radiography using different digital imaging systems and its influence on dose and image quality. Materials and Methods: The study was carried out in two hospitals from March 2016 to June 2016. Sixty ambulatory patients aged 21 to 60 years who were able to cooperate without difficulty and weighed between 60 to 80 kg were selected randomly. The active matrix flat panel imagers technology was employed in the direct radiography (DR) system for Hospital A, whilst Hospital B used the single read out computed radiography (CR) system. The dose area product (DAP) meter was utilized in measuring the entrance surface air kerma. The chest radiographs were evaluated by two radiologists. Results: The mean entrance surface doses (ESDs) for posteroanterior chest in Hospital A (0.098 mGy) was lower than that obtained in Hospital B (0.161 mGy). However, the ESDs at both centres were lower than the recommended value by the International Atomic Energy Agency (IAEA; 0.3 mGy). The quality of the images for chest radiography in both hospitals was adequate to make a diagnosis with ESDs and effective doses lower than those recommended by IAEA and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Conclusion: The study serves to highlight the practice of chest radiography with two different systems and its influence on image quality and dose. It can be concluded that there were significant differences in image quality and radiation dose for chest radiography practice using CR and DR.
      PubDate: Sat, 31 Mar 2018 19:30:00 +010
       
  • A Method for Body Fat Composition Analysis in Abdominal Magnetic Resonance
           Images Via ...

    • Abstract: Introduction: The present study aimed to suggest an unsupervised method for the segmentation of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in axial magnetic resonance (MR) images of the abdomen.Materials and Methods: A self-organizing map (SOM) neural network was designed to segment the adipose tissue from other tissues in the MR images. The segmentation of SAT and VAT was accomplished using a new level set method called distance regularized level set evolution (DRLSE). To evaluate the suggested method, the whole-body abdominal MRI was performed on 23 subjects, and three slices were selected for each case. Results: The results of the automatic segmentation were compared with those of the manual segmentation and previous artificial intelligent methods. According to the results, there was a significant correlation between the automatic and manual segmentation results of VAT and SAT.Conclusion: As the findings indicated, the suggested method improved detection of body fat. In this study, a fully automated abdominal adipose tissue segmentation algorithm was suggested, which used the SOM neural network and DRLSE level set algorithm. The proposed methodology was concluded to be accurate and robust with a significant advantage over the manual and previous segmentation methods in terms of speed and accuracy.
      PubDate: Sat, 31 Mar 2018 19:30:00 +010
       
  • A Validation Study on Radiation properties of a Novel LiF: Mg, Ti Known as
           IAP-100

    • Abstract: Introduction: LiF dosimeter has the most application in medicine. This study aimed to evaluate some dosimetric properties of a novel LiF: Mg, Ti.Materials and Methods: An ELEKTA Precise linear accelerator was used to calibrate dosimeters at 6 MV. In this survey, responses of dosimeters were evaluated up to 1000 cGy. Background effect was investigated in two different dosimeter states including irradiated and unirradiated.Thermoluminescence response dependence to dose rate was investigated, as well. Energy dependence was evaluated in diagnostic and therapeutic ranges. Furthermore, fading effect was evaluated by reading the dosimeters every 2 h up to 12 h post-irradiation. Results: The dosimeters had linear response up to 250 cGy. Readout values of dosimeters receiving 120 cGy at three dose rates of 21, 212, 425 cGy.min-1 were calculated equal to 125, 123, 121 cGy, respectively. The measured values of delivering 80, 120, and 150 cGy prescribed doses at 6 MV, 10 MV, and 15 MV were accurate at 6 MV and about 1.5 times higher than the prescribed doses at 10 and 15 MV. Thermoluminescence response in diagnostic energy range showed an uprising trend with increasing energy.Conclusion: The raising thermoluminescence response with increasing energy contradicts with the findings of Nunn. Due to the reproducibility and linear response of dosimeters in an acceptable dose range, they could be used in diagnostic and therapeutic fields. Effects of absorbed doses from background in low-dose studies, mainly in diagnostic radiology range, could be evaluated in more detail in future surveys.
      PubDate: Sat, 31 Mar 2018 19:30:00 +010
       
  • Radiological Assessment of the Artificial and Natural Radionuclide
           Concentrations of Wheat and ...

    • Abstract: Introduction: Artificial and natural radionuclides exist in the environmental materials, such as water, soil, rocks, and plant as well as in animals and human body tissues. Therefore, human being and environment are at constant radiation exposure. Regarding this, the present study aimed to determine the specific activities of radionuclides and perform the risk assessment wheat and barley samples in Karbala, Iraq. Materials and Methods: In this study, natural and artificial radioactivity concentrations were determined in wheat and barley samples, as well as their surrounding soil, using gamma ray spectrometrymethod by means of a high-purity germanium (HPGe) detector with 88% relative efficiency. According to the measured specific activities of radionuclides in food samples and according to annual consumption of wheat and barley by adult person excess lifetime cancer risk due to ingestion of radionuclides was calculated. Results: Specific activities of 226Ra, 232Th, 40K, and 137Cs in the soil samples varied within the ranges of 29.37-38.86, 23.24-45.70, 291.15-549.78, and 1.25-10.82Bq/kg, respectively. The excess lifetime cancer risk due to the ingestion of wheat and barley were calculated as 0.013×10-3 and 0.006×10-3, respectively, which are lower than the maximum acceptable value (10-3). Conclusion: As the findings of the present study indicated, the specific activities of natural radionuclides in the soil were close to that of the world average. The observation of artificial radiocaesium, which is released by nuclear accidents or weapon test, in all soil samples was indicative of the pollution of the studied regions by radioactive dust.
      PubDate: Sat, 31 Mar 2018 19:30:00 +010
       
  • Comparison of Image Quality of Low Voltage 64-slice multidetector CT
           Angiography with Standard ...

