Showing papers in "Iranian Journal of Medical Physics in 2018"

Radiosensitization of breast cancer cells using AS1411 aptamer-conjugated gold nanoparticles

Abstract: Introduction: A main choice for cancer treatment is radiotherapy. But, the radiotherapy disadvantage is damages caused by radiation given to normal tissues/organs surrounding cancer. One way to avoid this is via increasing radiosensitization of cancer cells. Gold nanoparticles (GNPs) have shown sensitizing effect on cancer cells by enhancing their absorbed dose. Unlike earlier delivery techniques developed for nanotherapeutics, active targeting can achieve specific effect and higher uptake of GNPs in tumors while leave healthy cells untouched and consequently improve the therapeutic index. To achieve active targeting, GNPs should be equipped with functional ligands which can recognize and adhere to the receptors of cancer cells. Aptamers are small DNA-molecule/RNA-fragments with high specificity and affinity towards target molecules. AS1411 aptamer can specifically bind to over-expressed nucleolin on the membrane of tumor cells including breast cancer. This aptamer is capable to enter cancer cells through specific ligand–receptor interaction. Greater uptake of GNPs by cells may induce increased radiation effects. Cancer stem cells are a small population of cells within a tumor capable for self-renewal and differentiation into various cell types. Materials and Methods: We hypothesized that conjugation of GNPs with AS1411 (AS1411/GNPs) could increase GNPs-mediated radiosensitization in breast cancer cells. We hypothesized that AS1411/GNPs would radiosensitize breast cancer stem/progenitor cells grown to three- dimensional (3D) mammospheres. Cytotoxicity studies of the GNPs and AS1411/GNPs were done on two different cancer cell lines of MCF-7 and MDA-MB-231 with MTT assay. Atomic absorption spectroscopy (AAS) confirmed the cellular uptake of particles. Radiosensitizing effect of GNPs and AS1411/GNPs on MDA-MB 231 and MCF- 7 cells assessed by clonogenic assay. Results: Clonogenic survival data revealed that AS1411/GNPs at 12.5 mg/L results in radiosensitization of breast cancer cells. Mammosphere of MCF-7 was more resistant than their monolayer counterparts. Conclusion: The combination of the sensitizing GNPs with the AS14411 aptamer can be regarded for improved treatment of breast cancer cells especially for the mammosphere MCF-7 cancer cells mimicking cancerous tumors.

AS1411 Aptamer Conjugated Gold Nanoclusters as a Targeted Radiosensitizer for Megavoltage Radiation Therapy of 4T1 Breast Cancer Cells

Abstract: Introduction: In the present study, AS1411 aptamer conjugated gold nanoclusters (GNCs) have been introduced as a targeted radiosensitizer for enhancing megavoltage radiation therapy efficacy. RT has identified as an effective therapeutic modality for many different types of solid tumors. However, equal radiation beams absorption by tumor and surrounding healthy tissues is still a great challenge in RT which is caused by attenuation coefficient factor similarity. In order to overcome this challenge and to increase the efficacy of radiation therapy, radiosensitizers has been recommended. Materials and Methods: GNCs with ultra-small gold core and bovine serum albumin shell (BSA) as a versatile Nano-platform were synthesized and conjugated to AS1411 aptamer (Apt-GNCs). Due to nucleolin overexpression in breast cancer cells and high affinity of the AS1411 aptamer to nucleolin, mouse mammary carcinoma cell line (4T1) was selected as malignant cells and murine fibroblast (L929) was used as a normal cell line. Results: Flow cytometry assessments reveal a significant increase of GNCs uptake by the cancer cells in the presence of the aptamer as the targeting agent. Inductively coupled plasma optical emission spectrometry (ICP-OES) measurements demonstrate 4 times more Apt-GNCs uptake by 4T1 cells than the normal cells at concentration ratio of 1:40 (4µM Aptamer and 160 µM GNCs at 24h incubation). Conclusion: Combination of megavoltage radiation therapy and Apt-GNCs as radiosensitizer causes effective cancer cells killing and obtaining dose enhancement factor (DEF) about 2.7 in clonogenic survival assay.

