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Publisher: Mashhad University of Medical Sciences   (Total: 14 journals)   [Sort by number of followers]

Showing 1 - 14 of 14 Journals sorted alphabetically
Archives of Bone and Joint Surgery     Open Access   (Followers: 7)
Avicenna J. of Phytomedicine     Open Access  
Intl. J. of Pediatrics     Open Access   (Followers: 4)
Iranian J. of Basic Medical Sciences     Open Access  
Iranian J. of Medical Physics     Open Access   (SJR: 0.138, h-index: 4)
Iranian J. of Neonatology     Open Access   (Followers: 4)
Iranian J. of Otorhinolaryngology     Open Access   (SJR: 0.266, h-index: 4)
J. of Cardio-Thoracic Medicine     Open Access   (Followers: 2)
J. of Evidence-based Care     Open Access   (Followers: 7)
J. of Fasting and Health     Open Access   (Followers: 1)
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
  [SJR: 0.138]   [H-I: 4]   [0 followers]  Follow
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   ISSN (Online) 2345-3672
   Published by Mashhad University of Medical Sciences Homepage  [14 journals]
  • 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

    • 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
  • Evaluation of the occupational exposure effects on radiographer’s
           blood cells working in ...

    • Abstract: Introduction: Due to the fact that radiology technologists are exposed to low-intensity ionizing radiation for a long time and the possible effects of low-energy radiation on the blood system, this study aimed to investigate the effects of occupational exposure on blood factors of radiographers working in the radiology departments in Khuzestan province.Materials and methods: This case-control study was conducted in Khuzestan province in 2015. blood samples were taken by cluster sampling from 95 radiology technologists and 85 non-radiated persons matched by interfering variables. The data were collected by performing a blood cell count (CBC) assay with a Sysmex cell counter. Data were analyzed using SPSS 16 software, t-test and Pearson correlation coefficient at a significant level of 0.05.Results: Comparison of mean blood factors have not shown any significant difference between two groups using t-test (p> 0.05) and there is no significant difference between the amount of blood factors of radiology technologists and others by gender.Conclusion: The findings of this study indicate that there are no harmful effects of occupational exposure on Radiographer’s blood factor levels but with increasing age and work experience in the group of radiographers, white blood cell count decreases.
      PubDate: Sun, 07 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 Impact of Low-level Exposure to Radiation in Natural Ecosystems of
           Najaf and Dhi Qar ...

    • Abstract: Introduction: This study investigated the exposure rates of background radiations in selected locations of Najaf and Dhi Qar cities, Iraq.Materials and Methods: Exposure rates were quantified using a portable Geiger–Müller meter. Frequent readings of gamma dose rates were recorded (82 and 101 nGy h-1).Results: The lowest absorbed doserate was found to be 43.5±17.4 nGyh-1 in Najaf (outdoor environments), and the highest was 174±8.7 nGy h-1 in Dhi Qar city (outdoor environments). Overall, the absorbed dose rates of background radiation fell within the worldwide range reported in other regions.Conclusion: The selected locations in Najaf and Dhi Qar cities showed normal absorbed doserates with no adverse biological effects on people in the studied areas.
      PubDate: Sun, 31 Dec 2017 20:30:00 +010
  • Effect of Helium-Neon Laser and Sodium Hypochlorite on Calf Thymus
           Double-Stranded ...