    • Abstract: Aims: Reduction of peak kilovoltage (KV) setting has been found as a useful approach to decrease radiation dose; but may has different effects on noise and accuracy of the diagnosis. This study will compare image quality of low (80 kV) and standard condition (100 kV).Materials and methods: This triple blind non-randomized parallel quasi-experimental study was conducted on 140 cases of questionable pulmonary emboli. CT angiography.Results: Image quality was two-fold better in 80 kV group (odds ratio=2.08). Main, segmental and subsegmental arteries had significantly higher vascular enhancement (P< 0.001) in 80 kV group. Similarly, 80 kV group had significantly higher mean number of measurable segmental arteries. Contrary, 80 kV had significantly higher mean of image noise in comparison with 100 kV group (68.4 vs. 43.1, P < 0.001). However, received radiation dosage in group with 80 kV was significantly lower than 100 kV group (0.94 versus 2.43 mSv, P < 0.001).Conclusion: Lower received radiation dosage, better quality of image but worse image noise of 80 kV versus 100 kV group shows acceptable evidence in support of reduction of voltage in suspicious cases to pulmonary emboli as a good policy of diagnosis by CT angiography.
      PubDate: Mon, 26 Mar 2018 19:30:00 +010
       
  • Cancer Risk Assessment due to the Accidental Exposure inside Neutron
           Laboratory using BEIR VII Model

    • Abstract: Introduction: The risk of cancer incidence for different combinations of ages/ organs at different neutron dose levels due to the exposure from an Americium-241/Beryllium (Am-241/Be), a standard neutron source for calibration purposes, has been estimated in this study.Methods: The ambient dose equivalent H*(10) at different distances from Am-241/Be mixed neutron source was measured by Berthold LB 6411 detector and cancer incidence risk for different organs of both male at female sex at different neutron exposure levels was determined by BEIR VII model. Result: With increasing the exposure age, the risk of cancer incidence for different organs decreases. As the H*(10) is increased, the risk of cancer incidence increments too. The most probable organ for cancer incidence at different levels of neutron irradiation in male and female sex was colon and bladder, respectively. On the other hand, prostate and uterus had the lowest radiation sensitivity and cancer incidence risk in male and female, respectively. Conclusions: Based on the obtained results, it can be concluded that the younger persons are more subject to the cancer incidence risk. The overall risk of site specific cancer incidence was highly dependent to the sex of exposed person, so that female sex was more exposed to the cancer incidence risk at all of the neutron irradiation levels understudy.
      PubDate: Mon, 26 Mar 2018 19:30:00 +010
       
  • Natural Radioactivity and Radon Concentrations in Parenteral Nutrition
           Samples Utilized in ...

    • Abstract: Introduction: This study has been carried out to measure the gamma emitters (238U, 232Th and 40K), alpha emitters (222Rn and 226Ra) and accordingly to evaluate some radiation hazard indices of radionuclides in Parenteral Nutrition samples utilized in Iraqi hospitals. Materials and Methods: The measurements have been done using gamma-ray spectroscopy with NaI(Tl) detector , solid state nuclear track detector (CR-39) and RAD-7 detector. The Hazard indices due to gamma ray have been calculated in the present work such as Radium Equivalent Activity (Raeq) and internal hazard index (Hin).Results: The specific activity of radionuclides belonging to the uranium series(238U) in Parenteral Nutrition samples ranged between (BDL - 1.81±0.42 Bq/kg), with a mean (1.17±0.20 Bq/kg) and the specific activity of radionuclides belonging to the thorium series (232Th) ranged between (0.09±0.03-0.28±0.06 Bq/kg) with a mean (0.185±0.026 Bq/kg) ,while the natural radionuclide(40K) was not detected in all samples. The value of Radon concentrations and Radium concentrations were detected using CR-39 detector were ranged between (2.00 - 29.97 mBq/L) with a mean (13.77±2.84 mBq/L) and ranged between (0.03 - 0.41 mBq/kg) with a mean (0.19±0.03 mBq/kg) respectively. A good correlation(0.91) between Radon-222 concentrations using CR-39 and RAD-7 detectors as well as a good correlation (r=0.9) was found between Uranium-238 and Radon-222. Conclusion: When comparing the results for the present work with worldwide average, we found that all values were within the recommended values given by UNSCEAR, WHO and OECD. In other words, Parenteral Nutrition samples under study is safe for consumption and could not have a hazard to the citizens.
      PubDate: Sun, 25 Mar 2018 19:30:00 +010
       
  • Effect of Pulsed-Modulated GSM-900 MHz Electromagnetics Field on
           Electrochemotherapy Efficacy ...

