فهرست مطالب

  • Volume:9 Issue:3, 2019
  • تاریخ انتشار: 1398/04/01
  • تعداد عناوین: 15
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  • J Eslami, Gh Mortazavi, S A R Mortazavi, M Paknahad* Page 257
  • L T Campos*, L A Magalhães, C E V de Almeida Pages 259-266
    Background
    Radiotherapy is an important technique of cancer treatment using ionizing radiation. The determination of total dose in reference conditions is an important contribution to uncertainty that could achieve 2%. The source of this uncertainty comes from cavity theory that relates the in-air cavity dose and the dose to water. These correction factors are determined from Monte Carlo calculations of ionization chambers. The main problem of this type of calculation is the extremely long computation time to achieve reasonable statistics.
    Objective
    The main purpose of this work is to present a combination with variance reduction techniques for the case of an ionization chamber in water.
    Methods
    The egs_chamber code allows for very efficient computation of ionization chamber doses and dose ratios by using various variance reduction techniques, and also permits realistic simulations of the experimental setup due to the use of EGSnrc C++ library. Russian roulette and Photon Cross Section Enhancement were used with egs_chamber code. Tests were performed to obtain the parameters of variance reduction techniques resulting in a maximum efficiency.
    Results
    It can be seen that the parameters which result in improved Monte Carlo calculation of the efficiency values are XCSE 64 and Russian Roulette (RR) 128.
    Conclusion
    This study determines the parameters of variance reduction techniques that result in an optimal computational efficiency.
    Keywords: Radiotherapy, Dosimetry, Variance Techniques, Monte Carlo, EGSnrc
  • A Mesbahi*, N Rasouli, M Mohammadzadeh, B Nasiri Motlagh, H Ozan Tekin Pages 267-278
    Purpose
    In the current study, using different radiobiological models, tumor control probability (TCP) and normal tissue complication probability (NTCP) of radiotherapy plans were calculated for three-dimensional conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) of prostate cancer.Methods and Materials: 10 prostate plans were randomly selected among patients undergoing radiation therapy of prostate cancer. For each patient, 3D-CRT and IMRT plans were designed to deliver, on average 76 Gy and 82 Gy to planning target volume, respectively. Using different radiobiological models including Poisson, equivalent uniform dose (EUD) and Lyman-Kutcher-Burman (LKB), TCP and NTCP were calculated for prostate and critical organs including bladder, rectum and femoral heads.
    Results
    IMRT plans provided significantly lower NTCP for bladder, rectum and femoral heads using LKB and EUD models (p-value <0.05). The EUD-calculated TCP for prostate cancer revealed no considerable improvement for IMRT plans relative to 3D-CRT plans. However, the TCPs calculated by Poisson model were dependent on α/β, and higher TCP for IMRT relative to 3D-CRT was seen for α/β higher than 5.
    Conclusion
    It can be concluded that IMRT plans were superior to 3D-CRT plans in terms of estimated NTCP for studied critical organs. On the other hand, different mathematical models provided different quantitative outcome for TCP of prostate cancer plans. More clinical studies are suggested to confirm the accuracy of studied radiobiological models.
    Keywords: Tumor Control Probability, Normal Tissue Complication Probability, Radiobiological Modelling, IMRT, 3D-CRT, Radiation Therapy, Prostate Cancer
  • M J Tahmasebi Birgani, N Chegeni, M Tahmasbi, M Hazbavi*, S M Hoseini Pages 279-284
    Background
    In radiotherapy, low-energy photon beams are better adapted to the treated volume, and the use of high-energy beams can reduce hot spots in the radiation therapy. Therefore, mixing low and high energies with different ratios can control the rate of hotspots, as well as the dose distribution of the target volume.
    Material and Methods
    The percentage depth doses (PDDs) were calculated at various depths, by using a fitted double exponential equation. Then, using quality factor equation and PDD of a 10×10 cm2 field, the amount of energy equivalent to each PDD and the value of weighting factors of 6, 18 MV energies were calculated to produce different energies. To validate the mathematical model, dosimetry of 10 MV energy was used. For this purpose, PDDs and dose Profile of 10 MV obtained from the mix were compared with ones obtained from the measurement
    Results
    The value of weighting factor of 6 MV energy required for the 10 ×10 cm2 field to create dose distribution of 15 MV energy using 6 and 18 MV energies was obtained as equal to 0.57. Comparison of percentage depth dose curves and dose profile shows good agreement with the practical measurements of 10 MV for 10×10 cm2 field using gamma index.