    • Abstract: Introduction: Low-energy helium-neon (He-Ne) laser beam lightis used in combination with sodium hypochlorite (Na2HOCl3) for clinical purposes. Regarding this, the present study aimed to investigate the effect of He-Ne laser (632.8 nm) and sodium hypochlorite on the calf thymus double-stranded deoxyribonucleic acid (ctdsDNA) molecule.  Materials and Methods: For the purpose of the study, ctdsDNA solutions (30µg/ml) were exposed to He-Ne laser (632.8 nm) light in the absence and presence of different concentrations of sodium hypochlorite for up to 60 sec. The levels of nucleic acids released as uncontaminated and contaminated proteins were considered as the markers of DNA damage in terms of hypochromasia (i.e., DNA strand breakage) and hyperchromasia (i.e., of DNA strands separation).  Results: The mean concentration of nucleic acids insignificantly (P > 0.05) decreased after exposure to laser light irradiation (hypochromic effect). Furthermore, laser irradiation insignificantly and inconsistency protected the ctdsDNA molecules from the effect of sodium hypochlorite.  Sodium hypochlorite at concentrations of 1 and 3 mmol reduced the levels of the nucleic acids released from contaminated protein by 29.2% and 78.3% of the pre-incubated levels (hyporchromasia effect). The He-Ne laser (632.8 nm) irradiation induced hypochromic effect on the uncontaminated and contaminated proteins, while sodium hypochlorite induced a remarkable hyperchromic effect at higher concentrations. Conclusion: As the finding indicated, a short time He-Ne laser light (632.8 nm) irradiation exerted minor significant effect on the ctdsDNA molecule. This laser light did not interact with sodium hypochlorite as a synergistic combination against the ctdsDNA molecule.  
      PubDate: Sun, 31 Dec 2017 20:30:00 +010
  • The Dosimetric Effects of Different Multileaf Collimator Widths on
           Physical Dose Distributions

    • Abstract: Introduction: Geometric changes in the multileaf collimator (MLC) led to dosimetric considerations in intensity-modulated radiation therapy (IMRT) due to the number and size of the pixels in the intensity map, which are determined by the MLC leaf width. In this study, we evaluated the dosimetric effects of different MLC widths on physical dose distributions for IMRT plans.Materials and Methods: Forty-two IMRT plans based on different MLC devices were generated and analyzed to study the effect of MLC width on plan quality.Results: Improvements in IMRT plan quality using 0.4 cm leaf width in comparison with 1 cm leaf width were evaluated. The 0.4 cm leaf-based plans resulted in significantly higher Dmean, D98%, D95% , D5%, and V95 (58.86 Gy, 95.11%, 96.57%, 104%, and 97.92%, respectively) compared to the 1 cm leaf plans (58.66 Gy, 92.56%, 94.56%, 104.14%, and 95.72%, respectively). Conformation number (CN) for planning target volume in 0.4 cm leaf plans was significantly higher than the 1 cm leaf plans (0.74 vs. 0.67; P<0.05). In addition, the 0.4 cm leaf plans significantly improved dose homogeneity compared to the 1 cm leaf plans (1.08 vs. 1.10; P<0.05). We found that 0.4 cm leaf width significantly decreased the integral dose to normal tissue compared to the 1 cm leaf width (from 56.09 to 49.46 Gy.Kg P<0.05).  Conclusion: No significant clinical differences were observed between the two plans for a serially functioning tissue, while the differences in mean doses were statistically significant for parallel functioning normal tissues.
      PubDate: Sun, 31 Dec 2017 20:30:00 +010
  • Indoor Radon Measurement in Dwellings of Khorramabad City, Iran

    • Abstract: Introduction: Exposure to indoor radon increases the risk of lung cancer. This study examined the level of indoor radon in dwellings of Khorramabad city, by using passive alpha-track detector (CR-39) during winter of 2016. Materials and Methods: In the present study, we detected the concentration of indoor radon in 56 dwellings. A passive sampling instrument (alpha-track detector with CR-39 polycarbonate films) was utilized to measure indoor radon gas concentration. The distribution map of indoor radon concentration was prepared using Arc GIS software.  Results: Radon concentration in the dwellings varied from 1.08 to 196.78 Bq/m3, with a mean value of 43.43±40.37 Bq/m3. The average annual effective dose received by the residents of the studied area was estimated to be 1.09 mSv. Our results showed a significant difference between the average radon concentrations in houses and apartments, with a higher level in houses. Conclusion: Indoor radon concentration in 10.1% of the dwellings was determined to be higher than the limit (100 Bq/m3) recommended by the World Health Organization.
      PubDate: Sun, 31 Dec 2017 20:30:00 +010
  • Optimization of Dose and Image Quality in Full-fiand Computed Radiography
           Systems for Common ...