Radiological Assessment of the Artificial and Natural Radionuclide Concentrations of Wheat and Barley Samples in Karbala, Iraq

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

Effects of Arbutin on Radiation-Induced Micronuclei in Mice Bone Marrow Cells and Its Definite Dose Reduction Factor

Abstract: Introduction: Interactions of free radicals from ionizing radiation with DNA can induce DNA damage and lead to mutagenesis and carsinogenesis. With respect to radiation damage to human, it is important to protect humans from side effects induced by ionizing radiation. In the present study,the effects of arbutin were investigated by using the micronucleus test for anti- clastogenic activity, to calculate the ratio of polychromatic erythrocyte to polychromatic erythrocyte plus normochromatic erythrocyte (PCE/PCE+NCE) in order to show cell proliferation activity. Materials and Methods: Arbutin (50, 100, and 200 mg/kg) was intraperitoneally (ip)administered to NMRI mice two hours before gamma radiation at 2 and 4 gray (Gy). The frequency of micronuclei in 1000 PCEs (MnPCEs) and the ratio of PCE/PCE+NCE were calculated for each sample. Data were statistically evaluated using one-way ANOVA,Tukey HSD test, and t-test. Results: The findings indicated that gamma radiation at 2 and 4 Gy extremely increased the frequencies of MnPCE (P<0.001) while reducing PCE/PCE+NCE (P<0.001) compared to the control group. All three doses of arbutin before irradiation significantly reduced the frequencies of MnPCEs and increased the ratio of PCE/PCE+NCE in mice bone marrow compared to the non-drug-treated irradiated control (P<0.001). All three doses of arbutin had no toxicity effect on bone marrow cells. The calculated dose reduction factor (DRF) showed DRF=1.93 for 2Gy and DRF=2.22 for 4 Gy. Conclusion: Our results demonstrated that arbutin gives significant protection to rat bone against the clastogenic and cytotoxic effects of gamma irradiation.

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.

Radiological Hazard Resulting from Natural Radioactivity of Soil in East of Shazand Power Plant

Abstract: Introduction: Nuclear radiation is potentially harmful to humans and soil contamination with radionuclides is the main source of human radiation exposure. These radionuclides can., enter to human body through the food chain. In this study, 34 soil samples were collected from between Arak city and Shazand Power Plant over 20 km length and analyzed. Materials and Methods: The specific activities of 226Ra, 232Th, 40K, and 137Cs were measured in soil samples, using gamma-ray spectrometry and a high-purity germanium (HPGe) detector. For all the samples, we calculated radiological hazards such as 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. Results: The specific activities of 226Ra, 232Th, 40K, and 137Cs in the soil samples varied from 18.92 to 43.11, 25.31 to 54.27, 230.17 to 728.25, and from in and Hex wereless than unity. Excess lifetime cancer risk of the samples ranged from 0.21×10-3 to 0.31×10-3, which are close to the mean world value (0.29×10-3) butlower than the acceptable value (10-3). Conclusion: The radiological parameters estimated from the specific activities of the radionuclides in soil were within the acceptable range, and therefore, radiation exposure poses no significant risks to the resident population in the vicinity of the power plant.

Effects of Occupational Exposure on Blood Cells of Radiographers Working in Diagnostic Radiology Department of Khuzestan Province

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

Mechanical performance of three-dimensional bio- nanocomposite scaffolds designed with digital light processing for biomedical applications

Abstract: Introduction: The need for biocompatible and bioactive scaffolds to accelerate the regeneration and repair of fractured bones has been considered for bone tissue engineering applications during recent decades. The new methods were developed to produce scaffolds to improve the tissue quality, size of cavities, control the porosity and increase the scaffold compressive strength under different loads. The presence of compounds such as hydroxyapatite (HA), which contains calcium and phosphorus ions, is essential for bone marrow transplantation. The use of carbon nanotubes can be considered to improve mechanical, chemical and biological properties, much like bone collagen. However, the construction of bio-nanocomposite scaffold which includes all of the above properties is very important in accelerating bone repair and also in reducing the problems of using other conventional scaffold methods. Materials and Methods: In this paper, the fabrication of a bio-nanocomposite scaffold with a three-dimensional printing method, digital light processing (DLP) has been investigated. The used compounds of photopolymer resin, carbon nanotubes and hydroxyapatite are solvent by ultrasonic and magnet stirrer, then a scaffold model designed in SOLIDWORKS software applied to the DLP 3D printer. Results: The addition of single wall carbon nanotubes (SWCNT) increases the compressive strength of the samples more than two times, beside it leads to an increase in the porosity of the samples due to the addition of SWCNTs. The scaffold porosity was recorded around 75 and 85%, which is associated with a proper compressive strength around 2 -4 MPa. Addition of 2.5 to 5 wt% SWCNT to HA and photopolymer resin can leads to a better mechanical performance compared to the pure sample. Conclusion: The results obtained from this work showed that the above process was successful methodology in preparation of novel scaffold bio-nanocomposites using DLP technique for using in bone tissue engineering.

