Journal of Biomedical Physics and Engineering
Year:2019 | Volume:9 | Issue:1|Papers Count:13

Background: The paper points out the present limited possibility of using the verbal description of injuries for the needs of experts from the field of road transportation as relevant criminalistics traces, as well as the options of the FORTIS system that creates a new area for a deeper interdisciplinary approach in the field of expert evidence. Further a description of how to create injury signatures and contact signatures and the possibilities of their evaluation and mutual comparison based on the proven individual attributes are described Objective: To evaluate pedestrian injuries by the new proper FORTIS system and to show FORTIS valuability in the assessment of mechanical violence and mechanism of injuries. Material and Methods: Cases of traffic injuries including photodocumentation, graphic schemes, medical files and autopsy protocols processed by the new FORTIS forensic system. Results: A collision between a pedestrian and a vehicle represents a matrix of physical violence having an effect on the pedestrian´ s body and a matrix of the pedestrian´ s body´ s response to this violence. The analysis of individual cases shows the valuability of the FORTIS system. Conclusion: It is apparent that for the needs of traffic accidents analysts the FORTIS system has more options for being used in forensic medicine, as it covers not only a field of evaluation of traffic injuries but also all kinds of injuries and accidents (rail accidents, air accidents, violent crimes, etc. ).

Background: The dosimetric parameters required in lung cancer radiation therapy are taken from a homogeneous water phantom; however, during treatment, the expected results are being affected because of its inhomogeneity. Therefore, it becomes necessary to quantify these deviations. Objective: The present study has been undertaken to find out inter-and intralung density variations and its dosimetric impact on lung cancer radiotherapy using Monte Carlo code FLUKA and PBC algorithms. Material and Methods: Density of 100 lungs was recorded from their CT images along with age. Then, after PDD calculated by FLUKA MC Code and PBC algorithm for virtual phantom having density 0. 2 gm/cm3 and 0. 4 gm/cm3 (density range obtained from CT images of 100 lungs) using Co-60 10 x10 cm2 beams were compared. Results: Average left and right lung densities were 0. 275± 0. 387 and 0. 270± 0. 383 respectively. The deviation in PBC calculated PDD were (+)216%, (+91%), (+)45%, (+)26. 88%, (+)14%, (-)1%, (+)2%, (-)0. 4%, (-)1%, (+)1%, (+)4%, (+)4. 5% for 0. 4 gm/cm3 and (+)311%, (+)177%, (+)118%, (+)90. 95%, (+)72. 23%, (+)55. 83%, (+)38. 85%, (+)28. 80%, (+)21. 79%, (+)15. 95%, (+)1. 67%, (-) 2. 13%, (+)1. 27%, (+)0. 35%, (-)1. 79%, (-)2. 75% for 0. 2 gm/cm3 density mediums at depths of 1mm, 2mm, 3mm, 4mm, 5mm, 6 mm, 7 mm, 8mm, 9mm, 10mm, 15mm, 30mm, 40mm, 50mm, 80mm and 100 mm, respectively. Conclusion: Large variations in inter-and intra-lung density were recorded. PBC overestimated the dose at air/lung interface as well as inside lung. The results of Monte Carlo simulation can be used to assess the performance of other treatment planning systems used in lung cancer radiotherapy.

