ORIGINAL_ARTICLE
Dosimetric Comparison of 3D Tangential Radiotherapy of Post-Lumpectomy Breast at Two Different Energies
Introduction: Radiation therapy following breast conserving surgery is one of the most common procedures performed in any radiation oncology department. A tangential parallel-opposed pair is almost always the technique of choice for this purpose. This technique is often performed based on 3D treatment planning. The aim of this study was to compare 3D treatment planning for two different energies (Cobalt 60 versus 6 MV photon beams) in tangential irradiation of breast conserving radiotherapy. In this comparison, homogeneity of isodoses within the breast volume and dose received by lungs were considered. Materials and Methods: In this study, twenty patients with breast cancer treated with conservative surgery were included. A CT scan was performed on selected patients. Three-dimensional treatment planning with 6 MV photon beams was carried out for patients on the Eclipse 3D treatment planning system (TPS). The volumes receiving lower than 95% (Vol<95) (cold areas) and greater than 105% (Vol>105) (hot areas) of the reference dose, and the volume of lung receiving ≥30Gy (Vol≥30Gy) were derived from dose volume histograms (DVHs). Dose homogeneity index was calculated as: DHI = 100 – (Vol>105 + Vol<95). In the second stage, each patient was replanned with Cobalt 60 and the quantities of interest were obtained from the DVHs. Results: Comparing 3D treatment planning by 6 MV and Cobalt 60 photons, cold areas were reduced (p<0.001), hot areas were decreased (p<0.7), DHI was improved (P<0.001) and Vol≥30Gy was reduced (P<0.017) with 6 MV photons. Discussion and Conclusion: Our results indicate that treatment planning with Cobalt 60 causes more cold areas in the treated volume as compared with 6 MV photons. Cold areas within the target volume of the breast result in reduced tumor control probability. The plan can be optimized to limit dose to lung volume by using 6 MV photons. So lung fibrosis is more likely to occur with Cobalt 60. In addition, DHI was improved with 6 MV photon beams. Improvement of dose homogeneity can lead to higher tumor control probability and cosmetic results, and less skin and lung side effects. Hence, 3D treatment planning with 6 MV photon beams is a more suitable option for patients with breast cancer treated with conserving surgery
https://ijmp.mums.ac.ir/article_7210_8cba514c850e3a13b52eea7649313537.pdf
2011-06-01
1
8
10.22038/ijmp.2011.7210
Breast Cancer
Cobalt 60
Tangential Irradiation
3D Treatment Planning
6MV Photon Beam
Robab
Anbiaee
1
Assistant Professor, Radiotherapy and Oncology Dept., Imam Hossein Hospital, Shahid Beheshti University, Tehran, Iran
AUTHOR
Seyed Mahmoud Reza
Aghamiri
smr.aghamiri@sbu.ac.ir
2
Associate Professor, Nuclear Engineering-Medical Radiation Dept., Faculty of Nuclear Engineering, Shahid Beheshti University, Tehran, Iran
AUTHOR
Zahra
Falahatpour
3
M.Sc in Nuclear Engineering-Medical Radiation, Faculty of Nuclear Engineering, Shahid Beheshti University, Tehran, Iran
AUTHOR
ORIGINAL_ARTICLE
Cytotoxicity and Phototoxicity of Chlorophyll a/Hydroxypropyl-γ-cyclodextrin Complex on Leishmania Major Promastigotes
Introduction: Cutaneous leishmaniasis (CL) is a widespread disease that is epidemic in Iran, too. Photodynamic therapy (PDT) is an attractive modality to treat cancer and hyper proliferative diseases based on the use of a photosensitizer in the presence of oxygen and proper wavelength of light. In consideration of lesion location, lack of systemic involvement and inefficiency of current treatments, nowadays this modality is purposed for treating Leishmaniasis. In this paper, efficacy of PDT using a natural dye (chlorophyll a) on Leishmania major promastigotes is reported. Material and Methods: The experiments was done on Leishmania major parasites (MRHO/IR/75/ER) in the presence of Chlorophyll a /Hydroxypropyl-γ-cyclodextrin(chl a/CD) complex as a photosensitizer. At first, dye uptake by promastigotes was evaluated via fluorimetric assessments after different incubation periods. Then dye cytotoxicity was evaluated at different concentration after 24 h incubation. Finally PDT experiments were designed with two doses of light and 10 µM of photosensitizer. Considering all possible controls, the percentage of the parasite survival at 24 hours post treatment was assessed by MTS method. All experiments were repeated at least three times. Results: On the basis of the dye uptake data, 24h was considered for incubating of photosensitizer with promastigotes. IC50 of chl a/CD complex was about 42.6 µM. After parasites irradiation by light at 248 j/cm2, more than 50% of cell death was recorded that is significant in comparing with similar groups without dye, without light, and lower dose of light. In these conditions, ED50 of PDT on promastigotes is determined nearly 246 J/cm2. Discussion and Conclusion: Considering low cytotoxicity in darkness and adequate phototoxicity of chl a/CD complex in comparison with other photosensitizers such as AlPhtalocyanine chloride, it can be introduced as a promising candidate for futher use in PDT experiments on amastigotes and Leishmaniasis animal models.
