A Pilot Study of Safer Radiation Dosage to the Heart and Its Subregions.

Background and Objectives: The real impact of ionizing radiation on the heart and poorer overall survival for patients with non small cell lung cancer (NSCLC) remains unclear. This study aims to determine the safe dose constraints to the heart's subregions that could prevent patients' early non-cancerous death and improve their quality of life. Methods and Materials: A retrospective cohort study was performed containing 51 consecutive patients diagnosed with stage III NSCLC and treated using 3D, Intensity-modulated radiation therapy (IMRT), and Volumetric modulated arc therapy (VMAT) radiotherapy. For a dosimetric analysis, these structures were chosen: heart, heart base (HB), and region of great blood vessels (GBV). Dose-volume histograms (DVH) were recorded for all mentioned structures. Maximum and mean doses to the heart, HB, the muscle mass of the HB, and GBV were obtained. V10-V60 (%) parameters were calculated from the DVH. After performed statistical analysis, logistic regression models were created, and critical doses calculated. Results: The critical dose for developing a fatal endpoint for HB was 30.5 Gy, while for GBV, it was 46.3 Gy. Increasing the average dose to the HB or GBV by 1 Gy from the critical dose further increases the possibility of early death by 22.0% and 15.8%, respectively. Conclusions: We suggest that the non-canonical sub-regions of the heart (HB and GBV) should be considered during the planning stage. Additional constraints of the heart subregions should be chosen accordingly, and we propose that the mean doses to these regions be 30.5 Gy and 46.3 Gy, respectively, or less. Extrapolated DVH curves for both regions may be used during the planning stage with care.

Lead exposure in clinical imaging - The elephant in the room.

PURPOSE: Radiation Protection Apparel (RPA) is used during diagnostic imaging and interventional procedures to minimise incidental radiation exposure. The majority of RPA in use are lead-containing, which has until now been considered safe. A recent single-centre study has demonstrated that the external surface of 63 % of RPA was contaminated with lead dust. The purpose of this study was to reproduce this investigation with a larger sample size across Europe and assess whether decontamination procedures were possible. METHOD: The routine RPA Quality Control (QC) process was adapted to include lead dust contamination tests and decontamination if present. The presence of lead dust was determined using a commercially available colorimetric method. RPA that failed initial QC or could not be decontaminated were removed from use. RESULTS: From June to October 2019, 728 RPA from 85 imaging centres from five countries underwent initial QC. Of these, 712 were tested for lead dust contamination which was present on 162 (23 %). Following cleaning, 85 (12 %) remained contaminated and were removed from use. Linear regression analysis shows a significant correlation between type of RPA and contamination, (p = 0.0015). There was no correlation between contamination and imaging department, year of manufacture, country and RPA condition (p-values 0.98, 0.90, 0.94 and 0.14 respectively). CONCLUSIONS: Lead dust contamination is present on 23 % of RPA that would pass routine QC procedures. Approximately half were not amenable to decontamination and were removed from use. Procedures were introduced for the routine handling of RPA, and updated QC steps for assessment and cleaning. Lead-free RPA should be considered.