Sharif Digital Repository

Today the hydrocarbon materials rank in the list of requirements of the modern societies. The increased growth of the human population, their industrial economic activities, transportation etc. requires sufficient supplies of our resources. Therefore, the hydrocarbon resources need to be discovered and evaluated accurately. There are different methods that are used to measure underground hydrocarbon resources such as well logging. In this method, a measuring device is lowered into a well to evaluate several parameter of the surrounding soil. Nuclear well logging is a sub category of well logging that uses nuclear rays to do this measurement. This method has different types of sondes which... 

In this Thesis, a nuclear borehole logging tool has been designed and constructed for measuring the bulk density of a formation by the use of gamma rays. One of the main applications of this tool is obtaining of porosity. It also is useful in the detection of formations containing oil and gas. This tool consists of: a gamma ray source 60Co, a single gamma ray detector NaI(Tl), lead shield and electronic modules. The cylindrical sond is entered into a borehole and the surrounding formation is subjected to the emitted gamma rays from the source. The formation density can be determined from the measurement of the scattered photons reaching the detector from the formation. The purpose of the... 

Environmental conditions of various cities of Iran are deteriorating due to various contributing effects of increased traffic, deforestation, industrial pollution etc. Arak is an example in point. It is a city of about 440,000 inhabitants. It is located at the edge of the main central desert (Kavir) of Iran. It lacks any appreciable vegetation or wooded areas and it is the home of a number of major industries. These include aluminum smelting, petrochemical industry, refinery, power plant and various other heavy manufacturing facilities. It was suggested to perform an air sampling of the city for a whole year (2010-2011) to determine the concentration of various elements by instrumental... 

Method of Prompt Gamma Neutron Activation Analysis (PGNAA) is useful for controlling some massive production processes such as cement industry and mineral materials. Difficulty of other methods of analysis such as XRF comparing with PGNAA is that mass of sample is small and it doesn’t determine heterogeneity of mixture. On the other hand, need to sampling is also another problem of these analysis methods because sampling is terminated and it doesn’t supervise on production continuously, in fact its quality can’t be revealed simultaneously and there is a long time between sampling and control of process. Usually, analysis methods such as XRF are useful for processes that are controlled... 

City of Karaj with 2 million population used to enjoy very clean and accommodating air and environment . This congenial condition was due to agricultural and gardening activities of the local population . This way of life has undergone a profound change due to a change in the economic activities of the local population from farming and agriculture to industrial activities . And this has brought particulate matter wich has been exacerbated in the recent years . With the additional onslaught of the dust storms coming from the neighboring countries due to drying up of rivers and lagoons .The main object of this work was to obtain the spectrum of the PM and the additional component of PM that... 

Ionizing radiation can modify physical, chemical and biological properties of the irradiated materials. At present, the principal industrial applications of radiation are sterilization of health care products including pharmaceuticals, irradiation of food and agriculture products and materials modification. In the above application the wide range of the required doses together with different product densities require spatial mechanical design of the irradiators to be able to properly handle the specified tasks. In the multipurpose irradiators the design of system and positioning of the source must be done in such a way that a nearly optimum dose distaition in the product boxes in... 

Gamma irradiation systems are used extensively in the industry in order to sterilize medical devices, disinfect hygienic materials or increase the shelf life of agricultural produce. The method of gamma irradiation is superior to the older methods of heat or chemical treatment because it is by far a simpler operation. In this method only a single parameter of time is controlled whereas in the other mentioned methods five or six different parameters need to be controlled. The design of irradiation systems including the size, location of products and arrangement of source rack pencils. In order to optimize the design it is needed to study the products dose distribution in a wide range of... 

Almost half of all cancer patients receive radiation therapy as main or part of the treatment process. Before performing radiation therapy, first it is necessary to determine the patient’s treatment plan and estimate the outcome of it based on the dose distribution. The quality of treatment is dependent on the accuracy of dosimetry calculations that lies in Monte Carlo algorithms. Unfortunately, most of the computation time is long and not suitable for clinical applications. On the other hand, a real treatment planning will be possible if all aspects of radiation therapy should be considered. The radiation source that is obtained from a medical linear accelerator head is one of these... 

In this project a dual density logging tool has been designed and constructed for measuring the bulk density of a formation using gamma rays. One of the main applications of this tool is obtaining porosity. It also is useful in the detection of formations containing oil and gas. In this work, MCNP Monte Carlo code was used to simulate the performance of the scattered gamma rays under various sond-formation parametric condition. The results coming from this code are applied to determine the fundamental parameters of gamma-gamma density tools like, Energy window, thickness of lead, optimum distance between each detectors. Furthermore, a novel method based on summation of back scatter and... 

Ahwaz is typical of a polluted city. It ranks in the third place after Tehran and Esfahan and with the onslaught Of the dust storms it has acquired the dubious distinction of 1st polluted city in the world. The pollution status of this city was investigated from May 2012 to May 2013. 110 air filters were collected during this period. The air filters were analysed with AAS and INAA techniques. with the use of AAS we measured the concentration of Cd, Cu, Fe, Mg, Mn, Ni and Pb elements. For the use of INAA method on the air filters we used two reactors of MNSR at Esfahan and the 5MW research reactor of Tehran. We managed to measure twenty five elements of Al , As , Br , Ca , Ce , Cl , Co , Cr ,... 