Assessment of Radiation Dose to the Lens of the Eye and Thyroid of Patients Undergoing Head and Neck Computed Tomography at Five Hospitals in Mashhad, Iran

Abstract: Introduction: In recent years, the number of computed tomography (CT) scans, which is a high-dose technique, has increased significantly. Head and neck CT is performed frequently and thyroid, particularly in children, has always been considered a sensitive organ. In recent years, radiobiologists and health physicists have been more concerned about the safety of lenses of the eyes, as cataract is no longer considered a deterministic effect. Material and Methods: In the present study, incurred doses to the thyroid and lens of the eye of 140 patients who underwent common head and neck CT at five hospitals were measured by thermoluminescent dosimeters (TLD-100). The patients were divided into two age groups of pediatrics and adults. TLD chips were placed on the patient’s skin surface. For each patient, scan parameters, sex and age were recorded. Exposed TLDs were read by a manual TLD reader. Results: The verage absorbed dose of the thyroid, as well as the lenses of the left and right eyes were 5.89±1.74, 15.84±2.81 and 16.25±2.57, respectively, for the pediatric patients and 5.00±1.17, 17.64±1.69 and 24.41±1.89 for adults. Patient-specific organ doses were influenced by the scanned region, scan protocol and patient's age. Conclusion: In the present study, the mean eye dose was much lower than the 500 mGy threshold recommended by International Commission on Radiological Protection (ICRP) for lens of the eye damage, thus, it appears to be clinically safe. While CT scan remains a crucial tool, further dose reduction can be achieved by controlling different factors affecting patient doses.

Local Diagnostic Reference Levels for Some Common Diagnostic X-Ray Examinations In Sabzevar County of Iran

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 (ie, 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 054, 064, 199, 383, 147, 215, 054, 078, 122, and 101 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

Telecobalt machine beam intensity modulation with aluminium compensating filter using missing tissue approach

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.

Optimization of Dose and Image Quality in Full-fiand Computed Radiography Systems for Common Digital Radiographic Examinations

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.

A Survey on the Radiation Protection Status among Radiology Staff

Abstract: Introduction: Radiation exposure during radiological examination is a health concern, of which radiology professionals should be cognizant. We sought to evaluate the radiation protection knowledge, attitudes, and practice (KAP) amongst radiology staff of hospitals across 10 provinces of Iran. Materials and Methods: For evaluating the level of radiation protection KAP, 553 radiology staff were enrolled. A 32-item questionnaire was designed to assess radiation protection KAP, the validity which was confirmed by members of the Medical Physics and Biostatistics departments. The questionnaire evaluated the respondents' knowledge, practice, and attitudes towards the basic principles of radiation protection, the necessity of using protective equipment, and their performance in the implementation of radiation protection recommendations. Results: We found no significant difference in the level of radiation protection KAP between male and female radiology staff and among those with different educational levels and ages (P>0.05). However, there was a significant association between radiation protection KAP and working experience, hospital size, and hospital type (P 0.05). Conclusion: Our results showed that the level of radiation protection KAP among radiology staff is inadequate. This might be due to the lack of ongoing training courses concerning protection against ionizing radiation. Thus, sustained training of radiation protection principles can promote KAP among the staff of radiology departments, and in turn, reduce public dose from medical diagnostic modalities.