    • Abstract: Introduction: Electrochemotherapy (ECT) is a cancer treatment method to permeabilize cell membrane allowing the access of non-permeant molecules to the cytosol of cells. Nevertheless, environmental electromagnetic fields (EMFs) may disturb ECT efficiency through interfering in cancer cells death induced by treatment. In the present study, we inquired whether or not electromagnetic fields 900 MHz pulsed modulated by 217 Hz extremely low-frequency fields would give rise to change cell viability after ECT. Methods and material: The 4T-1 cells were exposed to 900 MHz radiofrequency (RF) modulated by 217 Hz fields at 17, 162 or 349 µW/cm2 power densities (related to 3, 4, 5 Watt antenna input powers at 15 cm distance) by GSM-900 MHZ simulator. After exposure, the cells were divided into several groups: no treatment, chemotherapy, electric pulse or ECT. The cell viability was evaluated by MTT assay after 24h. Results: The results demonstrated that 900 MHz Radiofrequency pulsed-modulated by 217 Hz electromagnetic fields at 349 µW/cm2 increased viability of the cells treated with electric pulses 70 V/cm, 5 kHz (16%), ECT 70 V/cm, 5 kHz (20%) or ECT 60 V/cm, 5 kHz (16%), each compared to the same treatment group without any exposure. However, the fields had no significant effect on chemotherapy efficacy. Conclusion: The results of the current study indicated that environmental pulsed-modulated RF fields have probably an adverse influence on some antitumor therapies. Thus, such effect should be taken into consideration in finding optimal protocols of treatment. In view of clinical significance of cancer treatments, further in vivo studies are necessary to confirm the findings and investigate more effects of the electromagnetic fields.
      PubDate: Fri, 23 Mar 2018 19:30:00 +010
       
  • Impact of Silicone gel breast prosthesis on photon beam therapy of
           recurrence carcinoma post ...

    • Abstract: Introduction Silicone gel breast implants are used for breast reconstruction post mastectomy. In the event of cancer recurrence, the radiation oncologists are forced to irradiate through the prosthesis device. Due to prosthesis higher atomic number dose perturbations occur during treatment. This study determined the influence of silicone gel thickness on the photon beam distribution. Materials and MethodsA Varian linear accelerator, water phantom (dimensions 30 × 30 × 30 cm3), silicone gel breast prosthesis and Omni-Pro Accept software were used in the study. With the gantry positioned at at a source-to-surface distance (SSD) of 100 cm, the collimators were adjusted to a field size of 10 × 10 cm2 and the 6 MeV photon beam was used. Omni-Pro Accept software was used to plot the percentage depth dose curves and the beam profiles. The results obtained with a Monte Carlo Nuclear Particle (MCNP) Code were validated with the measurement data. The beam profile and percentage depth dose curves were also measured for silicone gel thicknesses (4, 6, 8, 10, 12, 14 and 16 cm) and width 16.5 cm aligned 1 cm below the surface of the water.ResultsThe measured and calculated percentage depth dose (PDD) ratio was 0.03. The measured and calculated beam profiles were 0.5% and 0.9% respectively. For the silicone gel prosthesis, the depth dose values at 0.5 cm below the prosthesis were 2.8%.ConclusionDose perturbations below the breast prosthesis are insignificant, breast prosthesis are safe in the event of carcinoma recurrences.
      PubDate: Wed, 14 Mar 2018 20:30:00 +010
       
  • Designing and Developing an Advanced Optical Computed Tomography System
           for Radiation Dosimetry

    • Abstract: Background: Studies have shown that Optical Computed Tomography has the ability to measure radiation absorption dose and can be used in dosimeter radiation therapy. Due to the need for radiotherapy sections to confirm the distribution of absorption dose of complex fields by polymerizing a dosimeter gel, the design and construction of a computed tomography system for use in dosimetry of radiation therapy is carried out.Materials and method: An advanced Charge-Coupled Device(CCD) based optical-CT scanning system (OCT) has been developed in laboratory with the capability of high resolution 3D dosimetry. This system is used for 3D gel dosimetry. To investigate its accuracy, the OCT system was compared with the MRI as a gold standard system. A number of parameters were also checked for the correct functioning of the system.Results: By designing and developing an advanced OCT system, the Calibration curve is plotted for OCT and MRI and the achieved dose values are compared. Obtained OCT and MRI dose amounts are 1.98 and 2 Gy, respectively, and, with a relative difference of 2%. Conclusion: By applying OCT system in radiotherapy dosimetry, we can help improve and also increase the quality of patient treatment.
      PubDate: Sat, 10 Mar 2018 20:30:00 +010
       
  • A New Method for Detecting Sperms in Microscopy Images: Combination of
           Zernike Moments and ...

