Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
12
4
2015
12
01
Medium-Term Stability of the Photon Beam Energy of An Elekta CompactTM Linear Accelerator Based on Daily Measurements of Beam Quality Factor
230
234
EN
Mohammad Amin
Mosleh-Shirazi
0000-0003-3021-6489
Physics Unit, Department of Radiotherapy and Oncology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
2- Ionizing and Non-ionizing Radiation Protection Research Center, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
amosleh@sums.ac.ir
Saeed
Rahimi
Department of Medical Physics and Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
Sareh
Karbasi
Physics Unit, Department of Radiotherapy and Oncology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
karbasi59@yahoo.com
10.22038/ijmp.2016.6835
<strong>Introduction</strong> <br/>In this study, we aimed to assess the medium-term energy stability of a 6MV Elekta Compact<sup>TM</sup> linear accelerator. To the best of our knowledge, this is the first published article to evaluate this linear accelerator in terms of energy stability. As well as investigating the stability of the linear accelerator energy over a period of several weeks, the results will be useful for estimation of the required tolerance values for the beam quality factor (BQF) of the PTW QUICKCHECK webline<sup>TM</sup> (QCW) daily checking device. <br/><strong>Materials and Methods</strong> <br/>Over a 13 week period of routine clinical service, 52 daily readings of BQF were taken and then analyzed for a 10×10 cm<sup>2</sup> field. <br/><strong>Results</strong> <br/>No decreasing or increasing trend in BQF was observed over the study period. The mean BQF value was estimated at 5.4483 with a standard deviation (SD) of 0.0459 (0.8%). The mean value was only 0.1% different from the baseline value. <br/><strong>Conclusion</strong> <br/>The results of this medium-term stability study of the Elekta Compact linear accelerator energy showed that 96.2% of the observed BQF values were within ±1.3% of the baseline value. This can be considered to be within the recommended tolerance for linear accelerator photon beam energy. If an approach of applying ±3 SD is taken, the tolerance level for BQF may be suggested to be set at ±2.5%. However, further research is required to establish a relationship between BQF value and the actual changes in beam energy and penetrative quality.
Radiotherapy,Linear Accelerator,Quality Control,Photons,Beam,energy
https://ijmp.mums.ac.ir/article_6835.html
https://ijmp.mums.ac.ir/article_6835_4b7b15ee54de46f3acddad280506bca3.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
12
4
2015
12
01
Assessment of the Preventive Effect of Pilocarpine on Radiotherapy-Induced Xerostomia in Patients with Head and Neck Cancers
235
241
EN
Mohammad Hasan
Akhavan Karbasi
Department of Oral Medicine, School of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
gole_yakh85@yahoo.com
Hassan
Zarghani
Department of Radiology, Birjand University of Medical Science, Birjand, Iran
hmedicalphysics@gmail.com
Seyed Ali
Akhavan
Radiotherapist, Ramezanzadeh Radiotherapy Center, Yazd, Iran
Nastaran
Donyadide
Department of Oral Medicine, School of Dentistry, Sharekord University of Medical Sciences, Sharekord, Iran
n.donyadide@gmail.com
Pejman
Shamshiry
School of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
10.22038/ijmp.2016.6836
<strong>Introduction</strong> <br/>Xerostomia is one of side-effects of radiotherapy for head and neck cancers. No definitive method has been proposed for the treatment of this condition. However, pilocarpine is considered effective for the management of chronic xerostomia. The purpose of the present study was to assess the preventive effect of pilocarpine. <br/><strong>Materials and Methods</strong> <br/>This study was performed on 34 patients with head and neck cancers, undergoing radiation therapy (5000 cGy). The patients were randomly divided into two groups. The case group was administered 16 drops of pilocarpine (2%) eye drops per day, while the control group received normal saline; the treatment plan continued for four weeks. Unstimulated whole saliva flow rate was measured at four stages: two weeks before radiotherapy (baseline), the first day of radiotherapy, and two and four weeks after the initiation of radiotherapy. <br/><strong>Results</strong> <br/>At baseline and the first day of radiotherapy, no significant differences were observed in the amount of saliva between the case and control groups (P<br/><strong>Conclusion</strong> <br/>According to the findings, pilocarpine was found to be effective for the prevention of xerostomia. Moreover, it could restrain the decline in the amount of saliva and reduce the rate of xerostomia.