    • Abstract: IntroductionA fine balance of image quality and radiation dose can be achieved by optimization to minimize stochastic and deterministic effects. This study aimed in ensuring that images of acceptable quality for common radiographic examinations in digital imaging were produced without causing harmful effects. Materials and MethodsThe study was conducted in three phases. The pre-optimization involved ninety physically abled patients aged between 20 to 60 years and weighed between 60 and 80 kilograms for four common digital radiographic examinations. Kerma X_plus, DAP meter was utilized to measure the entrance surface dose (ESD) while effective dose (ED) was estimated using CALDose_X 5.0 Monte Carlo software. The second phase, an experimental study utilized an anthropomorphic phantom (PBU-50) and Leeds test object TOR CDR for relative comparison of image quality. For the optimization phase, the imaging parameters with acceptable image quality and lowest ESD from the experimental study was related to patient’s body thickness. Image quality were evaluated by two radiologists using the modified evaluation criteria score lists. ResultsSignificant differences were found for image quality for all examinations. However significant difference for ESD were found for PA chest and AP abdomen only. The ESD for three of the examinations were lower than all published data. Additionally, the ESD and ED obtained for all examinations were lower than that recommended by radiation regulatory bodies. ConclusionOptimization of image quality and dose was achieved by utilizing an appropriate tube potential, calibrated automatic exposure control and additional filtration of 0.2mm copper.
      PubDate: Sun, 31 Dec 2017 20:30:00 +010
  • Determination of Dose-Equivalent Response of A Typical Diamond
           Microdosimeter in Space ...

    • Abstract: Introduction: Microdosimeters are helpful for dose equivalent measurement in unknown radiation fields. The favorable physical and mechanical properties of the detector-grade chemical vapor deposition diamond materials have made the diamond microdosimeters suitable candidate for radioprotection applications in space. The purpose of this work is the investigation of the dose equivalent response of a typical diamond microdosimeter with laser-induced graphitized electrodes for use in space radiation fields.Materials and Methods: The Geant4 Monte Carlo simulation toolkit was applied to simulate the particle transport within the microdosimeter, and to determine the mean chord length and the dose equivalent response of the microdosimeter, based on the lineal energy dependent quality factor.  Results: The linear stopping power of the protons and alpha particles with energies higher than 5 MeV and 10 MeV respectively can be estimated within20% of deviation using the microdosimeter response. The fluence to dose equivalent conversion coefficients calculated affirms that there is an adequate agreement between the calculated coefficients and other research group results.Conclusion: The reasonable agreement between the dose equivalents calculated in this study and the results reported by other researchers confirmed that this type of microdosimeter could be a promising candidate suitable for the measurement of the dose equivalent in space radiation fields.
      PubDate: Sun, 31 Dec 2017 20:30:00 +010
  • Telecobalt Machine Beam Intensity Modulation with Aluminium Compensating
           Filter Using Missing ...

    • Abstract: Introduction: The present study aimed to generate intensity-modulated beams with Aluminium compensating filters for a conventional telecobalt machine based on the outputs of a treatment planning system (TPS) performing forward planning and cannot simulate directly the compensating filter.Materials and Methods: In order to achieve the beam intensity modulation during treatment planning with the TPS, we used a bolus placed on the surface of a tissue-equivalent phantom. The treatment plans replicated on the telecobalt machine with the bolus were represented with compensating filters placed at a certain distance from the phantom surface. An equation was proposed for the conversion of the bolus thickness to the compensating filter thickness such that any point within the phantom would receive the planned dose. Correction factors were introduced into the proposed equation to account for the influences of field size, treatment depth, and applied bolus thickness. The proposed equation was obtained based on the analyses of empirical data measured in a full scatter water phantom with and without the compensating filter. Results: According to the results, the dosimetric verification of the proposed approach outputs in a solid water phantom with calibrated Gafchromic EBT2 films were comparable to that of the TPS with deviation of ±4.73% (mean: 2.98±1.05%).Conclusion: As the findings of the present study indicated, the discrepancy between the measured doses and TPS-estimated doses was within the tolerance of ±5%, which is recommended for dose delivery in external beam radiotherapy. Therefore, the proposed approach is recommended for clinical application. 
      PubDate: Sun, 31 Dec 2017 20:30:00 +010
  • Local Diagnostic Reference Levels for Some Common Diagnostic X-Ray
           Examinations In Sabzevar ...