https://ijmp.mums.ac.ir/article_7211_79d5d61f539818f8db086b1c4ae4de2a.pdf
2011-06-01
9
18
10.22038/ijmp.2011.7211
Chlorophyll a
Cutaneous Leishmaniasis
Hydroxypropyl-γ-Cyclodextrin
Photodynamic Therapy (PDT)
Azam
Jafari Parizi
1
M.Sc. in Medical physics, Kerman University of Medical Sciences, Kerman, Iran.
AUTHOR
Ameneh
Sazgarnia
sazgarniaa@mums.ac.ir
2
Associate Professor of Medical Physics, Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
LEAD_AUTHOR
Pouran
Layegh
3
Assistant Professor of Dermatology, Research Center for Skin Diseases and Cutaneous Leishmaniasis, Mashad University of Medical Sciences, Mashad, Iran.
AUTHOR
Omid
Rajabi
4
Associate Professor in Medicinal Chemistry, Medicinal Chemistry, Faculty of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
AUTHOR
Habibollah
Esmaily
5
Assistant Professor, Community Medicine &Public Health Dept., Faculty of Health, Mashhad University of Medical Sciences, Mashhad, Iran.
AUTHOR
ORIGINAL_ARTICLE
Dosimetry Comparison of Water Phantom and Complete Eye Definition for 125I and 103Pd Brachytherapy Plaques
Introduction: In this paper, by complete definition of human eye containing the various parts and their materials, the difference between this model and a homogeneous water phantom are compared for two ophthalmic plaques using 125I and 103Pd. Material and methods: The simulation of the two phantoms were performed in the MCNP-4C code and by using the geometry of a three-dimensional eye, different parts of the eye including the lens, cornea, retina, choroid, sclera, anterior chamber, optic nerve and tumor were defined in the eye phantom. Also, for two ophthalmic brachytherapy sources, 20 mm COMS plaques containing 24 125I or 103Pd sources were simulated. The depth dose and doses in different parts of the eye were calculated by using the *F8 tally in the MCNP code. Results: The results showed that the doses in different parts of the eye in the two phantoms were different and depended on the ophthalmic plaques. The dose increased in the tumor and decreased in some parts of the eye such as the lens. Discussion and Conclusion: Complete definition of human eye in simulation of ophthalmic brachytherapy leads to better results. As the effects of eye definition are different in the tumor and healthy tissues, the results for the eye phantom provide more accurate information for calculation of treatment time and the type of ophthalmic brachytherapy used.
https://ijmp.mums.ac.ir/article_7212_e96c01bbed563d87f2f1fa21f04fbc82.pdf
2011-06-01
19
26
10.22038/ijmp.2011.7212
Brachytherapy
Dosimetry
Melanoma
Monte Carlo Simulation
Ophthalmic Plaques
Zohreh
Dehghannia Rostami
1
Graduated M.Sc. Student of Nuclear Physics, Physics Dept., KN Toosi University of Technology, Tehran, Iran.
AUTHOR
Seyed Farhad
Masoudi
masoudi@kntu.ac.ir
2
Associate Professor, Physics Dept., KN Toosi University of Technology, Tehran. Iran
LEAD_AUTHOR
Somayeh
Asadi
s_asadi@sina.kntu.ac.ir
3
Graduated M.Sc. Student of Nuclear Physics, Physics Dept., KN Toosi University of Technology, Tehran, Iran.
