Biophysics & Radiotherapy
Ruhollah Ghahramani-Asl; Aida OmidBakhsh; parisa soleimanpor
Articles in Press, Accepted Manuscript, Available Online from 27 February 2024
Abstract
Background: The spread of the Covid-19 disease and the occurrence of respiratory symptoms in affected patients have increased requests for high resolution computed tomography (HRCT) imaging and have increased the workload and radiation exposure of employees in radiology departments.Materials and Methods: ...
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Background: The spread of the Covid-19 disease and the occurrence of respiratory symptoms in affected patients have increased requests for high resolution computed tomography (HRCT) imaging and have increased the workload and radiation exposure of employees in radiology departments.Materials and Methods: The present descriptive-analytical study was conducted by examining the number of CT scans performed between 1398 and 1402 in the affiliated hospitals of Sabzevar University of Medical Sciences. Results: According to the graphs comparing the years 1398 to 1402, it can be seen that the highest number of requests for CT scan in these five years is related to Shahrivar 1400 with the number of 9677 requests was registered in this month, which can indicate the high prevalence of the Corona virus in this month. After that, Mordad 1400 has the second rank with 9394 requests, which to some extent reveals the fact that 1400 was a critical year in terms of the spread of the Corona pandemic and in overall, the year 1400 was the worst year in terms of the spread of the Corona pandemic, which accounted for the highest spread of the virus.Conclusion: The spread of respiratory diseases and the increase in requests for HRCT scans and the lack of manpower in these departments causes the amount of radiation exposure to reach the limits of the body's tolerable dose and sometimes exceed this amount, which it is recommended to take necessary measures to prevent more serious problems for radiology personnel at risk.
Biophysics & Radiotherapy
Zohreh Danaei; Hamid Reza Baghani; Ali Asghar Mowlavi
Volume 27, Issue 5 , November and December 2020, , Pages 605-613
Abstract
Introduction: Radon is a natural radioactive gas that easily enter to respiratory tract and cause considerable biologic damages. The main objective of this study was to determine the dose from the alpha and gamma radiations of radon decay chain products in trachea tissue using Monte Carlo simulation. ...
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Introduction: Radon is a natural radioactive gas that easily enter to respiratory tract and cause considerable biologic damages. The main objective of this study was to determine the dose from the alpha and gamma radiations of radon decay chain products in trachea tissue using Monte Carlo simulation. Materials and Methods: At first a trachea-equivalent cylindrical phantom was simulated by MCNPX Monte Carlo code. Then, dose profiles from alpha and gamma-emitter progenies were separately calculated. The daughter radionuclides were considered as suspended particles with uniform distribution inside the trachea inner volume. Results: The results showed that the received dose by trachea in alpha decay is considerably higher than that of gamma decay. The maximum administered dose by alpha decay was 1.72×10-16 Gy/decay. 218Po was had the highest dose among the studied alpha emitter daughter nuclides. The maximum administered dose by gamma decay was also equal to the 17.55×10-19 Gy/decay, where 214Pb and 214Bi had almost the same contribution in calculated dose. Conclusion: The daughter radionuclides from radon decay chain, especially alpha emitter products of 218Po and 214Po, can be considered as a serious danger viewpoint to the internal exposure. These daughter nuclides can attach to the inner wall of trachea and remain in the respiratory system for long periods of time which can cause to the continuous exposure of trachea. Reducing the biologic effects of these internal radiation source requires especial schemes in order to avoid entering the radon and its radioactive daughters to human respiratory system, as much as possible.
Biophysics & Radiotherapy
Mehrdad Yadegari; Amin Bigham-Sadegh; Ali Saberi; Ali Parvizi; Elham Moghtadaiee-Khorasgani
Volume 27, Issue 3 , September and October 2020, , Pages 483-491
Abstract
Introduction:Tendon rupture is one of the most common problems in livestock and human. Tendon has a special blood flow network that is fed from outside to inside. The most important factor in tendon healing is blood flow which is very slow. Various methods that have been implemented to treat and repair ...
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Introduction:Tendon rupture is one of the most common problems in livestock and human. Tendon has a special blood flow network that is fed from outside to inside. The most important factor in tendon healing is blood flow which is very slow. Various methods that have been implemented to treat and repair these raptures are time-consuming.
