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Simulation of Sound Field of Multiple Sound Sources
Kohoutek, Jan ; Kurc, David (referee) ; Schimmel, Jiří (advisor)
The main task of this bachelor thesis is description of interaction of sound waves in field. To understand the whole topic important physical laws related to sound waves propagation are defined. It also deals with frequency and directional response of ideal point source which compares with real measured responses of direct-radiating electrodynamic loudpeaker. Thesis are shown some examples of sound fields on which are specified their behavior. It also desribe main properties for right functionality of line-array source. In practical part are measured acoustic pressure values which lead to creating a interpolation map of sound pressure level. This obtained map was compared with theoretical acoustic field. Part of this bachelor thesis is program which enable to simulate acoustic field created under variable sound and environment properties.
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Sound emission directivity model
Zdvyhal, Marian ; Hájek, Roman (referee) ; Hejčík, Jiří (advisor)
This diploma thesis solves creation of a computing model of sound propagation for determination of acoustic pressure level around multiple point sound source with consideration of sound directivity of each source (compresor and fan). Thesis contains neccesary theoretical knowledge for creation of computing model and basics of sound measuring, theoretical computing model, measurement data of real unit and model configuration for real measured values. Computing code of the model in Visual Basic for MS Excel is a part of the thesis.
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Simulation of Sound Field of Multiple Sound Sources
Kohoutek, Jan ; Kurc, David (referee) ; Schimmel, Jiří (advisor)
The main task of this bachelor thesis is description of interaction of sound waves in field. To understand the whole topic important physical laws related to sound waves propagation are defined. It also deals with frequency and directional response of ideal point source which compares with real measured responses of direct-radiating electrodynamic loudpeaker. Thesis are shown some examples of sound fields on which are specified their behavior. It also desribe main properties for right functionality of line-array source. In practical part are measured acoustic pressure values which lead to creating a interpolation map of sound pressure level. This obtained map was compared with theoretical acoustic field. Part of this bachelor thesis is program which enable to simulate acoustic field created under variable sound and environment properties.
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Sound emission directivity model
Zdvyhal, Marian ; Hájek, Roman (referee) ; Hejčík, Jiří (advisor)
This diploma thesis solves creation of a computing model of sound propagation for determination of acoustic pressure level around multiple point sound source with consideration of sound directivity of each source (compresor and fan). Thesis contains neccesary theoretical knowledge for creation of computing model and basics of sound measuring, theoretical computing model, measurement data of real unit and model configuration for real measured values. Computing code of the model in Visual Basic for MS Excel is a part of the thesis.
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Centre of rotation stability setting for the INFINIA camera
BAKI, Marcel
My bachelor thesis focus on Centre of rotation stability for Infinia cameraAt my work I got closely familiarize with scintillation camera Infinia Hawkeye, which is located in the department of nuclear medicine in the České Budějovice. The aim of my work was to determine whether the centre of rotation (C.O.R.) takes place around a fixed axis, and thus whether there is not movement. The method that I chose to accomplish my goals, was to test the camera , which was performing by 360° acquisition around a point source 99mTc. The point source was fitted to a rod and placed on the Infinia camera on patient's pallet. Testing was carried out with two collimators LEHR and LEGP in modes H and L. The testing was performed by radiological physicist, always in the afternoon to ensure smooth running of the workplace. The test confirmed my hypothesis that the value will be within the values specified by the manufacturer. Testing was performed once a month for half a year. In In this days because we are apperceiving tremendous technological progress, and devices which allow us to produce more perfectly and detailed images and contribute to better diagnosis and treatment are created it is very important to ensure the quality control. Over the last few years progress in gamma camera designs , have improved all aspects of image quality, particularly in tomographic images. As the system complexity increases, it becomes more important that all nuclear medicine employees are able to recognize the various types of aberrations or artefacts that can occur in nuclear medicine imaging systems. The primary purpose of the quality control program in department for nuclear medicine is to verify that the images accurately reflect distribution of the radiopharmaceutical within the patient. The purpose of quality control is detect changes of gamma camera system that may adversely affect the interpretation of clinical studies. There are large number of factors that contribute to the final quality of the image ( including uniformity, resolution - both intrinsic and energy, pulse frequency, centre of rotation system, rotational stability of the detector head). On a everyday examinations there is a limited amount of time that can be reasonably devoted to quality control system. Hence the main goal of quality control program should be to monitor those parameters that are most sensitive to changes in system performance and are most likely to impact clinical studies. Therefore , the main objective of quality control program should be monitor the parameters that are most sensitive to changes in system performance and most likely have a impact on the clinical studies. Specials series of quality control tests were designed to ensure the optimal performance of the camera. Over the whole time of the entire period of clinical operation, technicians or physicists regularly perform various quality control tests, some daily, others weekly or monthly. The purpose of these tests is monitor day to day camera performance and detect changes from the baselines values. Additional quality control test may be performed to compare characteristics of different systems and to optimize the quality of clinical studies.
