@article { author = {Almayahi, Basim}, title = {Determination of Radionuclide Concentration in Human Teeth in Najaf Governorate, Iraq}, journal = {Iranian Journal of Medical Physics}, volume = {14}, number = {4}, pages = {173-182}, year = {2017}, publisher = {Mashhad University of Medical Sciences}, issn = {2345-3672}, eissn = {2345-3672}, doi = {10.22038/ijmp.2017.22715.1219}, abstract = {Introduction: 238U decays with alpha particles emission into 234Th and the series ends with 206Pb. The unstable nucleus loses the energy with emitting ionizing alpha particles for reaching a stable state. It is undergoing alpha decay with decay energy (4.679 MeV). Alpha particles enter the human and animal bodies through inhalation of air or ingestion of contaminated food and water. This study aimed to perform a radiological analysis on the natural alpha particle emission rates of the human teeth as the biomarkers of radiation exposure and environmental pollution. Materials and Methods: This study was conducted on 68 teeth samples of 27 males and 41 females collected from the hospitals distributed across Najaf governorate, including many districts in Iraq. Alpha particle emission rates were measured using CR-39 nuclear track detector. Results: The mean emission rate of alpha particles in the female teeth was 0.0396±0.0070 mBq cm-2, which was relatively higher than that in the male teeth (0.0390±0.0048 mBq cm-2). Nevertheless, there was no significant difference between the female and male teeth regarding the emission rate of alpha particles. Furthermore, the emission rate of alpha particles in the teeth of the samples taken from Kufa (0.0417±0.0057 mBq cm-2) was higher than those obtained from Najaf (0.0384±0.0053 mBq cm-2). Conclusion: As the findings of this study revealed, Najaf governorate had a lower emission rate of alpha particles as compared to other sites of the worldwide. Therefore, it could be concluded that there is no negative consequence threatening the people’s health in this regard.}, keywords = {Biomarkers,Radioisotopes,Teeth}, url = {https://ijmp.mums.ac.ir/article_8933.html}, eprint = {https://ijmp.mums.ac.ir/article_8933_34528480d08a5275d248800c1dff66db.pdf} } @article { author = {ERINOSO, WASIU and Obed, Rachel and Olowookere, Christopher}, title = {Film Reject Analysis and Radiation Doses Received by Patients in Selected Hospitals in Southwestern Nigeria}, journal = {Iranian Journal of Medical Physics}, volume = {14}, number = {4}, pages = {183-189}, year = {2017}, publisher = {Mashhad University of Medical Sciences}, issn = {2345-3672}, eissn = {2345-3672}, doi = {10.22038/ijmp.2017.19521.1179}, abstract = {Introduction: A reject rate is the percentage of diagnostic images repeated due to errors during radiological examinations. The present study aimed to evaluate the patient radiation doses and analyze the film reject rate as part of quality assurance program in three diagnostic centers in Nigeria. Materials and Methods: This study was conducted in three hospitals, namely Federal Medical Center (FMC), General Hospital (GH), and Sacred Heart Hospital (SHH), located in Abeokuta, Ogun State, Southwestern Nigeria. For the purpose of the study, the accepted and rejected radiographs during different X-ray examinations were recorded. A total of 376 rejected and accepted radiographs were evaluated in the three hospitals, and the economic losses due to rejected films were determined. The quality control (QC) tests, which involve kilo voltage (kV), milliampere seconds (mAs), etc, were carried out on the facilities of two out of three hospitals using Victoreen 6000m QC kits. The results of the QC tests and exposure parameters were used to estimate the patient doses for different examinations carried out during the study. Results: Based on the results of the study, the SHH  had the highest estimated annual loss of $225, followed by the FMC and GH with annual monetary losses of $208 and $166, respectively. In addition, the anteroposterior projection of the lumbosacral spine had the highest mean dose (15±1.64 mGy) in this study, which was observed in the SHH. Additionally, at FMC, all the estimated doses were low. Conclusion: Regarding the monetary loss and increase in patient dose burden involved in repeated examinations, it is essential to train personnel on the factors leading to repeated exposures.