Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
5
Issue 1,2
2008
06
01
Study of Gentamicin Effect on Staphylococcus Aureus in the Presence of Electromagnetic Field
1
8
EN
Asghar
Tanomand
Instructor, Maragheh Faculty of Nursing- Tabriz University of Medical Sciences, Tabriz, Iran
tanomanda@yahoo.com
Amir
Afshin khaki
Associate Professor, Department of Anatomical Sciences, Tabriz University of Medical Sciences and
National Public Health of Management Center, Tabriz, Iran
Hossin
Mehrad
Instructor, Department of Medical, Islamic Azad University, Tabriz, Iran
Hassan
Montazam
Instructor, Department of Microbiology, Islamic Azad University, Bonab, Iran
Maghasood
Kafshnochi
Instructor, Department of Microbiology, Islamic Azad University, Bonab, Iran
10.22038/ijmp.2008.7521
Introduction: Nowadays the medical, therapeutic and pharmacological application of magnetic fields <br/>(MF) and its biological effect has raised question about the safety of MF. This study aimed at <br/>scrutinizing the effect of static MF on the resistance of S. aureus to antibiotic. <br/>Materials and Methods: This prospective, case–control study was conducted to evaluate the effect of <br/>low intensity (0.5 mT) static MF on the growth rate and the antibiotic resistance of S. aureus sensitive to <br/>gentamicin. The studied bacterium is a nosocomial type and the growth rate was calculated by colony <br/>counting to understand the effect of MF on it. In the next stage, the rate of bacterial growth along with <br/>the different concentration of antibiotic was studied and the Minimum Inhibitory Concentration (MIC) <br/>and Minimum Bactericidal Concentration (MBC) were determined. <br/>Results: It is concluded that the 0.5 mT MF didn't affect the growth rate of S. aureus after 24 and 48 hours. <br/>The 0.5 mT MF induced a 50 percent decline of MIC and MBC of gentamicin after a 48 hour incubation (MIC <br/>= 4 6g /cc, MBC = 8 6g /cc in the case group vs. MIC = 8 6g /cc, MBC = 16 6g /cc in the control group). <br/>Conclusion: Low–intensity MF didn't affect the bacterial growth rate. However, the bactericidal effects <br/>of gentamicin were greater in the presence of MF. It is possible to apply the static MF for enhancing the <br/>effect of antibiotic on S. aureus.
Staphylococcus aureus,MIC,MBC,Gentamicin,Electromagnetic Field,Drug resistance
https://ijmp.mums.ac.ir/article_7521.html
https://ijmp.mums.ac.ir/article_7521_550e9a68c7f770dea0fc4d38127495da.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
5
Issue 1,2
2008
06
01
Determination of Dosimetric Parameters of the Second Model of Pd-103 Seed Manufactured at Agricultural, Medical and Industrial Research School
9
22
EN
Gholamreza
Raisali
Associate Professor, Radiation Application Research School, Nuclear Science and Technology Research
Institute, Atomic Energy Organization of Iran, Tehran, Iran
graisali@aeoi.org.ir
Mahdi
Sadeghi
0000-0001-5055-4544
Assistant Professor, Agricultural, Medical and Industrial Research School, Nuclear Science and Technology
Research Institute, Atomic Energy Organization of Iran, Karaj, Iran
sadeghi.m@iums.ac.ir
Vahideh
Ataeinia
M. Sc. in Medical Applications of Radiation, Nuclear Engineering Dept, Faculty of Engineering, Science
and Research Unit, Islamic Azad University, Tehran, Iran
Arjang
Shahvar
B. Sc. in Physics, Agricultural, Medical and Industrial Research School, Nuclear Science and
Technology Research Institute, Atomic Energy Organization of Iran, Karaj, Iran
Maryam Ghasemi
Ghonchehnazi
M. Sc. in Medical Physics, Medical Physics Dept., Faculty of Medical Sciences, Isfahan University of
Medical Sciences, Isfahan, Iran
10.22038/ijmp.2008.7526
Introduction: The use of low energy isotopes such as 103 Pd in brachytherapy for the treatment of cancers <br/>such as prostate, eye, head, neck, breast and cervix is increasing. In this regard, different models of Pd- <br/>103 seeds have been designed and manufactured at the Agricultural, Medical and Industrial Research <br/>School (AMIRS) of Atomic Energy Organization of Iran. In this research, the dosimetric parameters of <br/>the second model of Pd-103 seed manufactured at AMIRS have been calculated and measured. <br/>Materials and Methods: The dosimetric parameters of the second Pd-103 seed manufactured at AMIRS <br/>were determined according to TG-43U1 protocol using Monte Carlo calculations (MCNP4C computer <br/>code) and measurements performed using TLD-GR200A