Title: Enhancement of precision and accuracy by Monte-Carlo simulation of a well-type pressurized ionization chamber used in radionuclide metrology
Language: English
Authors: Kryeziu, Durim 
Qualification level: Doctoral
Keywords: Monte-Carlo simulation; PENELOPE simulation code; Radionuclide Metrology; Ionisation chamber; radioactive standard solution; Radionuclide calibration factor; Volume correction factor
Monte-Carlo simulation; PENELOPE simulation code; Radionuclide Metrology; Ionisation chamber; radioactive standard solution; Radionuclide calibration factor; Volume correction factor
Advisor: Tschurlovits, Manfred
Assisting Advisor: Maringer, Franz Josef
Issue Date: 2006
Number of Pages: 290
Qualification level: Doctoral
Abstract: 
The aim of this work was to test and validate the Monte-Carlo (MC) ionisation chamber simulation method in calculating the activity of radioactive solutions. This is required when no or not sufficient experimental calibration figures are available as well as to improve the accuracy of activity measurements for other radionuclides. Well-type or 4[pi][gamma] ISOCAL IV ionisation chambers (IC) are widely used in many national standard laboratories around the world. As secondary standard measuring systems these radionuclide calibrators serve to maintain measurement consistency checks and to ensure the quality of standards disseminated to users for a wide range of radionuclide where many of them are with special interest in nuclear medicine as well as in different applications on radionuclide metrology.
For the studied radionuclides the calibration figures (efficiencies) and their respective volume correction factors are determined by using the PENELOPE MC computer code system. The ISOCAL IV IC filled with nitrogen gas at approximately 1 MPa is simulated. The simulated models of the chamber are designed by means of reduced quadric equation and applying the appropriate mathematical transformations. The simulations are done for various container geometries of the standard solution which take forms of: i) sealed Jena glass 5 ml PTB standard ampoule, ii) 10 ml (P6) vial and iii) 10 R Schott Type 1+ vial.
Simulation of the ISOCAL IV IC is explained. The effect of density variation of the nitrogen filling gas on the sensitivity of the chamber is investigated. The code is also used to examine the effects of using lead and copper shields as well as to evaluate the sensitivity of the chamber to electrons and positrons. Validation of the Monte-Carlo simulation method has been proved by comparing the Monte-Carlo simulation calculated and experimental calibration figures available from the National Physical Laboratory (NPL) England which are deduced from the absolute activity measurements. Monte-Carlo ionisation chamber simulation method proved that the simulated results are costs only by statistical and not by systematic errors. Based on Monte-Carlo simulation methods the energy-dependent photon-efficiency curves for radioactive solution on 5 ml ampoule and P6 vial for the ISOCAL IV IC are constructed. The Monte-Carlo determined energy-dependent photon efficiency curve, so called the sensitivity function and the theoretical curve showed a very good conformity.

The aim of this work was to test and validate the Monte-Carlo (MC) ionisation chamber simulation method in calculating the activity of radioactive solutions. This is required when no or not sufficient experimental calibration figures are available as well as to improve the accuracy of activity measurements for other radionuclides. Well-type or 4[pi][gamma] ISOCAL IV ionisation chambers (IC) are widely used in many national standard laboratories around the world. As secondary standard measuring systems these radionuclide calibrators serve to maintain measurement consistency checks and to ensure the quality of standards disseminated to users for a wide range of radionuclide where many of them are with special interest in nuclear medicine as well as in different applications on radionuclide metrology.
For the studied radionuclides the calibration figures (efficiencies) and their respective volume correction factors are determined by using the PENELOPE MC computer code system. The ISOCAL IV IC filled with nitrogen gas at approximately 1 MPa is simulated. The simulated models of the chamber are designed by means of reduced quadric equation and applying the appropriate mathematical transformations. The simulations are done for various container geometries of the standard solution which take forms of: i) sealed Jena glass 5 ml PTB standard ampoule, ii) 10 ml (P6) vial and iii) 10 R Schott Type 1+ vial.
Simulation of the ISOCAL IV IC is explained. The effect of density variation of the nitrogen filling gas on the sensitivity of the chamber is investigated. The code is also used to examine the effects of using lead and copper shields as well as to evaluate the sensitivity of the chamber to electrons and positrons. Validation of the Monte-Carlo simulation method has been proved by comparing the Monte-Carlo simulation calculated and experimental calibration figures available from the National Physical Laboratory (NPL) England which are deduced from the absolute activity measurements. Monte-Carlo ionisation chamber simulation method proved that the simulated results are costs only by statistical and not by systematic errors. Based on Monte-Carlo simulation methods the energy-dependent photon-efficiency curves for radioactive solution on 5 ml ampoule and P6 vial for the ISOCAL IV IC are constructed. The Monte-Carlo determined energy-dependent photon efficiency curve, so called the sensitivity function and the theoretical curve showed a very good conformity.
URI: https://resolver.obvsg.at/urn:nbn:at:at-ubtuw:1-16712
http://hdl.handle.net/20.500.12708/12040
Library ID: AC05032914
Organisation: E141 - Atominstitut der Österreichischen Universitäten 
Publication Type: Thesis
Hochschulschrift
Appears in Collections:Thesis

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