Case Study
A Novel Robotic Radiation Shielding Device for Electrophysiologic Procedures: A Prospective Study
Avishag Laish-Farkash, MD, PhD 1 , Emanuel Harari, MD 1 , Michael Rahkovich, MD, Yonatan Kogan, MD, Gergana Marincheva, MD, Guy Scheinman, MD, Eyal Ben-Assa, MD, and Eli I. Lev, MD Ashdod, Israel
Background A robotic Radiaction Shielding System (RSS) was developed to provide a full-body protection to all medical personnel during fluoroscopy-guided procedures, by encapsulating the imaging beam and blocking scattered radiation.
Objectives We aimed to evaluate its efficacy in real-world electrophysiologic (EP) laboratory- both during ablations and cardiovascular implantable electronic devices (CIED) procedures.
Methods A prospective controlled study comparing consecutive real-life EP procedures with and without RSS using highly sensitive sensors in different locations.
Results Thirty-five ablations and 19 CIED procedures were done without RSS installed and 31 ablations and 24 CIED procedures (17 with usage levels ≥70%) were done with RSS. Overall, there was 95% average usage level for ablations and 88% for CIEDs. For all procedures with ≥70% usage level and for all sensors, the radiation with RSS was significantly lower than radiation without RSS. For ablations, there was 87% reduction in radiation with RSS (76%-97% for different sensors). For CIEDs, there was 83% reduction in radiation with RSS (59%-92%). RSS usage did not increase procedure time and radiation time. User feedback showed a high-level of integration in the clinical workflow and safety profile for all types of EP procedures.
Conclusions For both CIED and ablation procedures the radiation with RSS was significantly lower than without RSS. Higher usage level brings higher reduction rates. Thus, RSS may have an important role in full-body protection to all medical personnel from scattered radiation during EP and CIED procedures. Until more data is available, it is recommended to maintain existing standard shielding. (Am Heart J 2023;261:127–136.)
Fluoroscopy-guided procedures are the leading source of occupational ionizing radiation exposure for electrophysiologic (EP) personnel.1 High cumulative doses of X-ray radiation might increase the risk for malignancies, 1 early development of cataracts,2 and orthopedic problems due to the heavy weight of lead aprons. 3 Reducing high radiation exposure during medical procedures is the principal task of many professional societies and advisory groups.4 , 5
Current radiation protection of interventional personnel include: reduced radiation imaging systems, personal protective clothing, ceiling-mounted shields, and table skirts. Newer dedicated solutions, such as suspended radiation protection system6 and a remote-controlled robotic system7,8 provide protection only to the main operator; limit free movement (Zero-Gravity, Biotronik, Switzerland), and require a significant learning curve (CorPath, Corindus, A Siemens Healthineers Company, Waltham, MA). The application of a lead-attenuator across the patient’s abdomen/pelvis reduces radiation exposure,9,10 but is limited during femoral access procedures.
The radiaction shielding system (RSS) is a novel robotic radiation shielding system that provides full-body protection to all medical personnel in the catheterization laboratory (CL) during fluoroscopy-guided procedures, by encapsulating the imaging beam and blocking the scattered radiation at its origin. It is comprised of an upper shield around the image detector and lower shield around the X-ray source, thereby creating a barrier around the imaging beam11 ( Figure 1A).
A, The Radiaction Shielding System (RSS) - a novel robotic radiaction shielding system that provides full-body protection to all medical personnel in the catheterization laboratory during fluoroscopy-guided procedures, by encapsulating the imaging beam and blocking the scattered radiation at its origin. B, During CIED implantations we used a “modified RSS deployment mode” in which one of the upper segments remain undeployed, so that the surgical field was visible and accessible to the operator. Sterile covers were used for the upper and lower RSS segments.
Our bench tests showed significant radiation reduction performance under full usage of the system in the absence of conventional shielding, potentially providing 93% to 94% exposure reduction to physicians in coronary procedures and 87% to 93% to all medical team members. For the real-world first-in-man use of RSS, mean radiation rate reduction was above 90% for all sensor locations in both CL and EP procedures.11 User’s feedback proved the feasibility and ease of use of the system within a short learning curve, with no apparent disturbance to the patient’s well-being.11
The first-in-man data was small and methodologically limited. The aim of the current study was to prospectively test the efficacy of RSS in reducing radiation exposure to medical personnel during routine EP procedures and implantations of cardiovascular implantable electronic devices (CIED) in the EP laboratory in controlled study.