dosimeters in a Perspex phantom. The <br/>parameters include dose rate constant, geometry function, radial dose function, anisotropy function, <br/>anisotropy factor and anisotropy constant. <br/>Results: It was found that by using MCNP4C code the calculated dose rate constant in water and <br/>Perspex was 0.706±0.001 and 0.501±0.001 cGyh -1 U -1 , respectively. Using the calculated geometry <br/>function, the radial dose function and the anisotropy function were determined by experimental and <br/>theoretical methods in water and Perspex phantom. Also, the calculated value of anisotropy constant in <br/>water was equal to 0.88. <br/>Discussion and Conclusion: A discrepancy of less than 10% between the calculated and the measured <br/>values indicates a reasonable agreement between the simulation and the measurement method. Also, the <br/>dosimetric parameters of this seed have been compared to the dosimetric parameters of the first Pd-103 <br/>seed manufactured at AMIRS and some other seeds. The obtained results indicate that the seeds <br/>manufactured at AMIRS have acceptable dosimetric parameters suitable for brachytherapy applications. <br/>
Brachytherapy,Pd-103 Seed,TG-43U1 Protocol,Monte Carlo Simulation,Thermoluminescent Dosimetry
https://ijmp.mums.ac.ir/article_7526.html
https://ijmp.mums.ac.ir/article_7526_1a8c71d395704c29e7ea3f46bb927b5a.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
5
Issue 1,2
2008
06
01
Comparing 511 keV Attenuation Maps Obtained from Different Energy Mapping Methods for CT Based Attenuation Correction of PET Data
23
34
EN
Maryam
Shirmohammad
M.Sc. Student, Department of Medical Physics and Biomedical Engineering and Research Centre for Science and
Technology in Medicine, Tehran University of Medical Sciences, Tehran, Iran
Mohammad Reza
Ay
Assistant Professor, Department of Medical Physics and Biomedical Engineering and Research Centre for Science and
Technology in Medicine, Tehran University of Medical Sciences, Tehran, Iran
mohammadreza_ay@sina.tums.ac.ir
Saeed
Sarkar
Associate Professor, Department of Medical Physics and Biomedical Engineering and Research Centre for Science and
Technology in Medicine, Tehran University of Medical Sciences, Tehran, Iran
Arman
Rahmim
Assistant Professor, Department of Radiology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
10.22038/ijmp.2008.7527
Introduction: The advent of dual-modality PET/CT scanners has revolutionized clinical oncology by <br/>improving lesion localization and facilitating treatment planning for radiotherapy. In addition, the use of <br/>CT images for CT-based attenuation correction (CTAC) decreases the overall scanning time and creates <br/>a noise-free attenuation map (6map). CTAC methods include scaling, segmentation, hybrid <br/>scaling/segmentation, bilinear and dual energy methods. All CTAC methods require the transformation <br/>of CT Hounsfield units (HU) to linear attenuation coefficients (LAC) at 511 keV. The aim of this study is <br/>to compare the results of implementing different methods of energy mapping in PET/CT scanners. <br/>Materials and Methods: This study was conducted in 2 phases, the first phase in a phantom and the <br/>second one on patient data. To perform the first phase, a cylindrical phantom with different <br/>concentrations of K2HPO4 inserts was CT scanned and energy mapping methods were implemented on <br/>it. For performing the second phase, different energy mapping methods were implemented on several <br/>clinical studies and compared to the transmission (TX) image derived using Ga-68 radionuclide source <br/>acquired on the GE Discovery LS PET/CT scanner. <br/>Results: An ROI analysis was performed on different positions of the resultant 6maps and the average <br/>6value of each ROI was compared to the reference value. The results of the 6maps obtained for 511 keV <br/>compared to the theoretical values showed that in the phantom for low concentrations of K 2 HPO 4 all <br/>these methods produce 511 keV attenuation maps with small relative difference compared to gold <br/>standard. The relative difference for scaling, segmentation, hybrid, bilinear and dual energy methods was <br/>4.92, 3.21, 4.43, 2.24 and 2.29%, respectively. Although for high concentration of K 2 HPO 4 the three <br/>methods; hybrid scaling/segmentation, bilinear and dual energy produced the lowest relative difference of <br/>10.91, 10.88 and 