فهرست مطالب

Medical Physics - Volume:14 Issue: 2, 2017
  • Volume:14 Issue: 2, 2017
  • تاریخ انتشار: 1396/03/29
  • تعداد عناوین: 8
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  • Umit Kara, Huseyin Ozan Tekin, Mehmet Nuri Kivrak, Gokberk Yagci Pages 60-65
    Introduction
    Teaching styles and methods have been constantly changing in the recent years. In the 1980s and 90s, the world was introduced to various developed devices, such as smart boards and early generation smart phones that had an immediate innovative effect on education. These advancements has resulted in a considerable improvement in the current educational techniques. The innovations in medical techniques and their quality is of paramount importance. The aim of this study was to provide an innovative and useful software on radiological applications and contribute to the related literature.
    Materials And Methods
    The Medical Imaging Teacher (MIT) program was created and the prototype application was implemented on the Android platform for free use. The programing and testing of the usability of the application were performed by the users of the Google Play Store.
    Results
    In this program, we have developed new software to simulate the X-ray images of the body by considering the peak kilovoltage (kVp), milliamperage per second (mAs), and film focus distance (FFD) values. The application has been downloaded more than 1,000 times without paid advertising. We enrolled 131 participants, who made comments and gave 4.8 points on average.
    Conclusion
    It can be concluded that with innovative digital programs, such as the MIT, the medical machine-based learning and medical applications have risen to new levels. The software on medical testing and examination is gaining increasing popularity among the health-related applications for smart phones.
    Keywords: Medical Imaging, X-ray, Mobile Applications
  • Shahnawaz Ansari, Subrat Satpathy Pages 66-74
    Introduction
    Single isocentre half-beam block (HBB) technique permits the avoidance of hot and cold spots. This technique is very useful in sparing the underlying ipsilateral lung and heart, if the left breast is treated. The major advantage of this technique is that it facilitates the complete sparing of both contralateral breast and lung. Regarding this, the present study aimed to analyse the dosimetric results obtained from the HBB technique in the treatment of breast cancer using three different algorithms.
    Materials And Methods
    For the purpose of the study, a total dose of 5000 cGy was prescribed to the planning target volume (PTV) in 25 fractions per fraction daily, five days a week. The PTV was derived by using 4-7 mm isotropic expansion of the clinical target volume (CTV) clipping 1-3 mm from the patient’s surface in the breast-conserving cases. Three plans were created for each patient using three different algorithms, including convolution, fast superposition, and superposition with the same parameters.
    Results
    The mean doses of PTV-breast and CTV-supraclavicular fossa (SCF) were tabulated and analysed. In the PTV-breast, the maximum and minimum mean doses were 5428.8 and 4930.2 cGy, which were observed in the fast superposition and convolution algorithms, respectively. In the CTV-SCF, the maximum and minimum mean doses were 5428.8 and 5126.8 cGy, respectively, detected in only fast superposition algorithm.
    Conclusion
    As the findings of the present study indicated, the convolution algorithm gives slightly better dosimetric results in breast cancer treatment, compared to the fast superposition and superposition algorithms. Therefore, it is prudent to apply the HBB technique with convolution algorithm using the Elekta XiO planning system in the treatment of breast cancer including supraclavicular lymph node metastasis.
    Keywords: Isocenter, algorithm, dosimetry, Beam, planning target volume
  • Athiyaman Mayilvaganan, Hemalatha Athiyaman, Arun Chougule, Kumar Hs Pages 75-86
    Introduction
    To estimate the accuracy levels of Lagrange, Newton backward interpolation, and linear interpolation methods in estimating the output factors for square fields used in linear accelerator for 6 MV photons at various depths.
    Materials And Methods
    Ionization measurements were carried out in radiation field analyzer in linear accelerator for 6 MV beams at the depths of 5 and 10 cm by 0.6 cc Farmer-type ionisation chamber. Dosimetry was performed by ion collection method with 0.5 cm2 interval for square fields from 4 × 4 cm2 to 40 × 40 cm2 field sizes. The measured output factor values for 10 square field sizes with equal interval were taken for interpolating the intermediate square field size values. The Lagrange and Newton backward methods were used for predicting the intermediate output factors.