Head and neck neoplasms,Pilocarpine,Radiotherapy,Saliva,Xerostomia
https://ijmp.mums.ac.ir/article_6836.html
https://ijmp.mums.ac.ir/article_6836_8c47e323345186f22f8d9cbde0d2e71c.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
12
4
2015
12
01
A Model of Time-dependent Biodistribution of 153Sm-Maltolate Complex and Free 153Sm Cation Using Compartmental Analysis
242
250
EN
Amir
Hakimi
0000-0002-0462-9928
Health Physics and Dosimetry Laboratory, Department of Energy Engineering and Physics, Amir Kabir University of Technology, Tehran, Iran
amir.hakimi@aut.ac.ir
Amir Reza
Jalilian
Nuclear Science Research School, Nuclear Science and Technology Research Institute, Tehran, Iran
jalilain@yahoo.cpm
Ali
Ghanbarzadeh
Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Hamed
Rezaee Jam
Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran
10.22038/ijmp.2016.6837
<strong>Introduction</strong> <br/>Compartmental analysis allows the mathematical separation of tissues and organs to determine activity concentration in each point of interest. Biodistribution studies on humans are costly and complicated, whereas such assessments can be easily performed on rodents. <br/>In this study, we aimed to develop a pharmacokinetic model of <sup>153</sup>Sm-maltolate complex as a novel therapeutic agent and free<sup> 153</sup>Sm cation in normal rats using compartmental analysis to evaluate the behavior of this complex. <br/><strong>Materials and Methods</strong> <br/>We developed a physiologically-based pharmacokinetic model for scaling up the activity concentration in each organ with respect to time. In the mathematical model, physiological parameters including organ volume, blood flow rate, and vascular permeability were used. The compartments (organs) were connected anatomically, which allowed the use of scale-up techniques to predict new complex distribution in each body organ. <br/><strong>Results</strong> <br/>The concentration of <sup>153</sup>Sm-maltolate complex and free<sup> 153</sup>Sm cation in various organs was measured at different time intervals. The time-dependent behavior of the biodistribution of these two radiotracers was modeled, using compartmental analysis; the detected behaviors were drawn as a function of time. <br/><strong>Conclusion</strong> <br/>The variation in radiopharmaceutical concentration in organs of interest could be described by summing seven to nine exponential terms, which approximated the experimental data with a precision of > 1% in comparison with the original data from animal studies.
Biodistribution,Modeling,Compartmental Analysis,Samarium- 153,Maltolate
https://ijmp.mums.ac.ir/article_6837.html
https://ijmp.mums.ac.ir/article_6837_a8cb507a5cacbbbbdedc9a61aaccc82d.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
12
4
2015
12
01
A Hybrid Neural Network Approach for Kinematic Modeling of a Novel 6-UPS Parallel Human-Like Mastication Robot
251
261
EN
Hadi
Kalani
Center of Excellence on Soft Computing and Intelligent Information Processing (SCIIP)
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
hadi.kalani@yahoo.com
Alireza
Akbarzadeh
Center of Excellence on Soft Computing and Intelligent Information Processing (SCIIP)
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
ali_akbarzadeh@um.ac.ir
Sahar
Moghimi
Center of Excellence on Soft Computing and Intelligent Information Processing (SCIIP)
Department of Electrical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
s.moghimi@um.ac.ir
10.22038/ijmp.2016.6838
<strong>Introduction</strong> <br/>we aimed to introduce a 6-universal-prismatic-spherical (UPS) parallel mechanism for the human jaw motion and theoretically evaluate its kinematic problem. We proposed a strategy to provide a fast and accurate solution to the kinematic problem. The proposed strategy could accelerate the process of solution-finding for the direct kinematic problem by reducing the number of required iterations in order to reach the desired accuracy level. <br/><strong>Materials and Methods</strong> <br/>To overcome the direct kinematic problem, an artificial neural network and third-order Newton-Raphson algorithm were combined to provide an improved hybrid method. In this method, approximate solution was presented for the direct kinematic problem by the neural network. This solution could be considered as the initial guess for the third-order Newton-Raphson algorithm to provide an answer with the desired level of accuracy. <br/><strong>Results</strong> <br/>The results showed that the proposed combination could help find a approximate solution and reduce the execution time for the direct kinematic problem, The results showed that muscular actuations showed periodic behaviors, and the maximum length variation of temporalis muscle was larger than that of masseter and pterygoid muscles. By reducing the processing time for solving the direct kinematic problem, more time could be devoted to control calculations.. In this method, for relatively high levels of accuracy, the number of iterations and computational time decreased by 90% and 34%, respectively, compared to the conventional Newton method. <br/><strong>Conclusion</strong> <br/>The present analysis could allow researchers to characterize and study the mastication process by specifying different chewing patterns (e.g., muscle displacements).