5%, respectively. For patients it was found that for soft tissues all the mentioned energy <br/>mapping methods produce acceptable attenuation map at 511 keV. The relative difference of scaling, <br/>segmentation, hybrid, and bilinear methods compared to TX method was 6.95, 4.51, 7, and 6.45% <br/>respectively. For bony tissues, the quantitative analysis showed that scaling and segmentation method <br/>produce high relative difference of 26 and 23.2%, respectively and the relative difference of hybrid and <br/>bilinear in comparison to TX method was 10.7 and 20%, respectively. <br/>Discussion and Conclusion: Based on the result obtained from these two studies it can be concluded <br/>that for soft tissues all energy mapping methods yield acceptable results while for bony tissues all the <br/>mentioned methods except the scaling and segmentation yield acceptable results.
PET/CT,XCOM,TX
https://ijmp.mums.ac.ir/article_7527.html
https://ijmp.mums.ac.ir/article_7527_7eec0987584a57fe9199b2823ce73a43.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
5
Issue 1,2
2008
06
01
Investigation of the Field Size Effect on Wedge Field Isodose Curves Angle for Two Energies; 6 & 18 MV, produced by VARIAN 2100C Linac
35
43
EN
Mohammad Javad T
ahmasebi
Associated Professor, Medical Physics & radiotherapy Dept., Golestan Hospital, Ahwaz University of
Medical Sciences, Ahwaz, Iran
mjtahmasebib@yahoo.com
Mohammad Ali
Behrooz
Professor, Medical Physics Dept., Ahwaz University of Medical Sciences, Ahwaz, Iran
Shole
Arvandi
Assistant Professor, Radiotherapy & Oncology Dept., Golestan Hospital, Ahwaz University of Medical
Sciences, Ahwaz, Iran
Davood
khezerloo
M.Sc. Medical Physics Dept., Ahwaz University of Medical Sciences, Ahwaz, Iran
Mojtaba
karbalai
M.Sc. Medical Physics Dept., Golestan Hospital, Ahwaz University of Medical Sciences, Ahwaz, Iran
10.22038/ijmp.2008.7528
Introduction: Nowadays, considerable developments in the field of radiotherapy have been achieved. <br/>They include the advances made in the equipments and treatment planning techniques which require <br/>highly complex calculations. Such achievements have made it possible to treat cancer patients not only <br/>with higher radiation dose but also with higher precision and consequently increasing the chance of <br/>curing the cancer. However, the conventional techniques requiring physical wedge are still being used <br/>but with a lesser frequency. One of the wedge parameters needed to be measured is the wedge angle. It is <br/>the angle that the horizontal line creates with the tilted isodose curve at a specific depth and for a certain <br/>field size. <br/>In this study, the variation of wedge angle for different field sizes was evaluated using dosimetric and <br/>mathematical method. <br/>Material and Methods: For the wedge fields with a dimension of 6×6 to 20×20 cm 2 , the wedge angle <br/>for two photon energies of 6 and 18 MV was measured by the dosimetric method. For these <br/>measurements, the conventional wedges having the nominal wedge angle of 15, 30, 45 & 60 were used. <br/>The theoretical method suggested by Saw et al. is also used to indirectly calculate the slope of isodose <br/>curve by the dose profile and percent depth dose data. The dose profile, percentage depth dose and <br/>isodose curves were drawn for all the field sizes and the tilt of isodose curve at 10 cm depth, according to <br/>international definition, is considered as the wedge angle. The data were obtained using the theoretical <br/>equation of wedge angle and it was compared to the dosimetric data. <br/>Results: The result obtained in this work shows that the wedge angle increases with the field size. For a <br/>6×6 cm 2 field size, the calculated wedge angle has the highest difference in comparison to the nominal <br/>wedge angle. The difference is equal to 14.7 degree for a 45° wedge and a 6 MV photon. The highest <br/>difference for a 45° wedge angle, a field size of 10×10 cm 2 and a 6 MV photon is 9.2 degree. Comparing <br/>the calculated and measured wedge angles shows a maximum difference of 4 degree for 6 and 18 MV <br/>photon beams. <br/>Discussion and Conclusion: The wedge angle varies with field size. In order to get a better dose <br/>distribution in the conventional radiotherapy, it is necessary to use the appropriate wedge angle which <br/>generates the desired slope for the isodose line and for the specific field size.
