Mashhad University of Medical SciencesIranian Journal of Medical Physics2345-367210120130301Review Article: Application of Electrical Impedance Spectroscopy in Bladder Cancer Screening12189710.22038/ijmp.2013.897ENAhmad KeshtkarMedical Physics Department, Medical Faculty, Tabriz University of Medical Sciences, Tabriz, IranJournal Article20121230<span style="font-family: Times New Roman;">Introduction</span> <br/><span style="font-family: Times New Roman;">Bladder cancer is the most common malignancy in elderly people and most bladder cancers are transitional cell carcinomas (TCC). Bladder pathology is usually investigated visually by cystoscopy and this technique can represent different conditions ranging from simple inflammation to flat CIS. However, biopsies must be taken from the suspected area to obtain diagnostic information. This is a relatively high cost procedure in terms of both time and money and is associated with discomfort for the patient and increased morbidity. </span><br/><span style="font-family: Times New Roman;">Materials and Methods</span> <br/><span style="font-family: Times New Roman;">Electrical impedance spectroscopy (EIS), a minimally invasive screening technique, can be used to separate malignant areas from non-malignant areas in the urinary bladder. The feasibility of adapting this technique to screen bladder cancer, and abnormalities during cystoscopy has been explored and compared with histopathological evaluation of urinary bladder lesions. Both ex vivo and in vivo studies were carried out in this study.</span> <br/><span style="font-family: Times New Roman;">Results</span> <br/><span style="font-family: Times New Roman;">The impedance data were evaluated in both malignant and benign groups and a significant difference between these two groups was revealed. In all measurements, the impedivity of malignant bladder tissue was significantly higher than the benign tissue, especially at lower frequencies (p<0.001)</span> <br/><span style="font-family: Times New Roman;">Conclusion</span> <br/><span style="font-family: Times New Roman;">This technique can be a complimentary method for cystoscopy, biopsy, and histopathological evaluation of the bladder abnormalities. </span><br/><span style="font-family: Times New Roman;"> </span>Mashhad University of Medical SciencesIranian Journal of Medical Physics2345-367210120130301Asymmetric Rectangular Waveform in Stimulation with High Frequency Alternating Current Reduces the Threshold for Neural Conduction Block223091510.22038/ijmp.2013.915ENAlireza ArianfarBiomedical Engineering Deptartment, University of Isfahan, Isfahan, I.R. IranAmin MahnamBiomedical Engineering Deptartment, University of Isfahan, Isfahan, I.R. IranJournal Article20130710<span style="font-family: Times New Roman;">Introduction</span> <br/><span style="font-family: Times New Roman;">Abnormal neural impulses in the nervous system may lead to various diseases and disabilities. High frequency alternating currents (HFAC) has been used to block the propagation of such impulses and improve the symptoms or disabilities. The technique is safe, reversible, and relatively selective, and its reliability, the optimum stimulation parameters, and elimination of the onset response have been the focus of related studies in the last decade. In this work, a series of computational simulations were performed to evaluate the performance of asymmetric biphasic rectangular waveforms for HFAC.</span> <br/><span style="font-family: Times New Roman;">Materials and Methods</span> <br/><span style="font-family: Times New Roman;">Computer simulations were carried out in NEURON software based on the MRG model, a detailed model of mammalian peripheral nerve fibers. The current threshold for the block and the injected charge per phase were assess for different forms of this waveform and compared with symmetric rectangular, sinusoidal, DC, and monophasic stimulations. The effect of fiber diameter and the stimulation frequency were also evaluated for this waveform.</span> <br/><span style="font-family: Times New Roman;">Results</span> <br/><span style="font-family: Times New Roman;">The threshold charge per phase to induce nerve conduction block was significantly lower for the proposed asymmetric biphasic stimulation. The minimum thresholds were achieved for the waveforms with short anodic long cathodic phases. The threshold was reduced with increasing the asymmetry of the waveform and reduction of the frequency. </span><br/><span style="font-family: Times New Roman;">Conclusion</span> <br/><span style="font-family: Times New Roman;">Simulations performed in this study demonstrated that the proposed stimulation with asymmetric biphasic rectangular waveforms significantly reduces the current threshold and requires much less charge injection per phase to induce nerve conduction block. This is very important for clinical use due to less damage to the tissue. </span>Mashhad University of Medical SciencesIranian Journal of Medical Physics2345-367210120130301In Vitro and in Vivo studies of the Effects of Cold Argon Plasma on Decreasing the Coagulation Time313691610.22038/ijmp.2013.916ENElham