    Results
    The percentage of deviation from the measured value was estimated for all the three methods. The calculated output factor values of the two proposed methods were compared with the standard linear interpolation method used in routine clinical practice. It was observed that the Lagrange and Newton backward methods were not significantly different from the measured value (P=0.77). The linear interpolation values were significantly different from the measured value (P
    Conclusion
    It is recommended to use the Lagrange and Newton backward interpolation methods to estimate the intermediate output factors to increase accuracy in treatment delivery. The routine linear interpolation method can be applied only for small intervals. This proposed interpolation method is highly associated with the measured values in all the interval levels.
    Keywords: Field Size, Interpolation, Linear Accelerator, Output factor
  • Behzad Foulady, Leila Ibrahimighavamabadi, Matharh Bozar, Abbas Mohamadi, Kamran Ahmadi Pages 87-91
    Introduction
    The ionizing radiation is increasingly applied in various fields for industrial and medical purposes due to its benefits. The aim of this study was to measure the radiation levels in six radiology departments of two educational hospitals in Ahvaz, Iran.
    Materials And Methods
    The radiation levels were measured at six locations of six radiology departments, including behind the patient observation window, staff rest room, office, patient waiting room, behind the door of the X-ray room, and outdoor. These measurements were carried out while the X-ray equipment was in on and off status, using the halogen-quenched Geiger-Mueller counter.
    Results
    According to the results, the range of radiation levels inside the radiology departments at X-ray units with on/off status were0.36±0.12 to 0.09±0.02 µSv/h and 0.13±0.02 to 0.09±0.03 µSv/h, respectively. Furthermore, significant differences were observed between the indoor and outdoor radiation levels in all locations.
    Conclusion
    As the findings indicated, the surveyed X-ray equipment in the radiology departments of two educational hospitals was safe. The radiation dose levels were within the safe recommended limits in all locations except two points due to some structural problems, which were recognized and would be corrected as soon as possible.
    Keywords: hospital, ionizing radiation, Radiology, Radiation protection
  • M. H. Kharita, K. M. Wannus Khedr Pages 92-97
    Introduction
    Extensive use of diagnostic radiology is the largest contributor to total population radiation doses. Thus, appropriate equipment and safe practice are necessary for good-quality images with optimal doses. This study aimed to perform quality control (QC) audit for radiography and fluoroscopy devices owned by private sector in Syria (2005-2013) to verify compliance of performance of X-ray machines with the regulatory requirements stipulated by the national regulatory body.
    Materials And Methods
    In this study, QC audit included 487 X-ray diagnostic machines, (363 radiography and 124 fluoroscopy devices), installed in 306 medical diagnostic radiology centers in 14 provinces in Syria. We employed an X-ray beam analyzer device (NERO model 8000, Victoreen, USA), which was tested and calibrated at the National Secondary Standard Dosimetry Laboratory traceable to the IAEA Network of Secondary Standard Dosimetry Laboratories. Standard QC tool kits were used to evaluate tube and generator of the X-ray machines, which constituted potential (kVp), timer accuracy, radiation output consistency, tube filtration, small and large focal spot sizes, X-ray beam collimation and alignment, as well as high- and low-resolution and entrance surface dose in fluoroscopy.
    Results
    According to our results, most of the assessed operating parameters were in compliance with the standards stipulated by the National Regulatory Authority. In cases of noncompliance for the assessed parameters, maximum value (28.77%) pertained to accuracy of kVp calibration for radiography units, while the lowest value (2.42%) belonged to entrance surface dose in fluoroscopy systems.
    Conclusion
    Effective QC program in diagnostic radiology leads to obtaining information regarding quality of radiology devices used for medical diagnosis and minimizing the doses received by patients and medical personnel. The findings of this QC program, as the main part of QA program, illustrated that most of the considered diagnostic X-ray devices had
    acceptable performance and few of them need to be recalibrated for some parameters.
    Keywords: Diagnostic X-ray, fluoroscopy, Quality Control, Radiography
  • Peyman Lotfalinezhad, Sedigheh Kashian, Mohsen Saleh Kotahi, Ali Asghar Fathivand Pages 98-103
    Introduction
    Considering the risk of radiation, the measurement of the natural radiation sources seems to be necessary. In this study, the concentrations of the natural radionuclides, namely 226Ra, 232Th, and 40K, were measured in the soil samples taken from different locations of Golestan, Iran. The measurement results can also be used as a baseline to evaluate the impact of non-nuclear activities and the routine releases of nuclear installations.
