Search

Medical imaging plays a major role in coronavirus disease-2019 (COVID-19) patient diagnosis and management. However, the radiation dose received from medical procedures by these patients has been poorly investigated. We aimed to estimate the cumulative effective dose (CED) related to medical exposure in COVID-19 patients admitted to the intensive care unit (ICU) in comparison to the usual critically ill patients. We designed a descriptive cohort study including 90 successive ICU COVID-19 patients admitted between March and May 2020 and 90 successive non-COVID-19 patients admitted between March and May 2019. In this study, the CED resulting from all radiological examinations was calculated and clinical characteristics predictive of higher exposure risk identified. The number of radiological examinations was 12.0 (5.0-26.0) [median (interquartile range) in COVID-19 vs. 4.0 (2.0-8.0) in non-COVID-19 patient (P0.001)]. The CED during a four-month period was 4.2 mSv (1.9-11.2) in the COVID-19 vs. 1.2 mSv (0.13-6.19) in the non-COVID-19 patients (P0.001). In the survivors, the CED in COVID-19 vs. non-COVID-19 patients was ≥100 mSv in 3% vs. 0%, 10-100 mSv in 23% vs. 15%, 1-10 mSv in 56% vs. 30% and1 mSv in 18% vs. 55%. The CED (P0.001) and CED per ICU hospitalization day (P = 0.004) were significantly higher in COVID-19 than non-COVID-19 patients. The CED correlated significantly with the hospitalization duration (r = 0.45, P0.001) and the number of conventional radiological examinations (r = 0.8, P0.001). To conclude, more radiological examinations were performed in critically ill COVID-19 patients than non-COVID-19 patients resulting in higher CED. In COVID-19 patients, contribution of strategies to limit CED should be investigated in the future.

To establish national reference levels (RLs) in interventional procedures under CT guidance as required by the 2013/59/Euratom European Directive. Seventeen categories of interventional procedures in thoracic, abdominopelvic, and osteoarticular specialties (percutaneous infiltration, vertebroplasty, biopsy, drainage, tumor destruction) were analyzed. Total dose length product (DLP), number of helical acquisitions (NH), and total DLP for helical, sequential, or fluoroscopic acquisitions were recorded for 10 to 20 patients per procedure at each center. RLs were calculated as the 3rd quartiles of the distributions and target values for optimization process (TVOs) as the median. RLs and TVOs were compared with previously published studies. Results on 5001 procedures from 49 centers confirmed the great variability in patient dose for the same category of procedures. RLs were proposed for the DLPs and NHs in the seventeen categories. RLs in terms of DLP and NH were 375 mGy.cm and 2 NH for spinal or peri-spinal infiltration, 1630 mGy.cm and 3 NH for vertebroplasty, 845 mGy.cm and 4 NH for biopsy, 1950 mGy.cm and 8 NH for destruction of tumors, and 1090 mGy.cm and 5 NH for drainage. DLP and NH increased with the complexity of procedures. This study was the first nationwide multicentric survey to propose RLs for interventional procedures under CT guidance. Heterogeneity of practice in centers were found with different levels of patient doses for the same procedure. The proposed RLs will allow imaging departments to benchmark their practice with others and optimize their protocols. • National reference levels are proposed for 17 categories of interventional procedures under CT guidance. • Reference levels are useful for benchmarking practices and optimizing protocols. • Reference levels are proposed for dose length product and the number of helical acquisitions.

Purpose To establish diagnostic reference levels (DRLs) and achievable levels (ALs) for the most common fluoroscopically guided interventions (FGIs) performed in operating rooms using mobile C-arm equipment. Methods A national survey was performed in 57 centers in France. Anonymous data from 6817 patients undergoing FGIs were prospectively collected over a period of 7 months. DRLs (third quartile of the distribution) and ALs (median of the distribution) were determined for each type of intervention in terms of kerma area product (KAP) and fluoroscopy time (FT). Results DRLs and ALs were proposed for 31 procedure types related to seven surgical specialties: orthopedics (n = 9), urology (n = 3), vascular (n = 6), cardiology (n = 5), neurosurgery (n = 3), gastrointestinal (n = 3), and multi-specialty (n = 2). DRLs in terms of KAP ranged from 0.1 Gy·cm2 for hallux valgus to 78 Gy·cm2 for abdominal aortic aneurysm endovascular repair. A factor of 155 was obtained between the FTs for a herniated lumbar disk (0.2 min) and an abdominal aortic aneurysm endovascular repair (31 min). The highest variations were obtained within orthopedic procedures in terms of KAP (ratio 122) and within gastrointestinal procedures in terms of FT (ratio 9). Overall, the FGIs associated with the highest radiation exposure (KAP > 10 Gy·cm2) were found in the cardiology, vascular, and gastrointestinal specialties. Conclusions DRLs and ALs are suggested for a wide range of FGIs performed in operating rooms using a mobile C-arm. We aim at providing a practical optimization tool for medical physicists and surgeons.

PURPOSE To perform a benchmark of a new DACS-integrated patient skin dose mapping solution using on-phantom measurements with Gafchromic® films. MATERIALS AND METHODS To calculate cumulative patient skin dose distribution with 1-cm2 resolution, a Radiation Dose Monitor (RDM, Medsquare), using the Radiation Dose Structured Report (RDSR), tabulated backscatter and mass energy absorption coefficients together with site-specific corrections for table, mattress attenuation, and air kerma calibration factor. Peak skin dose (PSD) and two-dimensional (2D) skin dose distributions calculated with RDM were compared against on-phantom measurements with XR-RV3 Gafchromic® films considering two widely used x-ray equipment. Seventeen different settings which include simple and multiple beam projections with extreme angulations (up to 75°), all available fields-of-view (FOVs 48-11 cm), additional collimation, variable table height and lateral positions, and variable phantom thickness (12, 20, and 30 cm) were involved. RESULTS Due to a careful calibration of films using clinical beam qualities, 22.8% (k = 2) overall measurement uncertainty was achieved. Calculated and measured PSD values agreed with an average difference of 10% ± 7% and 9% ± 7% for 34 test conditions performed on Siemens Artis Zee and GEMS Innova IGS interventional systems, respectively. Finally, RDM's 2D skin dose maps closely matched those registered on XR-RV3 films considering the 1-cm2 resolution. While RDM correctly reproduced beam overlapping due to variable tube projections, FOV, table positions, etc., few challenges were identified related to conversion of rectangular fields to square areas in the RDSR and a stair-step effect visible for large tube projections (>45°). CONCLUSION The accuracy of RDM's DACS-integrated skin dose mapping software was acceptable considering measurement uncertainties associated with Gafchromic® films.