The study is a prospective controlled study comparing consecutive real-life EP procedures with and without RSS. The shield system RSS (Radiaction Ltd. Tel-Aviv, Israel) is a novel robotic system. As described previously,11 it is comprised of upper and lower robotic extendable shields assembled on the C-arm around the X-ray tube and image receptor. RSS is a lead-free system and the radiation blocking material is Tungsten. The weight of the RSS is insignificant when compared to the C- arm. RSS was fully tested and validated for C-arm compatibility and was found to be perfectly safe and not impacting C-arm operation and safety. Both shields are mechanically attached to the C-arm with existing holes and screws of the C-arm (nonintrusively). The design of the shields ensures that the risk of either part falling loose from its fixation is as low as nonexistent. The device utilizes sensors and controls to deploy and retract its attenuating segments and accommodate C-arm angulation and table movement. The RSS design ensures that the skirts cannot fold inward towards the imaging beam and interfere with the imaging.
RSS has a small control panel that is mounted on the table rail and sits next to the C-arm’s control panel. The operator of the RSS is usually the main physician or radiographer.
Before rotating the C-arm, the operator retracts the shields to allow free C-arm motion. Once the C-arm reaches the desired orientation, the shields are quickly deployed by extending the telescopic segments and their flexible edges. During panning movements, the RSS can be operated in Hover Mode, where the segments are partially deployed. During CIED implantations we used a “modified RSS deployment mode” in which one of the upper segments remain undeployed, so that the surgical field was visible and accessible to the operator ( Figure 1 B). In addition, in cases of obtaining axillary or subclavian vascular access, we temporarily used an “access mode” in which the whole upper shield was neutralized during the vascular puncture alone. Both modes (“modified RSS deployment mode” and “access mode”) could be under full deployment mode or Hover mode.
Five Radiation sensors were placed in the EP Cath Lab, including on the physician’s body. The sensors’ locations in the EP laboratory are described in Supplementary Figure 1 and are different for ablation procedures and for CIED implantation procedures: During ablation procedures: Sensor 1 was located at head height, in front of the main physician, other side of table. Sensor 2- at head height, in front of the second physician, other side of table. Sensor 3- on the main physician, upper body. Sensor 4- on the main physician, lower body. Sensor 5 was located under the table. During CIED implantations from the left side of the patient: Sensor 1 was located at head height, in front of the second physician, other side of table. Sensor 2- at head height, in front of the main physician, other side of table. Sensor 3- on the main physician, upper body (chest). Sensor 4- on the main physician, lower body. Sensor 5 was located under the table. During right-sided CIED implantations, the setting of the sensors was similar to that during ablation, however, sensors 1 and 2 were switched in order to keep sensor 2 closer to radiation source, similar to left sided CIED procedures.
Thus, in all procedures, the location of sensors 1 and 2 were in front of the physicians, at head height, on the monitor. Sensors 3 (chest height) and 4 (pelvis height) were placed on the physicians (main operator), outside the lead aprons (or outside Zero-Gravity shielding system, in case of using it), therefore they reflect the added protection of RSS only.
Radiation measurements per procedure were taken before and after the installation of the shield system. While the system was installed, the usage level of the system was measured. The usage level was measured as a percentage of time in which the Shields were deployed from the total time radiation was used. All radiation measurements were normalized by the Dose Area Product (DAP) retrieved from the fluoroscopy imaging system at the end of each procedure. The frame rate used in most procedures in this study was 7.5-15 frames per second. The average of the normalized measurements was compared between the control and study phases, to assess the Shield’s radiation reduction performance. Total X-ray time (including total fluoroscopic time and total acquisition time) was taken from the fluoroscopy imaging system at the end of each procedure. Procedure time was measured from the moment the patient entered the room until he left.