AUTHOR
ORIGINAL_ARTICLE
Optimal Feature Extraction for Discriminating Raman Spectra of Different Skin Samples using Statistical Methods and Genetic Algorithm
Introduction: Raman spectroscopy, that is a spectroscopic technique based on inelastic scattering of monochromatic light, can provide valuable information about molecular vibrations, so using this technique we can study molecular changes in a sample. Material and Methods: In this research, 153 Raman spectra obtained from normal and dried skin samples. Baseline and electrical noise were eliminated in the preprocessing stage with subsequent normalization of Raman spectra. Then, using statistical analysis and Genetic algorithm, optimal features for discrimination between these two classes have been searched. In statistical analysis for choosing optimal features, T test, Bhattacharyya distance and entropy between two classes have been calculated. Seeing that T test can better discriminate these two classes so this method used for selecting the best features. Another time Genetic algorithm used for selecting optimal features, finally using these selected features and classifiers such as LDA, KNN, SVM and neural network, these two classes have been discriminated. Results: In comparison of classifiers results, under various strategies for selecting features and classifier, the best results obtained in combination of genetic algorithm in feature selection and SVM in classification. Finally using combination of genetic algorithm and SVM, we could discriminate normal and dried skin samples with accuracy of 90%, sensitivity of 89% and specificity of 91%. Discussion and Conclusion: According to obtained results, we can conclude that genetic algorithm demonstrates better performance than statistical analysis in selection of discriminating features of Raman spectra. In addition, results of this research illustrate the potential of Raman spectroscopy in study of different material effects on skin and skin diseases related to skin dehydration.
https://ijmp.mums.ac.ir/article_7213_89c5b9d9756576ed73690a7356d464d4.pdf
2011-06-01
27
33
10.22038/ijmp.2011.7213
classification
Genetic Algorithm
Raman Spectroscopy
Zohreh
Dehghani Bidgoli
1
Ph.D. Student, Biomedical Engineering Dept., Faculty of Electrical Engineering, Tarbiat Modares University, Tehran, Iran.
AUTHOR
Mohammad Hosein
Miranbaygi
miranbmh@modares.ac.ir
2
Associate Professor, Biomedical Engineering Dept., Faculty of Electrical Engineering, Tarbiat Modares University, Tehran, Iran.
LEAD_AUTHOR
Rasool
Malekfar
3
Associate Professor, Physics Dept., Faculty of Basic Sciences, Tarbiat Modares University, Tehran, Iran.
AUTHOR
ORIGINAL_ARTICLE
Calculating of Dose Distribution in Tongue Brachytherapy by Different Radioisotopes using Monte Carlo Simulation and Comparing by Experimental Data
Introduction: Among different kinds of oral cavity cancers, the frequency of tongue cancer occurrence is more significant. Brachytherapy is the most common method to cure tongue cancers. Long sources are used in different techniques of tongue brachytherapy. The objective of this study is to asses the dose distribution around long sources, comparing different radioisotopes as brachytherapy sources, measuring the homogeneity of delivered dose to treatment volume and also comparing mandible dose and dose of tongue in the regions near the mandible with and without using shield. Material and Method: The Monte Carlo code MCNP4C was used for simulation. The accuracy of simulation was verified by comparing the results with experimental data. The sources like Ir-192, Cs-137, Ra-226, Au-198, In-111 and Ba-131 were simulated and the position of sources was determined by Paris system. Results: The percentage of mandible dose reduction with use of 2 mm Pb shield for the sources mentioned above were: 35.4%, 20.1%, 86.6%, 32.24%, 75.6%, and 36.8%. The tongue dose near the mandible with use of shied did not change significantly. The dose homogeneity from the most to least was obtained from these sources: Cs-137, Au-198, Ir-192, Ba-131, In-111 and Ra-226. Discussion and Conclusion: Ir-192 and Cs-137 were the best sources for tongue brachytherapy treatment but In-111 and Ra-226 were not suitable choices for tongue brachytherapy. The sources like Au-198 and Ba-131 had rather the same performance as Ir-192
https://ijmp.mums.ac.ir/article_7214_1fb573d20739d5187e450ceee62e713a.pdf
2011-06-01
35
44
10.22038/ijmp.2011.7214
Brachytherapy
Dose Distribution
Monte Carlo
Simulation
Tongue Cancer
Banafsheh
Zeinali Rafsanjani
1
M.Sc. of Nuclear Engineering, Medical Radiation Trends, Faculty of Mechanical Engineering, Shiraz University, Shiraz, Iran.
