|dc.description.abstract||Cardiac computed tomography angiography (CCTA) has become an invaluable tool for the detection of cardiac disease. However, radiation brings potential risks of radiation-induced cancers. Diagnostic Reference Levels (DRLs) identify unusually high radiation doses, which makes it a useful tool for targeting dose optimisation. The literature shows no established DRLs for CCTA in Saudi Arabia or Australia. This thesis aims to: 1) propose national DRLs (NDRLs) for CCTA in these countries; 2) identify the associated factors for dose variation in current CT centres.
Methods: A structured survey was designed to record information about the CCTA protocols, patient parameters, volume CT dose index (CTDIvol) and dose-length product (DLP). The data were collected from 11 and nine CT centres in Saudi Arabia and Australia, respectively. A stepwise regression analysis was performed to assess the contribution of tube voltage (kV), padding time technique, cross-sectional area (CSA) of chest and weight to DLP.
Results: The Saudi NDRL values in CTDIvol and DLP were 43 mGy and 808 mGy cm, respectively while the Australian NDRLs were 22 mGy and 268 mGy cm, respectively. The stepwise regression showed that kV was the most significant predictor of DLP followed by padding technique then CSA, while patient weight had no significant effect on DLP.
Conclusions: The findings show that DRLs in both countries are comparable or lower than DRLs in published studies due to the implementation of dose-saving technologies such as prospective ECG gating mode. Additionally, a wide variation in median dose between CT centres, which indicated the potential for using DRLs to encourage dose optimisation in current departmental CCTA protocols. Associated factors for dose variation include employing the RGM protocol, high-kV, use of the padding time, and larger CSA of the chest. Findings should provide baseline guidance for optimising CCTA examinations in CT imaging centres in Saudi Arabia and Australia.||en_AU|
|dc.publisher||University of Sydney||en_AU|
|dc.publisher||Faculty of Health Sciences||en_AU|
|dc.rights||The author retains copyright of this thesis. It may only be used for the purposes of research and study. It must not be used for any other purposes and may not be transmitted or shared with others without prior permission.||en_AU|
|dc.subject||diagnostic reference levels||en_AU|
|dc.subject||cardiac computed tomography angiography||en_AU|
|dc.subject||coronary computed tomography angiography||en_AU|
|dc.subject.other||POST DG EXPORT SUBMISSION||en_AU|
|dc.title||Dose Optimisation and Establishment of Diagnostic Reference Levels in Cardiac Computed Tomography Angiography||en_AU|
|dc.type.pubtype||Doctor of Philosophy Ph.D.||en_AU|
|dc.description.disclaimer||Access is restricted to staff and students of the University of Sydney . UniKey credentials are required. Non university access may be obtained by visiting the University of Sydney Library.||en_AU|
|Appears in Collections:||Sydney Digital Theses (University of Sydney Access only)|