Background: Before treatment planning and dose delivery, quality assurance of multi-leaf collimator (MLC) has an important role in intensity-modulated radiation therapy (IMRT) due to the creation of multiple segments from optimization process. Objective: The purpose of this study is to assess the quality control of MLC leaves using EBT3 Gafchromic films. Material and Methods: Leaf Position accuracy and leaf gap reproducibility were checked with Garden fence test. The garden fence test consists of 5 thin bands A) 0. 2 Cm width spaced at 2 Cm intervals and B) 1 Cm width spaced at 1 Cm intervals. Each leaf accuracy was analyzed with measuring the full-width half-maximum (FWHM). Maximum and average leaf transmission were measured with gafchromic EBT3 films from Ashland for both 6 MV and 18 MV beams. Results: Leaf positions were found to be in a range between 1. 78 – 2. 53 mm, instead of nominal 2 mm for the test A and between 9. 09 – 10. 36 mm, instead of nominal 10 mm for the test B. The Average radiation transmission of the MLC was noted 1. 79% and 1. 98% of the open 10x10 Cm2 field at isocenter for 6 MV and 18 MV beams, respectively. Maximum radiation transmission was noted 4. 1% and 4. 4% for 6 MV and 18 MV beams, respectively. Conclusion: In this study, application of gafchromic EBT3 films for the quality assurance of Euromechanics multileaf collimator was studied. Our results showed that the average leaf leakage and positional accuracy of this type of MLC were in the acceptance level based on the Protocols.

Background: Estimating dosimetric parameters for small fields under non-reference conditions leads to significant errors if done based on conventional protocols used for large fields in reference conditions. Hence, further correction factors have been introduced to take into account the influence of spectral quality changes when various detectors are used in non-reference conditions at different depths and field sizes. Objective: Determining correction factors (KNR and KNCSF) recommended recently for small field dosimetry formalism by American Association of Physicists in Medicine (AAPM) for different detectors at 6 and 18 MV photon beams. Methods: EGSnrc Monte Carlo code was used to calculate the doses measured with different detectors located in a slab phantom and the recommended KNR and KNCSF correction factors for various circular small field sizes ranging from 5-30 mm diameters. KNR and KNCSF correction factors were determined for different active detectors (a pinpoint chamber, EDP-20 and EDP-10 diodes) in a homogeneous phantom irradiated to 6 and 18 MV photon beams of a Varian linac (2100C/D). Results: KNR correction factor estimated for the highest small circular field size of 30 mm diameter for the pinpoint chamber, EDP-20 and EDP-10 diodes were 0. 993, 1. 020 and 1. 054; and 0. 992, 1. 054 and 1. 005 for the 6 and 18 MV beams, respectively. The KNCSF correction factor estimated for the lowest circular field size of 5 mm for the pinpoint chamber, EDP-20 and EDP-10 diodes were 0. 994, 1. 023, and 1. 040; and 1. 000, 1. 014, and 1. 022 for the 6 and 18 MV photon beams, respectively. Conclusion: Comparing the results obtained for the detectors used in this study reveals that the unshielded diodes (EDP-20 and EDP-10) can confidently be recommended for small field dosimetry as their correction factors (KNR and KNCSF) was close to 1. 0 for all small field sizes investigated and are mainly independent from the electron beam spot size.

Background: While the benefits of cone-beam computed tomography (CBCT) are well known in maxillofacial imaging, the use of this modality is not risk-free. Objective: The aim of this study was to evaluate the exposure doses received by patients during maxillofacial imaging with CBCT. Methods: Entrance surface dose (ESD) was measured by using thermoluminescent dosimeters (TLDs) attached to the eyes lids, parotid glands and thyroid of 64 patients in two imaging centers (A and B). Phantom dosimetry was performed by a cylindrical poly-methyl methacrylate (PMMA) head-size phantom and an ionization chamber for different exposure parameters. NewTom VGi and Planmeca Promax 3D CBCT scanners were used at centers A and B, respectively. Results: The mean ESD of the eyes, parotid glands and thyroid were 2. 57, 2. 33 and 0. 28 mGy in center A, 0. 35, 2. 11 and 0. 37 mGy in center B, respectively. ESD of the eyes revealed a significant difference in two centers; in center B, it was 86. 4% lower than center A. In the phantom dosimetry, the measured doses of NewTom VGi were 2. 63 and 2. 08 mGy, respectively by changing field of view (FOV) size from 8×8 cm2 (height × diameter) to 6×6 cm2. For Planmeca Promax 3D, it ranged from 0. 98 to 3. 24 mGy depending on exposure parameters. Conclusion: There is a wide range of radiation doses dependent on the units, patients and selected scan parameters. Inappropriate selection of exposure settings, especially FOV size, can seriously increase patient dose.