    • Abstract: Introduction: In recent years, modern microscopic imaging in parallel with digital image processing techniques, have provided ability of computerized analyzing of semen in order to men infertility treatment. The main challenge of these methods is to distinguish sperms from other semen particles which may be hampered by low contrast of microscopic images and the possibility of neighboring sperms to touch each other. Material and Methods: A new method which is based on combination of zernike moments and spatial processing is introduced in this article for sperm detection. In the first step of the proposed algorithm candidate selection is performed in which the zernike moments are estimated thanks to their rotation and noise resistance nature. In the second step the pruning is performed by utilizing the connectivity of candidates and morphological processing which leads to extract correct sperms. Results: The proposed algorithm was examined on microscopic images. The obtained results showed the ability of the proposed method in sperm detection in such way that it could detect 85 percent of sperms in lack of any false detection. In a more practical situation (i.e. false detection rate equal with 5 percent) the detection rate of the proposed algorithm increased up to 94 percent. Conclusion: Two existing methods including Watershed Segmentation Algorithm (WSA) and Morphological Contour Synthesis (MCS) were implemented and examined on the same data set in order to compare with the proposed algorithm. The comparisons showed superiority of the proposed method against its alternatives in such way that it detected sperms at least 3% and 13% better than WSA and MCS respectively, in lack of any false detection. By considering full detection (i.e. TPR= 100%) the rate of false detections of proposed algorithm has been at least 4% and 14% better than its alternatives.
      PubDate: Tue, 06 Mar 2018 20:30:00 +010
       
  • The effect of breast phantom composition on dose distribution in Accuboost
           brachytherapy

    • Abstract: Introduction: Long period treatments in teletherapy are not suitable for old and working patients, and those living far from the clinics. Accelerated Partial Breast Irradiation (ABPI) with high dose rate (HDR) brachytherapy has been a suitable alternative for these patients because of its limited number of fractions. The Accuboost system is a device for delivering APBI treatment. This kind of brachytherapy is carrying out with parallel-opposed photons emitted from 192Ir sources in the circle applicators. The objective of this study is to investigate the effects of breast phantom material composition on the dose distribution caused by Accuboost brachytherapy using MCNP5 Monte Carlo simulation.Materials and Methods: Different inhomogeneous breast phantoms composed of various materials, were simulated in this study. Dosimetric evaluations including dose distribution comparisons between the different breast materials and water were performed.Results: The dose values at different positions of each phantom show an insignificant mean percentage difference compared to the dose to water. The highest percentage differences between the doses of different compositions and water were found to be about 6% near the skin.Conclusions: According to the results, the dose distributions in breast phantoms containing different materials has not shown significant difference from that of water phantom. Therefore, it doesn’t seem necessary to replace the current TPSs using TG-43 formalism with the model-based patient specific dosimetry methods.
      PubDate: Sat, 24 Feb 2018 20:30:00 +010
       
  • Evaluation of dose calculations accuracy of Isogray treatment planning
           system in craniospinal ...

    • Abstract: Introduction: Craniospinal radiotherapy is a treatment technique for the whole central nervous system (CNS) tumors, and requires meticulous attention to technique and dosimetry. Treatment planning system (TPS) is one of the main equipment in radiotherapy, so evaluation of its accuracy for dose calculation is essential. The goal of this study was evaluation the validity of Isogray treatment planning system in craniospinal radiotherapy techniques. To achieve this goal the radiation dose measured in Rando Phantom was compared with the dose calculated by the treatment planning software. Materials and Methods: Brain and spinal CT-Scan of Rando Phantom were obtained. Two techniques were planned. In the first technique, both brain and spinal cord were irradiated with 6 MV photon. In the second technique, brain was irradiated with 6 MV photon and spinal cord with 18 MeV electron beam. The dose of tumor and organs at risks (OAR) were measured by Thermoluminescent dosimeter (TLD). The dose inside and outside the treatment field in both photon and electron beam was also measured with TLD and compared to the corresponding values calculated by TPS.Results: In both electron and photon beams the differences between the measurement and calculation dose for the locations inside the treatment field was less than %4 for %90 of the measurement points. However, for locations outside the treatment field borders the difference was %10 to %40. According to these differences, the Isogray has sufficient dosimetric accuracy.Conclusion: The comparison between the results of practical dosimetry and treatment planning software supports the validity of Isogray treatment planning system. In both techniques, the maximum difference between the measured dose by TLD and calculated by TPS was observed in mandibule.
      PubDate: Fri, 23 Feb 2018 20:30:00 +010
       
  • Evaluation of the portal imaging system performance for an Elekta Precise
           Linac in radiotherapy.

    • Abstract: PurposeThe Electronics portal imaging device (EPID) provides 2D planar and 3D volumetric cone beam images to improve accuracy of treatment delivery. A successful utilization of EPIDs for treatment verification in radiation therapy requires periodic quality assurance. This study implement a quality assurance (QA) programme to evaluate functionality of the megavoltage portal imaging system to be confident in applying corrections for patient set-up uncertainties.MethodsThe first step was verification of the safety features. Afterwards, the uniformity of EPID response was evaluated across the flat panel detector. Contrast resolution and spatial resolution of the EPID were also evaluated using detail counting of the Los Vegas phantom images by visualization method and measuring the modulation transfer function of the edge, respectively. Moreover, a combination of smoothing methods was used for optimal implementation of the edge algorithm for the noisy portal images. Finally, the central ray position on the EPID surface at different gantry angles was determined to evaluate mechanical stability of the supporting arm. ResultsThe safety interlocks were found to be functional. The EPID response variation was less than 3% across the detector. Contrast resolution was found to agree with the recommended tolerance; however, the visualization method was widely observer-dependent. The value of f50 for spatial resolution was 0.401±0.005 lp/mm for 6 MV. The supporting arm deviation was within ±1 mm.ConclusionThe periodic QA of image guidance system gives confidence to apply set-up corrections in clinic.
      PubDate: Tue, 20 Feb 2018 20:30:00 +010
       
  • Analysis of the effect of pullback speed and skin-vein distance on the
           performance of ...

