ORIGINAL_ARTICLE
Investigating the Effects of Cut-Out Shield on High-Energy Electron Fields Using MAGIC Normoxic Polymer Gel
Introduction The use of cut-outs in electron applicators make changes on output, isodose, and percentage depth dose (PDD) curves. These changes and electron beam dose distribution in the form of three-dimensional (3D) can be measured by gel dosimeters. Materials and Methods Dosimetry was performed with and without a square shield (6×6 cm2 field). The energies were 4, 9, and 16 MeV and phantom was filled with MAGIC gel polymer. For each section, transverse relaxation rate (R2) maps were obtained from MRI images and percentage depth doses and isodose curves were plotted. Results Average energy was 3.029 MeV for the energy of 4 MeV and 8.155 MeV for the energy of 9 MeV. Surface dose was higher in shielded field compared with the open one (due to electron scattering between the phantom and lead) which increased with increasing of energy. In the open field, for energies equal to 4, 9, and 16 MeV, the surface dose was 6.40, 6.48, and 7.20 Gy and for the shielded mode, they were 6.63, 7.04, and 7.31 Gy, respectively. Also error values showed less errors and higher accuracy on curves by increasing of energy. Conclusion Investigation of an isodose pattern in the shielded mode showed scattering due to the lead, which is on the applicator. Overall, the results of this study demonstrated the value and potential of this dosimetric method with respect to characteristics such as stability, responsiveness and specially ability to show three-dimensional electron beam dose distribution.
https://ijmp.mums.ac.ir/article_2175_24977706d0e1530f1d68ebe97be47674.pdf
2013-09-01
78
86
10.22038/ijmp.2013.2175
Electron
MAGIC polymer gel
Shield
Hadis
Ansari Mehr
numb_nox@yahoo.com
1
Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
LEAD_AUTHOR
Azim
Arbabi
2
2- Department of Medical Physics, Imam Hosein Hospital, Shahid Beheshti Medical University, Tehran, Iran
AUTHOR
Mohammad Hasan
Zahmatkesh
3
Department of Medical Physics, Novin Medical Radiation Institute, Tehran, Iran
AUTHOR
Mahmood
Allahverdi
4
Department of Medical Physics, Tehran University of Medical Sciences, Tehran, Iran
AUTHOR
Saeid
Bagheri
5
Novin Medical Radiation Institute, Shahid Beheshti University, Tehran, Iran
AUTHOR
ORIGINAL_ARTICLE
Evaluation of Maximum Patient Skin Dose Arising from Interventional Cardiology Using Thermoluminescence Dosimeter in Mashhad, Iran
Introduction The increasing practice of interventional fluoroscopy in diagnosis and treatment of cardiovascular disease has risen attention to improve radiation protection of patients and cardiologists in these relatively high dose techniques. Therefore, nowadays there is an emphasis on the measurement of radiation dose received by patients and cardiologists arising from the relevant procedures. Materials and Methods Maximum skin dose of 90 patients in two hospitals in Mashhad have been measured by a grid of 30 thermoluminescent dosimeters (TLDs). The X-ray units were Axiom Artis Siemens in both hospitals which were equipped with integrated dose area product (DAP) meters. The procedures were divided into two groups: diagnostic procedures (angiography and angiography with measurement of left or right ventricle and pulmonary artery) and therapeutic procedures (angioplasty with or without dilatation or stent and angiography with angioplasty). DAP value, fluoro time, and cumulative dose at Interventional Reference Point (CDIRP) were also registered for each procedure. Results The mean values of maximum skin dose (MSD) and DAP for diagnostic procedures were 68.51 mGy and 20.96 Gy.cm2, respectively and for therapeutic procedures 344.18 mGy and 70.94 Gy.cm2, respectively. A good correlation was found between MSD and DAP (R=0.88) but correlation between MSD and CDIRP was stronger (R=0.90). Conclusion MSD values did not exceed the 2000 mGy dose threshold for deterministic effects. The highest MSD obtained for diagnostic procedures was 229.40 mGy and for therapeutic procedures it was 820.50 mGy. The results show that CDIRP can be a fairly good estimate of MSD.
https://ijmp.mums.ac.ir/article_2176_7edda409612d58a817f1190e212df554.pdf
2013-09-01
87
94
10.22038/ijmp.2013.2176
Interventional Cardiology
Maximum Skin Dose
TLD
Mohammad Taghi
Bahreyni Toossi
bahreynimt@mums.ac.ir
1
Medical Physics Research Center, Medical Physics Department, Mashhad University of Medical Sciences, Mashhad, Iran.
LEAD_AUTHOR
Seyedeh Farideh
Baradaran
2
Medical Physics Research Center, Medical Physics Department, Mashhad University of Medical Sciences, Mashhad, Iran.