    Conclusion
    The simultaneous use of high and low photon energies with different weighting factors to achieve desirable energy makes possible the treatment of tumors located at various depths without the need for different modes of energy in the accelerator leading to a decrease in the cost of the equipment and a safer treatment of the cancerous patients.
    Keywords: Percentage Depth Dose, Weighting Factors, Mathematical Model, Dose Profile
  • K Ebrahimnejad Gorji, R Abedi Firouzjah, F Khanzadeh, N Abdi, Goushbolagh, A Banaei, Gh Ataei* Pages 285-294
    Introduction
    In this study, organ radiation doses were calculated for the renal agent 99mTc-DTPA in children. Bio-kinetic energy of 99mTc-DTPA was evaluated by scintigraphy and estimates for absorbed radiation dose were provided using standard medical internal radiation dosimetry (MIRD) techniques.
    Material and Methods
    In this applied research, fourteen children patients (6 males and 8 females) were imaged using a series of planar and SPECT images after injecting with technetium-99m diethylenetriaminepentaacetic acid (99mTc-DTPA). A hybrid planar/SPECT method was used to plot time-activity curves to obtain the residence time of the source organs and also MIRDOSE software was used to calculate the absorbed dose of every organ. P-values were calculated using t-tests in order to make a comparison between the adsorbed doses of male and female groups..
    Results
    Mean absorbed doses (µGy/MBq) for urinary bladder wall, kidneys, gonads, liver and adrenals were 213.5±47.8, 12.97±6.23, 12.0±2.5, 4.29±1.47, and 3.31±0.96, respectively. Furthermore, the mean effective dose was 17.5±3.7 µSv/MBq. There was not any significant difference in the mean absorbed dose of the two groups.
    Conclusion
    Bladder cumulated activity was the most contribution in the effective dose of patients scanned with 99mTc-DTPA. Using a hybrid planar/SPECT method can cause an increase in accumulated activity accuracy for the region of interest. Moreover, patient-specified internal dosimetry is recommended.
    Keywords: Internal Dosimetry, Hybrid Planar, SPECT Method, MIRDOSE Software, 99mTc-DTPA
  • Zamanlou M., Akbari M.*, Jamshidi A. A., Amiri A., Nabiyouni Pages 295-302
    Background
    Lumbar motion analysis is used as a clinical method in the diagnosis and treatment of low back pain (LBP). So far, no studies have shown if manipulating the sacroiliac joint (SIJ) will change spinal kinematics.
    Objective
    The main objectives of this study were to investigate the effects of SIJ manipulation on the lumbar kinematics in subjects with innominate rotation and to compare lumbar kinematics among experiment and control groups.
    Material and Methods
    This study was a quasi-experiment-control trial study. 21 LBP patients with anterior or posterior innominate rotations in experiment group and 22 asymptomatic subjects in control group were evaluated. Lumbar kinematic variables (LKV) include lumbar range of motion (ROM) and speed, lumbar lateral flexion and rotation asymmetry were evaluated using Qualysis Track Manager (QTM) twice within two days in control group, and these parameters with pelvic asymmetry and disability were tested before and after intervention in the experiment group.
    Results
    While pre-intervention experiment group exhibited significantly lower lumbar lateral flexion (p=0.0001), rotation (p=0.008) ROM and lower lateral flexion speed (p=0.014), post-intervention experiment group exhibited significantly lower lumbar lateral flexion (p=0.01) ROM in comparison with control group. Pelvic asymmetry (p=0.049) and disability (p=0.01) significantly decreased in the experiment group after manipulation, but LKV did not change significantly after the intervention (p˃0.05).
    Conclusion
    Experiment groups had different lumbar kinematics in comparison with control group before and after SIJ manipulation. Despite the changes in pelvic asymmetry and disability, intervention had no effect on lumbar kinematics.
    Keywords: SIJ Manipulation, Kinematics, Innominate, Asymmetry, Disability
  • M Zarenezhad, S M Dehghani*, F Ejtehadi, M R Fattahi, M Mortazavi, S M B Tabei Pages 303-316
    Background
    Cholestatic disorders are divided in the extra and intra-hepatic that created due to the severe liver diseases. ABCB11 encodes the bile salt export pump and this gene is mutated in several forms of intrahepatic cholestasis. So far, some molecular features of this gene was studies.