Design and Development of an Indigenous in-house Tissue-Equivalent Female Pelvic Phantom for Radiological Dosimetric Applications

Abstract: Introduction: The present study is aimed to design and develop a tissue-equivalent pelvic phantom, mimicking the Indian female pelvic dimensions by means of locally available and cost-effective tissue substitutes having equivalent radiological properties. Materials and Methods: For the purpose of the study, the real female pelvic bones were embedded for preparation. Paraffin wax, Aloe-vera powder, purified borax, and sodium benzoate, were used to obtain the proper density and effective atomic number. A hollow three-dimensional outer surface and the internal organs moulds were fabricated using gypsona bandage. The internal organs moulds were filled with semi-solid paraffin wax mixture, stabilized, and then embedded with pelvic bones and internal organs at the right anatomical positions. The surface mould, along with the bones and internal organs, were stabilized in their position in the final form, and verified with computed tomography (CT). Results: The physical dimensions of the given female pelvic phantom were comparable with the mean dimensions of the Indian female pelvis. Furthermore this tissue-equivalent phantom was radiologically equivalent to the Indian human female pelvis in all respects. The CT numbers of the uterus, bladder, rectum, muscles, fats, bone, and cavities were 39.9, 30.5, 24.7, 34.6, -86.8, 578.6, and -220.9 HU, respectively. Furthermore, the relative electron densities of the muscle, fat and bones were 1.035, 0.913, and 0.779 in the phantom. Conclusion: The dimensions and physico-radiological properties of the tissue substitutes provided a good inhomogeneous female pelvic phantom differing in dimensions with imported pelvic phantoms. Therefore, this phantom can be used for radiological dosimetric applications.

Advanced Analysis of PRVEP in Anisometropic Amblyopia

Abstract: Introduction: to identify the pattern-reversal visual evoked potential (PRVEP) waveform descriptor by evaluating discrete wavelet transform (DWT) in order to optimize stimulus in the diagnosis of anisometropia amblyopia. Materials and Methods: The PRVEP testing was performedfor 31 normal individuals and 35 patients with amblyopia. The stimuli were consisted of spatial frequencies of 1, 2, and 4 cycles per degree (cpd) and contrast levels of 100%, 50%, 25%, and 5%. The results were analyzed in the dimensions of time and time-frequency. DWT descriptor were extracted at level 7 (7P descriptor) for Haar, Daubechies 2, Daubechies 4, Symlet 5, Biorthogonal 3.5, Biorthogonal 4.4, and Coiflet 5 wavelets for 12 stimuli and compared between the two groups. The correlation between different spatial frequencies at the same contrast level and the similarities between reconstructed signals and original waveforms were evaluated. Results: There were a significant reduction in P100 amplitude and a significant elevation in latency among the patient group. In the patients with amblyopia, 7P descriptor decreased in all analysis except for the frequency of 4 cpd and the contrast of 5% using bior4.4. No significant correlation was observed between different frequencies at a special contrast; however, there was a significant correlation between reconstructed signals and the original ones. Conclusion: The 7P descriptor could be used to distinguish between normal and abnormal signals in anisometropia amblyopia. Considering the results, DWT with coif5, db4, bior4.4, and bior3.5 wavelets can be utilized as a good indicator for selecting optimum stimulus.

The Practice of Chest Radiography Using Different Digital Imaging Systems: Dose and Image Quality

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

A phantom study for the optimization of image quality and radiation dose for common radiographic examinations in digital radiography

Abstract: Introduction: Phantom studies facilitate the implementation of radiation dose surveillance as a function of radiographic technical parameters for minimizing patient radiation dose. The evidence of such investigations can then be used to evaluate technical parameters used in the radiographic procedures to reduce radiation dose without compromising the image quality. Material and Methods: This experimental study was carried out using an anthropomorphic phantom and the Leeds test object. Computed radiographic system was utilized and the images were printed for objective evaluation. Dose-area-product (DAP) readings were obtained using a DAP meter for the technical parameters employed for the radiographic procedures. Results: The use of 0.2 mm additional copper filtration resulted in the lowest radiation doses for all four radiographic procedures (i.e. posteroanterior chest, anteroposterior abdomen and lumbar sacral spine projections). The highest tube potential appropriate to the body part being imaged, patient size, image receptor response and required information resulted in the minimum radiation dose to the patient without compromising the image quality. The focus to film distance utilized for the radiographic procedure must be in accordance with the focus to grid distance specified by the manufacturer when using the bucky to eliminate grid “cut-off.” Conclusion: The optimization of image quality and radiation dose can be accomplished by using a phantom and selecting the imaging parameters that yield an acceptable image quality with the lowest entrance surface dose while considering the adjustment for patient size.