}, keywords = {diagnostic imaging,Image Quality,Quality Control,Radiation Dose}, url = {https://ijmp.mums.ac.ir/article_8881.html}, eprint = {https://ijmp.mums.ac.ir/article_8881_a682b5ba20c17921b41a71d1124a6bca.pdf} } @article { author = {Mesbahi, Asghar and Rasuli, Naser and Nasiri, Behnam and mohammadzadeh, mohammad}, title = {Radiobiological Model-Based Comparison of Three-Dimensional Conformal and Intensity-Modulated Radiation Therapy Plans for Nasopharyngeal Carcinoma}, journal = {Iranian Journal of Medical Physics}, volume = {14}, number = {4}, pages = {190-196}, year = {2017}, publisher = {Mashhad University of Medical Sciences}, issn = {2345-3672}, eissn = {2345-3672}, doi = {10.22038/ijmp.2017.22508.1213}, abstract = {Introduction: Radiobiological modeling of radiotherapy plans are used for treatment plan comparisons. The current study aimed to compare the three-dimensional conformal radiation therapy (3DCRT) and intensity-modulated radiation therapy (IMRT) plans for nasopharyngeal cancer using radiobiological modeling. Materials and Methods: This study was conducted on 10 patients with nasopharyngeal carcinoma, who were planned for 3DCRT and IMRT treatments by using the TiGRT treatment planning system. The planning target volume (PTV) doses of 70 and 72 Gy were administered for the 3DCRT and IMRT plans, respectively. The BIOLPLAN software and the Niemierko’s equivalent uniform dose (EUD) model were utilized for the estimation of tumor control probability (TCP) and normal tissue complication probability (NTCP). The NTCPs of the spinal cord, brain stem, parotid glands, middle ears, temporomandibular joints (TMJ), mandible, and thyroid were calculated by using two radiobiological models. Results: According to the results, the mean TCPs for 3DCRT and IMRT plans were 89.92%±8.92 and 94.9%±3.86, respectively, showing no statistically significant difference (P=0.08). The NTCPs of the parotid glands, thyroid gland, spinal cord, TMJ, and mandible were considerably lower in the IMRT plans, compared to those in the 3DCRT plans. On the other hand, the calculated NTCPs for the middle ears and brain stem increased for the IMRT plans, which were not statistically significant. On average, the NTCPs of the critical organs were lower based on the EUD model than the Lyman-Kutcher-Burman model. Conclusion: From the radiobiological point of view, the IMRT plans were significantly advantageous over the 3DCRT plans with some small variations in each patient. On average, the two radiobiological models generated different NTCPs depending on the studied organs. Consequently, more studies are needed for the optimization of radiobiological models for the prediction of the treatment outcomes in radiation therapy.}, keywords = {Nasopharyngeal,Cancer,Intensity Modulated Radiotherapy,Radiobiology}, url = {https://ijmp.mums.ac.ir/article_9072.html}, eprint = {https://ijmp.mums.ac.ir/article_9072_6a78b3d277de37d5e8f0006583548492.pdf} } @article { author = {Ahmad, Misbah and Ahmad, Habib and Khattak, Muhammad and Shah, Kamran and Shaheen, Wajeeha and Shah, Jawad and Iqbal, Shaheen}, title = {Assessment of Occupational Exposure to External Radiation among Workers at the Institute of Radiotherapy and Nuclear Medicine, Pakistan (2009-2016)}, journal = {Iranian Journal of Medical Physics}, volume = {14}, number = {4}, pages = {197-202}, year = {2017}, publisher = {Mashhad University of Medical Sciences}, issn = {2345-3672}, eissn = {2345-3672}, doi = {10.22038/ijmp.2017.22606.1216}, abstract = {Introduction: Assessment of occupational exposure to external radiation and the analysis of associated trends are imperative to observe changes that have taken place over time due to regulatory operations or technological advancements. Herein, we describe the occupational radiation exposure to workers employed in Nuclear Medicine (NM), Radiotherapy (RT), and Diagnostic Radiology (DR) departments at the Institute of Radiotherapy and Nuclear Medicine, Peshawar, Pakistan, and to evaluate the related trends during 2009-2016. Materials and Methods: A retrospective analysis of the dose records of 4320 film dosimeters was performed during 2009-2016. The analyzed quantities included annual collective effective dose, annual average effective dose, distribution of workers, and their annual average effective doses in various effective dose intervals, as well as the maximum and minimum annual individual effective doses. Results: The annual average effective doses in RT, NM, and DR were within the ranges of 1.07-1.45, 1.25-1.55, and 1.03-1.60 mSv, respectively. The majority (90%) of the workers received effective doses in the interval of 1-4.99 mSv, while 10% of the workers received doses within the range of the minimum detectable level-0.99 mSv.  