    Objective
    Using a developed web server, we identified high number of rare codons in this gene, and four cases were related to BSEP-deficient patients which can be used for drug design.
    Material and Methods
    By in-silico modelling of ABCB11, some of rare codons in different locations of ATP8b1 gene were identified and evaluated. Using several web servers a number of mutations that converted non-rare codons to rare codon in these patients were identified.
    Results
    Some of these rare Codons were located at special positions by mutation of which, the new side chains do not seem suitable for protein structure and function. Furthermore, this mutation changed the protein folding rate that may have a critical role in proper folding. Thus, primary change of these codons contributes to BSEP deficiency.
    Conclusion
    This work is a comprehensive analysis of rare codons of ABCB11 and assessment of a number of these rare codon in protein levels. Rare codons evaluation can enhance our understanding of ABCB11 structural protein of ABCB11, and help us to develop mutation-specific therapies in design of new drugs.
    Keywords: ABCB11, Bioinformatics Analysis, Rare Codon, Mutation
  • A Safari, H Parsaei*, A Zamani, B Pourabbas Pages 317-326
    Background
    Scoliosis is the most common type of spinal deformity. A universal and standard method for evaluating scoliosis is Cobb angle measurement, but several studies have shown that there is intra- and inter- observer variation in measuring cobb angle manually.
    Objective
    Develop a computer- assisted system to decrease operator-dependent errors in Cobb angle measurement.
    Methods
    The spinal cord in the given x-ray image of the spine is highlighted using contract-stretching technique. The overall structural curvature of the spine is determined by a semi-automatic algorithm aided by the operator. Once the morphologic curve of the spine is determined, in the last step the cobb-angle is estimated by calculating the angle between two normal lines to the spinal curve at the inflection points of the curve.
    Results
    Evaluation results of the developed algorithms using 14 radiographs of patients ( 4 - 40 years old) with cobb angle ranges from 34 - 82 degrees, revealed that the developed algorithm accurately estimated cobb angle. Statistical analysis showed that average angle values estimated using the developed method and that provided by experts are statistically equal. The correlation coefficient between the angle values estimated using the developed algorithm and those provided by the expert is 0.81.
    Conclusion
    Compared with previous algorithms, the developed system is easy to use, less operator-dependent, accurate, and reliable. The obtained results are promising and show that the developed computer-based system could be used to quantify scoliosis by measuring Cobb angle.
    Keywords: Cobb-angle Measurement, Curve-fitting, Scoliosis, Spinal Curvature Measurement
  • A Dikshit, Ratnaparkhi*, D Bormane, R Ghongade Pages 327-334
    Background
    In this paper, a generic hesitant fuzzy set (HFS) model for clustering various ECG beats according to weights of attributes is proposed. A comprehensive review of the electrocardiogram signal classification and segmentation methodologies indicates that algorithms which are able to effectively handle the nonstationary and uncertainty of the signals should be used for ECG analysis. Extensive research that focuses on incorporating vagueness in the form of fuzzy sets, fuzzy rough sets and hesitant fuzzy sets (HFS) has been in past decades.
    Objective
    The paper aims to develop an enhanced entropy based on the clustering technique for calculating the weights of the attributes to finally generate appropriately clustered attributes.
    Material and Methods
    Finding optimal attributes to make a decision has always been a matter of concern for the researchers. Metrics used for optimal attribute generation can be broadly classified into mutual dependency, similarity, correlation and entropy based metrics in fuzzy domain .The experimentation has been carried out on ECG dataset in a hesitant fuzzy framework with four attributes.
    Results
    We propose a novel correlation based on an algorithm that takes entropy based weighted attributes as input which effectively generates a relevant and non-redundant set of attributes. We have also derived correlation coefficient formulas for HFSs and applied them to clustering analysis under framework of hesitant fuzzy sets. The results show the comparison of the proposed mathematical model with the existing similarity based on algorithms.
    Conclusion
    The selection of optimal relevant attributes certainly highlights the robustness and efficacy of the proposed approach. The entire experimentation and comparative results help us conclude that selection of optimal attributes in hesitant fuzzy domain certainly prove to be a powerful tool in order to express uncertainty in the process of data acquisition and classification.