AUTHOR
Arash
Gholoobi
3
Department of Cardiology, Imam Reza educational hospital, Faculty of medicine, Mashad University of Medical Sciences, Mashhad, Iran
AUTHOR
Hosein
Nademi
4
Specialized Hospital Cardiovascular Jvadalaymh, Mashhad, Iran.
AUTHOR
ORIGINAL_ARTICLE
Extraction and 3D Segmentation of Tumors-Based Unsupervised Clustering Techniques in Medical Images
Introduction The diagnosis and separation of cancerous tumors in medical images require accuracy, experience, and time, and it has always posed itself as a major challenge to the radiologists and physicians. Materials and Methods We Received 290 medical images composed of 120 mammographic images, LJPEG format, scanned in gray-scale with 50 microns size, 110 MRI images including of T1-Wighted, T2-Wighted, and Proton Density (PD) images with 1-mm slice thickness, 3% noise and 20% intensity non-uniformity (INU) as well as 60 lung cancer images acquired using the 3D CT scanner, GE Medical System LightSpeed QX/i helical, yielding 16-bit slices taken from various medical databases. By applying the Discrete Wavelet Transform (DWT) on the input images and constructing the approximate coefficients of scaling components, the different parts of image were classified. In next step using k-means algorithm, the appropriate threshold was selected and finally the suspicious cancerous mass was separated by implementation image processing techniques. Results By implementing the proposed algorithm, acceptable levels of accuracy 92.06%, sensitivity 89.42%, and specificity 93.54% were resulted for separating the target area from the rest of image. The Kappa coefficient was approximately 0.82 which illustrate suitable reliability for system performance. The correlation coefficient of physician’s early detection with our system was highly significant (p<0.05). Conclusion The precise positioning of the cancerous tumor enables the radiologists to determine the progress level of the disease. The low Positive Predictive Value (PPV) and high Negative Predictive Value (NPV) of the system is a warranty of the system and both clinical specialist and patients can trust the software and output.
https://ijmp.mums.ac.ir/article_2178_1ba1cabb9290c4472de50141a12a70cb.pdf
2013-09-01
95
108
10.22038/ijmp.2013.2178
discrete wavelet transform
K-Means Clustering
Image Processing
Lung cancer
Mammograms
MR images
Javad
Hadadnia
jhaddadnia@yahoo.com.
1
Center for New Research of Medical Technologies Sabzevar University of Medical Sciences, Sabzevar, Iran
LEAD_AUTHOR
Khosro
Rezaee
rezaeekhosro@ymail.com
2
Biomedical Engineering Department, Hakim Sabzevari University, Sabzevar, Iran
AUTHOR
ORIGINAL_ARTICLE
Determination of Dosimetric Characteristics of IrSeed 125I Brachytherapy Source
Introduction Low dose rate brachytherapy sources have been widely used for interstitial implants in tumor sites, particularly in prostate. Dosimetric characteristics of a new IrSeed 125I brachytherapy source have been determined using the LiF thermoluminescent dosimeter (TLD) chips. Materials and Methods Dose rate constant, radial dose function, and anisotropy function around the IrSeed 125I source were measured in a plexiglass phantom using TLD-100 chips. A plexiglass slab phantom with dimensions of 30×30×7.3 cm3 was used to measure dose distribution around the source. Results Dose rate constant was measured to be equal to 0.965±0.006 cGyh-1U-1. Radial dose function, anisotropy function, and geometry function have been presented as tabulated data for the IrSeed source. Conclusion Basically, the dosimetric parameters presented here for this new IrSeed source have clinical and treatment planning applications.