    Materials And Methods
    A total of 42 soil samples were collected. The samples were sealed for at least three weeks to ensure the secular equilibrium between 226Ra and 232Th and their respective radioactive progenies. The activity concentrations of natural radionuclides in soil samples were measured using a shielded HPGe detector.
    Results
    The average activity concentrations of 226Ra, 232Th, and 40K were 23, 31, and 453 Bq.kg-1, respectively. To assess the radiological hazards, the Ra equivalent activity as well as the external and internal hazard indices were estimated. Radium equivalent varied within the range of 58.4-142.6 Bq.kg-1 with a mean value of 102.4 Bq.kg-1. The estimated mean values of Hex and Hin (0.28 and 0.34, respectively) in the area under investigation were lower than unity as desirable. Therefore, it did not pose any health risks to the population of the area.
    Conclusion
    The results of this study were compared with those of other studies carried out in other countries. As the findings of the present study indicated, the health-related risks causing by the naturally accruing radionuclides was very low in the investigated area.
    Keywords: exposure, gamma spectrometry, Iran, Natural radioactivity
  • Asghar Mesbahi, Dogukan Akcay, Ismail Volkan Tekcan, Zumre Arican Alikus Pages 104-113
    Introduction
    The aim of this retrospective study was to evaluate the variations in delivered dose to the bladder, rectum, and femoral heads of prostate cancer patients during a course of treatment by image-guided radiation therapy (IGRT).
    Materials And Methods
    Overall, 15 patients with prostate cancer were selected and. Each week, for each patient five consecutive cone beam computed tomography (CBCT) images were taken after bony anatomy alignment by using two orthogonal radiographic images, as well as CBCT images. Dose distributions and dose volume histograms (DVH) for all the original and CBCT plans were obtained. Maximum, as well as mean doses and volumes of the bladder, rectum, and both femoral heads were recorded for each CBCT plan and compared with the original CT plan. For all the studied body parts, the differences in DVH between CBCT plans and original CT plan were calculated and compared.
    Results
    Considering all the 75 CBCT images for the 15 patients, average of changes in mean doses and volumes were 17.8%, 41.8%, 7.1%, and 36.8% for the bladder and rectum, respectively. There was a significant (P
    Conclusion
    Our results showed that changes in volumes of the bladder and rectum alter their received inter-factional mean doses. Further attention to the volume variations of the bladder and rectum during a radiotherapy course is recommended for more accurate IGRT treatment.
    Keywords: image guided radiation therapy, Cone beam computed tomography, Prostate cancer, volumetric modulated arc therapy
  • Farshad Namdari, Masoumeh Dadpay, Morteza Hamidi, Hosein Ghayoumi Zadeh Pages 114-121
    Introduction
    A varicocele is the abnormal dilation and tortuosity of venous plexus above the testicles. The pattern of abnormal heat distribution in the scrotum can be detected through thermal imaging, which is a distant, non-contact, and non-invasive method. The aim of the present study is to detect and grade varicocele.
    Materials And Methods
    This study was conducted on 50 patients with high probability of varicocele, who referred to a hospital affiliated to the AJA University of Medical Sciences, Tehran, Iran. The evaluation procedure included thermal imaging, clinical diagnosis, and ultrasound test. The gold standard method was based on ultrasound examination. The thermal imaging was performed using a non-contact infrared camera.
    Results
    This paper presented two methods for diagnosing and grading varicocele. The first method was based on the patterns and models of thermal asymmetry in the testicles (including three asymmetric and symmetric patterns). The second method was based on the temperature differences. The obtained results demonstrated that the use of temperature differences in the diagnosis of varicocele was better than the other proposed method. In addition, a temperature difference of 0.5°C in the pampiniform venous plexus was an important indicator for the diagnosis of varicocele using thermal imaging. The accuracy of thermography in grading varicocele was 76%.
    Conclusion
    According to the results of the study, thermography is a useful method for initial varicocele screening and can be applied as a supplement to other diagnostic techniques due to its low cost and lack of radiation exposure. Thermography was concluded to be a precise technique for the diagnosis of varicocele; however, its capability to determine the varicocele grading was comparatively low.
    Keywords: Diagnostic imaging, Thermography, Varicocele