Magnetic Graphene Oxide Nanocarrier as a drug delivery vehicle for MRI monitored magnetic targeting of rat brain tumors

Abstract: Introduction: Glioblastoma multiform is the most common malignant brain tumor, with an invasive nature. Despite the development of conventional therapies such as surgery, radiotherapy and chemotherapy, because of high recurrence rates, the prognosis remains very poor. Over the last decade, nanotechnology has represented an innovative method as nanoparticle-based drug delivery carriers to overcome the BBB transport. Multifunctional magnetic nanoparticles are powerful tools for current clinical diagnostics, imaging and therapeutic procedures. Materials and Methods: Magnetic targeting studies were carried out in C6 glioma tumor-bearing Wistar rats using intravenous magnetic nanoparticles administration under permanent magnetic phantom. Animals were placed ventrally on a platform with their head positioned between two blocks of NdFeB permanent magnet (1.3 tesla). Measurements of magnetic density in the space between the two blocks were carried out using a tangential B-probe Teslameter (LEYBOLD, Germany). MNP (9 mg/kg) were injected into the tail vein of rats, seventeen days after implantation and retained in the magnetic field for 2h. To evaluate brain- targeting ability of nanoparticles, the rats were imaged with MRI before the administration of nanoparticles and after the magnetic targeting. Immediately following MRI, the animals were sacrificed and the brains were collected for Prussian blue staining. Results: Magnetic NGO/PLGA nanoparticles with a diameter of 71.8 nm, a zeta potential of -33.07±0.07 mV presented superior superparamagnetic properties with a saturation magnetization of 15.98 emu/g. The results of MR T2 images and Prussian blue staining of rat brains indicated MNPs could overcome the BBB for glioma targeting in the presence of a permanent magnetic field. The measured magnetic density at the GBM area was 450 mT, the value measured 2.5 cm caudal to the tumor was 325 mT, indicating that the tumor would be exposed to a maximum magnetic force. Furthermore, the MRI images demonstrated MNPs could be used in noninvasive MR imaging techniques and enhance the MRI sensitivity to offer better chemotherapy and real time monitoring. Conclusion: In the present study, for the first time, we combined the concepts from these two fields to synthesize magnetic NGO nanoparticles and indicated its high-level specificity to magnetic targeting C6 glioma rats, that its ability to serve as an excellent contrast enhancement agent for MRI.

A New Method for Detecting Sperms in Microscopy Images: Combination of Zernike Moments and Spatial Processing

Abstract: Introduction: In recent years, modern microscopic imaging in parallel with digital image processing techniques, have facilitated computerized semen analysis. However, in these methods, distinguishing sperms from other semen particles can be hampered by low contrast of microscopic images and the possibility of neighboring sperms touching each other. Materials and Methods: This article introduced a new method based on combination of Zernike moments and spatial processing in sperm detection. In the first step, Zernike moments were estimated due to their rotation and noise-resistant nature to mark pixels with some chance of belonging to sperms. In the second step, pruning was executed considering the connectivity of candidates and using morphological processing, to extract sperms. The proposed algorithm was examined on microscopic images exhibiting several sperms with different morphologies. Results: The obtained results showed the ability of the proposed method in sperm detection, such that it could detect 85% of the sperms without any false detection. In a more pragmatic situation, where false detection rate was 5%, the detection rate of the proposed algorithm increased to 94%. Conclusion: Comparing the proposed method with watershed segmentation algorithm (WSA) and morphological contour synthesis (MCS) revealed the superiority of the proposed method to its alternatives in such a way that it detected sperms at least 3% and 13% better than WSA and MCS, respectively, without any false detection. Furthermore, the rate of false detections in the proposed algorithm was at least 4% and 14% better than its alternatives.