https://ijmp.mums.ac.ir/article_2179_5f8f8508fabb297d7328e5c3ae593e4e.pdf
2013-09-01
109
117
10.22038/ijmp.2013.2179
125I
Brachytherapy
Dosimetry
TG-43
TLD
Vahid
Lohrabian
vahidlohrabian@yahoo.com
1
Educational Development Center, Ilam University of Medical Sciences, Ilam, Iran
LEAD_AUTHOR
Shahab
Sheibani
2
Nuclear Science Research School, Nuclear Science and Technology Research Institute, Tehran, Iran
AUTHOR
Mahmoud Reza
Aghamiri
3
Department of Radiation Medicine, University of Shahid Beheshti, Tehran, Iran
AUTHOR
Behroz
Ghozati
4
Department of Radiation Medicine, University of Shahid Beheshti, Tehran, Iran
AUTHOR
Hosein
Pourbeigi
5
Nuclear Science Research School, Nuclear Science and Technology Research Institute, Tehran, Iran
AUTHOR
Hamid Reza
Baghani
6
Department of Radiation Medicine, University of Shahid Beheshti, Tehran, Iran
AUTHOR
ORIGINAL_ARTICLE
Autonomous Drug-Encapsulated Nanoparticles: Towards a Novel Non-Invasive Approach to Prevent Atherosclerosis
Introduction This paper proposes the concept of autonomous drug-encapsulated nanoparticle (ADENP) as a novel non-invasive approach to prevent atherosclerosis. ADENP consists of three simple units of sensor, controller (computing), and actuator. The hardware complexity of ADENP is much lower than most of the nanorobots, while the performance is maintained by the synergism in the swarm architecture. Materials and Methods Since high accumulation of low density lipoprotein (LDL) macromolecules within the arterial wall plays a critical role in the initiation and development of atherosclerotic plaques, the task of the swarm of ADENPs is autonomous feedback control of LDL level in the interior of the arterial wall. In this study, we consider two specific types of ADENPs with distinguishing capabilities. The performance of each type is evaluated and compared on a well-known mathematical model of the arterial wall through computer simulation. Results Simulation results demonstrate that the proposed approach can successfully reduce the LDL level to a desired value in the arterial wall of a patient with very high LDL level that is corresponding to the highest rates of cardiovascular disease events. Moreover, it is shown that ADENP is capable of distinguishing between healthy and unhealthy arterial walls to reduce the drug side effects. Conclusion The proposed approach is a promising autonomous non-invasive method to prevent and treat complex diseases such as atherosclerosis.
https://ijmp.mums.ac.ir/article_2180_381486b81031f4eafd64d724f8883991.pdf
2013-09-01
118
132
10.22038/ijmp.2013.2180
Atherosclerosis
Low Density Lipoprotein
Nonlinear Control
Swarm Control
Nanoparticles
Alireza
Rowhanimanesh
rowhanimanesh@ieee.org
1
Department of Electrical Engineering, Center of Excellence on Soft Computing and Intelligent Information Processing (SCIIP), Ferdowsi University of Mashhad, Mashhad, Iran.
LEAD_AUTHOR
Mohammad Reza
Akbarzadeh Totonchi
2
Department of Electrical Engineering, Center of Excellence on Soft Computing and Intelligent Information Processing (SCIIP), Ferdowsi University of Mashhad, Mashhad, Iran
AUTHOR
ORIGINAL_ARTICLE
Calculations of Linac Photon Dose Distributions in Homogeneous Phantom Using Spline
Introduction Relative dose computation is a necessary step in radiation treatment planning. Therefore, finding an approach that is both fast and accurate seems to be necessary. The purpose of this work was to investigate the feasibility of natural cubic spline to reconstruct dose maps for linear accelerator radiation treatment fields in comparison with those of the simulation. Materials and Methods A natural cubic spline algorithm was used to reproduce dose calculations of linac radiation treatment fields resulting from GEANT4 application for tomographic emission (GATE) simulation. The spline algorithm was used to compute percent depth dose of radiation therapy fields for 6 MV X-rays, which were calculated by simulation of Elekta Compact Linac. It reconstructed 2-dimensional dose maps and created isodose distributions. This dose maps were evaluated and compared with the simulation, where the γ -index was used. Results A good agreement was found between the doses calculated from the simulation and the spline. In particular, an average γ-index passing rate of 0.24 was obtained for sample percent depth dose distributions, and an average γ -index passing rate of 0.20 was observed for sample dose profiles. Conclusion Natural cubic spline has been established to calculate dose maps from field characteristics. The feasibility and possibility of natural cubic spline to calculate dose maps for linac radiation therapy fields in a homogeneous phantom has been demonstrated.