Background: Rapid advances in technology, especially in the field of telecommunication, have led to extraordinary levels of mothers’ exposures to radiofrequency electromagnetic fields (RF-EMFs) prior to or during pregnancy. Objective: The main goal of this study was to answer this question whether exposure of women to common sources of RF-EMFs either prior to or during pregnancy is related to speech problems in the offspring. Materials and Methods: In this study, mothers of 110 three-to-seven-yearold children with speech problems and 75 healthy children (control group) were interviewed. These mothers were asked whether they had exposure to different sources of EMFs such as mobile phones, mobile base stations, Wi-Fi, cordless phones, laptops and power lines. Chi square test was used to analyze the differences observed between the control and exposed groups. Results: Statistically significant associations were found between the use of cordless phone and offspring speech problems for both before pregnancy and during pregnancy maternal exposures (P=0. 005 and P=0. 014, respectively). However, due to high rate of mobile phone use in both groups, this study failed to show any link between mobile phone use and speech problems in offspring. Furthermore, significant associations were observed between living in the vicinity of power lines and speech problems again for both before pregnancy and during pregnancy maternal exposures (P=0. 003 and P=0. 002, respectively). However, exposure to other sources of nonionizing radiation was not linked to speech problems. Moreover, exposure to ionizing radiation (e. g. radiography before and during pregnancy) was not associated with the occurrence of speech problems. Conclusion: Although this study has some limitations, it leads us to this conclusion that higher-than-ever levels of maternal exposure to electromagnetic fields could be linked to offspring speech problems.

Introduction: Automatic and accurate arterial input function (AIF) selection has an essential role for quantification of cerebral perfusion hemodynamic parameters using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI). The purpose of this study is to develop an optimal automatic method for arterial input function determination in DSC-MRI of glioma brain tumors by using a new preprocessing method. Material and Methods: : For this study, DSC-MR images of 43 patients with glioma brain tumors were retrieved retrospectively. Our proposed AIF selection framework consisted an effcient pre-processing step, through which non-arterial curves such as tumorous, tissue, noisy and partial-volume affected curves were excluded, followed by AIF selection through agglomerative hierarchical (AH) clustering method. The performance of automatic AIF clustering was compared with manual AIF selection performed by an experienced radiologist, based on curve shape parameters, i. e. maximum peak (MP), full-width-at-half-maximum (FWHM), M (=MP/ (TTP × FWHM)) and root mean square error (RMSE). Results: Mean values of AIFs shape parameters were compared with those derived from manually selected AIFs by two-tailed paired t-test. The results showed statistically insignificant differences in MP, FWHM, and M parameters and lower RMSE, approving the resemblance of the selected AIF with the gold standard. The intraclass correlation coefficient and coefficients of variation percent showed a better agreement between manual AIF and our proposed AIF selection than previously proposed methods. Conclusion: The results of current work suggest that by using efficient preprocessing steps, the accuracy of automatic AIF selection could be improved and this method appears promising for efficient and accurate clinical applications.

