Please use this identifier to cite or link to this item: https://www.um.edu.mt/library/oar/handle/123456789/109801
Title: Optimisation of the CT pulmonary angiogram (CTPA) scan protocol at a local general hospital in Malta
Authors: Bellizzi, Andrea (2022)
Keywords: Pulmonary embolism -- Malta
Hospitals -- Malta
Tomography -- Malta
Tomography -- Image quality
Radiation -- Dosage
Issue Date: 2022
Citation: Bellizzi, A. (2022). Optimisation of the CT pulmonary angiogram (CTPA) scan protocol at a local general hospital in Malta (Master’s dissertation).
Abstract: Purpose Due to the increase in CTPA examinations being performed locally and the relative radiation risks associated with it, this study aimed at optimising the current CTPA protocol (100 kV with 50% IR) present at a local public general hospital in Malta by using a lower kV technique combined with a high Iterative Reconstruction (IR) (>50%) value. Objectives To identify the optimal IR value through a phantom study. Apply this in combination with a lower kV technique as the experimental protocol in the clinical setting and compare it to the current protocol in terms of radiation dose and image quality. Methodology The study was divided into 2 phases. Phase 1 consisted of an experimental study using an anthropomorphic phantom to identify the optimal IR value to be used in combination with the lower kV technique. During phase 2, 64 patients were recruited and equally divided into a control and experimental groups. The patients forming part of the control group were scanned using the current protocol while another 32 patients were imaged using the experimental protocol. The volume CT dose index (CTDIVOL), dose length product (DLP), size specific dose estimate (SSDE) and effective dose (ED) were calculated. Objective image quality was recorded in terms of contrast to noise ratio (CNR) and signal to noise ratio (SNR). Subjective image evaluation was performed by 3 radiologists performing Absolute Visual Grading Analysis (VGA) to assess image quality by using an image quality score tool. The resultant image quality scores were analysed using Visual Grading Characteristics (VGC). Results From the image quality and dose results in phase 1, the optimal scan protocol was found to be 60% IR combined with 80kV. The application of this protocol in a clinical setting resulted in a reduction (p<0.05) in mean CTDIVOL (49%), DLP (48%), SSDE (52%) and effective dose (49%). Objective image quality was improved (p<0.05) both in CNR (32%) and SNR (13%). Subjective image quality scores were higher for the current protocol but variation between the two protocols was not significant (p>0.05). Conclusions The results suggested that when applying the experimental protocol (80kV combined with 60% IR), radiation dose was reduced by approximately 50%, while still maintaining image quality at an acceptable diagnostic level.
Description: M.Sc. Radiography(Melit.)
URI: https://www.um.edu.mt/library/oar/handle/123456789/109801
Appears in Collections:Dissertations - FacHSc - 2022
Dissertations - FacHScRad - 2022

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