The minimum and maximum annual individual effective doses were 0.30 mSv and 3.96 mSv as recorded in RT and NM, respectively. The annual average effective doses measured for NM, RT, and DR were 1.39, 1.23, and 1.30 mSv, respectively. These values are comparable with the worldwide annual average effective doses. Conclusion: All the workers received doses below the annual dose limit. The status and trends of doses showed that radiation protection conditions were adequate.}, keywords = {Dose Limit,Effective Dose,occupational exposure,Radiation Protection,Ionizing radiation}, url = {https://ijmp.mums.ac.ir/article_9149.html}, eprint = {https://ijmp.mums.ac.ir/article_9149_0431b18bd1afdfbb1a799293db15874e.pdf} } @article { author = {Mosayebi Samani, Mohsen and Firoozabadi, Seyed Mohamad and Ekhtiari, Hamed}, title = {Consideration of Individual Brain Geometry and Anisotropy on the Effect of tDCS}, journal = {Iranian Journal of Medical Physics}, volume = {14}, number = {4}, pages = {203-218}, year = {2017}, publisher = {Mashhad University of Medical Sciences}, issn = {2345-3672}, eissn = {2345-3672}, doi = {10.22038/ijmp.2017.22243.1209}, abstract = {Introduction: The response variability between subjects, which is one of the fundamental challenges facing transcranial direct current stimulation (tDCS), can be investigated by understanding how the current is distributed through the brain. This understanding can be obtained by means of computational methods utilizing finite element (FE) models. Materials and Methods: In this study, the effect of realistic geometry and white matter anisotropy on the head electrical current density intensity (CDI) distribution was measured using a magnetic resonance imaging (MRI)-derived FE model at the whole brain, below electrodes, and cellular levels. Results: The results revealed that on average, the real geometry changes the CDI in gray matter and the WM by 29% and 55%, respectively. In addition, WM anisotropy led to an 8% and 36% change of CDI across GM and WM, respectively. The results indicated that for this electrode configuration, the maximum CDI occurs not below the electrode, but somewhere between the electrodes, and its locus varies greatly between individuals.  In addition, by investigating the effect of current density components on cellular excitability, significant individual differences in the level of excitability were detected. Conclusion: Accordingly, consideration of the real geometry in computational modeling is vital. In addition, WM anisotropy does not significantly influence the CDI on the gray matter surface, however, it alters the CDI inside the brain; therefore, it can be taken into account, especially, when stimulation of brain’s internal regions is proposed. Finally, to predict the outcome result of tDCS, the examination of its effect at the cellular level is of great importance.}, keywords = {Brain,Finite Element,Individual Difference,tDCS}, url = {https://ijmp.mums.ac.ir/article_8763.html}, eprint = {https://ijmp.mums.ac.ir/article_8763_c65de058c7da074f18752243fd6a08f3.pdf} } @article { author = {Nyathi, Mpumelelo}, title = {Determination of Optimum Planar Imaging Parameters for Small Structures with Diameters Less Than the Resolution of the Gamma Camera}, journal = {Iranian Journal of Medical Physics}, volume = {14}, number = {4}, pages = {219-228}, year = {2017}, publisher = {Mashhad University of Medical Sciences}, issn = {2345-3672}, eissn = {2345-3672}, doi = {10.22038/ijmp.2017.24559.1246}, abstract = {Introduction: The limited spatial resolution of the gamma camera hinders the absolute quantification of planar images of small structures. The imaged structures are affected by partial volume effects (PVEs), which can spread activity and lead to underestimation of the regional distribution.  The use of optimum planar parameters reduces the impact of the limited spatial resolution of the gamma camera and the statistical noise inherent to low photon count, thus improving quantification. In this study, we aimed to determine the optimum planar imaging parameters for small structures. Materials and Methods: A thyroid protocol was used to acquire planar images of the spheres A, B, and C (16 mm, 12 mm, and 11 mm in diameter, respectively) whilst filled with a targeted activity concentration of technetium-99m. One sphere was mounted at the centre of the Jaszczak Phantom and the other two adjacent to its walls using capillary stems fitted on the spheres. The phantom was filled with distilled water. The targeted activity concentrations used were 74 kBq/mL, 100 kBq/mL, 150 kBq/mL, and 300 kBq/mL. Images of the same count per pixel were acquired on 64  64, 128  128, 256  256, 512  512, and 1024  1024 pixels using a vertical detector mounted 5 cm above the phantom. All the images were quantified using ImageJ software, version 1.48a, Java 1.70_51 [64-bit]. Results: The optimum planar imaging parameters established were a matrix size of 128 128 pixels and technetium-99m solution of activity concentration of 300 kBq/ml. Conclusion: The use of optimal imaging parameters reduces the impact of PVEs, leading to improved quantitative accuracy.