    • Abstract: Introduction: Endovenous laser treatment (ELT) is a new treatment method for the reflux of great saphenous vein. Successful ELT depends on the selection of optimum parameters to achieve optimal vein damage while avoiding side effects such as skin burning. Mathematical modeling of ELT can be used for better understanding of the ELT process. The objective of this study is to examine the effect of laser pullback speed and vein to skin distance on the efficiency of ELT technique.Materials and Methods: Using finite element method, optical–thermal damage models were formulated and implemented to simulate ELT process. First, light distribution was modeled using the diffusion approximation of the transport theory, then temperature rising was calculated based on the bioheat equation. Finally, by considering the temperature field, laser-induced tissue damage volume was estimated by means of Arrhenius damage model.Results: Our results showed that the laser pullback speed and the vein to skin distance can affect the ELT process. It was suggested that laser pullback speed of 1 mm/s, 2 mm/s and 4mm/s are suitable for the treatment of varicose veins located at 15mm, 10mm and 5 mm to the skin surface respectively.Conclusions: It was suggested that laser pullback speed in the ELT should be determined by considering the geometry of varicose veins especially skin- vein distance.
      PubDate: Wed, 14 Feb 2018 20:30:00 +010
       
  • Numerical analysis of thermal interaction of cell-phone radiation within
           human eye tissues

    • Abstract: Introduction: The study presents a numerical analysis of penetration depth and Specific Absorption Rate (SAR) with varying distance between the source of radiation and exposed human eye tissues (cornea, posterior chamber, anterior chamber, lens, sclera, vitreous humor and Iris) at 900 and 1800 MHz frequencies, respectively. In addition, corresponding temperature increase inside various eye tissues is also calculated. Materials and Methods: A theoretical model based upon tissue dielectric and thermal properties, Maxwell equations, Joules law of heating, microscopic form of ohm law has been proposed to find the realistic situation of the cell phone radiation interaction between various human eye tissues.Results: Rise in temperature is found to be highest in anterior chamber than vitreous, sclera, lens and cornea and posterior chamber. By assuming the distance of 5cm and exposure time of 30 minutes, the maximum rise in temperature for anterior chamber was estimated to be 1.20C for 900 MHz and 2.20C for 1800 MHz frequencies. Conclusion: This could be due to disposal of excess heat by perfusion of blood in case of vitreous, posterior chamber, sclera and lens tissues and cooling produced due to convection / conduction in case of cornea tissue. But no such mechanism for heat disposal is available in case of anterior chamber tissues.
      PubDate: Fri, 09 Feb 2018 20:30:00 +010
       
  • Radiological hazard resulting from natural radioactivity of soil in east
           of Shazand Power Plant

    • Abstract: IntroductionNatural and artificial radionuclides are the main sources of human radiation exposure. Radionuclides can affect human health by transferring from soil to plants and entering the human body through the food chain. In this research, 34 soil samples between Arak city and Shazand Power Plant over 20 km length were investigated.Materials and MethodsThe specific activities of 226Ra, 232Th, 40K, and 137Cs of soil samples were measured in 20 km length between Arak City and Shazand Power Plant, using gamma-ray spectrometry and a high-purity germanium (HPGe) detector. For all samples calculated radiological hazards such radium equivalent (Raeq), dose rate in air (D), Internal and external hazard indices (Hin, Hex ), annual gonadal dose equivalent (AGDE) and Excess Lifetime Cancer risk. ResultsSpecific activities of 226Ra, 232Th, 40K and 137Cs in the soil samples varied from 18.92 to 43.11, from 25.31 to 54.27, from 230.17 to 728.25 and from
      PubDate: Fri, 02 Feb 2018 20:30:00 +010
       
  • Evaluation of Knowledge, Attitude, and performance of radiographers
           towards radiation ...

    • Abstract: Introduction: Nowadays, diagnostic methods based on X-ray play a significant role in medical diagnosis and treatment. In addition to the benefits, X-rays have harmful effects for patients and radiographers, obeying radiation protection principles leads to lower exposure and will reduces the probability of radiation risk. Therefore, the aim of this study was to assess the level of awareness, attitude, and performance of radiographers.Materials and Methods: This descriptive-analytic study was performed in Southern Khorasan province in 2017. The research tool was a questionnaire including questions about knowledge, attitude, and performance. Based on census sampling method, 100 radiographers and senior radiology students were included in the study. The collected data were analyzed using descriptive statistics and SPSS20 software.Results: The mean score for knowledge, attitude, and performance was 61.8 ± 13.8, 67.4 ± 21.5 and 50.7 ± 18.4 respectively. Gender had no significant effect on any of knowledge, attitude and performance factors. The educational degree had no significant effect on performance, but it significantly affected the knowledge and attitude of participants, so that by increasing their level of education, their knowledge and attitudes increased. Discussion: The score for knowledge of the participants was 61.9 ± 13.8, which was a good score in comparison with the score of the other studies. Regarding the attitude and performance of the participants, the score was 67.4 ± 21.5 and 50.7 ± 18.4 respectively, which was less favorable than other studies, but the performance was much better.Conclusion: According to the level of knowledge, attitude and performance of radiographers and also, considering the willingness of the participants to attend retraining classes, holding these courses can be an important and effective factor in increasing the level of knowledge, attitude, and performance of the radiation workers towards the principles of radiation protection.
      PubDate: Thu, 25 Jan 2018 20:30:00 +010
       
  • An assessment of in vitro radiosensitivity parameters of breast cancer
           cells following exposure ...

