JOURNAL OF BIOMEDICAL PHYSICS AND ENGINEERING
Year:2020 | Volume:10 | Issue:2|Papers Count:15

Limb loss results in significant debilitation and reduces the quality of life of the affected individuals [1]. To restore the lost limb’ s function, myoelectric systems have been widely used in powered prostheses [2]. With this approach, the motor intent is estimated from the electromyogram (EMG) signals recorded by electrodes which are placed on the skin surface above the residual muscles [1]. The principle of commercial myoelectric schemes has not changed in several decades, and is referred to as conventional control [2]. This technique uses a measure of amplitude (such as mean absolute value over a time window) of the EMG signals recorded by electrodes placed at two control sites, preferably over a pair of antagonist muscles of the residual limb, to control a single motion i. e. degree of freedom (DoF), for example hand opening closing [2]. To change the DoF, a mode switch is conducted by muscle co-contraction or a hardware switch [2]. The mode switch, however, results in an unnatural control of multiple DoFs [2]...

Background: Hysterosalpingography (HSG) is an indispensable tool for diagnosing infertility in females. The procedure exposes female reproductive organs to ionizing radiation as the genitals are irradiated during the process. Investigating patient absorbed dose during the procedures is essential for effective radiological protection of the patient. Objective: This study aims to investigate the radiation dose received by patient during HSG examination in the study environment in order to enhance optimization of procedures and the associated dose, thereby minimizing radiation risks. Material and Methods: The prospective pilot study, was conducted in four tertiary healthcare institutions in Southwest Nigeria. Thermoluminescence dosimeter (TLD 100) was used to determine the Entrance Surface Dose (ESD) of 80 patients presented for HSG investigation. The corresponding effective dose, ovary, uterus and urinary bladder doses were evaluated using PCXMC software. Results: The mean entrance surface doses (ESD) obtained from the four centers were 18. 58± 6. 31 mGy, 15. 18± 2. 27 mGy, 17. 44± 3. 43 mGy and 34. 24± 11. 98 mGy for SW1, SW2, SW3 and SW4 centers, respectively. The corresponding mean of effective doses were 1. 54± 0. 63 mSv, 1. 24± 0. 28 mSv, 1. 41± 0. 30 mSv and 2. 53± 0. 94 mSv for SW1, SW2, SW3 and SW4 centers, respectively. The resulting mean doses to the ovary, urinary bladder and uterus were also presented. Conclusion: The results obtained in general are comparable with international standards. It was, however, recommended that study centers with high doses should conduct dose audit in order to enhance patient safety.

Background: Intracavitary brachytherapy plays a major role in management of cervical carcinoma. Assessment of dose received by OAR’ s therefore becomes crucial for the estimation of radiation toxicities in HDR brachytherapy. Objective: Purpose of this study is to evaluate the role of in vivo dosimetry in HDR brachytherapy and to compare actual doses delivered to OAR’ s with those calculated during treatment planning. Material and Methods: In this retrospective study, 50 patients of cervical carcinoma were treated by Microselectron HDR. Out of 50 patients, 26 were treated with a dose of 7 Gy and 24 with a dose of 9 Gy, prescribed to point A. Brachytherapy planning and evaluation of dose to bladder and rectum was done on TPS & in vivo dosimetry was performed using portable MOSFET. Results: Calibration factors calculated for both dosimeters are almost equal and are 0. 984 cGy/mV and 1. 0895 cGy/mV. For bladder, dose deviation was found to be within ± 5% in 28 patients, ± 5-10% in 14 patients, ± 10-15% in 4 patients. Deviation between TPS-calculated dose and dose measured by MOSFET for rectum was within ± 5% in 31 patients, ± 5– 10% in 8 patients, and ± 10– 15% in 7 patients. Conclusion: TPS calculated doses were slightly higher than that measured by MOSFET. The use of small size MOSFET dosimeter is an efficient method for accurately measuring doses in high-dose gradient fields typically seen in brachytherapy. Therefore, to reduce the risk of large errors in dose delivery, in vivo dosimetry can be done in addition to TPS computations.

