Ordre de grandeur des doses délivrées en radiodiagnostic

Cumulative Radiation Exposure in Covid-19 Patients Admitted to the Intensive Care Unit

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 (P < 0.001)]. 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 (P < 0.001). 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% and <1 mSv in 18% vs. 55%. The CED (P < 0.001) 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, P < 0.001) and the number of conventional radiological examinations (r = 0.8, P < 0.001). 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.

Role of 3D intraoperative imaging in orthopedic and trauma surgery

Intraoperative three-dimensional (3D) imaging is now feasible because of recent technological advances such as 3D cone-beam CT (CBCT) and flat-panel X-ray detectors (FPDs). These technologies reduce the radiation dose to the patient and surgical team. The aim of this study is to review the advantages of 3D intraoperative imaging in orthopedic and trauma surgery by answering the following 5 questions: What are its technical principles? CBCT with a FPD produces non-distorted digital images and frees up the surgical field. The high quality of these 3D intraoperative images allows them to be integrated into surgical navigation systems. Human-robot comanipulation will likely follow soon after. Conventional multislice CT technology has also improved to the point where it can be used in the operating room. What can we expect from 3D intraoperative imaging and which applications have been validated clinically? We reviewed the literature on this topic for the past 10 years. The expected benefits were determined during the implantation of pedicular screws: more accurate implantation, fewer surgical revisions and time savings. There are few studies in trauma or arthroplasty cases, as robotic comanipulation is a more recent development. What is the tolerance for irradiation to the patient and surgical team? The health drawbacks are the harmful radiation-induced effects. The deterministic effects that we will develop are correlated to the absorbed dose in Gray units (Gy). The stochastic and carcinogenic effects are related to the effective dose in milliSievert (mSv) of linear evolution without threshold. The International Commission on Radiological Protection (ICRP) states that irradiation for medical purposes with risk of detriment is acceptable if it is justified by an optimization attempt. The radioprotection limits must be known but do not constitute opposable restrictions. The superiority of intraoperative 3D imaging over fluoroscopy has been demonstrated for spine surgery and sacroiliac screw fixation. How does the environment need to be adapted? The volume, access, wall protection and floor strength of the operating room must take into account the features of each machine. The instrumentation implants and need for specialized staff result in additional costs. Not every system can track movements during the CBCT acquisition thus transient suspension of assisted ventilation may be required. Is it financially viable? This needs to be calculated based on the expected clinical benefits, which mainly correspond to the elimination of expenses tied to surgical revisions. Our society's search for safety has driven the investments in this technology. LEVEL OF EVIDENCE: V, Expert opinion.

Exposure to Ionizing Radiation in Patients Undergoing Transfemoral Transcatheter Aortic Valve Implantation

Transcatheter aortic valve implantation (TAVI) is currently becoming an alternative to surgical valve replacement for patients at low risk, a population that is likely to experience an increase in the radiation-induced cancer risk following TAVI. We aimed to evaluate the overall exposure to ionizing radiation in patients who underwent transfemoral TAVI, including the procedure itself as well as the procedures performed in the preintervention work-up and the post-TAVI interventions. All patients who underwent transfemoral TAVI for symptomatic aortic stenosis in our center over a 26 months period were included. Dosimetric indicators from preprocedural coronary angiography and computed tomography (CT), the TAVI procedure, and any postprocedural interventions (electrophysiology study and/or pacemaker implantation) were collected and converted into an effective dose. A total of 119 transfemoral TAVI procedures were included. The mean cumulative effective dose (ED) was 37.3 mSv. Three irradiating procedures were necessary for 84 patients (71% of the population, i.e., coronary angiography, CT scan and the TAVI procedure itself), whereas 30 patients (25%) required a fourth procedure, and 5 required a fifth (4%). The majority of the dose was from the CT, while only 11% of the dose derived from the TAVI procedure itself. In conclusion, overall exposure to ionizing radiation for patients who underwent transfemoral TAVI seems acceptable, and the majority of the overall ED comes from the CT scan.

Impact of Obesity on Overall Radiation Exposure for Patients Who Underwent Radiofrequency Ablation of Atrial Fibrillation

Patients who underwent radiofrequency ablation of atrial fibrillation are exposed to X-rays not only during the procedure but also during the preprocedural computed tomography. No study has investigated the cumulative effective dose received by patients who underwent atrial fibrillation ablation and identified factors influencing this dose. We aimed to evaluate the overall exposure to ionizing radiation in patients who underwent radiofrequency ablation of atrial fibrillation. The secondary objective was to estimate the impact of obesity on this exposure. All patients who underwent a first attempt of radiofrequency ablation of atrial fibrillation in our center over a 21 months period were included. Dosimetric indicators from preprocedural computed tomography and the ablation procedure were collected and converted into an effective dose. A total of 144 radiofrequency ablation of atrial fibrillation were included. The mean cumulative effective dose was 11.4 mSv, and 82% of the dose was from the computed tomography. Obese patients received a dose that was 75% higher than normal-weight patients, and this increase remained significant by multivariate analysis. In conclusion, overall exposure to ionizing radiation for patients who underwent radiofrequency ablation of atrial fibrillation seems acceptable, and the majority of the overall effective dose comes from the computed tomography. Obese patients are exposed to a 75% higher dose than normal-weight patients.