}, keywords = {Medical Imaging,Radioisotope Imaging,Partial Volume Effects}, url = {https://ijmp.mums.ac.ir/article_9267.html}, eprint = {https://ijmp.mums.ac.ir/article_9267_2020713899b0a0e8b080c581dfdbd514.pdf} } @article { author = {Tekin, Huseyin and singh, V. and Altunsoy, Elif Ebru and Manici, Tugba and Sayyed, Mohammed I.}, title = {Mass Attenuation Coefficients of Human Body Organs using MCNPX Monte Carlo Code}, journal = {Iranian Journal of Medical Physics}, volume = {14}, number = {4}, pages = {229-240}, year = {2017}, publisher = {Mashhad University of Medical Sciences}, issn = {2345-3672}, eissn = {2345-3672}, doi = {10.22038/ijmp.2017.23478.1230}, abstract = {Introduction: Investigation of radiation interaction with living organs has always been a thrust area in medical and radiation physics. The investigated results are being used in medical physics for developing improved and sensitive techniques and minimizing radiation exposure. In this study, mass attenuation coefficients of different human organs and biological materials such as adipose, blood, bone, brain, eye lens, lung, muscle, skin, and tissue have been calculated. Materials and Methods: In the present study, Monte Carlo N-Particle eXtended (MCNP-X) version 2.4.0 was used for determining mass attenuation coefficients, and the obtained results were compared with earlier investigations (using GEometry ANd Tracking [GEANT4] and FLUKA computer simulation packages) for blood, bone, lung, eye lens, adipose, tissue, muscle, brain, and skin materials at different energies. Results: The results of this study showed that the obtained results from MCNP-X were in high accordance with the National Institute of Standards and Technology data. Conclusion: Our findings would be beneficial for use of present simulation technique and mass attenuation coefficients for medical and radiation physics applications.}, keywords = {Attenuation Coefficient,Monte Carlo,MCNP-X}, url = {https://ijmp.mums.ac.ir/article_8846.html}, eprint = {https://ijmp.mums.ac.ir/article_8846_680172fb24272839282a60ff11a74078.pdf} } @article { author = {Saeedimoghadam, Mehdi and Zeinali, Banafshae and Kazempour, Mehdi and Jalli, Reza and Sina, Sedigheh}, title = {Monte Carlo Study of Several Concrete Shielding Materials Containing Galena and Borated Minerals}, journal = {Iranian Journal of Medical Physics}, volume = {14}, number = {4}, pages = {241-250}, year = {2017}, publisher = {Mashhad University of Medical Sciences}, issn = {2345-3672}, eissn = {2345-3672}, doi = {10.22038/ijmp.2017.17873.1157}, abstract = {Introduction: The heavyweight concretes have been widely used for constructing medical or industrial radiation facilities with photon sources. Materials and Methods: In this study, heavy concretes containing galena (PbS) and several borated minerals are proposed as suitable materials against photons. The shielding properties of 21 galena concretes containing seven borated minerals with three mixing patterns were evaluated using MCNP4C Monte Carlo code. The attenuation of the gamma radiation is computed under the conditions of narrow and beam geometries. The x-ray sources with 40, 60, 90, and 120 kVp and gamma rays of 99mTc, 131I, 137Cs, and 511 keV annihilation photons were considered. The photon flux values and the x-ray spectrum after applying all the concretes were compared to the ordinary ones. Regarding the results, more photon attenuations obtained by using high density concretes simulation in comparison to ordinary concrete. Results: The results revealed that the concretes containing orthopinokiolite as the borated material made by the third mixing pattern, had the most photon attenuation. According to the results, the shielding properties of the concretes containing different borated minerals were alike against high photon energies, whereas in low energy photons the attenuation depended on the type of borated mineral used in the concretes. Conclusion: The high-density heavy-weighted concretes could be effectively used as multi-purpose shield for radiotherapy rooms and nuclear reactors due to the borated minerals.