Kinematic Problem,Mastication Robot,Neural Networks,Newton-Raphson Method
https://ijmp.mums.ac.ir/article_6838.html
https://ijmp.mums.ac.ir/article_6838_f41d25095439dc2b6bb47b4665307b0d.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
12
4
2015
12
01
Experimental Evaluation of Depth Dose by Exit Surface Diode Dosimeters for Off-Axis Wedged Fields in Radiation Therapy
262
270
EN
Alireza
Mohammadkarim
Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Ph.D student, Department of Medical Physics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
alireza_mokm@yahoo.com
Hasan Ali
Nedaie
Department of Radiotherapy, Oncology and Medical Physics, Tehran University of Medical Sciences, Tehran, Iran
Mahmoud
Allahverdi
Department of Medical Physics, Tehran University of Medical Sciences, Tehran, Iran
alahverdi@sina.tums.ac.ir
Mahbod
Esfehani
Department of Radiation Oncology, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran
md_esfahani@yahoo.com
Alireza
Shirazi
0000-0002-7579-1798
Department of Medical Physics, Tehran University of Medical Sciences, Tehran, Iran
shirazia@sina.tums.ac.ir
Ghazale
Geraily
0000-0003-2616-5586
Department of Medical Physics, Tehran University of Medical Sciences, Tehran, Iran
ghazalegraily@yahoo.com
10.22038/ijmp.2016.6839
<strong>Introduction</strong> <br/>Evaluation of the delivered dose of externally wedged photon beams by external diode dosimeters during the treatment process requires the estimation of exit surface dose correction factors in various wedge angles and field sizes. <br/><strong>Materials and Methods</strong> <br/>A system of absorbed dose evaluation, using p-type diode dosimeters placed on the exit surface of a phantom, was characterized for externally wedged photons with the maximum square field size. The values of wedge correction factor on the exit surface of the polystyrene phantom were determined for <sup>60</sup>Co and 6 MV photons. Then, the wedge correction factors were estimated at desirable depths. <br/><strong>Results</strong> <br/>Based on the findings, the deviation of off-axis wedge correction factors of the exit surface wedged fields from the central axis factor may be as large as ±10% at the evaluated depths. The results showed that the absorbed dose at each depth of patient tissue could be estimated by applying an accurate exit wedge correction factor for that particular depth, with negligible probable errors (below 1.5%). <br/><strong>Conclusion</strong> <br/>In case positioning a diode dosimeter on the patient’s entrance surface of a phantom of patients is troublesome, the diode dosimeter can be placed on the exit surface in order to evaluate the absorbed dose for externally wedged photons. Based on the findings, exit dose correction factors for wedged beams cannot be discarded; in fact, these factors are variable at different directions of externally wedged beams. <br/><strong> </strong>
Absorbed Dose,Diode Dosimeter,Wedge,Field Size,Radiation Therapy
https://ijmp.mums.ac.ir/article_6839.html
https://ijmp.mums.ac.ir/article_6839_2e78cdc22ed718d5a96547c205cecd58.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
12
4
2015
12
01
Determination of Radionuclide Concentrations in Tea Samples Cultivated in Guilan Province, Iran
271
277
EN
Zahra
Poursharif
Department of Food Science & Technology, Ferdowsi University of Mashhad, Mashhad, Iran
poursharif_kh@yahoo.com
Ali
Ebrahiminia
Department of Biochemistry & Biophysics, Faculty of Medicine, Guilan University of Medical Sciences, Rasht, Iran
Mohsen
Asadinezhad
0000-0001-6096-765X
Department of Biochemistry & Biophysics, Faculty of Medicine, Guilan University of Medical Sciences, Rasht, Iran
asadinejad_m@yahoo.com
Abolfazl
Nickfarjam
0000-0002-8313-3014
Department of Medical Physics, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
nickfarjam6262@gmail.com
Abolghasem
Haeri
Radiological Protection Department, Nuclear science & technology research institute, Atomic Energy Organization of Iran, Tehran, Iran
haeri80@gmail.com
Karim
Khoshgard
0000-0003-3629-3389
Department of Medical Physics& Medical Engineering, Kermanshah University of Medical Sciences, Kermanshah, Iran
khoshgardk@gmail.com
10.22038/ijmp.2016.6842
<strong>Introduction</strong> <br/>Foodstuffs are known to contain natural and artificial radionuclides. Determination of radionuclide concentration is of great significance for the protection of human health. The main objective of the present study was the quantification of radionuclides in tea samples, cultivated in Guilan Province in North of Iran. <br/><strong>Materials and Methods</strong> <br/>The activity concentrations of <sup>226</sup>Ra, <sup>232</sup>Th, <sup>40</sup>K, and <sup>137</sup>Cs in 18 tea samples were measured, using a gamma spectrometry system. In addition, radium equivalent index (Ra<sub>eq</sub>) and radiation hazard index (HI) were calculated. ANOVA test was used for the statistical analysis of the data <br/><strong>Results</strong> <br/>The concentration of<sup> 137</sup>Cs was below the minimum detectable activity (MDA). The concentrations of<sup> 226</sup>Ra and <sup>232</sup>Th ranged from < MDA to 0.042 and < MDA to 0.037 Bq/kg respectively. The mean concentration of <sup>40</sup>K was 410±15 Bq/kg. Based on the findings, the concentration of <sup>40</sup>K was significantly higher than other radionuclides (P<0.01). Also, the mean Ra<sub>eq</sub> value was estimated at 31.8±1.2 Bq/kg, and HI in the samples ranged from 0.075 to 0.093. <br/><strong>Conclusion</strong> <br/>According to the findings, the activity level of radionuclides in tea samples was found to be within the acceptable range and therefore, non-threatening to public health.
