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Determination of optically stimulated luminescence dosimetric characteristics and suitability for entrance surface dose assessement in diagnostic x-ray examinations

The availability of Optically Stimulated Luminescence (OSL) dosimeter system developed by Landauer Inc. (Glenwood IL) has greatly improved radiation dosimetry application in the medical field. Recent studies with OSL dosimeters (nanoDots) gave much emphases to patient radiation exposure in radiother...

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Main Author: Musa, Yahaya
Format: Thesis
Language:English
Published: 2018
Subjects:
QC Physics
Online Access:http://eprints.utm.my/id/eprint/81634/1/YahayaMusaPFS2018.pdf
http://eprints.utm.my/id/eprint/81634/
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spelling my.utm.816342019-09-10T01:50:14Z http://eprints.utm.my/id/eprint/81634/ Determination of optically stimulated luminescence dosimetric characteristics and suitability for entrance surface dose assessement in diagnostic x-ray examinations Musa, Yahaya QC Physics The availability of Optically Stimulated Luminescence (OSL) dosimeter system developed by Landauer Inc. (Glenwood IL) has greatly improved radiation dosimetry application in the medical field. Recent studies with OSL dosimeters (nanoDots) gave much emphases to patient radiation exposure in radiotherapy but ignoring the potential risks from radiographic examinations. This study focused on the measurement of entrance surface dose (ESD) resulting from radiographic examination. Monitoring procedures have been developed by the International Atomic Energy Agency (IAEA) to estimate ESD, while considering exposure parameters and patient’s characteristics. However, dosimetric properties of the OSL system must be characterized to ascertain its suitability for ESD measurements in medical radiography due to energy dependence and over-response factors of the Al2O3 material. This thesis consists of three phases: 1) evaluating stability of the new OSL dosimetry system, 2) characterizing the nanoDots in radiographic energy range from 40 kV to 150 kV with typical doses ranging from 0 to 20 mGy, and 3) assessing suitability of the nanoDots for ESD measurement in routine X-ray examinations. The dosimetric characteristics of the nanoDots in the above energy range are presented in this study, including repeatability, reproducibility, signal depletion, element correction factor, linearity, angular and energy dependence, and dose measurement accuracy. Experimental results showed repeatability of below 5% and reproducibility of less than 2%. OSL signals after sequential readouts were reduced by approximately 0.5% per readout and having good linearity for doses between 5 – 20 mGy. The nanoDots OSL dosimeter showed significant angular and energy dependence in this energy range, and corresponding energy correction factors were determined in the range of 0.76 – 1.12. ESDs were determined in common diagnostic X-ray examinations using three different methods including direct (measured on phantom/patient) and indirect (without phantom) measurements with nanoDots OSL dosimeters, and CALDose_X 5.0 software calculations. Results from direct and indirect ESD measurements showed good agreement within relative uncertainties of 5.9% and 12%, respectively, in accordance with the International Electrotechnical Commission (IEC) 61674 specifications. However, the measured results were below ESDs calculated with CALDose_X 5.0 software. Measured eye and gonad doses were found to be significant compared to ESDs during anterior-posterior (AP) abdomen and AP skull examinations, respectively. The results obtained in this research work indicate the suitability of utilizing nanoDots OSL dosimeter for entrance surface dose assessment during diagnostic X-ray examinations. 2018 Thesis NonPeerReviewed application/pdf en http://eprints.utm.my/id/eprint/81634/1/YahayaMusaPFS2018.pdf Musa, Yahaya (2018) Determination of optically stimulated luminescence dosimetric characteristics and suitability for entrance surface dose assessement in diagnostic x-ray examinations. PhD thesis, Universiti Teknologi Malaysia. http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:124969
institution Universiti Teknologi Malaysia
building UTM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Teknologi Malaysia
content_source UTM Institutional Repository
url_provider http://eprints.utm.my/
language English
topic QC Physics
spellingShingle QC Physics
Musa, Yahaya
Determination of optically stimulated luminescence dosimetric characteristics and suitability for entrance surface dose assessement in diagnostic x-ray examinations
description The availability of Optically Stimulated Luminescence (OSL) dosimeter system developed by Landauer Inc. (Glenwood IL) has greatly improved radiation dosimetry application in the medical field. Recent studies with OSL dosimeters (nanoDots) gave much emphases to patient radiation exposure in radiotherapy but ignoring the potential risks from radiographic examinations. This study focused on the measurement of entrance surface dose (ESD) resulting from radiographic examination. Monitoring procedures have been developed by the International Atomic Energy Agency (IAEA) to estimate ESD, while considering exposure parameters and patient’s characteristics. However, dosimetric properties of the OSL system must be characterized to ascertain its suitability for ESD measurements in medical radiography due to energy dependence and over-response factors of the Al2O3 material. This thesis consists of three phases: 1) evaluating stability of the new OSL dosimetry system, 2) characterizing the nanoDots in radiographic energy range from 40 kV to 150 kV with typical doses ranging from 0 to 20 mGy, and 3) assessing suitability of the nanoDots for ESD measurement in routine X-ray examinations. The dosimetric characteristics of the nanoDots in the above energy range are presented in this study, including repeatability, reproducibility, signal depletion, element correction factor, linearity, angular and energy dependence, and dose measurement accuracy. Experimental results showed repeatability of below 5% and reproducibility of less than 2%. OSL signals after sequential readouts were reduced by approximately 0.5% per readout and having good linearity for doses between 5 – 20 mGy. The nanoDots OSL dosimeter showed significant angular and energy dependence in this energy range, and corresponding energy correction factors were determined in the range of 0.76 – 1.12. ESDs were determined in common diagnostic X-ray examinations using three different methods including direct (measured on phantom/patient) and indirect (without phantom) measurements with nanoDots OSL dosimeters, and CALDose_X 5.0 software calculations. Results from direct and indirect ESD measurements showed good agreement within relative uncertainties of 5.9% and 12%, respectively, in accordance with the International Electrotechnical Commission (IEC) 61674 specifications. However, the measured results were below ESDs calculated with CALDose_X 5.0 software. Measured eye and gonad doses were found to be significant compared to ESDs during anterior-posterior (AP) abdomen and AP skull examinations, respectively. The results obtained in this research work indicate the suitability of utilizing nanoDots OSL dosimeter for entrance surface dose assessment during diagnostic X-ray examinations.
format Thesis
author Musa, Yahaya
author_facet Musa, Yahaya
author_sort Musa, Yahaya
title Determination of optically stimulated luminescence dosimetric characteristics and suitability for entrance surface dose assessement in diagnostic x-ray examinations
title_short Determination of optically stimulated luminescence dosimetric characteristics and suitability for entrance surface dose assessement in diagnostic x-ray examinations
title_full Determination of optically stimulated luminescence dosimetric characteristics and suitability for entrance surface dose assessement in diagnostic x-ray examinations
title_fullStr Determination of optically stimulated luminescence dosimetric characteristics and suitability for entrance surface dose assessement in diagnostic x-ray examinations
title_full_unstemmed Determination of optically stimulated luminescence dosimetric characteristics and suitability for entrance surface dose assessement in diagnostic x-ray examinations
title_sort determination of optically stimulated luminescence dosimetric characteristics and suitability for entrance surface dose assessement in diagnostic x-ray examinations
publishDate 2018
url http://eprints.utm.my/id/eprint/81634/1/YahayaMusaPFS2018.pdf
http://eprints.utm.my/id/eprint/81634/
http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:124969
_version_ 1646010318519795712
score 13.211869

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