Background: Diazinon is one of the most common pesticides in the world playing a similar role to radiation and it could cause DNA breaks and genetic effects. Objective: In this study, radiosensitivity of a lymphoblastic cell line pretreated by Diazinon was investigated. Material and Methods: In this case-control study, the human lymphoblastic T-cell line was divided into 6 groups based on receiving radiation or/and Diazinon. After that, the DNA damage, in all of the groups, were counted by cytokinesis-block micronuclei assay using different indices. Results: The mean frequency of micronuclei, nuclear bridges and nuclear buds in cell groups exposed by both Diazinon and radiation were remarkably higher than the other groups which just received radiation or Diazinon alone. The interaction between radiation and Diazinon treatment was statistically significant for NBUDS index. Conclusion: The results indicated that the Diazinon contamination could affect the radiosensitivity index of cancerous cells while further molecular and in-vivo studies are needed to investigate genetic and toxic effects of Diazinon on DNA and its repair system.

Background: Neutron contamination is produced in electron beams of linac when tooth or dental materials are located in the path of beam. Objective: This study aims to determine the neutron dose contamination from different dental restoration materials in electron mode of a linac. Material and Methods: In this experimental study, the neutron dose contamination was calculated in the presence of tooth and tooth restored by Ceramco C3 veneer, Eclipse or amalgam. The electron mode included 8, 12, and 14 MeV electron beams of Siemens Primus linac at different depths before and after tooth. MCNPX code was used to simulate the linear accelerator and dental restoration materials. Tooth and tooth restoration materials were located in the beams’ central axis and the neutron dose was scored in 3 × 3 × 1 cm3 voxels at different depths before and after the tooth. Results: The highest neutron dose contamination was observed for the combination of the tooth and Eclipse in 12 and 14 MeV beams and the maximum calculated relative neutron dose was 1. 53 for tooth and Eclipse for 14 MeV electron beam. Conclusion: Tooth and dental materials lead to neutron dose contamination production, therefore, in order to avoid having harmful effects on normal tissues due to the neutron beam in head and neck cancer, it is recommended that treatment planning performed should not place tooth with dental restoration materials in the path of the beam and lower energy electron beams be used.

Background: Electroporation has become a routine technique for rapid drug delivery for the treatment of cancer. Because of its simplicity and wide range of application, it has been applied for the transfer of gold-nanoparticles and can facilitate entry into target cancer cells. Objective: The aim of this study is finding optimal conditions in order to obtain high GNPs-uptake and cell viability by means of electroporation. Materials and Methods: In this in vitro study, exponential electrical pulse with electric field intensity ranging from 0. 2-2 kV/cm, pulse length of 100 μ s and the pulse number of 2 was used. Electroporated cell viability was investigated using MTS assay and GNPs-cellular uptake was assayed using graphite furnace atomic absorption spectrometry (GFAAS). Finally, electroporation results were compared with passive method. Results: The maximum uptake occurred at 1. 2 to 2 kV/cm and passive method happened. The cell viability of 1. 2 kV/cm and passive method was about 90%, while the cell viability in 2 kV/cm drastically decreased to 50%. The findings showed that using two pulses of 1. 2 kV/cm and 100 μ s is a convenient way and surrogate of passive method for internalizing GNPs into cells. Conclusion: It is concluded that the electroporation-GNPs method could create an opportunistic context for colon cancer therapy. This type of treatment is especially attractive for highly immunogenic types of cancers in patients who are otherwise not surgical candidates or whose tumors are unresectable.