    • Abstract: Purpose: To assess the radiosensitivity parameters for SK-BR-3 (SKBR3) breast cancer cells to be implemented in the cutting-edge treatment planning systems (TPS) for accelerated partial-breast irradiation (APBI). Methods: The cell survival fraction (SF) and its relevant radiosensitivity coefficients, α and β, in linear-quadratic (LQ) formalism were evaluated for 6 MV X-rays and 60Co γ-rays using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. During the irradiation time, the medium temperature was kept at 4°C which prevented the repair of sublethal radiation damages over the exposure time and caused the survival fractions were independent of the dose rate.Results: Fitting the LQ model to experimental data, the α, β, and α/β radiosensitivity parameters were obtained as 0.156±0.027 Gy-1, 0.026±0.007 Gy-2, and 6.0 Gy for 6 MV x-rays and 0.162±0.028 Gy-1, 0.028±0.007 Gy-2, and 5.8 Gy for 60Co gamma radiation, respectively. Average relative biological effectiveness (RBE) values were 0.91 and 0.96 for 6 MV X-rays and 60Co γ-rays, respectively. The derived LQ parameters were also compared with those from previously in vitro studies for different breast cancer cell lines using various regimes such as radiotherapy (RT) modality with different dose rates and delivered doses. Conclusion: The results of this study provide essential constant values of α and β parameters. The data could be used for improvement the TPS to include the effect of different biological responses to radiation in treatment plans of APBI.
      PubDate: Thu, 25 Jan 2018 20:30:00 +010
       
  • Advanced Analysis of Pattern Reversal Visual Evoked Potential (PRVEP) in
           Anisometropic Amblyopia

    • Abstract: Purpose: To identify descriptor of pattern reversal visual evoked potential (PRVEP) waveforms by evaluating discrete wavelet transform (DWT) scalograms in order to optimize spatial frequency and contrast of stimuli in the diagnosis of anisometropia amblyopia.Methods: Pattern reversal visual evoked potentials (PRVEPs) were done for thirty one normal, and thirty five amblyopic eyes. The stimuli consisted of spatial frequencies of 1, 2 and 4 cycles per degree (cpd) and contrast levels of 100%, 50%, 25% and 5%. Results were analyzed in time and time-frequency domain. The energy percentage of a single wavelet coefficient to the total energy of level 7 in predetermined time intervals (7P descriptor) was extracted for Haar (haar), Daubechies 2 (db2), Daubechies 4 (db4), Symlet 5 (sym5), Biorthogonal 3.5 (bior3.5), Biorthogonal 4.4 (bior4.4), and Coiflet 5 (coif5) wavelets for 12 stimuli and compared between the two groups. Correlation between different spatial frequencies at the same contrast level as well as similarities between reconstructed signals and VEP waveforms were evaluated. Results: In time domain analysis, P100 amplitude and latency showed significant reduction and increase respectively in the patient group. In the amblyopic group, 7P descriptor decreased in all analysis, except at frequency of 7cpd and contrast of 5% using bior4.4. A week correlation was seen between different frequency at a special contrast and a strong correlation was between reconstructed signals and originals.Conclusion: 7P descriptor extracted from the DWT of PRVEP signals can be used for differentiating normal and abnormal signals in anisometropia amblyopia. Our findings showed that performing the DWT using coif5, db4, bior4.4, and bior3.5 wavelets can be utilized as a good indicator for selecting optimum spatial frequency and contrast.
      PubDate: Wed, 17 Jan 2018 20:30:00 +010
       
  • Radiation Dose Measurement on Surface of Indigenously Made Inhomogeneous
           Female Pelvic Phantom ...

    • Abstract: Introduction: Megavoltage X-ray photon beams are used for the treatment of carcinoma cervix patients because they produce a skin-sparing effect. Ideally, the radiation dose to the surface should be negligible, but due to contamination surface receives significant doses. Therefore, the knowledge of how different field parameters affect the surface dose is essential for proper treatment. The purpose of this study is to find out the effect of various physical parameters on the surface doses. Materials and Methods: The effect of different field dimensions, source-to-surface distances, and open or block tray fields on surface doses were determined. MOSFET dosimetric system was used for dose measurements for 6 MV photon beam. Measured surface doses were compared with TPS computed dose values in the same dosimetric conditions. Results: The measured percentage depth dose for 10x10 cm2 field at phantom surface (PDD0) were 13.32%, 12.95% and 13.87% (open field) and 36.87%, 36.31% and 35.88% (block tray) and computed dose values were 7.83%, 7.73% and 7.65% (open field) and 16.33%, 16.12% and 15.88% (block tray) at 80 cm, 100 cm, and 120 cm SSD respectively. Conclusion: The surface dose increases with increase of field sizes and decreases with increases of SSDs. The surface doses in block tray fields were significantly higher than open fields. TPS computes a smaller amount of surface doses in same dosimetric conditions. Pelvic phantom surface creates more realistic dosimetric condition than flat surface phantoms.
      PubDate: Mon, 15 Jan 2018 20:30:00 +010
       