Background: Osteoporosis is a systemic skeletal disease characterized by low bone mineral density (BMD) and micro-architectural deterioration of bone tissue, leading to bone fragility and increased fracture risk. Since Panoramic image is a feasible and relatively routine imaging technique in dentistry; it could provide an opportunistic chance for screening osteoporosis. In this regard, numerous panoramic derived indices have been developed and suggested for osteoporosis screening. Jaw trabecular pattern is one of the main bone strength factors and trabecular bone pattern assessment is important factor in bone quality analysis. Texture analysis applied to trabecular bone images offers an ability to exploit the information present on conventional radiographs. Objective: The purpose of this study was to evaluate the relationship between Jaw trabecular pattern in panoramic image and osteoporosis based on image texture analyzing using local binary pattern. Material and Methods: An experiment is evaluated in this paper based on a real hand-captured database of panoramic radiograph images from osteoporosis and non-osteoporosis person in Namazi Hospital, Shiraz, Iran. An approach is proposed for osteoporosis diagnosis consisting of two steps. First, modified version of local binary patterns is used to extract discriminative features from jaw panoramic radiograph images. Then, classification is done using different classifiers. Results: Comparative results show that the proposed approach provides classification accuracy about 99. 6%, which is higher than many state-of-the-art methods. Conclusion: High classification accuracy, low computational complexity, multiresolution and rotation invariant are among advantages of our proposed approach.

Background: Gold nanoparticles (GNPs) are among the most promising radiosensitive materials in radiotherapy. Studying the effective sensitizing factors such as nanoparticle size, concentration, surface features, radiation energy and cell type can help to optimize the effect and possible clinical application of GNPs in radiation therapy. In this study, the radiation sensitive polymer gel was used to investigate the dosimetric effect of GNP size in megavoltage (MV) photon beam radiotherapy. Material and Methods: GNPs with the size of 30nm, 50nm and 100nm in diameter were used. Transmission electron microscope (TEM) and dynamic light scattering (DLS) were applied to analyze the size of nanoparticles. The MAGICA polymer gel was synthesized and impregnated with different sizes of GNPs. The samples were irradiated with 6MV photon beam and 24 hours after irradiation, they were read using a Magnetic Resonance Imaging (MRI) scanner. Macroscopic Dose Enhancement Factor (DEF) was measured to compare the effect of GNP size. The MAGICA response of the 6MV x-ray beam was verified comparing Percentage Depth Dose (PDD) curve extracted from polymer gel dosimetry and Treatment Planning System (TPS). Results: MAGICA polymer gel dose response curve was linear in the range of 0 to 10 Gy. DEFs by adding 30nm, 50nm and 100nm GNPs were 1. 1, 1. 17 and 1. 12, respectively. PDD curves of polymer gel dosimeter and treatment planning system were in good agreement. Conclusion: The results indicated a substantial increase in DEF uses a MV photon beam in combination with GNPs of different sizes and it was inconsistent with previous radiobiological studies. The maximum DEF was achieved for 50nm GNPs in comparison with 30nm and 100nm leading to the assumption of self-absorption effect by larger diameters. According to the outcomes of this work, MAGICA polymer gel can be recommended as a reliable dosimeter to investigate the dosimetric effect of GNP size and also a useful method to validate the current radiobiological and simulation studies.

Background: This study aims to evaluate the effect of exercise training on heart rate variability (HRV) and to determine the correlation between parameters of HRV and the ejection fraction in patients with heart failure after percutaneous coronary intervention. Material and Methods: Fifty patients with left ventricular ejection fraction ≤ 40% undergone percutaneous coronary intervention were randomly allocated in either an exercise training (ET) group or a control group. The ET group performed exercise training for 45 minutes, three times a week for seven weeks. Patients in both groups received a leaflet for daily exercising at home. HRV parameters comprising, the standard deviation of normal R-R intervals (SDNN), the square root of the mean of the squares of successive R-R intervals differences (RMSSD), the percentage of successive R-R intervals differing from more than 50 ms (PNN50), using 24-hour Holter electrocardiographic monitoring was measured. Results: After the intervention, the SDNN improved in the ET group (P=0. 002), while changes in all remaining HRV indices were insignificant (P≥ 0. 05). The control group showed no significant changes in any HRV parameters (P≥ 0. 05). Changes in SDNN in the ET group were significantly different from the control group (P=0. 003). At baseline, our results revealed a significant weak correlation between ejection fraction and SDNN (r =0. 279, P=0. 047). However, ejection fraction did not correlate significantly with RMSSD and PNN50. Conclusion: Exercise training is safe and feasible in post percutaneous coronary intervention patients, even in those with reduced ejection fraction. In a seven-week period, exercise training was effective in improving HRV in heart failure patients after percutaneous coronary intervention.