Background: Male infertility is defined as an inability to impregnate a fertile female; it is a widespread problem which is usually caused by some male factors such as low quantity and quality of sperm, specifically oligospermia and azoospermia. Objective: This study aimed to evaluate the bio-positive effects of low power density Wi-Fi radiation on the reproductive system of infertile and healthy mice. Materials and Methods: In this experimental study, thirty adult male Balb/c mice were randomly divided into 5 groups. Groups oligospermic-sham (OS), oligospermic-exposure 1 (OE1) and oligospermic-exposure 2 (OE2) received Busulfan, 10 mg/kg, intraperitoneally, but the control-sham (CS) and control-exposure (CE) groups left without Busulfan therapy. Groups CE, OE1 and OE2 were exposed to 2. 4 GHz Wi-Fi radiation while, the CS and OS were sham exposed to Wi-Fi radiation without energizing the Wi-Fi router. The right and left testes and right epididymis were dissected out and histopathological, histomorphologic changes and the quality of the sperms were analyzed. Results: Low power density Wi-Fi radiation significantly increased sperm concentration in the CE group compared to that in CS, while enhancement of spermatid cells was not significant. Sperm concentration in OE2 was more than that in OE1 as the spermatid cells enhanced. Conclusion: Findings revealed that radiation hormesis induced by low power density Wi-Fi radiation have biological beneficial effects on mouse sperm concentration and sperm histomorphometric parameters.

Background: Ionizing radiation is present in all environment of the Earth’ s surface, beneath the Earth and in the atmosphere. Human beings are exposed to external radiation from their surroundings naturally and also to internal radiation from food, water and air they consume. Then, it is important to measure and develop knowledge about radiation. Objective: This study is designed to evaluate the risks of radiation outdoors and indoors and in hot spring in Gachine area of Bandar Abbas. Materials and Methods: The device used in this cross sectional study was environmental radiation surveymeter. Indoor gamma radiation in Gachine area was carried out inside 115 dwellings. Measurement for hot spring waters was carried out at one meter above water level. Dose rates were recorded for an hour. Results: Our results indicate the outdoor dose rate gamma radiation in Gachine area is higher than the global mean dose rate. Moreover, Gachine Bala has the highest outdoor gamma radiation (78. 87 nGy/h) and Gachine Paien has the lowest gamma background radiation (71. 62 nGy/h). Conclusion: This study demonstrates that indoor mean dose rate of gamma radiation in this area is higher than the global mean dose rate. Estimated indoor mean dose rates were for Gachine Paien (110. 58 nGy/h), Gachine Bala (111. 83 nGy/h), Ship industry dwelling (109. 30 nGy/h) and Jamal Ahmad (107. 84 nGy/h). The highest dose rate above hot spring was obtained from Chostaneh (1320 nGy/h).

Background: Muscle fatigue has been known to influence brain activity, but very little is known about how cortical centers respond to muscle fatigue. Objective: This study was conducted to investigate the effects of muscle contraction and fatigue induced by two different percents of maximal voluntary contraction (MVC) on Electroencephalography (EEG) signals. Material and Methods: In this quasi-experimental study, EEG signals were recorded from twenty-one healthy human subjects during three phases (rest, pre fatigue and post fatigue) contraction of Adductor pollicis muscle (APM) at 30% and 70% MVC. The mean powers of EEG bands (alpha, beta and gamma) were computed offline in the frequency domain. Results: None of the three phases with each percent of MVC revealed significant differences for all bands (p>0. 05). Comparison of two hemispheres showed that right hemisphere gamma band activity was enhanced during pre-fatigue state at 30% MVC (p= 0. 042) and post-fatigue state at 70% MVC (p= 0. 028). Right hemisphere beta band activity also increased prominently at 70% MVC in post-fatigue condition (p = 0. 030). Conclusion: These results suggest muscle contraction and fatigue at 30% and 70% MVC have no significant effect on EEG activity, but the trends of beta and gamma band activities are almost similar in each percent of 30% and 70% MVC. Right brain hemisphere shows more activity than left hemisphere in beta and gamma rhythm after fatigue state at 70% MVC.