A Method for Body Fat Composition Analysis in Abdominal Magnetic Resonance Images Via Self-Organizing Map Neural Network

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

Dynamic Modeling of the Electromyographic and Masticatory Force Relation Through Adaptive Neuro-Fuzzy Inference System Principal Dynamic Mode Analysis

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

Assessment of the Specific Activity of Alpha- and Beta-emitting Radionuclides in Groundwater, Anka, Nigeria

Abstract: Introduction: After the lead poisoning outbreak came to light in Zamfara State, Nigeria, people living near gold mines were worried about environmental safety, especially drinking water quality. This study examined the gross alpha and gross beta activity concentrations in groundwater in different locations of Anka, Zamfara State, Nigeria, to measure the possible radiation dose and potential health effects. Material and Methods: In this study, 32 water samples were collected from hand dug wells and boreholes in Anka, Nigeria, through stratified random sampling method. The ISO 9696 and ISO 9697 methods were adapted using Eurysis system-multiple-channel-gas-filled proportional counter to measure gross alpha and gross beta activity concentration. Results: The ranges of alpha and beta activity concentration in groundwater of the area were 0.114 to 3.698 Bq/l and 0.071 to 4.823 Bq/l with the geometric means of 0.961 Bq/l and 2.134 Bq/l, respectively. These amounts were higher than the reference limits of 0.5 Bq/l and 1 Bq/l for gross alpha and beta activity concentrations, respectively. Additionally, the total annual effective dose equivalent was more than that (0.1 mSv/y) of recommended by World Health Organization (WHO). Conclusion: The mean concentrations of alpha and beta activities in the samples were above the limits recommended by WHO. These excessive radiations might negatively affect the environment and inhabitants.

Evaluation of the Portal Imaging System Performance for an Elekta Precise Linac in Radiotherapy

Abstract: Introduction: Electronic portal imaging devices (EPIDs) provide two- and three-dimensional planar and volumetric cone beam images to improve the accuracy of radiation treatment delivery. Periodic quality assurance (QA) of EPIDs is essential for dosimetric verification in radiotherapy. In this study, a QA program was implemented to evaluate the function of the EPID to be confident in applying corrections for the uncertainty of patient set-up. Material and Methods: Firstly, the safety features were verified, and the uniformity of EPID response was evaluated using flat panel detector. Additionally, the contrast and spatial resolutions of the EPID were assessed using detail counting of the Los Vegas phantom images by visualization method and measuring the modulation transfer function using edge technique, respectively. Moreover, a combination of smoothing methods was used for optimal use of edge detection algorithm for the noisy portal images. Finally, the location of the central ray on the EPID surface at different gantry angles was determined to evaluate the mechanical stability of the supporting arm. Results: The safety interlocks were found to be functional.The EPID response variation was less than 3% according to the results obtained from the detector. The contrast resolution met 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 the photon energy of 6 MV. The supporting arm deviation was within ±1 mm. Conclusion: The periodic QA of image guidance system gave confidence to apply the corrections for set-up in clinic.

The effect of CT contrast agents on treatment planning and dose calculation in radiation therapy of pelvis cancers

Abstract: Introduction: Using contrast medium in diagnosis and identifying of an organ from its surrounding tissue is very useful. These contrast mediums alter radiation absorption of studied organs. The aim of this study is to identify the influences of contrast media in treatment planning system of the pelvis. Materials and Methods: Seven patients with pelvis area cancer with two sets of CT image, one with contrast medium and another without it, have been used and influences of contrast medium in treatment planning system for these patients were studied. Results: After using contrast medium 2.63% increase in MU for RL field and 0.79%, 1.05%, 1.42% decrease in MU for AP, PA, RL fields have been obtained in rectum, respectively. For Bladder cancer, 0.34% decrease in MU of AP filed and 1.57%, 0.46%, 0.39% increase in MU for PA, RL and LL fields have been calculated, respectively. For cervix cancer, 1.1% decrease for AP field and 0.68% increase for PA field have been obtained. Conclusion: According to the DVHs and calculated MUs, the results showed that the dose differences between the plans for the CT images with and without contrast medium were less than about 1% and was clinically tolerable.