Materials and Methods: 10 male New Zealand rabbits with weight 1-2/5 kg were selected and kept for one month. The posterior organs of the rabbits were shaved and anesthetized. Then, under sterile conditions, the SDFT tendon was cut through the skin, the rabbits were divided into two groups of five and the control group and received three groups of samples at a dose of 1μg/kg of Theranekron, and during the days of 3, 10 And 30 ultrasound examinations. After 30 days, the samples were euthanasia for pathological investigations, and the lesion was removed and sent to the lab.
Results: The results of the thirtieth day of ultrasound examination showed a significant improvement in the tendon fibroblasts, similar to the normal area of the damaged region of echogenicity. Histopathologic results show the beneficial effects of Theranekron during this study. Therefore, the number of collagen fibers accumulated in the tissue in the treated group significantly increased.
Conclusion: It was concluded that Theranekron was effective in healing tendons and reducing inflammation.
Biophysics & Radiotherapy
Narges Araste; Hossein Tavakoli-Anbaran
Volume 27, Issue 1 , May and June 2020, , Pages 17-26
Abstract
Background: The Compton scattered annihilation gammas between PET detectors reduce spatial resolution by making an incorrect Line of Response. This paper, by presenting a new method, tried to remove these errors from PET imaging. In this way, the detectors were insulated so that scattered gammas from ...
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Background: The Compton scattered annihilation gammas between PET detectors reduce spatial resolution by making an incorrect Line of Response. This paper, by presenting a new method, tried to remove these errors from PET imaging. In this way, the detectors were insulated so that scattered gammas from a detector can not enter other detectors of the PET ring. Method: First of all, the Siemens PET BiographTM 6 scanner ring was simulated and then all detectors of this ring were isolated to resolve this error and investigate its impact on the Response Function of PET detectors. Results: The analysis of the results of simulation showed that, the isolation of PET detectors reduced counts of detectors in the energy window, especially at the lower threshold (350 to 400 keV). This reduction with a spherical soft issue was less than without that. So that the maximum of the relative percentage difference for counts of detectors between connect and disconnect them was 70% (in 400 keV) and 12% (in 350 keV) in the absence and presence of soft tissue, respectively. Conclusion: Although the isolation of the detectors boosted the resolution of PET, it removed some true coincidences and reduced the sensitivity of PET; there for, it did not have much effect on image quality of PET. Also, a slight decrease in the count, with the soft tissue, shows the greater effect of the isolation of PET-detectors in improving image quality in abdominal imaging in comparison with other imaging such as head and neck imaging.
Biophysics & Radiotherapy
Hossein Tavakoli-Anbaran; Nadere Naderi
Volume 26, Issue 6 , March and April 2020, , Pages 665-675
Abstract
Ionizing radiation modifies the molecular structure of the cell and ultimately disrupts its function. Brachytherapy by the Gamma Iridium-192 source is one of the most widely used radiotherapy methods in cervical and prostate cancer. For this reason, in the research, we investigated the damage to the ...
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Ionizing radiation modifies the molecular structure of the cell and ultimately disrupts its function. Brachytherapy by the Gamma Iridium-192 source is one of the most widely used radiotherapy methods in cervical and prostate cancer. For this reason, in the research, we investigated the damage to the DNA molecule by photons and secondary electrons of the source at different distances, and then we obtained the dose rates in the defined dimensions of DNA. In this work, using the MCNPX code, we calculated the flux and photon dose and secondary electrons from iradium-192 Brachytherapy, in approximate dimensions of DNA in a water phantom. Then, using the electron flux obtained, through the MCDS code, we investigated the efficiency of DNA breaks at different distances from the source. The simulations indicated that DNA damage is different at various distances from the source and it depends on the number of secondary electrons reaching that region as well as its energy. With increasing the distance from the source, the values of the probability distribution function of DNA single-strand and two-strand breaks diminish. It was also observed that these values had peaks at distances of 0.04 and 2.5 cm from the source, where the maximum probability of single-strand break at those distances was 8.06% and 3.9%, respectively, and the maximum probability of the two-strand break at those distances was 0.54% and 0.11%, respectively. It is notable that the dose reaching the DNA at these distances was 27.202 and 0.005 mGy/h, respectively.