Background: Electromyographic (EMG) signals obtained from a contracted muscle contain valuable information on its activity and health status. Much of this information lies in motor unit potentials (MUPs) of its motor units (MUs), collected during the muscle contraction. Hence, accurate estimation of a MUP template for each MU is crucial. Objective: To investigate the possibility of improving MUP template estimation using the wavelet denoising technique. Material and Methods: In this analytical study, several MUP template estimators were developed by combining conventional estimation methods and wavelet denoising techniques. A MUP template was initially estimated using conventional methods such as mean, median, median-trimmed mean, or mode. Thereafter, it was post-processed using the wavelet denoising technique. Results: Evaluation results of the studied estimators using 40 simulated EMG signals with a true template for each constituent MUP train showed that augmented wavelet-based template estimation methods are more reliable than conventional methods. However, on average, wavelet denoising was not much effective. Around 40 MUPs of a MU is sufficient to estimate its MUP template. Conclusion: Although wavelet techniques are effective in EMG signal analysis, here wavelet denoising did not practically improve MUP template estimation. Considering computational simplicity and estimation error, the two methods median and median-trimmed mean are practical estimators that can provide a good estimation of a MUP template for a MU when approximately 40 MUPs are available. Nevertheless, the baseline noise level in the MUP templates estimated using the median-trimmed mean method is slightly lower than that in the templates estimated using the median method.

Background: Mechanical occlusion of the Left atrial appendage (LAA) using a purpose-built device has emerged as an effective prophylactic treatment in patients with atrial fibrillation at risk of stroke and a contraindication for anticoagulation. A crucial step in procedural planning is the choice of the device size. This is currently based on the manual analysis of the “ Device Landing Zone” from echocardiographic images. Objective: We aimed to develop an algorithm for automated segmentation of the LAA landing zone from 3D echocardiographic images of the LAA. Material and Methods: In this experimental study, 2D axial images were derived from the 3D echo datasets. After image pre-processing, binary images were created using a thresholding method. A binary image matrix was then formed and scanned using 8-adgacency approach resulting in segmentation of the objects with a closed circumference within the image. Erosion/dilation techniques were then applied to remove small objects. A feature-based approach was then used to firstly detect the LAA region and secondly to identify the device landing zone. Results: A total of 22 datasets were used in this study. The algorithm produced up to 9 axial images as the proposed landing zone. The selected axial images were compared to the echocardiographic images. In 18 cases (81. 8%), the algorithm successfully segmented the LAA and proposed the landing zone based on the defined features. Conclusion: We have developed a simple and fast algorithm for semi-automated segmentation of the LAA landing zone. Further studies are needed to assess the accuracy of the proposed landing zones by this method.

Background: The HU linearity is an essential parameter in a quantitative imaging and the treatment planning systems of radiotherapy. Objective: This study aims to evaluate the linearity of Hounsfield unit (HU) in applying the adaptive iterative dose reduction (AIDR) on CT scanner and its comparison to the filtered back-projection (FBP). Material and Methods: In this experimental phantom study, a TOS-phantom was scanned using a Toshiba Alexion 6 CT scanner. The images were reconstructed using the FBP and AIDR. Measurements of HU and noise values were performed on images of the “ HU linearity” module of the TOS-phantom. The module had five embedded objects, i. e., air, polypropylene, nylon, acrylic, and Delrin. On each object, a circle area of 4. 32 cm2 was drawn and used to measure HU and noise values. The R2 of the relation between mass densities vs. HU values was used to measure HU linearities at four different tube voltages. The Mann-Whitney U test was used to compare unpaired data and p-value < 0. 05 was considered statistically significant. Results: The AIDR method produced a significant smaller image noise than the FBP method (p-value < 0. 05). There were no significant differences in HU values of images reconstructed using FBP and AIDR methods (p-value > 0. 05). The HU values acquired by the methods showed the same linearity marked by coinciding linear lines with the same R2 value (> 0. 999). Conclusion: AIDR methods produce the HU linearity as FBP methods with a smaller image noise level.