Radionuclide,Tea,gamma spectrometry
https://ijmp.mums.ac.ir/article_6842.html
https://ijmp.mums.ac.ir/article_6842_d3b375ec8e39392388d2b05b6d70782d.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
12
4
2015
12
01
Calculation of the Dose of Samarium-153-Ethylene Diamine Tetramethylene Phosphonate (153Sm-EDTMP) as a Radiopharmaceutical for Pain Relief of bone Metastasis
278
283
EN
Fatemeh
Razghandi
Department of Physics, School of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
Reza
Izadi
Department of Physics, School of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
izadi@um.ac.ir
Ali
Mowlavi
Department of Physics, Hakim Sabzevari University, Sabzevar, Iran
International Centre for Theoretical Physics, Associate and Federation Schemes, Medical Physics Field, Trieste, Italy
amolavi@ictp.it, amwolavi@hsu.ac.ir
10.22038/ijmp.2016.6843
<strong>Introduction</strong> <br/>One of the important applications of nuclear physics in medicine is the use of radioactive elements as radiopharmaceuticals. Metastatic bone disease is the most common form of malignant bone tumors. Samarium-153-ethylene diamine tetramethylene phosphonate (<sup>153</sup>Sm-EDTMP) as a radiopharmaceutical is used for pain palliation. This radiopharmaceutical usually emits beta particles, which have a high uptake in bone tissues. The purpose of this study was to calculate the radiation dose distribution of <sup>153</sup>Sm-EDTMP in bone and other tissues, using MCNPX Monte Carlo code in the particle transport model. <br/><strong>Materials and Methods</strong> <br/>Dose delivery to the bone was simulated by seeking radiopharmaceuticals on the bone surface. The phantom model had a simple cylindrical geometry and included bone, bone marrow, and soft tissue. <br/><strong>Results</strong> <br/>The simulation results showed that a significant amount of radiation dose was delivered to the bone by the use of this radiopharmaceutical. <br/><strong>Conclusion</strong> <br/>Thebone acted as a fine protective shield against rays for the bone marrow. Therefore, the trivial absorbed dose by the bone marrow caused less damage to bone-making cells. Also, the high absorbed dose of the bone could destroy cancer cells and relieve the pain in the bone.
Dose Distribution,MCNPX Code,153Sm-EDTMP
https://ijmp.mums.ac.ir/article_6843.html
https://ijmp.mums.ac.ir/article_6843_a6f303bd2548a02062cded40a4159984.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
12
4
2015
12
01
Evaluation of Organ and Effective Doses to Patients Arising From Some Common X-Ray Examinations by PCXMC Program in Sabzevar, Iran
284
291
EN
Hasan
Zarghani
Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Mohammad Taghi
Bahreyni Toossi
0000-0002-3698-5716
Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
bahreynimt@mums.ac.ir
10.22038/ijmp.2016.6844
<strong>Introduction</strong> <br/>The purpose of this study was to estimate organ and effective doses in patients undergoing some common X-ray examinations in Sabzevar, Iran. The effective dose is one of the best parameters for describing the amount of radiation dose received by a patient undergoing any diagnostic X-ray examination. The public dose from X-ray examinations depends on various factors, and its contribution to the overall public dose from medical applications widely varies in different societies; however, in Iran, limited data is available on this subject. <br/><strong>Materials and Methods</strong> <br/>In the present study, we aimed to estimate organ and effective doses arising from some common X-ray examinations on patients. Organ and effective doses were calculated by employing PCXMC program, based on Monte Carlo method. <br/><strong>Results</strong> <br/>The mean effective doses in this study were compared with similar findings reported in previous research. The applied methods in different studies are the main factors, which influence the effective dose values. <br/><strong>Conclusion</strong> <br/>Radiation doses to radiosensitive organs such as the ovaries, testicles, and thyroid may induce harmful effects, e.g., cancer and genetic effects. Therefore, we should try to maintain the organ doses as low as possible.
Effective Dose,organ dose,PCXMC program,Radiography,Radiation Effects
https://ijmp.mums.ac.ir/article_6844.html
https://ijmp.mums.ac.ir/article_6844_db8506c85cb96f8ef54e2afe8c6ee1ce.pdf