    • Abstract: Introduction: Diagnostic reference level (DRL) is a useful tool for the promotion of optimization. The national DRLs (NDRLs) are useful, brief, and robust guidelines for optimizing radiation protection in a country. The aim of this study was to extract the local DRLs (LDRLs) for some common radiologic examination in Sabzevar county.Materials and Methods: There are eight radiology departments in Sabzevar County, Iran. The entrance skin dose (ESD) distributions were determined by use of thermoluminescence dosimeter (TLD) chips for 10 standard projections (i.e., anterioposterior [AP] abdomen, AP and posteroanterior [PA] chest, AP and lateral [LAT] lumbar spine, AP pelvis, cervical AP, cervical LAT, as well as AP and LAT skull). The third quartiles of the measured ESDs were compared with the previously published data.Results: In the present study, the third quartile of the measured ESDs for the patients undergoing specific examination were selected as LDRLs. The calculated LDRLs for the chest PA, chest AP, lumbar spine PA, lumbar spine LAT, pelvis AP, abdomen AP, cervical AP, cervical LAT, skull PA, and skull LAT were 0.54, 0.64, 1.99, 3.83, 1.47, 2.15, 0.54, 0.78, 1.22, and 1.01 mGy, respectively.Conclusion: Our results were compared with the DRLs reported in Iran, UK, and Japan as well as those reported by the National Radiological Protection Board (NPRB) for the UK. The ESDs obtained in this study for the chest PA, cervical AP, cervical LAT, AP and LAT skull, abdomen AP, pelvis AP, lumbar PA, and lumbar LAT examinations did not exceed the DRL values reported by NPRB. 
      PubDate: Sun, 31 Dec 2017 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
  • Dynamic modeling of the EMG and chewing force relation through
           ANFIS-principal dynamic mode analysis

    • Abstract: Introduction: Researchers have employed surface electromyography to study the human masticatory system and the relation between the activity of masticatory muscles and the mechanical features of mastication. This relationship is of essential key in many applications including food texture analysis, control of prosthetic limbs, rehabilitation and tele-oported robots. Materials and Methods: In this paper a model is proposed by combing the concept of the fuzzy interface systems and principal dynamic mode analysis (PDM). We hypothesize that the proposed approach will provide nonlinear and dynamic characteristics which will improve the estimation results compared to those obtained with classical PDM analysis and still have those benefits of a PDM model including the sparse presentation of the system dynamics. After developing the 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 the biting force using the electromyography of temporalis and masseter muscles. Results: Our proposed method performs better (in terms of our evaluation criteria) in predicting the chewing force compared to the classical PDM analysis both during a simulation scenario and for predicting the chewing force. Inter-subject evaluation of the model performance proved that the model created using the data of one subject could be used in predicting the chewing force of other subjects. Conclusions: The proposed model will be helpful in the field of food analysis, using which the created force during chewing can be predicted based on the electrical activity of the Masseter and Temporalis muscles.
      PubDate: Sat, 16 Dec 2017 20:30:00 +010
  • A method for body fat composition analysis from abdominal MRI via SOM
           neural network

    • Abstract: Introduction: The present research suggests an unsupervised method for the segmentation of visceral adipose tissue and subcutaneous adipose tissue from axial abdominal MR images. Material and Methods: An SOM neural network was trained to segment adipose tissue from other tissues in images. A new method in level set algorithms called DRLSE is used for SAT and VAT segmentation. A total of 23 subjects had a whole-body abdominal MRI and three slices of each subject’s pictures were selected to evaluate the suggested method.Results: The results of the automatic segmentation were compared with those of the manual segmentation and previous artificial intelligent methods. A significant correlation was found between the automatic and manual segmentation of VAT and SAT.Conclusion: It can be concluded that the suggested method helps to increase accuracy in detecting 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 and was evaluated by manually segmented images. The proposed methodology showed to be accurate and robust, and had a significant advantage over the manual and previous methods segmentation in terms of speed and accuracy.
      PubDate: Thu, 14 Dec 2017 20:30:00 +010
  • An assessment of the radiation type and energy on the calibration of

