Comparison of Indoor and Outdoor Dose Rates from Environmental Gamma Radiation in Kurdistan Province

Abstract: Background & Aims: Studying about background radiation is important because human beings are continuously exposed to these radiations which leave energy in tissues and the transferred energy leads to undesirable biologic effects. The level of background radiation differs in indoor and outdoor places. Since, people spend more time indoors, in this research environmental gamma dose rate for indoor and outdoor places of Kurdistan towns was determined and compared. Methods: To estimate dose rate at outdoors, four stations in the length of main directions and one in the center of each city were selected. To estimate dose rate at indoors, two stations in each town according to the type of buildings were selected. In each station gamma dose rate was measured for one hour by RDS-110 servimeter at one meter height from the earth. Results: The average of outdoor and indoor environmental gamma dose rate for Kurdistan towns obtained as follows: Baneh 134 (SD=5), 166 (SD=25) nSv/h, Bijar 113 (SD=17), 141 (SD=8) nSv/h, Divandareh 110 (SD=8), 134 (SD=12) nSv/h, Saqez 105 (SD=12), 134 (SD=11) nSv/h, Sanandaj 110 (SD=12), 133 (SD=4) nSv/h, Qorve 114 (SD=20), 160 (SD=4) nSv/h, Kamyaran 92 (SD=4), 115 (SD=14) nSv/h, Marivan 110 (SD=9), 122 (SD=18) nSv/h. Conclusion: Data shows that indoor dose rates in Baneh (%24), Bijar (%24), Divandareh (%22), Saqez (%28), Sanandaj (%21), Qorveh (%40), Kamyaran (%25) and Marivan (%11) exceed outdoor dose rate in these towns. Keywords: Environmental gamma, Dose rate, Indoor, Outdoo

Noise Pollution and Traffic Noise Index on Mashhad Main Streets during the Busiest Hours of Summer

Introduction: Among the environmental pollutions, noise is very important for its physiological  and psychological effects on human. Traffic noise is one of the most important pollutants and the  hospitals  are  one  of  the  critical  places  regarding  this  type  of  noise.  For  these  reasons,  in  the  summer  of  1382,  the  traffic  noise  of  Mashhad  main  streets  around  the  hospitals  was  assessed  during the busiest hours.  Materials and Methods: The noise indexes such as L Aeq , L Afmax , L 10 , L 50  and L 90  were measured  by a Sound-Level-Meter, model Investigator 2260. The traffic load was also determined. On the  basis  of  these  results,  Noise  Pollution  Level  (NPL)  and  Traffic  Noise  Index  (TNI)  were  calculated. The assessment was done during three different periods of the days in twelve stations.   Results: Based on the obtained results, the maximum L Aeq  was recorded on Bahar Street during  the morning hours and on Koohsangi Street during the noon and night periods. Throughout the  three  periods  the  maximum  NPL  and  TNI  were  estimated  on  Bahar  and  Nakhrisi  Streets,  respectively.  The  correlation  between  all  of  the  indexes  was  analyzed  and  a  logarithmic  correlation was observed between L Aeq  and the traffic load.   Discussion  and  Conclusion:  On  the  basis  of  the  noise  standard  in  free  field  in  Iran,  noise  pollution is a serious problem in Mashhad

SIMIND Monte Carlo simulation of a single photon emission CT

In this study, we simulated a Siemens E.CAM SPECT system using SIMIND Monte Carlo program to acquire its experimental characterization in terms of energy resolution, sensitivity, spatial resolution and imaging of phantoms using ^99m Tc. The experimental and simulation data for SPECT imaging was acquired from a point source and Jaszczak phantom<b> .</b> Verification of the simulation was done by comparing two sets of images and related data obtained from the actual and simulated systems. Image quality was assessed by comparing image contrast and resolution.<b> </b> Simulated and measured energy spectra (with or without a collimator) and spatial resolution from point sources in air were compared. The resulted energy spectra present similar peaks for the gamma energy of ^99m Tc at 140 KeV. FWHM for the simulation calculated to14.01 KeV and 13.80 KeV for experimental data, corresponding to energy resolution of 10.01and 9.86&#x0025; compared to defined 9.9&#x0025; for both systems, respectively. Sensitivities of the real and virtual gamma cameras were calculated to 85.11 and 85.39 cps/MBq, respectively. The energy spectra of both simulated and real gamma cameras were matched. Images obtained from Jaszczak phantom, experimentally and by simulation, showed similarity in contrast and resolution. SIMIND Monte Carlo could successfully simulate the Siemens E.CAM gamma camera. The results validate the use of the simulated system for further investigation, including modification, planning, and developing a SPECT system to improve the quality of images