Background: Progressive familial intrahepatic cholestases (PFIC) are a spectrum of autosomal progressive liver diseases developing to end-stage liver disease. ATP8B1 deficiency caused by mutations in ATP8B1 gene encoding a P-type ATPase leads to PFIC1. The gene for PFIC1 has been mapped on a 19-cM region of 18q21-q22, and a gene defect in ATP8B1 can cause deregulations in bile salt transporters through decreased expression and/or activity of FXR. Point mutations are the most common, with the majority being missense or nonsense mutations. In addition, approximately 15% of disease-causing ATP8B1 mutations are annotated as splicing disrupting alteration given that they are located at exon-intron borders. Objective: Here, we describe the hidden layer of computational biology information of rare codons in ATP8B1, which can help us for drug design. Methods: Some rare codons in different locations of ATP8b1 gene were identified using several web servers and by in-silico modelling of ATP8b1 in Phyre2 and I-TASSER server, some rare codons were evaluated. Results: Some of these rare codons were located at special positions which seem to have a critical role in proper folding of ATP8b1 protein. Structural analysis showed that some of rare codons are related to mutations in ATP8B1 that are responsible for PFIC1 disease, which may have a critical role in ensuring the correct folding. Conclusion: Investigation of such hidden information can enhance our understanding of ATP8b1 folding. Moreover, studies of these rare codons help us to clarify their role in rational design of new and effective drugs.

Background: Considering that some vital organs exist in the head and neck region, the treatment of tumors in this area is a crucial task. The existence of air cavities, namely sinuses, disrupt the radiotherapy dose distribution. The study aims to analyze the effect of maxillary, frontal, ethmoid and sphenoid sinuses on radiotherapy dose distribution by Monte Carlo method. Material and Methods: In order to analyze the effect of the cavities on dose distribution, the maxillary, frontal, ethmoid and sphenoid sinus cavities were simulated with (3×3. 2×2) cm3, (2×2×3. 2) cm3, (1×1×1. 2) cm3 and (1×1×2) cm3 dimensions. Results: In the analysis of the dose distribution caused by cavities, some parameters were observed, including: inhomogeneity of dose distribution in the cavities, inhomogeneity of dose on the edges of the air cavities and dispersion of the radiations after the air cavity. The amount of the dose in various situations showed differences: before the cavity a 0. 64% and a 2. 76% decrease, a 12. 06% and a 17. 17% decrease in the air zone, and a 2. 25% and a 5. 9% increase after the cavity. Conclusion: The results indicate that a drop in dose before the air cavities and in the air zone occurs due to the lack of scattered radiation. Furthermore, the rise in dose was due to the passage of more radiation from the air cavity and dose deposition after the air cavity. The changes in dose distribution are dependent on the cavity size and depth. As a result, this has to be noted in the treatment planning and MU calculations of the patient.

The aim of the paper is to investigate effects of long term x-ray exposure on the human lymphocyte, reactive lymphocyte parameters and morphology of lymphocytes in x-ray technicians at Kirkuk hospitals. The study included 54 apparently healthy male x-ray technicians were matched with another 54 apparently healthy control to show any alteration in the lymphocytes, reactive lymphocytes and morphology. The investigated samples were divide into two groups depending on the work experience and working hours per day. The samples were tested for hematological parameters by complete blood cells count (CBC). The results showed that strong significant (P<0. 0001) increasing was recorded for the reactive lymphocytes in all groups of the diagnostic technicians compared with their controls and significantly increasing of lymphocytes observed for some groups. It was concluded that chronic exposure of x-ray can vary lymphocyte and reactive lymphocyte parameters significantly and working hours per day have discernible effects on lymphocyte morphology.