AUTHOR
Reza
Faghihi
faghihir@shirazu.ac.ir
2
Assistant Professor of Medical Radiation, Radiation Research Center, Faculty of Mechanical Engineering, Shiraz University, Shiraz, Iran.
LEAD_AUTHOR
ORIGINAL_ARTICLE
Investigation of Anisotropy Caused by Cylinder Applicator on Dose Distribution around Cs-137 Brachytherapy Source using MCNP4C Code
Introduction: Brachytherapy is a type of radiotherapy in which radioactive sources are used in proximity of tumors normally for treatment of malignancies in the head, prostate and cervix. Materials and Methods: The Cs-137 Selectron source is a low-dose-rate (LDR) brachytherapy source used in a remote afterloading system for treatment of different cancers. This system uses active and inactive spherical sources of 2.5 mm diameter, which can be used in different configurations inside the applicator to obtain different dose distributions. In this study, first the dose distribution at different distances from the source was obtained around a single pellet inside the applicator in a water phantom using the MCNP4C Monte Carlo code. The simulations were then repeated for six active pellets in the applicator and for six point sources. Results: The anisotropy of dose distribution due to the presence of the applicator was obtained by division of dose at each distance and angle to the dose at the same distance and angle of 90 degrees. According to the results, the doses decreased towards the applicator tips. For example, for points at the distances of 5 and 7 cm from the source and angle of 165 degrees, such discrepancies reached 5.8% and 5.1%, respectively. By increasing the number of pellets to six, these values reached 30% for the angle of 5 degrees. Discussion and Conclusion: The results indicate that the presence of the applicator causes a significant dose decrease at the tip of the applicator compared with the dose in the transverse plane. However, the treatment planning systems consider an isotropic dose distribution around the source and this causes significant errors in treatment planning, which are not negligible, especially for a large number of sources inside the applicator.
https://ijmp.mums.ac.ir/article_7215_0ea92531d93c2357698f2e2768c2f7f4.pdf
2011-06-01
45
52
10.22038/ijmp.2011.7215
Sedigheh
Sina
samirasina@yahoo.com
1
Ph.D. Student, Nuclear Engineering, Medical Radiation Trends, Faculty of Mechanical Engineering, Shiraz University, Shiraz, Iran.
AUTHOR
Reza
Faghihi
rfaghihi@yahoo.com
2
Assistant Professor of Medical Radiation, Faculty of Mechanical Engineering, Radiation Research Center, Shiraz University, Shiraz, Iran.
AUTHOR
Mehdi
Zehtabian
mehdizehtabian@yahoo.com
3
Ph.D. Student, Nuclear Engineering, Medical Radiation Trends, Faculty of Mechanical Engineering, Shiraz University, Shiraz, Iran.
LEAD_AUTHOR
Simin
Mehdizadeh
4
M.Sc. of Nuclear Engineering, Medical Radiation Trends, Radiation Research Center, Shiraz University, Shiraz, Iran.