    • 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
  • A study on slab-wooden dust-slab phantom for the development of thorax

    • Abstract: Introduction: Human body is a heterogeneous medium and the determination of accurate dose distribution inside it plays a crucial role in radiotherapy. Present study focus on analyzing the density and isodose depth profiles of 6 mega voltage (MV) beam in a SP34 slab -wooden dust (pine) - SP34 slab (SWS) heterogeneous phantom.Materials and Methods: Density of SP34 slab, wooden dust of pine and thoracic region of selected patients were calculated using CT images. Depth of isodose lines were measured for 6 MV on CT images of chest, SP34 slab phantom and SWS phantom. Dose at depths 2 cm, 13 cm and 21 cm was measured in both the phantoms. Patient specific QA was done using both the phantoms.Results: Mean density of lung, SP34 slabs and wooden dust were found to be 0.29, 0.99 and 0.27 gm/cc respectively. Depths of different isodose lines in SWS phantom were found to be equivalent to that of the mean depths of isodose lines in actual patients. The percentage variation between planned and measured doses was found to be higher in case of SWS phantom as compared to that in case of SP34 phantom. The percentage variation between planned and measured doses in patient specific QA were found to be higher in case of SWS phantom as compared to that in SP34 phantom. Conclusion: Density and isodose depth profiles of SWS phantom are found to be equivalent to that of the actual human thoracic region. Key words: Hounsfield number; patient specific quality assurance; SP34 slab phantom; thorax phantom; SWS phantom.
      PubDate: Mon, 27 Nov 2017 20:30:00 +010
  • Verification of Monitor unit calculations for eclipse Treatment Planning
           System by in- house ...

    • Abstract: Introduction: Computerized treatment planning is a rapidly evolving modality depends efficiently on hardware and software. Despite various ICRU recommendations suggest 5% deviation in dose delivery the overall uncertainty shall be less than 3.5% as suggested by B.J. Minjnheer. J. In house spread sheets are developed by the clinical medical physicist to cross verify the dose calculated by the TPS. The Task Group 40 & 114 recommends that the calculation results of any TPS should be independently verified.Materials and Methods: The Monitor unit verification calculation(MUVC) verification was tested for pre-approved and executed treatment plans taken from our Treatment Planning System (TPS) database (Make: Varian Medical System, Model, Eclipse version 13.7).. A total of 108 square fields and 120 MLC shaped fields for Head & Neck cancers, Ca-Cervix, Ca-Oesophagus were taken for evaluation. In house developed spreadsheet based on Microsoft Excel was used in this study. 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 lies in the range of 0.999 to 1.02 for square field geometries which showed that there was a deviation of 1% between the TPS calculated and the spread sheet calculated. The MU ratios were 0.995 for Head & Neck plans & 1.012 for Cervix plans with a standard deviation of 0.024 & 0.029 respectively. However we observed the mean MU ratio for Esophagus plans were 1.026 with the standard deviation of 0.040.Conclusion: The independent spreadsheet was designed and tested for most of the routine treatment sites and geometries. The designed spreadsheet is having good agreement with the Eclipse TPS version 13.8 for homogenous treatment sites such as Head & Neck and Cervix
      PubDate: Thu, 09 Nov 2017 20:30:00 +010
  • Radiological Assessment of the Artificial and Natural Radionuclide
           Concentrations of Some Wheat ...

