A wide variety of endovascular procedures across many medical disciplines have documented Ka,r exceeding 5000 mGy, representing a proportion of procedures which reach a significant radiation dose. These findings comprehensively summarize the specific fluoroscopically-guided procedures which most commonly exceed the threshold radiation dose and are supported by previous studies: Fluoroscopically-guided fenestration, endovascular aneurysm repair, pedicle screw placement, transforaminal lumbar interbody fusion, vertebral augmentation, and AVM embolization have all been previously associated with the highest level of radiation doses (Kirkwood et al. 2015; Srinivasan et al. 2014; Riabroi et al. 2018). Of note, the mean Ka,r and FT among all procedures performed by interventional radiology were significantly lower than those performed by neurointerventional radiology, neurosurgery, and vascular surgery. This study demonstrated a significant difference in radiation dose metrics between medical disciplines performing fluoroscopically-guided procedures. While the implications of these findings are not fully elucidated, it may imply that formal standards for radiation dose reduction, such as those put forth by the American College of Cardiology and SIR, have led to improved radiation safety practices (Stecker et al. 2009; Hirshfeld et al. 2018).
The RAD-IR study performed by Miller et al analyzed dosimetry data from a variety of interventional radiology and neurointerventional radiology procedures and proposed radiation reference levels for fluoroscopically-guided procedures (Miller et al. 2003; Miller et al. 2009). Their work was aimed at creating mean radiation dose thresholds that when exceeded, could prompt investigation into institution fluoroscopy equipment, procedure protocols, and operator technique to identify areas for improved radiation safety (Miller et al. 2009). Universal radiation dose reference values for all fluoroscopically-guided procedures would provide a means for individual institutions to oversee radiation safety and ensure that interventionalists across medical disciplines are practicing within the expected dose limits for the corresponding procedures.
While medical specialties performing fluoroscopy-guided procedures generally attempt to adhere to the radiation reduction principle of ALARA (as low as reasonably achievable), universal policies regarding patient follow-up when a significant radiation dose is reached are needed to optimize patient care (Hertault et al. 2015; Bartal et al. 2014). The post-procedural recommendations made by SIR when a significant radiation dose threshold is exceeded include: documentation in the patient’s medical record, clinical follow-up to assess for deterministic radiation-induced injury, providing written radiation follow-up instructions on the patient’s discharge instruction sheet, and procedural review by a qualified medical physicist (Stecker et al. 2009). The results of this study demonstrate that all physicians performing fluoroscopically-guided procedures may expect to exceed significant radiation dose thresholds occasionally. As such, structured, institution-wide post-procedural policies should be adopted to ensure adequate patient follow-up. Perry et al., for example, demonstrated the feasibility of a dose monitoring process utilizing software monitoring and documentation to alert physicians when procedures exceed Ka,r of 5000 mGy so clinical follow-up could be arranged to assess for skin injury (Perry et al. 2019). Particularly, all physician groups who perform the procedures that have shown to exceed significant dose thresholds should have an instituted failsafe method for the detection of high doses cases and post-procedural evaluation of the patients with a feedback loop to radiation safety officer/medical physicist after clinical evaluation and patient education.
Similarly, this study provides insight regarding the distribution of specific fluoroscopically-guided procedures which most commonly exceed significant radiation doses. It is critical to consider the adverse health risks associated with occupational radiation exposure and the cumulative impact of small radiation doses obtained during the course of a physician’s career. The cumulative radiation risks include premature cataract formation, early carotid atherosclerosis, and possibly left-sided brain malignancies (Roguin et al. 2013; Ciraj-Bjelac et al. 2010). With this in mind, more aggressive radiation safety practices may be used when performing the procedures listed in Fig. 1 to reduce physician and patient radiation dose. Specific steps which may be taken by interventionalists to reduce patient and operator dose include the use of radiation-absorbing pads, which have been demonstrated to reduce physician radiation dose by approximately 70% during procedures using femoral artery access (Miller et al. 2017; Fetterly et al. 2011). Further, utilization of real-time image noise-reduction technology have demonstrated significant reductions in radiation doses across interventional radiology, cardiology, and neurointerventional radiology-performed interventions (Söderman et al. 2013). Additionally, precisely adjusting collimator boundaries to the region of interest and limiting magnification modes may decrease the contribution of fluoroscopy to the overall radiation dose (NCRP Report 168 | NCRP | Bethesda, MD n.d.). Finally, utilizing the “last image-hold” feature and intermittent, pulsed fluoroscopy on lower frame rates are additional techniques which can minimize both patient and operator radiation doses. One further factor that should be considered regarding increased radiation safety practices is the complexity of the procedure to be performed. While some procedures may exceed significant dose thresholds owing to patient or case specific limitations, other procedures are inherently more complex and will have increased radiation dose exposure regardless of the case specifics (Bundy et al. 2018).
This study has limitations including the single-center, retrospective design of the analysis. Peak skin dose was not directly assessed in this current study; however, SIR recommends that Ka,r be used as the preferred best clinical approximation of skin dose (Stecker et al. 2009). Image magnification, which affects dose, was not recorded in dose management software and therefore not included in this study. Additionally, the procedures were categorized by MedWatch, the U. S Food and Drug Administration safety reporting program, which does not provide a detailed description of each individual procedure (FDA 2019). Finally, the current study only represents the experiences of physicians from a single-center, therefore potentially limiting the generalizability to other regions.
This study demonstrates that fluoroscopically-guided procedures with high radiation dose exceeding 5000 mGy reference point kerma are uncommon. The majority of cases exceeding 5000 mGy were performed by non-radiologists, who may not receive the same training in radiation physics, radiation biology, and dose reduction techniques as radiologists. This may provide an opportunity for radiology societies to reach out to other medical specialties which perform fluoroscopically-guided procedures to educate and collaborate on radiation safety and establish a multidisciplinary institutional database to ensure consistent follow-up for all high dose cases.