During medical imaging procedures, radiation is used to obtain pictures. Radiation can damage the DNA in human cells and cause gene mutations which can develop into cancer. This study will investigate the amount of radiation dose* the doctor receives when placing a singular stent in a narrowed artery of a patient’s heart under real-time medical imaging guidance (fluoroscopy). This study seeks to identify if patient size (measured as BMI) has an effect on the amount of radiation which scatters onto the doctor performing the stenting procedure.
Introduction: Ionising radiation used for image guidance during interventional procedures in the cardiac catheter laboratory contributes the largest amount of medical radiation dose of all imaging modalities in radiology. There is a paucity of information regarding the impact of the current obesity epidemic on radiation dose to the operator during percutaneous coronary interventions (PCI).
Methods: This study investigated a retrospective cohort of patients who underwent single vessel PCI between June 2015 and June 2017 at The Prince Charles Hospital in Chermside, Australia. All data were obtained from a single catheter laboratory equipped with a Siemens Artis Q Interventional Angiography System. Patients were grouped into five different categories according to their body mass index (BMI); underweight <18.5k/cm2, normal weight 18.5kg/cm2 – 25.0kg/cm2, overweight 25kg/cm2 – 30kg/cm2, obese 30kg/cm2 – 35kg/cm2, and, morbidly obese >35kg/cm2. Fluoroscopy time (minutes) and operator radiation dose in micro-Sievert (µSv) were compared between BMI groups.
Results: Of the 441 subjects who underwent single vessel PCI, >80% of patients were overweight, obese, or morbidly obese. Operator dose differed significantly between morbidly obese patients and normal weight patients- 31µSv (IQR:51) compared to 18µSv (IQR:28), p=0.006, and morbidly obese patients and overweight patients – 31µSv compared to 20µSv (IQR:33), p=0.015. Median fluoroscopy time was not found to significantly differ between any group of patient BMI.
Conclusions: Patient BMI is associated with an increased radiation dose delivered to the operator during single vessel PCI, however, it is not necessarily associated with longer more complex interventions. These findings suggest that patient thickness is responsible for increased scatter radiation onto the interventionist.
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*Notes; Commonly, dose area product (DAP) is used in the quantification of radiation dose output of any given imaging apparatus however for the purposes of this study effective dose (micro sievert) to the operator was used as it more accurately quantifies the radiation burden to the operator, not the general quantity of radiation used during the procedure.