    • Abstract: IntroductionArtificial and natural radionuclides there are in environmental materials such as water, soil, rocks, plant, animals, and human body tissues As such, humans and environments are at constant exposure of these radiation types. In this research specific activities of radionuclides and risk assessment of some samples of wheat and barley in Najaf zone (Iraq) were determined.Materials and MethodsIn this study, natural and artificial radioactivity concentrations were determined in wheat and barley and surrounding soil using gamma-ray spectrometry method employing high-purity germanium (HPGe) detector with 88% relative efficiency. According to measured specific activities of radionuclides in food samples and annual consumption excess lifetime cancer risk due gamma radiations were calculated.ResultsSpecific activities of 226Ra, 232Th, 40K and 137Cs in soil samples varied within the ranges of 29.37-38.86, 23.24–45.70, 291.15–549.78 and 1.25–10.82 Bq/kg, respectively. Moreover, specific activities of, 226Ra, 232Th, and 137Cs in the most of wheat and barley samples were lower than minimum detectable activity (MDA). 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).ConclusionResults of this study showed that the specific activities of natural radionuclides in soil were close to world average. In all soil samples observed artificial radio cesium nuclides. this radionuclide originated from nuclear accidents or weapon test which shows pollution of the studied regions by radioactive dust.
      PubDate: Sat, 04 Nov 2017 20:30:00 +010
  • Evaluating the Practice of Chest Radiography Using Different Digital
           Imaging Systems and their ...

    • Abstract: Introduction: The study was undertaken to evaluate the practice of chest radiography using different digital imaging system and its’ influence on dose and image quality. Materials and Methods: The study was carried out in two hospitals for four months 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 kilograms were selected randomly. The active-matrix, flat panel imagers technology was employed in the DR system for Hospital A while Hospital B used the single read out CR system. The 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 (ESD) of 0.098mGy for PA chest for Hospital A was lower than that of 0.161mGy obtained for Hospital B. However, the ESD at both centres were lower than 0.3mGy recommended by The International Atomic Energy Agency (IAEA). The quality of the images for chest radiography for the two hospitals were adequate to make a diagnosis with the ESD and effective dose lower than that recommended by IAEA and 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 are significant difference in image quality and radiation dose for chest radiography practice using CR and DR in this study.
      PubDate: Sat, 04 Nov 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
  • A Validation Study on Radiation properties of a Novel LiF: Mg, Ti Known as
           IAP-100 (Iranian)

    • Abstract: INTRODUCTION: LiF dosimeter has the most application in medicine. This study aims to evaluate some dosimetric properties of a novel LiF: Mg, Ti known as IAP-100.METHODS AND MATERIALS: An ELEKTA Precise linear accelerator was used to calibrate dosimeters at 6MV energy. In this survey responses of dosimeters to dose were evaluated up to1000 cGy. Background effect was investigated in two different states of dosimeters, including irradiated and unirradiated. Thermoluminescence response dependence to dose rate was investigated. Energy dependence was evaluated in diagnostic and therapeutic ranges. Also, fading effect was evaluated by reading the dosimeters each two hours up to 12 hours post-irradiation.RESULTS: The dosimeters had linear response up to 250 cGy. Passing one day from annealing the dosimeters showed no significant difference compared to the ones which were irradiated two weeks post-annealing. Readout values of dosimeters received 120 cGy at three dose rates of 21, 212, 425 cGy.min-1, were calculated as 125, 123, 121 cGy respectively. Measured values of delivering 80, 120 and 150 cGy prescribed doses at 6MV, 10MV and 15MV were accurate at 6 MV and about 1.5 times more than the prescribed dose at 10 and 15 MV. Thermoluminescence response in diagnostic energy range showed an increasing trend with increasing energy. DISSCUSION: Energy responses of the dosimeter in Megavoltage range are similar at 10 and 15 MV energy values. The increasing thermoluminescence response with increasing energy contradicts with the A.A. Nunn study. The decreasing trend with increasing dose rate is not considered to be statistically significant.CONCLUSIONS: Due to the reproducibility and linear response of the dosimeters in an acceptable dose range, they could be used in diagnostic and therapeutic fields. Effect of absorbed doses from background on low dose studies, mainly in diagnostic radiology range, could be evaluated in more details at subsequent surveys.
      PubDate: Sat, 23 Sep 2017 20:30:00 +010
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