Background: Some operating room personnel are occupationally exposed to genotoxic agents such as anesthetic gases and ionizing radiation. Adaptive response, as a defense mechanism, will occur when cells become exposed to a low dose of factors harming DNA (priming dose), which in the subsequent exposure to higher dose of those factors (challenging dose), show more resistance and sensibility. Objective: The aim of this study was to investigate adaptive response or synergy of ionizing radiation in the operating room personnel exposed to anesthetic gases by evaluation of the relative gene expression changes of effective genes for DNA repair such as Ku80, Ligase1 and P53. Material and Methods: In this case-control study, 20 operating room personnel and 20 nurses (who were not present in the operating room) as controls were studied. Venous blood samples were drawn from participants. In order to evaluate the adaptive response, a challenging dose of 2Gy gamma radiation was applied to blood samples. Moreover, RNA extraction and cDNA synthesis were performed. Gene expression level was studied by RT-qPCR and compared with the control group. Results: Ligase1 and P53 expression in the operating room personnel was significantly higher than that of the control group before irradiation (P˂ 0. 001). Statistically, there was no significant difference in the Ku80 and P53 expression in the operating room personnel before and after irradiation. Conclusion: Given the findings of this study, exposure to challenging dose of gamma radiation can induce adaptive response in expression of Ku80 and P53 genes in operating room personnel.

Accuracy of the radiotherapy requires some routine quality control and dosimetry calculations, which would be done by radiotherapy physicists. Due to the increasing use of computers and simulation software in medical science, as well as trends indicating its continued growth, this study aims to develop a new smart-phone application to perform common radiotherapy-related calculations. Computational formulas related to the parameters of conventional radiotherapy physics were obtained from radiotherapy physics textbooks, and the proposed application was developed using Java, based on the Android operating system. The developed application can be used on smart-phones with Android version 4 and higher, and it facilitates saving of data and results. By entering specific information, certain calculations can be made, including those applicable to superficial dosimetry, cobalt dosimetry (water phantom), cobalt dosimetry (in air), timer error, time dose fractionation (TDF) Dose, time dose fractionation (TDF) fractionation, superficial cone, superficial collimator, equivalent square, Linac dose, tissue phantom ratio 20-10, motorized wedge, field gap, biologically effective dose (BED), absolute Linac dosimetry, Mayneord F factor. The accuracy of the apps results checked with the present software installed on the PCs. Given that there are no existing applications in this field, the proposed App could be useful in facilitating and accelerating radiotherapy related calculations.

Global health authorities are trying to work out the current status of the novel coronavirus (COVID-19) outbreak and explore methods to reduce the rate of its transmission to healthy individuals. In this viewpoint we provide insights concerning how health care professionals can unintentionally shift the novel coronavirus type to more drug-resistant forms. It is worth noting that viruses usually have different sensitivities to physical and chemical damaging agents such antiviral drugs, UV and heat ranging from extremely sensitive (ES) to extremely resistant (ER) based on a bell-shaped curve. Given this consideration, the widespread infection of people with such ER viruses would be a real disaster. Here, we introduce a modified treatment method for COVID-19-associated pneumonia. In this proposed method, COVID-19 patients will receive a single dose of 100, 180 or 250 mSv X-ray radiation that is less than the maximum annual radiation dose of the residents of high background radiation areas of Ramsar that is up to 260 mSv. In contrast with antiviral drugs, a single dose of either 100, 180 or 250 mSv of low LET X-rays cannot exert a significant selective pressure on the novel coronavirus (SARS-CoV-2) and hence does not lead to directed accelerated evolution of these viruses. Moreover, Low Dose Radiation (LDR) has the capacity of modulating excessive inflammatory responses, regulating lymphocyte counts, and controling bacterial co-infections in patients with COVID-19.