Breast cancer is the second leading cause of cancer death among women. Mammography is considered the “gold standard” in the evaluation of the breast lesions from an imaging perspective. But this modality has limitations. Completed studies are used to overcome these limitations. The Positron Emission Mammography (PEM) is the one of these complementary methods. PEM imaging is a molecular imaging modality for the diagnosis of breast cancer. In this thesis, a commercial PEM system as Naviscan PEM has been simulated using the GATE program. This system consists of two parallel planes of detectors, each detector consists of 12 blocks with 6 × 2 array and each block consists of 169 crystals with 13... 

Total air particulate matter of the city of Isfahan has been measured for elemental characterization in four principal directions of the city and during the year 2007-2008. High volume air samplers using whatman 41 filters have been utilized and instrumental neutron activation analysis has been used as the analytical method. Twenty one elements arising from seasonal and geographical distributions of the various elements have been determined. These distribution patterns have been discussed in view of the prevailing wind direction, location of the industrial facilities, and the Pearson correlation coefficients  

Varian Clinac 2100 accelerator head was simulated using EGS5 Monte Carlo code. Phase space method was applied to this simulation. Two phase space plates were used in these simulations; one was inserted before the moveable jaws and the other one was placed after the jaws. The first plate was simulated for energy. And the second plate was to simulate each field size at the set energy. In the phase space method used in the EGS5 code one extracts the particle parametric information from a file as opposed to following the original particles that start at the source point. It is expected that this file to be a replica of the particles that pass the plate and further it should not add any... 

Radiation therapy is a treatment modality that is used in treatment of most newly diagnosed cancer patients. In this method the interaction of radiation with matter and their biological effects is used for cancer treatment. The energy and intensity of the radiation in radiotherapy should be considered in order to have a lethal effect on tumors. Linear accelerators are substitutes for previous methods of radiotherapy in all over the world. These machines can work in both electron and photon mode. The Monte Carlo technique has become ubiquitous in medical physics in the last 50 years. The range of applications is very broad in medical physics. The increased use of Monte Carlo techniques is... 

Metastatic bone is one of the most common causes pain in cancer patients. Because of Sm-153 emits gamma and beta, Sm-153 have been used for both of the diagnosis and treatment of metastases; Also Tc-99m have been used for the detection of metastases. Dosimetric studies in targeted radiotherapy require an accurate quantification of activity existing in different organs of a patient, which can be estimated from scintigraphic images. Quantitative imaging is difficult to perform because of several physical phenomena, such as scatter and attenuation, which lead to errors in activity determination and nuclear medicine image degradation.
In this work, we must determine the optimal... 

In radiotherapy, dose calculation is one of the most important stages that should be carefully done for patient treatment planning. Dose calculation methods have been developed from early dose algorithms that used analytical methods to relatively recent high precision monte carlo methods.Monte carlo methods while very accurate in dose estimations usually suffer from long computation time. In the recent time the emphasis for reduction of the computation time has been focused on software techniques as well as on hardware technology development. One example of hardware development has been graphic processing unit (GPU) which was introduced in 2006 by the Nvidia to accelerate the processing and... 

The Scattered radiation is the principal factor affecting the quality of the digital and screen-film mammography images. The contrast improvement factor and bucky factor which are also referred to as the benefit and risk of the anti-scattered grid cannot be properly assessed without a detailed knowledge of the scattered radiation. In this work the scatter to primary ratio has been calculated and an anti-scatter grid has been designed based on the reduction of the scattered radiation to reduce the patient dose to a minimum level and to improve the image quality simultaneously.The MCNPX 2.6.0 Monte Carlo code has been used to improve the geometry of the anti-scatter grid to both reduce the... 

Compact linear accelerator is equipped with a single fixed motorized wedge that produces different wedge angles by combining an open and a wedged field in the appropriate proportions.
In this work, the required data for the Treatment Planning System, TPS were generated for utilizing Compact motorized wedge, MW and was verified by dosimetry. To verify MW, the accumulated wedge profiles at a depth of 10 cm for different wedge angles were measured using 2-D Profiler and were calculated the wedge angles using an analytical formula. The validity of effective wedge angles 2-D Profiler has been done by determining the wedge angles in accordance with ICRU-24 for compact MW and Telecobalt... 

Dust phenomenon is a combination of tiny particle with urban pollution that it is harmful for respiratory disease. But this phenomenon has been prevalent in our country recently. We utilized NASA satellite pictures to observe dust storms in the present project. We have collected images of possible sources of dust on the days when we are faced with the dust storm phenomenon. Then by processing of NASA satellite pictures (recognition of distribution of optical and particle density in the dust particle arising and comparing results through analysis of these images to estimate the main characteristics of the sampling locations). we have find the desired location for taking samples of soil... 

Genetic significant dose to the Iranian population from diagnostic radiology procedures has been measured. A survey of 26500 radiology patients has radiological tests, age and sex distribution. A second survey has produced the radiological operational parameters, including kV, mAs, FTD, field size, filtration, film number & body orientation. Statistical demographic data have been obtained and from which child expectancy number have been calculated. A Rando phantom has been used for dosimetry phase of the gonad doses using TLD. Combining all of the above data a new GSD of 10.5 mrem/year has been calculated which is 14% higher than the previous number measured in 1980