    Keywords: Hesitant Fuzzy Sets, ECG, Correlation Coefficients, Entropy, Weights
  • M Morshedi, M Bakhshandeh*, A Piryaei, A Emami, M Zangeneh, A Razzaghdoust, H Ghadiri, F Zayeri Pages 335-344
    Background
    Diagnostic ultrasound has been used to detect human disease especially fetus abnormalities in recent decades. Although the harmful effects of diagnostic ultrasound on human have not been established so far, several researchers showed it has had bioeffects in cell lines and in experimental animals. Three-dimensional (3D), four-dimensional (4D), and color Doppler sonography are new techniques which are widely used in diagnostic fetal ultrasonography.
    Objective
    The study aims to evaluate some bioeffects of 3D, 4D, and color Doppler sonography in different exposure times according to the acoustic output which is set as ultrasound scanner’s default for fetal sonography in the second trimester on human dermal fibroblast (HDF) cells.
    Material and Methods
    Exposure times selected consist of 10, 40, 70, and 100 seconds for 3D sonography, 10, 20, and 30 minutes for 4D sonography, and 10, 30, and 50 seconds for color Doppler. Cell viability, cell proliferation, and apoptosis induction on HDF cells were assessed using MTT assay, immunocytochemistry of Ki-67, and Terminal Transferase-mediated dUTP End-labeling (TUNEL) assay, respectively.
    Results
    Exposure of cells to 3D, 4D, and color Doppler modes led to decreased cell viability and increased proliferation rate of HDF. None of the diagnostic ultrasound modes induced cell apoptosis. .
    Conclusion
    The results indicated that 3D, 4D, and color Doppler techniques may affect the cell viability and proliferation of HDF cells, however, have no effects on the induction of apoptosis probability. Further long-term studies with other molecular endpoints are required.
    Keywords: Diagnostic Ultrasound, 3-dimentional Ultrasound, 4-dimentional Ultrasound, Color Doppler Ultrasound, Human Dermal Fibroblast Cells
  • M R Bayatiani, F Seif*, S Hamidi, S Bagheri Pages 345-354
    Introduction
    Metal prostheses in patients affect the radiotherapy dose distribution. Metal prostheses with high density and atomic number cause major changes in scattering and attenuation of radiation. The present study aims to assess the impact of metal knee prosthesis with various dimensions and materials on radiotherapy dose distribution.
    Material and Methods
    In this research, the Varian Linac and water phantom were simulated using the MCNPX code. Dose distribution of photon beam in a water phantom, with and without the presence of knee prostheses made of cobalt-chromium-molybdenum alloy, steel, titanium, and titanium alloy used in men and women was investigated using the Monte Carlo simulation.
    Results
    The prosthesis led to an increase in dose in comparison with cases that there was used no prosthesis. According to values of the depth dose percentage, the maximum dose increase was found to be 6.8%, 6.1%, 4%, and 4.29%, and dose reduction 41.18%, 40.66%, 37.76%, and 37.51% for prosthetics with men’s knee dimensions made of cobalt-chromium-molybdenum alloy, steel, titanium alloy, and titanium, respectively. Above all, does increasing to 6.4%, 5.9%, 3.8%, and 3.94% and doses reducing to 40.87%, 40.36%, 36.94%, and 36.69 were observed in prosthetics for women. The highest amount of dose reduction for men’s prostheses made of mentioned materials was found to be 48.75%, 47.7%, 45%, and 45.8%, respectively. In addition, it was 46.36%, 45.8%, 43.8%, and 43.95% for women’s prostheses, respectively.
    Conclusion
    Material will have a significant impact if a part of the knee bone places behind the prosthesis. According to the obtained values, it is recommended to utilize prostheses made of titanium and titanium alloys for knee arthroplasty. The prosthesis can either increase or decrease dose in tumor or lead to increase dose at organs at risk.
    Keywords: Dose Distribution, Knee Prosthesis, Monte Carlo Simulation, Treatment Planning
  • I Rezaei, M Razeghi*, S Ebrahimi, S Kayedi, A Rezaeian Zadeh Pages 355-366
    Background
    Despite the potential benefits of virtual reality technology in physical rehabilitation, only a few studies have evaluated the efficacy of this type of treatment in patients with neck pain.
    Objective
    The aim of this study was to compare the effects of virtual reality training (VRT) versus conventional proprioceptive training (CPT) in patients with neck pain.
    Methods
    Forty four participants with nonspecific chronic neck pain were randomly assigned to VRT or CPT in this assessor-blinded clinical trial. A novel videogame called Cervigame® was designed for VRT. It comprises of 50 stages divided into unidirectional and two-directional stages ordered from easy to hard. CPT consisted of eye-follow, gaze stability, eye-head coordination and position and movement sense training. Both groups completed 8 training sessions over 4 weeks. Visual analogue scale score, neck disability index and Y-balance test results were recorded at baseline, immediately after and 5 weeks post-intervention. Mixed repeated measure ANOVA was used to analyze differences between mean values for each variable at an alpha level of 0.05.