AUTHOR
ORIGINAL_ARTICLE
Design and Manipulation 3D Imaging System by using Photodiode Grid
Introduction: Radiation imaging is one of the applicable methods in diagnostic medicine and nondestructive testing for industrial applications. In nondestructive 3D imaging, in addition to the radiation source, there is a requirement for a suitable detection system, data acquisition system, mechanical sections for moving objects, reconstruction algorithm and finally a computer for processing and control. Method and Materials: One of the most important components of a digital radiation imaging system is its detector. Light photodiode is a new light sensor which is used in digital imaging systems because of its high efficiency. In the present research, a photodiode grid has been implemented to design and make a detection system. The photodiode grid has an array of 10×10 photodiodes in a 50×50 mm2 area. Beside the photodiode grid, a control board has been designed. Furthermore, a mechanical system has been designed to move the objects in the horizontal and vertical directions, and also rotate it around its own axis. The maximum displacement in the horizontal and vertical directions is 60 cm with step accuracy of about 0.015 mm. Step accuracy of the rotational movement is about 0.9 degrees. Results: After the imaging system was constructed, background and uniformity of the system were tested. All the photodiodes in the imaging system showed good uniformity. The image data was transferred to a computer and processed using a MATLAB program to display the images on a monitor. As the physical resolution of the system is about the pixel size (5 mm), only the overall images of the object's dimensions were expected to be produced. Discussion and Conclusion: The fidelity of the detection system has been successfully tested using a visible light source and several test samples. The presented system is able to reconstruct 3D images and obtain cross-sectional images of the objects, by using the image processing algorithm specifically designed for it.
https://ijmp.mums.ac.ir/article_7216_533948ca47753efa643107a40ad2fee0.pdf
2011-06-01
53
64
10.22038/ijmp.2011.7216
Detector
Image reconstruction
Object moving system
3D imaging system
Photodiode
Tomography
Seyed Mahdi
Safavi
safavi.mahdi@gmail.com
1
M.Sc. in Nuclear Engineering, Faculty of Nuclear Engineering, Shahid Beheshti University, Tehran, Iran.
LEAD_AUTHOR
Hamid
Jafari
2
M.Sc. in Nuclear Engineering, Faculty of Nuclear Engineering, Shahid Beheshti University, Tehran, Iran.
AUTHOR
Alireza
Kamali Asl
3
Assistant Professor of Radiation Medical Engineering., Shahid Beheshti University, Tehran, Iran.
AUTHOR
Majid
Shahreyari
4
Professor, Nuclear Engineering Dept, Shahid Beheshti University, Tehran, Iran.
AUTHOR
ORIGINAL_ARTICLE
Design of an Elastic Arthroplastic Disc Optimized under Different Loads
Introduction: Due to limitations of current treatments for degenerative disc disease, arthroplastic methods to repair the diseased disc have been proposed. The artificial disc is a mobile implant for degenerative disc replacement that attempts to lessen the degeneration of the adjacent elements following interbody fusion procedures. Because the success of artificial disc replacement depends on maintenance or restoration of the mechanical function of the intervertebral disc, it is useful to study the initial mechanical performance of the disc after implantation in the spine. Materials and Methods: A three-dimensional finite element model of the L3–L4 disc was analyzed. The model took into account the material nonlinearities and it imposed different loading conditions. In this study, we validated the model by comparison of its predictions with several sets of experimental data; we determined the optimal Young’s modulus as well as the Poissan ratios for the artificial disc under different loading conditions. Results: The artificial disc was subjected to three loading conditions: 1) compression, 2) bending and 3) torsion. In each case, optimum elastic parameters were determined. Then, by using the root mean square method, optimum parameters for all loading conditions (and therefore minimum error) were calculated. Discussion and Conclusion: The results of this study suggest that a well-designed elastic arthroplastic disc preferably has Young’s modulus values of 18.63 MPa and 1.19 MPa for the annulus and nucleus sections, respectively. Elastic artificial disc with such properties can then achieve the goal of restoring the disc height and mechanical function of a normal disc under different loading conditions.
https://ijmp.mums.ac.ir/article_7217_1b06e0e358fe294244bf2d9a00934ffa.pdf
2011-06-01
65
74
10.22038/ijmp.2011.7217
Low back pain
Intervertebral disc
optimization
Finite Element
Arthroplasty
Azadeh
Ghouchani
azadeh_gh_e83@yahoo.com
1
M.Sc. in Biomedical Engineering, Biomedical Engineering Dept., Amir Kabir University of Technology, Tehran, Iran.
LEAD_AUTHOR
Hamid Reza
Katouzian
2
Associate Professor, Biomedical Engineering Dept., Amir Kabir University of Technology, Tehran, Iran.
AUTHOR
Mohammad
Ravari
3
Instructor, Biomedical Engineering Dept., Mashhad Branch, Islamic Azad University, Mashhad, Iran.
AUTHOR