}, keywords = {Photon,Monte Carlo,Photon Attenuation}, url = {https://ijmp.mums.ac.ir/article_8723.html}, eprint = {https://ijmp.mums.ac.ir/article_8723_95e1f4014a6340eecc38d31e0e17b521.pdf} } @article { author = {sari, fatemeh and Mahdavi, Seyed Rabi and Anbiaee, Robab and Shirazi, Alireza}, title = {The Effect of Breast Reconstruction Prosthesis on Photon Dose Distribution in Breast Cancer Radiotherapy}, journal = {Iranian Journal of Medical Physics}, volume = {14}, number = {4}, pages = {251-256}, year = {2017}, publisher = {Mashhad University of Medical Sciences}, issn = {2345-3672}, eissn = {2345-3672}, doi = {10.22038/ijmp.2017.22272.1210}, abstract = {Introduction: Siliconeprosthetic implants are commonlyutilizedfor tissue replacement and breast augmentation after mastectomy. On the other hand, some patients require adjuvant radiotherapy in order to preventlocal-regional recurrence and increment ofthe overall survival. In case of recurrence, the radiation oncologist might have to irradiate the prosthesis.The aim of this study was to evaluate the effect of silicone prosthesis on photon dose distribution in breast radiotherapy. Materials and Methods: The experimental dosimetry was performed using theprosthetic breast phantom and the female-equivalent mathematical chest phantom. A Computerized Tomographybased treatment planning was performedusing a phantom and by CorePlan Treatment Planning System (TPS). For measuring the absorbed dose, thermoluminescent dosimeter(TLD) chips (GR-207A) were used. Multiple irradiations were completed for all the TLD positions, and the dose absorbed by the TLDs was read by a lighttelemetry (LTM) reader. Results: Statistical comparisons were performed between the absorbed dosesassessed by the TLDs and the TPS calculations forthe same sites. Our initial resultsdemonstratedanacceptable agreement (P=0.064) between the treatment planning data and the measurements. The mean difference between the TPS and TLD resultswas 1.99%.The obtained findings showed that radiotherapy is compatible withsilicone gel prosthesis. Conclusion: It could be concludedthat the siliconbreast prosthesis has no clinicallysignificant effectondistribution of a 6 MV photon beam for reconstructed breasts.}, keywords = {Breast Implant,Phantom,Radiation Therapy,Silicon}, url = {https://ijmp.mums.ac.ir/article_9027.html}, eprint = {https://ijmp.mums.ac.ir/article_9027_ef56435e6bf508785c4bf0ae56c9470b.pdf} } @article { author = {Yarahmadi, Mehran and faramarzi, bahar and haghparast, abbas and saalehi, zeinab}, title = {Field-In-Field Plan Versus Tangential Wedged Beam Plan in Chest Wall Radiotherapy of Post-Mastectomy Patients: Treatment Planning Study}, journal = {Iranian Journal of Medical Physics}, volume = {14}, number = {4}, pages = {257-263}, year = {2017}, publisher = {Mashhad University of Medical Sciences}, issn = {2345-3672}, eissn = {2345-3672}, doi = {10.22038/ijmp.2017.22982.1223}, abstract = {Introduction: In this study, dose distribution of the chest wall in post-mastectomy breast cancer patients was evaluated and compared in the tangential wedged beam (TWB) and field-in-field (FIF) plans. Materials and Methods: Thirty-six patients with left-sided breast cancer were enrolled in this study. The FIF and TWB plans were generated for each patient to compare dosimetric parameters of the chest wall. The maximum dose (Dmax), homogeneity index (HI), conformity index (CI), and uniformity index (UI) were defined and used for comparison of the dosimetric parameters of the planning target volume (PTV) in both FIF and TWB plans. The percentage of volumes receiving at least 10, 20, 30, and 40 Gy of the left lung and 5, 10, 20, 25 and 30 Gy of the heart were used to compare the dosimetric results of the organs at risk. Statistical analysis was performed using SPSS, version 20. Results: The FIF plan had significantly lower HI (P=0.000) than the TWB plan, indicating that the FIF plan was better than the TWB plan in PTV. The V40lung (15.36±4.35 vs. 18.37±4.42) and V30heart (8.15±3.75 vs. 10.94±3.94; P=0.000) were significantly lower in the FIF plan than in the TWB plan. In addition, the monitor unit (MU) was significantly lower in the FIF plan than in the TWB plan (227.76 vs. 323.59; P=0.000). Conclusion: The FIF plan significantly reduced the dose volume of the left lung and heart in post-mastectomy radiotherapy compared to the TWB plan. Therefore, the FIF plan is recommended for this purpose.}, keywords = {Breast Cancer,High-Energy X-Ray,Field-In-Field Technique,Treatment Planning,TWB Plan}, url = {https://ijmp.mums.ac.ir/article_9164.html}, eprint = {https://ijmp.mums.ac.ir/article_9164_1b68cb00c9d9b176e2d81ba1125980f8.pdf} }