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

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

Assessment of X-Ray Crosstalk in a Computed Tomography Scanner with Small Detector Elements Using Monte Carlo Method

Abstract: Introduction: Crosstalk is a leakage of X-ray or light produced in a matrix of X-ray detectors or array of photodiodes in one element to other elements affecting on image contrast and spatial resolution. In this study, we assessed 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 performed using Monte Carlo simulation. In the first step, X-ray tube and its energy spectrum at the energies of 80, 100, 120, and 140 keV were simulated and validated by using SpekCalc and t-test. Then, other important parts of CT scanner, namely filters, detectors, and grids were simulated. X-ray crosstalk between CT detectors was calculated in air and in the presence of water phantom (as a simulator of human body) to compare the effect of scattered photons. Finally, the influence of some important parameters on X-ray crosstalk was evaluated. Results: In CT scanner with small elements, when using phantom, crosstalk increases by 16-50%. Using the lowest possible energies of X-ray, decreases the crosstalk up to 43% of its initial amount. Furthermore coating a 10 or 20 µm layer of tungsten or lead on the detector separators, decreases the X-ray crosstalk significantly. Conclusion: Choosing the proper high voltage, detectors’ material and its dimensions, scintillator impurities and septa material can decrease X-ray crosstalk.

Effect of Helium-Neon Laser and Sodium Hypochlorite on Calf Thymus Double-Stranded Deoxyribonucleic Acid Molecule: An in Vitro Experimental Study

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 (6328 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 (6328 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 (ie, DNA strand breakage) and hyperchromasia (ie, of DNA strands separation) Results: The mean concentration of nucleic acids insignificantly (P > 005) 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 292% and 783% of the pre-incubated levels (hyporchromasia effect) The He-Ne laser (6328 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 (6328 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

Effect of Silver Nanoparticles on Improving the Efficacy of 5-Aminolevulinic Acid-Induced Photodynamic Therapy

Abstract: Introduction: The most important limitation of 5-aminolevulinic acid (5-ALA)-induced photodynamic therapy (PDT) is the efficacy of the cells in converting 5-ALA to protoporphyrin IX. The present study aimed to investigate the effectiveness of silver nanoparticles (AgNPs) with the photosensitivity at the surface plasmon resonance wavelength on 5-ALA-mediated PDT. Material and Methods: First of all, the toxicity of 5-ALA, AgNPs, and combined 5-ALA and AgNPs was evaluated on DFW cell line derived from melanoma. After choosing the optimal concentration, both pulsed and continuous light irradiations were conducted at different doses using a light‑emitting diode source in the groups receiving 5-ALA, AgNPs, as well as 5-ALA and AgNPs combination, and the controls. The cell survival was evaluated 24 h after irradiation using MTT assay. Results: According to the results, light exposure did not significantly change cell survival in the absence or presence of AgNPs. However, light exposure in the presence of 5-ALA and AgNPs/5-ALA combination caused a significant reduction in the cell survival. The necessary light exposure to induce 50% cell death (ED50) in the presence of 5-ALA was 1280 mJ/cm2; however, this value was 280 mJ /cm2 in the presence of combined AgNPs and 5-ALA. Conclusion: As the findings indicated, PDT had a higher efficacy in the presence of combined 5-ALA and AgNPs than in the sole 5-ALA presence. Nonetheless, further studies are required to evaluate the definitive mechanism of these findings.

Assessment of the effects of radiation type and energy on the calibration of TLD-100

Abstract: Introduction: In radiation therapy, knowing the dose rates to healthy organs and tumors is beneficial, and thermoluminescent dosimeter (TLD) allows for this possibility. This study was aimed at determining the dose-response differences of TLDs in various types of radiation, energy levels, and dose rate calibrated with other types of radiation beams and energy and dose levels. Materials and Methods: In this study, LiF:Mg,Ti (TLD-100) was used for dosimetry. Photon and electron irradiation was performed by Elekta Precise Linear Accelerator. First, TLDs were calibrated in three different groups of 6 MV photon, 6 MeV electron, and 60Co teletherapy photon beam with 50 cGy dose. Next, each group was irradiated with 6 MV photon, 6 MeV electron, and 60Co teletherapy photon beam separately at three different dose levels of 20, 60, and 100 cGy. Results: TLDs calibrated with electron were significantly different at all dose levels and with all types of radiation from TLDs calibrated with photon or 60Co teletherapy photon beam (P=0.000). P-value of the TLDs calibrated with 6 MV photon versus 60Co was less than 0.94. The maximum standard deviation belonged to 100 cGy irradiation, while the least pertained to 20 cGy irradiation. Conclusion: Calibration of TLDs depends on the type of radiation.

The Impact of Low-level Exposure to Radiation in Natural Ecosystems of Najaf and Dhi Qar Cities, Iraq

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–Muller 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.