Please use this identifier to cite or link to this item: https://www.um.edu.mt/library/oar/handle/123456789/109602
Title: Optimising the pre-set exposure parameters for the standard anteroposterior (AP) projection of the pelvis : a phantom study
Authors: Fenech, Bradley Kevin (2022)
Keywords: Pelvis -- Radiography
X-rays -- Equipment and supplies
Diagnostic imaging
Radiation dosimetry
Issue Date: 2022
Citation: Fenech, B. K. (2022). Optimising the pre-set exposure parameters for the standard anteroposterior (AP) projection of the pelvis : a phantom study (Bachelor’s dissertation).
Abstract: Purpose To optimise the pre-set exposure parameters for an anteroposterior (AP) projection of the pelvis by adjusting kVp values and the use of an antiscatter grid to potentially reduce the patient's radiation dose while still obtaining a high-quality diagnostic image using an anthropomorphic phantom. Objective To identify the optimal kVp value and whether or not to use anti-scatter grids. Achieved by implementing different exposures using an anthropomorphic phantom to improve radiographic exposure protocols and ultimately improve radiographic practice for the benefit of the patient. Methodology A quantitative, prospective, experimental investigation carried out by altering kVp values in steps of 5 kVp between the range of 50 – 100 kVp, while keeping a fixed source-to-image distance (SID) of 100cm, a fixed collimation size of 43cm X 35cm and using an automatic exposure control (AEC) with fixed mA value of 160mA. Images of the phantom were obtained with and without the use of an antiscatter grid. The dose area product (DAP) was used as a relative estimation of the radiation dose delivered. The quality of the acquired images was evaluated using both subjective and objective methods. Objective evaluation of spatial and contrast resolution was performed by the researcher using test tools and formulae. The subjective image evaluation was performed through absolute visual grading analysis (VGA) by four radiologists who scored their confidence in visualising anatomical structures as outlined in the CEC guidelines. Visual grading characteristics (VGC) curves were then plotted from the scoresfor each image to analyse image quality. Results An exposure of 100 kVp using an antiscatter grid resulted in a 61% reduction in DAP value, and similar objective image contrast and spatial resolution as the original protocol. In addition, the quality of the image obtained using this exposure was subjectively scored better than the original protocol by the radiologists. Conclusion According to these findings, increasing the kVp value from 75 kVp to 100 kVp and using an antiscatter grid results in a 61% reduction in radiation dose and an image of better diagnostic quality when imaging an average-sized subject. Recommendations were provided for further research and the potential need to revisit image quality criteria.
Description: B.Sc. (Hons)(Melit.)
URI: https://www.um.edu.mt/library/oar/handle/123456789/109602
Appears in Collections:Dissertations - FacHSc - 2022
Dissertations - FacHScRad - 2022

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