Profile Curve,PDD Curve,Isodose Curve,Wedge Angle
https://ijmp.mums.ac.ir/article_7528.html
https://ijmp.mums.ac.ir/article_7528_2cab9efd47d08c430b6cfc8bc9e736ca.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
5
Issue 1,2
2008
06
01
The Measurement of Low Frequency Magnetic Field of Two Kinds of GSM900 Mobile Phone
43
53
EN
Mehri
Kaviani Moghadam
Ph.D. Student in Medical Physics, Tarbiat Modares University, Tehran, Iran
, Seyed Mohammad Jafar
Pourmir Firoozabadi
0000-0002-0607-257X
Associate Professor, Medical Physics Dept., Tarbiat Modares University, Tehran, Iran
pourmir@modares.ac.ir
M.
Lak
M.Sc. Student in Biomedical Engineering (Bioelectric), Science and Research Campus, Islamic Azad
University, Member of Young Researchers Club, Tehran, Iran
M.
Janahmadi
Professor, Physiology and Neuroscience Research Center, Shahid Beheshti Medical Sciences University,
Tehran, Iran
10.22038/ijmp.2008.7529
Introduction: The use of mobile communication systems has dramatically increased over the past <br/>decade. Although many studies have been performed to determine the effect of radio frequency (RF) but <br/>less attention has been paid to the possible biological impact of exposure to extremely low frequency <br/>(ELF) components. <br/>The objective of this study is two folds. One is to design the equipments needed for the measurement of <br/>the ELF fields of two types of GSM900 mobile phone. Secondly, use a protocol suitable for an accurate <br/>assessment of the ELF fields. <br/>Materials and Methods: First a home-made search coil was provided and calibrated precisely under <br/>several experiments. Using Fast Fourier Transform, the power spectrum density of the induced voltage in <br/>the search coil was analyzed and the amplitudes of 217 Hz and its harmonics were extracted and then the <br/>distribution of magnetic field in the back side of mobile phones was determined. <br/>Results: The values of B-field on the back side of the two kinds of GSM mobile phone were different. <br/>They were between 50 to 160 µT in Nokia 3310 and 14 to 30 µT in Nokia 8310. Considering the <br/>difference between the amplitudes of frequency components at 217 Hz and its harmonics in the two kinds <br/>of mobile phone, a range of magnetic flux density at different times in a five day period was measured. <br/>Discussion and Conclusion: These findings emphasize the need for considering the distribution of low <br/>frequency magnetic field from mobile phone when biological effects of magnetic fields are studied. To <br/>determine the intensity windowing effect, one must consider the physical characteristics of the <br/>fundamental frequency component wave (217 Hz) and its harmonics produced by the mobile phone <br/>similar to the one generated under a real situation.