https://ijmp.mums.ac.ir/article_2181_db4f29cfcc313c07a7607b43c7c052de.pdf
2013-09-01
133
138
10.22038/ijmp.2013.2181
γ –index
Cubic Spline
Dose Calculation
Hamid-Reza
Sadoughi
hr.sadoughi@mums.ac.ir
1
Medical Physics Research Center, Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
AUTHOR
Shahrokh
Nasseri
naserish@mums.ac.ir
2
Medical Physics Research Center, Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
AUTHOR
Mahdi
Momennezhad
momennezhadm@mums.ac.ir
3
Medical Physics Research Center, Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran
AUTHOR
Hadi
Sadoghi-Yazdi
sadoughi_y@yahoo.com
4
Department of Computer Engineering, Ferdowsi University of Mashhad, Mashhad,
AUTHOR
Mohammad-Hossein
Zare
5
Medical Physics Research Center, Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
AUTHOR
Mohammad-Hossein
Bahreyni-Toosi
bahreynimh@mums.ac.ir
6
Medical Physics Research Center, Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
LEAD_AUTHOR
ORIGINAL_ARTICLE
A New Method for Metal Artifact Reduction in CT Scan Images
Introduction In CT imaging, metallic implants inside the tissues cause metal artifact that reduce the quality of image for diagnosis. In order to reduce the effect of this artifact, a new method with more appropriate results has been presented in this research work. Materials and Methods The presented method comprised of following steps: a) image enhancement and metal areas extraction, b) sinogram transform of original image, c) metal segments and metal traces inside the sinogram transform of original image segmented by using Fuzzy C means, d) interpolation of metal traces inside the original image sinogram and filtering, and e) adding the image of metal parts to the filtered image to obtain the corrected image. Results Fifty CT scan images from Alzahra Hospital in Isfahan were used to evaluate the proposed method. The proposed method was applied to images which had implants in regions such as femur, hip, tooth, brain, and stomach. The results showed an intensively reduced in metal artifact and quality improvement of images till 90% for accuracy, compared with the radiologist report. Conclusion The proposed method reduced the effect of metal artifact by maintaining the specification of other tissues. Furthermore, the consumed time to process the suggested algorithm in this study was less than conventional methods. For instance, the consumed time for CT image, including a metal in the femur region was about 20% of the conventional method.
https://ijmp.mums.ac.ir/article_2182_6dec34b22d983088aa89b288eaf92a5c.pdf
2013-09-01
139
146
10.22038/ijmp.2013.2182
CT Scan
Interpolation
Metal Artifact
Mohsen
Safdari
1
Department of Biomedical Engineering, University Of Isfahan, Hezarjerib Street, Isfahan, Iran,
AUTHOR
Alireza
Karimian
karimian@eng.ui.ac.ir
2
Department of Biomedical Engineering, Faculty of Engineering, University of Isfahan, Hezarjerib Street, Isfahan, Iran
LEAD_AUTHOR
Mohammad reza
Yazdchi
3
Department of Biomedical Engineering, Faculty of Engineering, University of Isfahan, Hezarjerib Street, Isfahan, Iran
AUTHOR
ORIGINAL_ARTICLE
Effective Point of Measurement in Cylindrical Ion Chamber for Megavoltage Photon Beams
Introduction For dose measurement in Megavoltage (MV) photon beams with ion chambers, the effect of volume occupied by the air cavity is not negligible. Therefore, the result of measurement should be corrected with a displacement perturbation correction factor (Pdis) or using an effective point of measurement (EPOM). The aim of this study is to calculate the EPOM for cylindrical ion chamber and to evaluate the fixed EPOM that was recommended by standard dosimetry protocols. Materials and Methods Percent depth doses (PDDs) for 6 MV and 18 MV were measured with two types of chambers for different depths and field sizes. The EPOM was calculated using results obtained from measurement data for two types of chambers, comparison of the readings, and using dosimetry, mathematical, and statistical consideration. For displacement correction factor 12∆r'> =0, 12∆r'> = 0.6r and different 12∆r'>, the minimum standard deviations ratio (SDRs) were calculated at several depths and field sizes. Results Maximum level of SDRs was about 0.38% and 0.49% (when assuming variable 12∆r'>) for 6 MV and 18 MV, respectively (which was less than 0.5% and acceptable). This quantity was greater than one (for assuming 12∆r'> = 0.6r) and greater than 2 when there was no shift ( 12∆r'> =0) Conclusion The results show that the recommended shift for cylindrical ion chamber in dosimetry protocols (upstream of 0.6r) is not correct and using a fixed value for the EPOM at all photon beam energies, depths, and field sizes is not suitable for accurate dosimetry.
https://ijmp.mums.ac.ir/article_2184_b6a501729ee3389de158df7b53fc9d6e.pdf
2013-09-01
147
155
10.22038/ijmp.2013.2184
Cylindrical Chamber
Dosimetry Protocols
Effective Point of Measurement
Plane Parallel Chamber
Fatemeh
Seif
seif@arakmu.ac.ir
1
Department of Medical Physics & Khansari Hospital, Arak University of Medical Sciences, Arak, Iran
AUTHOR
Mojtaba
Karbalayi
mehdi_karbalaee@yahoo.com
2
Department of Medical Physics, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
AUTHOR
Mohamad Reza
Bayatiani
mr_kbi@yahoo.com
3
Department of Medical Physics & Khansari Hospital, Arak University of Medical Sciences, Arak, Iran
AUTHOR
Mitra
Karbalayi
karbalayi@yahoo.com
4
Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
AUTHOR
Mohamad Javad
Tahmasebi-Birgani
mjtmsebi@yahoo.com
5
Department of Medical Physics & Golestan Hospital, Medical Faculty, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
AUTHOR