  • A survey on radiation protection status in radiology staff

    • Abstract: Background: Exposure to radiation during radiological examination is of health concern, which relegating radiology professional should intellectualize. This study aimed to evaluate the radiation protection knowledge, attitude and practice (KAP) amongst hospitals radiology department staff in 10 provinces of Iran. This descriptive, cross-sectional study was administered to staff. Materials and Methods: In evaluating the level of radiation protection KAP, 553 staff participated in the survey. Questionnaire with 32 questions designed to assess. Validation was confirmed by faculty Medical Physics and biostatistics. Questions regarding the evaluation of respondents' knowledge, practice and attitude percentage about basic principles of protection, the necessity of using protective equipment and their performance in the implementation of the radiation protection recommendations.Results: There was not a statistically significant differences in the level of radiology staff KAP radiation protection with distinct gender and educational age (p>0.05). A significant correlation exists between practice age, hospital size and hospital type with KAP radiation protection of radiology department staff (p0.05).Conclusion: Our results showed that radiation protection KAP level of radiology staff was inadequate. This might be due to the lack of continuous training courses concerning protection against ionizing radiation. So, the continuous training of radiation protection principles can increase staff KAP level of radiation protection in radiology departments and so help to reduce public dose from medical diagnostic modalities.
      PubDate: Thu, 11 Jan 2018 20:30:00 +010
       
  • Plasmonic Photothermal property of Hollow Gold nanoshell irradiated by
           non-coherent Light: An ...

    • Abstract: Objective(s): Hollow gold nanoshells (HGN) have been introduced as one of the attractive nanostructures for biomedical applications due to interesting physicochemical properties and the tunable plasmonic absorption peaks from visible to near-infrared range. In this study, the plasmonic photothermal effect of HGN induced by non-coherent light on the DFW cell line was evaluated.Material and methods: After synthesis of Nanostructures, the temperature changes of the HGN and HGN-PEG were evaluated at different irradiation doses. After characterizing and determining cytotoxicity of the agents, DFW cells were irradiated by non-coherent light with and without the nanostructures for different exposure doses with two spectral bands of (67025) and (73025) nm. 24hrs after irradiating cells, rate of the cell survival was determined by MTT assay.Results: The HGN, HGN-PEG and light exposure did not have any significant effect on the cells survival, individually. PEGylation increased HGN size and decreased their polydispersity index, Zeta-potential and conductivity. The slope of temperature changes and also cell death caused by 730 nm were greater than 670 nm when the cells were irradiated in the presence of the HGN (or HGN-PEG). These changes became more significant with increasing exposure dose and also HGN (or HGN-PEG) concentration. The lowest cell survival occurred at a concentration of 250 μgr/ml from nanostructures and an exposure dose of 9 min (P
      PubDate: Tue, 09 Jan 2018 20:30:00 +010
       
  • Design and Development of Tissue Equivalent Female Pelvic Phantom for
           Radiological Dosimetric ...

    • Abstract: ABSTRACTAim:Design and develop a tissue equivalent pelvic phantom, mimicking Indian female pelvic dimensions, using analytical chemicals locally available, so as to achieve a cost effective phantom with equivalent radiological properties.Materials and Methods:Real bones of female cadavers (pelvic girdle, femur, vertebrae) were embedded for preparation. Paraffin wax amalgamated in suitable composition with alo-vera powder, purified borax and sodium benzoate was used to obtain density and effective atomic number effects. A hollow three dimensional outer surface and internal organs were fabricated using gypsona bandage moulds to mimic real pelvic surface. Internal organs moulds were filled first with semi-solid paraffin wax mixture, stabilized, later embedding pelvic bones and internal organs at right anatomical positions. The surface mould with bones and internal organs were stabilized in position in final form, and verified with x-ray computerized tomography (CT).Results:The physical dimensions of this female pelvic phantom are comparable with mean dimensions of Indian female pelvis. This tissue equivalent phantom is radiologically equivalent to Indian human female pelvis in all respects. The CT numbers 39.9HU (uterus), 30.5HU (bladder), 24.7HU (rectum), 34.6HU (muscles), -86.8HU (fat), 578.6HU (bone), and -220.9HU (cavities); relative electron densities of muscle, fat and bones are 1.035, 0.913, and 0.779 of phantom are comparable with human female pelvic tissue’s values.Conclusion:The dimensions and physico-radiological properties using tissue substitutes provided a good inhomogeneous female pelvic phantom differing in dimensions with commercially available imported pelvic phantoms. This will help in using the phantom for quality assurance work for radiological work, and radiotherapy treatment planning.
      PubDate: Sun, 07 Jan 2018 20:30:00 +010
       
  • Designing a liver phantom based on computed tomography images for
           dosimetry purposes

    • Abstract: PurposeIn this article, a model of liver phantom is designed for X-ray dosimetry. Besides, another method is applied using imaging for dosimetry of a real liver tissue to benchmark the results obtained by liver phantom and liver tissue. Materials and MethodsIn this study, first, a real liver tissue is converted into a phantom based on the gram-molecular weight of components of human liver tissue, mass percentage, and density of every element and it is simulated by MCNPX code for dosimetry. Then, using the DICOM images of abdomen region, the real liver tissue is contoured and the accurate geometry of segmented liver tissue is generated, and it is simulated by MATLAB software and MCNPX code for dosimetry purposes. Then, the obtained data is transferred into the MCNPX code.ResultsThe total amounts of equivalent doses along with the equivalent doses in the components of both the liver phantom and the segmented liver tissue are obtained. The results obtained from these two simulations are compared with each other to validate the efficiency of the phantom. In addition, the differences between the results have been evaluated. ConclusionsBy comparing the amounts of equivalent doses obtained from the prepared equivalent liver phantom and the real liver tissue, it is concluded that the liver phantom can be applied as a virtual liver for dosimetry.
      PubDate: Sat, 06 Jan 2018 20:30:00 +010
       
  • The effect of silver nanoparticles on improving the efficacy of
           5-aminolevulinic acid-induced ...

