Patients dose and risk assessment in fluoroscopically guided interventional procedures in Ghana

Introduction: The significant increases in the use of imaging and interventional procedures in recent times have brought along the issue of safety and protection of patients and users of diagnostic and interventional radiology equipment for complex procedures. Additionally, due to potential risk associated with these procedures, patients’ radiation protection issues have become the focus of most fluoroscopy guided interventional procedures globally. The objective of this study is to evaluate optimized angiographic exposure parameters, radiation dose, estimated risk levels and develop a radiation dose reference chart for the most commonly routine protocol in interventional procedures in Ghana. Methodology: Patients dose parameters were obtained from the structured dose reports of the PAC system of five diagnostic interventional equipment facilities, together with number of images per procedure and image quality assessment for dose optimisation protocols. The data retrieved from the PAC System include patients’ biodata, input and output indices including Kerma-Area Product (KAP) Fluoro and total Kerma-Area Product values. Additionally, fluoroscopy time and the number of radiographic images of at least 50 patients for each FGI procedure based on ICRP Publication 135 recommendations were also collected. The PC based Monte Carlo simulation software (PCXMC) was used to estimate ED from the total KAP and the KAP Fluoro values. Image quality (IQ) was assessed using human observer assessment and evaluation based on the assessment of the radiologists, who ranked the images from most acceptable images to least acceptable images and whether accepted on not accepted for clinical use. Patient radiation exposure was evaluated using estimated KAP Fluoro and Total KAP to estimate ED from each of the measured parameters. That is radiation risk levels were estimated based on Biological Effects of Ionising radiation (BEIR) report VII predictive models. These were done by assessing the dose and risk to patients and practioners during fluoroscopy guided interventional procedures for each of the nine most common routine procedure and the possible corrective measures needed for effective management of these procedure. Results: The study shows that the total KAP median dose value was 109 with a minimum and maximum values in the range of 2 to 835 Gy.cm² were recorded during Abdominal Aorta Endoprosthesis procedure. While KAP Fluoro minimum and maximum dose value were ranged from 1.59 to 734 Gy.cm² with a median value of 86 Gy.cm². The trend of the study shows significant comparative estimated dose values in terms of effective dose from the KAP median values with other studies. Additionally, abdominal aorta endoprosthesis procedures took much longer time to perform relative to the other studies with resultant high ED values. It was observed that, time taken, and images acquired for abdominal aorta endoprosthesis procedure could be as much as three-fold with significant dose value compared to other procedures. Furthermore, higher radiation dose quantity, in terms of KAP Fluoro and total KAP, in the case of Abdominal Aorta Endoprosthesis had a direct correlation to the number of images and the time taken to complete the procedure. Comparative analysis between these procedures shows significant variation among them. For instance Percutaneous Liver Drainage had the least effective dose and risk factors of 0.94 mSv and 0.34 LAR respectively. Whilst Abdominal Aorta Endoprosthesis had the highest effective dose and risk factor of 32 mSv and 29 LAR respectively. Finally, the number of images and the corresponding image quality assessment shows significant variation from a minimum of 2.7 to a maximum of 167 Gy.cm². This resulted in highest ED of 59.4 mSv with significant risk levels to both patients and practitioners (1 in 1000 to 1 in 500). Most of the procedures had low radiation risk levels (1 in 10,000 to 1 in 1000). Additionally, all the images were good enough for clinical use and ranged from 3 to 5 with less than 2% of the procedure having relative poor image quality with significant positive correlation to the dose and risk factor metrics. Conclusion: In conclusion it was observed that, the study results were comparable to other regional and international studies. In addition, it was also observed that, the time taken for each procedure to be completed had direct positive correlation with estimated patient dose metrics. That is, the higher the time taken for a procedure to be completed, the higher the dose values in terms of KAP Fluoro (Gy·cm²) and Total KAP (Gy·cm²) with significant correlation with the quality of images used during the procedure. Finally, the study found that the angiographic exposure input parameters were optimized and within accepted and recommened dose estimates (effective dose, estimated risk levels) and radiation dose reference chart has been developed for the most commonly routine protocol in interventional procedures in Ghana.