Evaluation of dose parameters defining the probability of deterministic effects in the skin of patients undergoing interventional radiological examinations

The study is devoted to the assessment of dose parameters determine the probability of deterministic effects in the skin for patients undergoing high-dose interventional radiological examinations. Particular attention is paid to the analysis of the geometry of the absorbed dose distribution over the patient’s skin for the main types of interventional examinations. The aim of this study was to clarify the methodology for assessment of the maximum absorbed dose in the patients’ skin, taking into account new data. The data collection was carried out in nine city hospitals from Sankt-Petersburg; detailed information about more than 400 procedures was obtained. The data about operation technique for the main types of interventional examinations, physical, technical, geometric and dosimetric parameters for each procedure were registered. Based on the statistical data on distribution of geometric procedure parameters (fields size and projections) possible localizations and values of the absorbed dose in certain areas of the patients’ skin were determined. An updated methodology for skin dose assessment based on the recorded dosimetric value of dose area product considering the radiation fields size was presented. As an alternative, an estimation of the maximum skin dose based on the cumulative air kerma at the patient’s reference point – «representative» point for the patient’s skin considering the tube rotation was proposed. This method does not require the information on used field size. The conservative conversion coefficients from the measured dosimetric values to the peak skin dose and trigger values to prevent deterministic effects in the patients’ skin were calculated.