    • Abstract: Purpose: The most important limitation of 5-aminolevulinic acid (5-ALA)-induced photodynamic therapy (PDT) is related to the efficacy of the cells in converting 5-ALA to PpIX. Silver nanoparticles (AgNPs), with the photosensitivity at the surface plasmon resonance wavelength (635 nm) were considered to improve the effectiveness of the 5ALA-mediated PDT. Methods: At first, the toxicity of 5ALA, silver nanoparticles and a combination of both was evaluated on DFW cell line derived from melanoma and an optimal concentration with a minimum toxicity was determined for PDT experiments. Then, both interrupted and continuous light irradiation were conducted at different doses using a LED source in the groups receiving 5ALA, AgNPs, a combination of 5ALA and AgNPs and the control group. 24 hrs after irradiation, the cell survival was evaluated using MTT assay. Results: Light exposure did not significantly change cells survival in the absence and presence of AgNPs. While light exposure in the presence of 5-ALA and silver nanoparticles with 5-ALA caused a significant reduction in cell survival, the highest cell death in the presence of 5-ALA, and combined AgNPs and 5- ALA was estimated at 76 and 77 percent after receiving 3915 and 1305 mJ/cm2 exposure, respectively. The necessary light exposure to induce 50% cell death (ED50) in the presence of 5-ALA was estimated at 1280 mJ /cm2, while it was estimated 280 mJ /cm2 in the presence of combined AgNPs and 5-ALA. The findings did not confirm the photodynamic property of AgNPs.Conclusion: According to our findings, the PDT efficacy in the presence of combined 5-ALA and AgNPs was higher than 5-ALA alone. Further studies are required to evaluate the definitive mechanism of these findings.
      PubDate: Fri, 29 Dec 2017 20:30:00 +010
       
  • An assessment of the radiation type and energy on the calibration of
           TLD-100

    • Abstract: Introduction: In radiation therapy it is useful to know the amount of dose which healthy organs and tumor received, so thermoluminescent dosimeters (TLD) enable this possibility.This study was aimed at determining dose response differences of TLDs in different types of radiation, different energies and dose levels while were calibrated with other types of radiation beam, energy and dose level.Materials and methods: In this study, LiF:Mg,Ti (TLD-100) was used for dosimetry. Photon and electron irradiation were performed with Elekta accelerator Precise model. First, TLDs were calibrated in three different groups of 6 MV photon, 6 MeV electron and the 60Co teletherapy photon beam with 50 cGy dose. Next, each group was irradiated with 6 MV photon, 6 MeV electron and the 60Co teletherapy photon beam separately in three different dose levels of 20, 60 and 100 cGy.Results: TLDs calibrated with electron have significantly differences at all doses and all types of radiation with TLDs calibrated with photon or the 60Co teletherapy photon beam (P-Value=0.000). P-Value of the TLDs calibrated with 6MV photon versus 60Co is less than 0.94. Maximum standard deviation is belong to 100 cGy irradiation and the least one is belong to 20 cGy irradiation.Conclusion: Calibration of TLDs depends on the type of radiation.Keywords: Calibration, Irradiation, TLD dosimetry, Energy
      PubDate: Thu, 14 Dec 2017 20:30:00 +010
       
  • Assessment of X-ray Crosstalk in a Computed Tomography Scanner with Small
           Detector Elements ...

    • Abstract: IntroductionCrosstalk is a leakage of X-ray or light produced in a matrix of radiation detectors or array of photodiodes in one element to other elements impacting on the spatial resolution and contrast of the image. The purpose of this research is assessment of X-ray crosstalk in a Computed Tomography (CT) scanner with small detector elements to estimate the effect of various parameters such as X-ray tube voltage, detector element sizes, scintillator material, impurities in the scintillator material and the material of detector separators on X-ray crosstalk. Materials and methods This study was done using Monte Carlo simulation. In the first step X-ray tube and its energy spectrum in the energies of 80, 100, 120 and 140 keV were simulated. The energy spectrums in these energies were validated by using SpekCalc and t-test. Then other important parts of CT, means filters, detectors and grid were simulated. X-ray crosstalk between CT detectors were calculated in air and also in presence of water phantom to comprise the effect of scattered photons. Finally the influences of some important parameters on the X-ray crosstalk were evaluated. Results In real condition in CT scan with small elements, means when using phantom, crosstalk increases 16-50%. The lowest possible used energies show the reduced crosstalk. Conclusion To decrease the X-ray crosstalk, the voltage of X-ray tube should be as low as possible. The detector elements with small surface and high thickness increase the crosstalk. The amount of crosstalk is reduced by using the proper material for detectors.
      PubDate: Sun, 22 Oct 2017 20:30:00 +010
       
 
 
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