JananiSama Technical and Vocational Training College, Islamic Azad University, Andisheh Branch, Andisheh, IranMahsa Ale-EbrahimYoung Researchers and Elite Club, Science and Research Branch, Islamic Azad University, Tehran, IranP MortazaviDepartment of Pathology, Faculty of Specialized Veterinary, Science and Research Branch, Islamic Azad University, Tehran, IranJournal Article20130710<span style="font-family: Times New Roman;">Introduction</span> <br/><span style="font-family: Times New Roman;">Cold plasma is a self-sterilized, painless, and non-contact method in surgeries. These properties allow it to be applied to the living tissues and heat-sensitive parts. The aim of this study was to design a new cold plasma producer device and evaluate the effects of cold argon plasma on decreasing the coagulation time of blood drop <em>in vitro</em> and that of the injured liver blood <em>in vivo</em>.</span> <br/><span style="font-family: Times New Roman;">Materials and Methods</span> <br/><span style="font-family: Times New Roman;">In an experimental study, two blood drops of a normal healthy human were placed on a glass slide. The experimental sample was irradiated by plasma until the complete coagulation occurred, while the control sample remained intact. The complete coagulation time was then measured for both samples. In another part of our study, 20 rats were divided into two experimental and control groups and anesthetized for experimentation. Livers of the rats in the control group were incised and the bleeding time was measured until complete coagulation. Livers of the experimental rats were irradiated by plasma after being incised, and the complete coagulation time was measured.</span> <br/><span style="font-family: Times New Roman;">Results</span> <br/><span style="font-family: Times New Roman;">Cold plasma treatment increased the speed of blood coagulation in both blood drop <em>in vitro</em> and the injured liver blood.<em>in vivo</em>. Histopathological examinations revealed that plasma treatment caused no significant tissue damages as compared with the control group.</span> <br/><span style="font-family: Times New Roman;">Conclusion</span> <br/><span style="font-family: Times New Roman;">The use of argon plasma coagulation device at the time of surgery, in addition to accelerating blood coagulation, caused no injury and burning on tissues. Plasma increases the platelets activation, fibroblasts proliferation and fibrin production. the mechanism of action is likely mediated by exogenous nitric oxide.</span>Mashhad University of Medical SciencesIranian Journal of Medical Physics2345-367210120130301Quality Control of Radiography Equipments in Golestan Province of IRAN374491710.22038/ijmp.2013.917ENAlireza Khoshbin KhoshnazarMedical Physicist, Department of Biochemistry and Medical Physics, Faculty of Medicine, Golestan University of Medical Sciences.Peyman HejaziMedical Physicist, Department of Pharmacology and Medical Physics, Faculty of Medicine, Semnan University of Medical sciencesMilad MokhtarianRadiology Technologist, 5th Azar Hospital, Golestan University of Medical Sciences.Shahin NooshiHealth Engineer, Health Affair of Golestan University of Medical Sciences, Golestan University of Medical SciencesJournal Article20130710<span style="font-family: Times New Roman;">Introduction</span> <br/><span style="font-family: Times New Roman;">The main goal of this study was to perform quality control test on all radiography units operating in Golestan province of IRAN.</span> <br/><span style="font-family: Times New Roman;">Materials and Methods</span> <br/><span style="font-family: Times New Roman;">Forty-four X-ray units were examined based on general accepted programs for quality control. Eight parameters including kVp accuracy, kVp reproducibility, mA-time reciprocity, exposure linearity, exposure reproducibility, timer accuracy, filtration, and beam alignment were measured and calculated. Measurements were carried out by a Baracuda X-ray beam analyzer.</span> <br/><span style="font-family: Times New Roman;">Results</span> <br/><span style="font-family: Times New Roman;">Variance of kVp reproducibility was acceptable in 100% of equipments. kVp accuracy was found to be unsatisfactory in 29.5% of equipments. Variance of mA-time reciprocity was measured to be within reliable limits. Thirty-nine percent of radiography equipments showed non-linear exposure attitude while 16.7 % of them exhibited unacceptable reproducibility of exposure. Moreover, beam misalignment was met in 29.5% of equipments. In 43.2% of radiography equipments, timer accuracy was out of permissible range.</span> <br/><span style="font-family: Times New Roman;">Conclusion</span> <br/><span style="font-family: Times New Roman;">Timer inaccuracy seems to be a common problem for X-ray units. Exposure non-linearity, mA-time non-reciprocity, kVp inaccuracy, beam misalignment, and finally non-reproducibility of exposure were found to have less importance.