Comparison of EBT and EBT3 RadioChromic Film Usage in Parotid Cancer Radiotherapy

Background: EBT and EBT3 radioChromic films have been used in radiotherapy dosimetry for years. Objective: The aim of the current study is to compare EBT and EBT3 radioChromic films in dosimetry of radiotherapy fields for treatment of parotid cancer. Methods: Calibrations of EBT and EBT3 films were performed with identical setups using a 6 MV photon beam of a Siemens Primus linac. Skin dose was measured at different points in the right anterior oblique (RAO) and right posterior oblique (RPO) fields by EBT and EBT3 films on a RANDO phantom. Results: While dosimetry was performed with the same conditions for the two film types for calibration and in phantom in parotid cancer radiotherapy, the measured net optical density (NOD) in EBT film was found to be higher than that from EBT3 film. The minimum difference between these two films under calibration conditions was about 2.9% (for 0.2 Gy) with a maximum difference of 35.5% (for 0.5 Gy). In the therapeutic fields of parotid cancer radiotherapy at different points, the measured dose from EBT film was higher than the EBT3 film. In these fields the minimum and maximum measured dose differences were 16.0% and 25.5%, respectively. Conclusion: EBT film demonstrates higher NOD than EBT3 film. This effect may be related to the higher sensitivity of EBT film over EBT3 film. However, the obtained dose differences between these two films in low dose range can be due to the differences in fitting functions applied following the calibration process

Measurement of Thyroid Dose by TLD arising from Radiotherapy of Breast Cancer Patients from Supraclavicular Field

Background: Breast cancer is the most frequently diagnosed cancer and the leading global cause of cancer death among women worldwide. Radiotherapy plays a significant role in treatment of breast cancer and reduces locoregional recurrence and eventually improves survival. The treatment fields applied for breast cancer treatment include: tangential, axillary, supraclavicular and internal mammary fields. Objective: In the present study, due to the presence of sensitive organ such as thyroid inside the supraclavicular field, thyroid dose and its effective factors were investigated. Materials and Methods: Thyroid dose of 31 female patients of breast cancer with involved supraclavicular lymph nodes which had undergone radiotherapy were measured. For each patient, three TLD-100 chips were placed on their thyroid gland surface, and thyroid doses of patients were measured. The variables of the study include shield shape, the time of patient’s setup, the technologists’ experience and qualification. Finally, the results were analyzed by ANOVA test using SPSS 11.5 software. Results: The average age of the patients was 46±10 years. The average of thyroid dose of the patients was 140±45 mGy (ranged 288.2 and 80.8) in single fraction. There was a significant relationship between the thyroid dose and shield shape. There was also a significant relationship between the thyroid dose and the patient’s setup time. Conclusion: Beside organ at risk such as thyroid which is in the supraclavicular field, thyroid dose possibility should be reduced. For solving this problem, an appropriate shield shape, the appropriate time of the patient’s setup, etc. could be considered

Evaluation of micronuclei and antioxidant status in hospital radiation workers occupationally exposed to low-dose ionizing radiation

Abstract Purpose There is scientific evidence that ionizing radiation (IR) can be responsible for various health hazards that are one of the concerns in occupational exposure. This study was performed to evaluate DNA damage and antioxidant status in hospital workers who are occupationally exposed to low doses of IR. Materials and methods In this study, twenty occupationally exposed to low doses of IR (CT and angiography) comprising with control groups which matched them. In order to investigate the effects of chronic irradiation of radiation workers, Micronuclei (MN) frequency and the antioxidant activity of Superoxide Dismutase (SOD), Catalase (CAT) and Total Antioxidant Capacity (TAC) were measured. Then, to check adaptation against high challenge dose, the samples (in all groups) were irradiated in vitro and MN frequency was compared. Finally, to investigated the effect of the high dose after the acute and chronic low dose of ionizing radiation, MN frequency was compared in two groups (the control group that was to in-vitro irradiated (acute low dose + high dose) and radiation workers (chronic low dose + high dose)). Results MN frequency in the occupationally exposed group (n = 30) increased significantly when compared to the control group (p-value  0.05). Conclusions We observed that exposure to low doses of IR leads to increased cytogenetic damage, could not cause an adaptive-response, and improve antioxidant capacity in radiation workers. Controlling healthcare workers' exposure is the first step to improving the health of hospital workers and the quality of patient care, thus decreasing human and economic costs

Assessment of skin dose in breast cancer radiotherapy: on-phantom measurement and Monte Carlo simulation