217 Hz,Magnetic Fields,Mobile Phones,GSM900
https://ijmp.mums.ac.ir/article_7529.html
https://ijmp.mums.ac.ir/article_7529_90d24046085275fb11ac4b7dd41e4a44.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
5
Issue 1,2
2008
06
01
Content Based Radiographic Images Indexing and Retrieval Using Pattern Orientation Histogram
55
66
EN
Abolfazl
Lakdashti
Ph.D. Student of Computer Engineering, Islamic Azad University, Research and Science Branch, Tehran, Iran
Mohammad Shahram
Moin
Assistant Professor and Director of Multimedia Research Group, IT Faculty, Iran Telecom Research
Center, Tehran, Iran
moin@itrc.ac.ir
Kambiz
Badie
Associate Professor and Director of IT Faculty, Iran Telecom Research Center, Tehran, Iran
10.22038/ijmp.2008.7530
Introduction: Content Based Image Retrieval (CBIR) is a method of image searching and retrieval in a <br/>database. In medical applications, CBIR is a tool used by physicians to compare the previous and current <br/>medical images associated with patients pathological conditions. As the volume of pictorial information <br/>stored in medical image databases is in progress, efficient image indexing and retrieval is increasingly <br/>becoming a necessity. <br/>Materials and Methods: This paper presents a new content based radiographic image retrieval approach <br/>based on histogram of pattern orientations, namely pattern orientation histogram (POH). POH represents <br/>the spatial distribution of five different pattern orientations: vertical, horizontal, diagonal down/left, <br/>diagonal down/right and non-orientation. In this method, a given image is first divided into image-blocks <br/>and the frequency of each type of pattern is determined in each image-block. Then, local pattern <br/>histograms for each of these image-blocks are computed. <br/>Results: The method was compared to two well known texture-based image retrieval methods: Tamura <br/>and Edge Histogram Descriptors (EHD) in MPEG-7 standard. Experimental results based on 10000 <br/>IRMA radiography image dataset, demonstrate that POH provides better precision and recall rates <br/>compared to Tamura and EHD. For some images, the recall and precision rates obtained by POH are, <br/>respectively, 48% and 18% better than the best of the two above mentioned methods. <br/>Discussion and Conclusion: Since we exploit the absolute location of the pattern in the image as well as <br/>its global composition, the proposed matching method can retrieve semantically similar medical images.
Radiographic Image Retrieval,Texture Feature,Pattern Orientation Histogram
https://ijmp.mums.ac.ir/article_7530.html
https://ijmp.mums.ac.ir/article_7530_9e7705aa8b772d3af05f12720cd326ae.pdf
Mashhad University of Medical Sciences
Iranian Journal of Medical Physics
2345-3672
5
Issue 1,2
2008
06
01
Monte Carlo Dose Calculation of 90 Sr/ 90 Y Source in Water Phantom
67
72
EN
Ali Asghar
Mowlavi
Assistant Professor, Physics Dept., School of Sciences, Sabzevar Tarbiat Moallem University,
Sabzevar, Iran
amowlavi@sttu.ac.ir
10.22038/ijmp.2008.7531
Introduction: 90 Sr/ 90 Y source has been used for the intravascular brachytherapy to prevent coronary <br/>restenosis in the patients who have undergone angioplasty. The aim of this research is to determine the <br/>dose distribution of 90 Sr/ 90 Y source in a water phantom. <br/>Materials and Methods: In the present work, MCNP code has been applied to calculate the dose <br/>distribution around a 3 cm length of 90 Sr/ 90 Y source in a 30×30×30 cm 3 water phantom. Also, the exact <br/>geometry of the source has been used in this simulation. Tally *F8:e which is suitable for beta ray <br/>dosimetry has been evaluated with less than %5 relative error in a sphere having 0.2 mm radius. <br/>Results: The isodose curve for 10, 20, 40, and 90% depth dose (PDD) were derived based on the <br/>calculated dose curves along the parallel and perpendicular axis to the source. <br/>Discussion and Conclusion: The results obtained in this work are in a good agreement with the <br/>experimental result published by Buckley et al. and the International Atomic Energy Agency (IAEA) <br/>report in a water phantom. Therefore, the result of this research can be used in the intravascular <br/>brachytherapy.
90 Sr/ 90 Y Source,Intravascular Brachytherapy,MCNP4C Code,Water Phantom,Isodose Curves
https://ijmp.mums.ac.ir/article_7531.html
https://ijmp.mums.ac.ir/article_7531_7964e672cff48cdf929509baa81665f5.pdf