</span>Mashhad University of Medical SciencesIranian Journal of Medical Physics2345-367210120130301Monte-Carlo Calculation of Radon Absorbed Dose in Optical Fiber as a Novel Method in Dosimetry and Radon Measurement455091810.22038/ijmp.2013.918ENMohsen MirhabibiDepartment of Physics, Payame Noor University , Tehran, IranAli NegarestaniDepartment of Physics, Kerman Graduate University of Industrial and Advanced Technology, Kerman, IranMohammad Reza RezaieDepartment of Physics, Kerman Graduate University of Industrial and Advanced Technology, Kerman, IranMohamad BolorizadehDepartment of Physics, Kerman Graduate University of Industrial and Advanced Technology, Kerman, IranAhmad AkhondDepartment of Physics, Payame Noor University , Tehran, IranJournal Article20130710<span style="font-family: Times New Roman;">Introduction</span> <br/><span style="font-family: Times New Roman;">Radon is a colorless and tasteless gas which exists in most soils. It is a substance that poses a potential risk for lung cancer in case a person is exposed to high levels over long periods of time. The Environmental Protection Agency (EPA) estimates that 90% of lung cancers per year are caused by radon. The aim of this paper is to estimate the absorbed doses of <sup>222</sup>Rn by MCNPX simulation in single-mode optical fiber (SMF) as a method proposed for dosimetry test. </span><br/><span style="font-family: Times New Roman;">Materials and Methods</span> <br/><span style="font-family: Times New Roman;">To calculate the absorbed dose of <sup>222</sup>Rn in SMF using MCNPX-2.6 code, the *F6 tally was applied. SMF was simulated by being exposed to radon while being located in the axis of the pipe.</span> <br/><span style="font-family: Times New Roman;">Results</span> <br/><span style="font-family: Times New Roman;">The absorbed doses due to beta, gamma, and alpha radiations emitted from radon in SMF obtained by Monte Carlo simulations were equal to 5.76311E-13, 5.06973E-15, and 4.83457E-14Gy/particle, respectively. Therefore, the total absorbed dose for radon in SMF was in the order of 6.29727E-13 Gy/particle. The MCNPX outputs are always normalized to one source particle. Therefore to calculate the absorbed dose in various radon concentrations, this result must be multiplied to the number of source particles in active volume around the SMF. The daily radon absorbed dose in a one-meter of SMF and 1 kBq/m<sup>3</sup> radon concentration is about 0.017 mGy which is in a dose range of TLD dosimeters.</span> <br/><span style="font-family: Times New Roman;">Conclusion</span> <br/><span style="font-family: Times New Roman;">The results show that the SMF can be regarded as a radon dosimeter and may be used for beta-particles dosimetry.</span>Mashhad University of Medical SciencesIranian Journal of Medical Physics2345-367210120130301Assessment of an Unshielded Electron Field Diode Dosimeter for Beam Scanning in Small- to Medium-Sized 6 MV Photon Fields515791410.22038/ijmp.2013.914ENMohammad Amin Mosleh-Shirazi1- Center for Research in Medical Physics and Biomedical Engineering, Shiraz University of Medical Sciences, Shiraz, Iran
2- Physics Unit, Department of Radiotherapy and Oncology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran0000-0003-3021-6489A. KetabiStudent Research Committee, and Department of Medical Physics, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IranSareh KarbasiPhysics Unit, Department of Radiotherapy and Oncology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, IranReza FaghihiDepartment of Medical Radiation and Radiation Research Center, School of Mechanical Engineering, Shiraz University, Shiraz, IranJournal Article20130710<span style="font-family: Times New Roman;">Introduction</span> <br/><span style="font-family: Times New Roman;">Radiotherapy planning systems require many percentage depth dose (PDD) and profile measurements and there are various dosimeters that can be used to obtain these scans. As dose perturbation is particularly troublesome in smaller photon fields, using a low-perturbation, unshielded electron field diode (EFD) in these fields is of interest. The aim of this work was to investigate the suitability of an unshielded diode for beam scanning in 3×3 cm<sup>2</sup>, 5×5 cm<sup>2</sup>, and 10×10 cm<sup>2</sup>, 6 MV fields. </span><br/><span style="font-family: Times New Roman;">Materials and Methods</span> <br/><span style="font-family: Times New Roman;">An EFD was used for all the scans. For comparisons in profile measurements, a tungsten-shielded photon field diode (PFD) was also used. PDDs were measured using the PFD and an RK ionization chamber. Results</span> <br/><span style="font-family: Times New Roman;">Very good agreement (0.4%) was found between the PDDs measured with EFD and PFD for the two larger fields. However, the difference between them exceeded 1.0% slightly for the smallest field, which may be attributed to the effect of the larger PFD perturbation. The RK chamber PDDs around 10 cm depth were 1-2% lower than those measured with the diodes. There was good agreement ( <br/><span style="font-family: Times New Roman;">Conclusion</span> <br/><span style="font-family: Times New Roman;">The EFD generally agrees well with the PFD and may even perform better in smaller fields.