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Daily test of the AXIS scintigraphic camera quality in the Nuclear Medicine Department in Pribram as an indicator of the apparatus stability for the last 5 years
HEFKA, Pavel
Daily test of the AXIS scintigraphic camera quality in the Nuclear Medicine Department in Pribram as an indicator of the apparatus stability for the last 5 years This Thesis is devoted to the choice of the most suitable routine check of the AXIS scintigraphic camera in the Nuclear Medicine Department in Pribram. In my Thesis I focused on the analysis of the recommended procedures and choice of the method, which during the routine operation of nuclear medicine will sufficiently prove the quality of the preparation of the apparatus for the examination and is not very time-consuming. The result of such an optimization analysis is the check procedure of the internal image homogeneity, which fully respects SÚJB recommendations and procedures recommended by the producer of the AXIS scintigraphic camera. Performance of the chosen method is described in detail and the method of the recording, acquisition and evaluation of the acquired data is presented. Checking of the AXIS apparatus in the described way has been performed in the Nuclear Medicine Department in Pribram for a long time. It enabled me to make an analysis of the long-term stability of the apparatus for the last 5 years. Acquired results have been compared with information given by the producer and results of the similar device in the Czech Republic. For clarity purposes the presentation of the recorded data and acquired results is arranged in tables and graphs. Collected data confirmed that the homogeneity values measured by means of the point source correspond well to the data stated for this apparatus by the producer. This has also confirmed my hypothesis on the correct choice of the method for testing the homogeneity by means of the point source. Therefore it is possible to state that the AXIS gamma camera with the supplement for the detection of positron emitters is stable and it is possible to apply it in the routine clinical operation even after 10 years of use provided that the good service care is ensured.
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DST-XL scintillation camera and stability of its visual field uniformity
RUDOLFOVÁ, Veronika
Visual field uniformity of DST-XL scintillation camera is assessed on daily basis during quality controls of instrumentation at the Department of Nuclear Medicine at Hospital in České Budějovice. Uniformity is a critical quality parameter in scintigraphic imaging. It indicates whether all points in visual field are displayed with equal efficiency (sensitivity). Also, it allows specialists to obtain quality images of how radiopharmaceuticals are distributed in a patient?s body. The objective of my bachelor?s thesis is to verify whether the measured values fall within the range set by the manufacturer. Assessments were carried out on a bi-weekly basis for the duration of six months between start of October 2010 and end of March 2011. The measurement method used at the Department of Nuclear Medicine at Hospital in České Budějovice employs homogeneous irradiation of the detector without collimator produced by a point source which allows assessment of intrinsic uniformity of the detector. Also, there is another method that determines total (extrinsic) uniformity of the camera. This method utilizes an area source to produce homogeneous irradiation of the detector. The important difference between the two methods is that the latter uses collimator, unlike the method used for the purposes of this thesis. Yet, both methods produce roughly the same outcomes. The results obtained from the tests of stability of DST-XL scintillation camera?s visual field uniformity fall within the range of values permitted by the manufacturer and confirm my hypothesis.
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Stability of the field of view uniformity in gamma kamera Infinia
KOLÁŘOVÁ, Hana
The methods of field-of-view uniformity measurement on Infinia scintillation cameras as applied within the daily quality control exercise are described, and the results are evaluated against the limiting levels specified by the manufacturer. Uniformity is a basic parameter describing the scintillation camera image quality. In order to assure a smooth and continuous operation of nuclear medicine departments, instrumentation must comply with quality requirements for the examination of patients. For Infinia scintillation cameras the manufacturer recommends their planar integral uniformity to be tested on a day-by-day basis. Infinia cameras are parts of SPECT/CT systems. If the planar parameters of the SPECT system are not very good, planar imaging is slightly affected but SPECT images in the tomographic mode can be ruined altogether.Two methods exist for uniformity measurement, using either a point source of ionizing radiation or a planar source of ionizing radiation, respectively. The main objective of this project was to collect measuring data from several departments, compare them and ascertain whether the data exceed the limit specified by the manufacturer. From the field-of-view uniformity measurements it can be concluded unambiguously that the limits specified by the manufacturer of the Infinia scintillation cameras were never exceeded. In other words, the performance of the detection technology was never so poor as to affect adversely the diagnostic information derived from the system. In conclusion, information gained within this work attests to the reliability of Infinia scintillation cameras.
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