Aim: The main purpose of the present study is assessment of skin dose in breast cancer radiotherapy. Background: Accurate assessment of skin dose in radiotherapy can provide useful information for clinical considerations. Materials and methods: A RANDO phantom was irradiated using a 6 MV Siemens Primus linac with medial and tangential radiotherapy fields for simulating breast cancer treatment. Dosimetry was also performed on various positions across the fields using an EBT3 radiochromic film. Similar conditions of measurement on the RANDO phantom including field size, irradiation angle, number of fields, etc. were subsequently simulated via the Monte Carlo N-Particle Transport code (MCNP). Ultimately, dose values for corresponding points from both methods were compared. Results: Considering dosimetry using radiochromic films on the RANDO phantom, there were points having underdose and overdose based on the prescribed dose and skin tolerance levels. In this respect, 81.25 and 18.75 of the points had underdose and overdose, respectively. In some cases, several differences were observed between the measurement and the MCNP simulation results associated with skin dose. Conclusion: Based on the results of the points which had underdose, it was suggested that a bolus should be used for the given points. With regard to overdose points, it was advocated to consider skin tolerance dose in treatment planning. Differences between the measurement and the MCNP simulation results might be due to voxel size of tally cells in simulations, effect of beam's angle of incidence, validation time of linac's head, lack of electronic equilibrium in the build-up region, as well as MCNP tally type. © 2020 Greater Poland Cancer Centr

In vivo study of interferon-?, transforming growth factor-�, and interleukin-4 gene expression induced by radioadaptive response

Introduction: In the present study, the radioadaptive role of the immune system induced by low dose (LD) was investigated for its in vivo protective activity. Materials and Methods: Quantitative analysis of cytokine gene expression was assessed for their in vivo activity in BALB/c mice. To evaluate the adaptive response induced by LD on the mice spleen lymphocyte, the cytokine interleukin (IL)-4, interferon (IFN)-?, and transforming growth factor (TGF)-� expression was measured by a real-time quantitative polymerase chain reaction. To verify the radioadaptive effect of LD, animals were preirradiated at 10 cGy from a 60 Co source and then challenge dose at 200 cGy was delivered. Independent sample student's t-test was employed to compare cytokine gene expression in radioadaptive (10 + 200 cGy), LD (10 cGy), high-dose (HD, 200 cGy), and control groups of animals. Results: Following the HD, the cytokine gene expression of IFN-?, IL-4, and TGF-� was significantly decreased compared to the control group (P = 0.0001). However, TGF-� expression was also decreased significantly in the LD and adaptive groups compared to the control group (P = 0.0001). IFN-?/IL-4 ratio in the adaptive group was significantly decreased compared to the HD group (P = 0.0001). Conclusion: These results indicate that the immune system plays an important role for radioadaptive response induction by LD radiation to adjust the harmful effects of HD irradiation. © 2021 Journal of Cancer Research and Therapeutics | Published by Wolters Kluwer-Medknow

Image Optimization in Single Photon Emission Computed Tomography by Hardware Modifications with Monte Carlo Simulation

Introduction: In Single Photon Emission Computed Tomography (SPECT), the projection data used for image reconstruction are distorted by several factors, including attenuation and scattering of gamma rays, collimator structure, data acquisition method, organ motion, and washout of radiopharmaceuticals. All these make reconstruction of a quantitative SPECT image very difficult. Simulation of a SPECT system is a convenient method to assess the impact of these factors on the image quality. Materials and Methods: The SIMIND Monte Carlo program was employed to simulate a Siemens E.CAM SPECT system. Verification of the simulation was performed by comparing the performance parameters of the system. The verified system was used for SPECT simulations of homogenous and inhomogeneous voxelized phantoms in conjugation with hardware modifications. The resulting data were compared with those obtained from the simulated system without any modifications. Image quality was assessed by comparing the Structural SIMularity index (SSIM), contrast, and resolution of images. Results: The energy spectra acquired from both simulated and real SPECT systems demonstrated similar energy peak regions. The resulting full-widths-at-half-maximums were 13.92 keV for the simulation and 13.58 keV for experimental data, corresponding to energy resolutions of 9.95% and 9.61%, and with calculated sensitivities of 85.39 and 85.11 cps/MBq, respectively. Better performance parameters were obtained with a hardware-modified system constructed using a 0.944 cm thickness NaI(Tl) crystal covered by a layer of 0.24 cm aluminum, a  slat of 4.5 cm Pyrex as a backscattering medium, and a parallel hole collimator of Pb-Sb alloy with 2.405 cm thickness. Conclusion: The modeling of a Siemens E.CAM SPECT system was performed with the SIMIND Monte Carlo code. Results obtained with the code are in good agreement with experimental results. The findings demonstrate that the proposed hardware modifications in the system appear to be suitable for further improvement of the performance parameters of the system, indicating that future investigations can be conducted on using the system for supplementary studies on image improvement in the field of nuclear medicine