</span></span>Mashhad University of Medical SciencesIranian Journal of Medical Physics2345-367210120130301Effect of Echo Time on the Maximum Relationship between Contrast Agent Concentration and Signal Intensity Using FLAIR Sequence596791910.22038/ijmp.2013.919ENMahmood NazarpoorDepartment of Radiology, Faculty of Paramedicine, Tabriz University of Medical Sciences, Tabriz, IranMasoud PoureisaDepartment of Radiology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, IranMohammad Hosein DaghighiDepartment of Radiology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, IranJournal Article20130710<span style="font-family: Times New Roman;">Introduction</span> <br/><span style="font-family: Times New Roman;">Contrast-enhanced fluid-attenuated inversion recovery (FLAIR) is one of the MRI sequences that can be used for detection and evaluation of pathological changes in the brain. In this work, we have studied the effect of different echo times (TE) on the maximum relationship between signal intensity and concentration of the contrast agent using the FLAIR sequence.</span> <br/><span style="font-family: Times New Roman;">Materials and Methods</span> <br/><span style="font-family: Times New Roman;">For assessment of the relationship between signal intensity (SI) and concentration, a water-filled phantom containing vials of different concentrations of Gd-DTPA (0 to 19.77 mmol/L) was used. The mean SI was obtained in the region of interest when T1-weighted images were implemnted. The SI was corrected for coil non-uniformity. </span><br/><span style="font-family: Times New Roman;">Results</span> <br/><span style="font-family: Times New Roman;">This study showed that an increase in TE is associated with a decrease in the maximum relationship between SI and concentration.</span> <br/><span style="font-family: Times New Roman;">Conclusion</span> <br/><span style="font-family: Times New Roman;">TE is an important parameter when the SI is measured in clinical FLAIR studies. The concentration leading to a maximum SI depends on this parameter, with the relevant concentration range decreasing at high TE. </span>Mashhad University of Medical SciencesIranian Journal of Medical Physics2345-367210120130301Monte Carlo Study of the Effect of Backscatter Materail Thickness on 99mTc Source Response in Single Photon Emission Computed Tomography697792010.22038/ijmp.2013.920ENJalil Pirayesh IslamianMedical Physics Department, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.Mohammad Taghi Bahreyni ToossiMedical Physics Research Center, Medical Physics Department, Mashhad University of Medical Sciences, Mashhad, Iran0000-0002-3698-5716Mahdi MomennezhadNuclear Medicine Department, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, IranSeyyed Rasool ZakaviNuclear Medicine Department, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, IranRamin SadeghiNuclear Medicine Department, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, IranJournal Article20130710<span style="font-family: Times New Roman;">Introduction</span> <br/><span style="font-family: Times New Roman;">SPECT projections are contaminated by scatter radiation, resulting in reduced image contrast and quantitative errors. Backscatter constitutes a major part of the scatter contamination in lower energy windows. The current study is an evaluation of the effect of backscatter material on FWHM and image quality investigated by Monte Carlo simulation. </span><br/><span style="font-family: Times New Roman;">Materials and Methods</span> <br/><span style="font-family: Times New Roman;">SIMIND program was used for simulation of a Siemen’s dual-head variable angle scintillation gamma camera. Planar and SPECT scanning of a <sup>99m</sup>Tc source and a Jaszczak phantom for varying thicknesses of Perspex slabs, as a backscatter media, were analyzed using the photopeak and scatter windows. Simulated planar images and reconstructed tomographic images were evaluated qualitatively, by two nuclear medicine specialists, and quantitatively, by Structural Similarity (SSIM) Index. </span><br/><span style="font-family: Times New Roman;">Results</span> <br/><span style="font-family: Times New Roman;">In the <sup>99m</sup>Tc photopeak window, no significant change in total counts due to backscatter material was measured. In the scatter windows, scattering was overestimated compared with a simulated backscatter free SPECT system. For instance, at a thickness of 10 cm, total counts of a <sup>99m</sup>Tc source detected in the 72 keV windows eventually doubled with increasing backscatter material, compared with the situation without backscatter material. The backscatter contribution plateaued when more than 7 cm of scatter material was placed but there were optimized results for a backscatter thickness of 4.5 cm. Better image quality for the thickness was confirmed by the results of eye interpretation and also by SSIM algorithm.</span> <br/><span style="font-family: Times New Roman;">Conclusion</span> <br/><span style="font-family: Times New Roman;">Backscatter should be taken into account, particularly in model-based scatter correction methods in SPECT for an accurate simulation system optimization. </span>