Radiation doses, cancer risks and optimization process of routine computed tomography (CT) exminations in Johor

ABSTRACT The concerns towards radiation–induced cancer from Computed Tomography (CT) examinations have led to the encouragement of CT dose monitoring and further optimization of the scanning parameters. Therefore, in this study, radiation dose from CT scan and its related risks to the patients from...

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Main Author:	Abdul Karim, Muhammad Khalis
Format:	Thesis
Language:	English
Published:	2017
Subjects:	QC Physics
Online Access:	http://eprints.utm.my/id/eprint/79411/1/MuhammadKhalisPFS2017.pdf
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spelling	my-utm-ep.794112018-10-16T07:30:36Z Radiation doses, cancer risks and optimization process of routine computed tomography (CT) exminations in Johor 2017 Abdul Karim, Muhammad Khalis QC Physics ABSTRACT The concerns towards radiation–induced cancer from Computed Tomography (CT) examinations have led to the encouragement of CT dose monitoring and further optimization of the scanning parameters. Therefore, in this study, radiation dose from CT scan and its related risks to the patients from current CT practice were analysed. In the first stage, this thesis started the discussion on the level of current knowledge among radiology personnel towards CT radiation risk and its optimization. There is no significant difference of the current knowledge of CT optimization between the two professions of interest herein, the medical and the allied health groups. A CT dose survey was conducted in 8 CT facilities for a 6-month period, encompassing data for 1024 patients with various CT examinations that included regions of the abdomen, brain and thorax. CT-EXPO (Version 2.3.1, Germany) software was used to validate the dose information such as CT Dose Index (CTDI) and dose-length product (DLP). The proposed Diagnostic Reference Levels (DRLs) were indicated by rounding off the third quartiles (Q3s) of whole dose distributions for weighted CTDI (CTDIw) (in mGy), volume CTDI (CTDIvol) (in mGy) and DLP (in mGy.cm) and their values were; 16, 17, and 650 respectively for CT abdomen; 70, 70, and 1030 respectively for CT Brain and 15, 16, and 670 respectively for CT thorax. In the second stage, the cancer risks of the CT examinations were estimated and the calculation was based on International Commission on Radiation Protection (ICRP) Publication 103 Report and Biological Effects of Ionizing Radiation (BEIR) VII Report. Based on BEIR VII recommendation, the study discovered that the lifetime attributable risks (LARs) of 100,000 populations who underwent abdominal CT examinations for stomach cancer were 2.3 for male and 1.0 for female; while for colon cancer the LARs were 2.3 for male and 0.7 for female. The effectiveness of optimization of CT parameters and application of shielding in routine CT procedures were evaluated. Of 7 protocols (P1 – P7), the k factors were constant for all protocols and decreased by ~8% compared to the universal k factor. It is of interest that k factors from CT-EXPO were found to vary between 0.010 for protocol P5 and 0.015 for protocol P3 due to inconsistency in tube potential and pitch factor. The application of breast shielding to routine CT thorax protocols reduced by 14% the breast’s equivalent dose. Hence, this study supports the importance of initiating protection and optimization processes of routine CT examinations in order to offer safer imaging practices. 2017 Thesis http://eprints.utm.my/id/eprint/79411/ http://eprints.utm.my/id/eprint/79411/1/MuhammadKhalisPFS2017.pdf application/pdf en public phd doctoral Universiti Teknologi Malaysia, Faculty of Science Faculty of Science
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	QC Physics
spellingShingle	QC Physics Abdul Karim, Muhammad Khalis Radiation doses, cancer risks and optimization process of routine computed tomography (CT) exminations in Johor
description	ABSTRACT The concerns towards radiation–induced cancer from Computed Tomography (CT) examinations have led to the encouragement of CT dose monitoring and further optimization of the scanning parameters. Therefore, in this study, radiation dose from CT scan and its related risks to the patients from current CT practice were analysed. In the first stage, this thesis started the discussion on the level of current knowledge among radiology personnel towards CT radiation risk and its optimization. There is no significant difference of the current knowledge of CT optimization between the two professions of interest herein, the medical and the allied health groups. A CT dose survey was conducted in 8 CT facilities for a 6-month period, encompassing data for 1024 patients with various CT examinations that included regions of the abdomen, brain and thorax. CT-EXPO (Version 2.3.1, Germany) software was used to validate the dose information such as CT Dose Index (CTDI) and dose-length product (DLP). The proposed Diagnostic Reference Levels (DRLs) were indicated by rounding off the third quartiles (Q3s) of whole dose distributions for weighted CTDI (CTDIw) (in mGy), volume CTDI (CTDIvol) (in mGy) and DLP (in mGy.cm) and their values were; 16, 17, and 650 respectively for CT abdomen; 70, 70, and 1030 respectively for CT Brain and 15, 16, and 670 respectively for CT thorax. In the second stage, the cancer risks of the CT examinations were estimated and the calculation was based on International Commission on Radiation Protection (ICRP) Publication 103 Report and Biological Effects of Ionizing Radiation (BEIR) VII Report. Based on BEIR VII recommendation, the study discovered that the lifetime attributable risks (LARs) of 100,000 populations who underwent abdominal CT examinations for stomach cancer were 2.3 for male and 1.0 for female; while for colon cancer the LARs were 2.3 for male and 0.7 for female. The effectiveness of optimization of CT parameters and application of shielding in routine CT procedures were evaluated. Of 7 protocols (P1 – P7), the k factors were constant for all protocols and decreased by ~8% compared to the universal k factor. It is of interest that k factors from CT-EXPO were found to vary between 0.010 for protocol P5 and 0.015 for protocol P3 due to inconsistency in tube potential and pitch factor. The application of breast shielding to routine CT thorax protocols reduced by 14% the breast’s equivalent dose. Hence, this study supports the importance of initiating protection and optimization processes of routine CT examinations in order to offer safer imaging practices.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Abdul Karim, Muhammad Khalis
author_facet	Abdul Karim, Muhammad Khalis
author_sort	Abdul Karim, Muhammad Khalis
title	Radiation doses, cancer risks and optimization process of routine computed tomography (CT) exminations in Johor
title_short	Radiation doses, cancer risks and optimization process of routine computed tomography (CT) exminations in Johor
title_full	Radiation doses, cancer risks and optimization process of routine computed tomography (CT) exminations in Johor
title_fullStr	Radiation doses, cancer risks and optimization process of routine computed tomography (CT) exminations in Johor
title_full_unstemmed	Radiation doses, cancer risks and optimization process of routine computed tomography (CT) exminations in Johor
title_sort	radiation doses, cancer risks and optimization process of routine computed tomography (ct) exminations in johor
granting_institution	Universiti Teknologi Malaysia, Faculty of Science
granting_department	Faculty of Science
publishDate	2017
url	http://eprints.utm.my/id/eprint/79411/1/MuhammadKhalisPFS2017.pdf
_version_	1747818220847366144

Radiation doses, cancer risks and optimization process of routine computed tomography (CT) exminations in Johor

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