    Results
    There were significant improvements in all variables in both groups immediately after and 5 weeks after the intervention. Greater improvements were observed in the visual analogue scale and neck disability index scores in VRT group, and the results for all directions in Y-balance test were similar in both groups. No side effects were reported.
    Conclusion
    Improvements in neck pain and disability were greater in VRT than CPT group. Cervigame® is a potentially practical tool for rehabilitation in patients with neck pain.
    Keywords: Neck Pain, Virtual Reality, Proprioception, Cervicocephalic Kinesthesia, Rehabilitation, Physical Therapy
  • S M J Mortazavi, Gh Mortazavi, S A R Mortazavi, M Paknahad* Pages 367-372
    Man has been exposed to different levels of natural background radiation since the creation of human life. There are inhabited areas around the world with extraordinary levels of natural background radiation. The level of natural radiation in these areas is up to two orders of magnitude higher than other places. Areas such as Yangjiang, China; Guarapari, Brazil; and Kerala, India are among the areas with high levels of natural radiation. Ramsar a coastal city in North Iran has some inhabited areas with the highest known levels of background radiation around the world. People who live in high background radiation areas (HBRAs) such as Ramsar do not record any detrimental biological effects. While some cytogenetic studies conducted in HBRAs have shown increased frequencies of unstable chromosome aberration, other investigations failed to find a significant difference. This short review is an attempt to verify if induction of chromosomal anomalies in the lymphocytes of the residents of high background radiation areas is associated with increased cancer risk.
    Keywords: Human Lymphocytes, High Background Radiation Areas, Natural Radiation, Cancer Risk
  • V. R Nafisi*, M Eghbal Pages 373-380
    Fast reduction of blood water volume due to ultra-filtration via hemodialysis machine and critical threshold of blood water volume can result in clinical complications such as hypotension. When blood water volume reduces during hemodialysis process, the concentration of blood forming elements will increase. One of the methods for the monitoring of the concentration changes is ultrasonic speed measurement.In this paper, we optimize the ultrasonic speed measurement method in such a way that it would be compatible with conventional air detector in a hemodialysis machine. Air bubble detecting and the relative blood water volume estimating can be achieved by adding the “sing-around” ultrasonic speed measurement method to the current hemodialysis machine; air bubble detection is achieved by monitoring the decline in the ultrasonic wave amplitude (because of air bubbles) and the protein concentration measurement is achieved by measuring the transit time of the wave. Therefore, the optimized method can be applied to the air detection device of a hemodialysis machine.
    Keywords: Hemodialysis, Blood Volume Monitoring, Ultrasonic Speed Measurement, Air Detector
  • J Welsh, J J Bevelacqua, M Keshavarz, S A R Mortazavi, S M J Mortazavi* Pages 381-388
    Telomere length and stability is a biomarker of aging, stress, and cancer. Shortening of telomeres and high level of DNA damages are known to be associated with aging. Telomere shortening normally occurs during cell division in most cells and when telomeres reach a critically short length, DNA damage signaling and cellular senescence can be triggered. The induction of an adaptive response by space radiation was first documented in 2003. Telomere length alterations are among the most fascinating observations in astronauts and residents of high background radiation areas. While study of the chronic exposure to high levels of background ionizing radiation in Kerala, India failed to show a significant influence on telomere length, limited data about the NASA astronaut Scott Kelly show that exposure to space radiation can induce telomeres to regain length. Interestingly, his telomeres shortened again only a couple of days after returning to Earth. The difference between these situations may be due to the differences in radiation dose, dose-rate, and/or type of radiation. Moreover, Scott Kelly’s spacewalks (EVA) could have significantly increased his cumulative radiation dose. It is worth noting that the spacewalks not only confer a higher dose activity but are also characterized by a different radiation spectrum than inside the space craft since the primary particles would not interact with the vehicle shell to generate secondary radiation. Generally, these differences can possibly indicate the necessity of a minimum dose/dose-rate for induction of adaptive response (the so called Window effect).
    Keywords: Diagnostic Ultrasound, 3-dimentional Ultrasound, 4-dimentional Ultrasound, Color Doppler Ultrasound, Human Dermal Fibroblast Cells