RSS was installed for 3 weeks in the EP laboratory at Assuta Ashdod University MC. During these 3 weeks all the procedures were performed with RSS, including: electrophysiological studies (EPS), radiofrequency (RF) ablations (either with- or without Carto 3D-mapping system), cryoballoon pulmonary vein isolation ablations, and CIED implantations. Implantation of leadless pacemakers were included in the group of ablations (“simple ablations”) due to the similarity in the setting of the procedure. Since the study did not include active intervention in patients, the local institutional Helsinki committee exempted us from obtaining informed consent.
Radiation measurements while using RSS were compared to radiation measurements taken during the previous 3 weeks, when RSS was not installed. In both setups standard protection measures were used (ie, tablemounted drapes and a ceiling suspended shield), therefore the measured reduction rates reflect the added protection of the RSS only. We aimed to compare the overall radiation measurements at different locations in the lab and the mean radiation per type of procedure while using RSS vs without installing RSS. Only procedures with 70% usage level and above were included in the final calculations for the comparison in radiation reduction.
Highly sensitive sensors were used for radiation dose measurements (Supplementary Figure 2). Minimum sensitivity of the Mirion DMC 3,000 sensor for clinical environment was 0.01 uSv. Normalized exposures were calculated by dividing total dose (in uSv) to the Dose Area Product ( Gy °ø m ^ 2).
Physicians and medical staff were requested to fill in feedback questions after at least 2 weeks of using the Shield System. Different questionnaires were filled by those who operate the fluoroscopy imaging system and the shield system (physicians and X-ray operators), and by the supporting staff in the room (nurses and medical technicians).
Radiation doses were normalized to patient’s dose area product, therefore taking into account the time of X-ray and other parameters that affect the magnitude of the X-ray (eg, patient body mass index (BMI), C-arm angulations). Radiation reduction was calculated in relation to the same calculations without the shields.
A Mann-Whitney test was conducted separately for each sensor location and for each procedure type (ablation/ CIED) to test whether there were differences between the normalized sensors’ measurements in the control and study phases. This test was selected since the measured radiation did not distribute normally, and the selected test does not assume a normal distribution in the dependent variable. The measurements that the tests were conducted with were from procedures that had more than 0.7 usage level.
During the study period 35 ablation procedures and 19 CIED procedures were done without RSS and served as controls. During the study period 31 ablation procedures and 24 CIED procedures were done with RSS. In all of the ablation procedures and in 17 of the CIED procedures RSS usage level was above 70% and these procedures were included in the study group.
A Mann-Whitney test was conducted separately for each sensor location and for each procedure type (Ablation/CIED) to test whether there were differences between the sensors’ measurements in the control and study phases. This test was selected since the radiation measured did not distribute normally, and the selected test does not assume a normal distribution in the dependent variable. The measurements that the tests were conducted with were from procedures that had more than 0.7 usage level.
Tables I to IV and Figures 2 , 4 , 5 summarize the results of the radiation measurements for ablations procedures with RSS vs without RSS.
Average ablation procedures time was shorter with RSS (93 minutes) vs without RSS (124 minutes) ( p = .048) and average X-ray time was not significantly different between the groups (28 minutes without RSS vs 21 minutes with RSS) (Figure 3).
Table II and Figure 4 show the usage level per type of ablation procedure. Overall, during 78% of total radiation time in the RSS group RSS was fully deployed; 95% of radiation time had any RSS usage (either Hover mode or fully deployed).
As shown in Table I, for all ablation procedures with usage level 70% and above, and for all the 5 sensors, the radiation with the system was statistically significantly lower than the radiation without the system. Overall, there was 87% reduction in radiation with RSS use (76%-97% for the different sensors, Table III ).
Table IV and Figure 5 show radiation reduction per procedure type and per sensor location. We did not see any noise or signal disturbances when using the RSS during Carto procedures, however, RSS’s lower robotic extendable shield assembled on the C-arm around the X-ray tube could not fully extend due to the presence of the magnet of the Carto system attached below the table. Indeed, sensor 5 demonstrated relatively lower rate of radiation reduction during Carto procedures.
There were no problems or inconvenience in using intraprocedural trans-esophageal echocardiography (TEE) or general anesthesia simultaneously with RSS. In these cases, the faceguard was removed and the flow of the procedure was going on smoothly.
Figures 2 and 6 and Tables I to III and V summarize the results of the radiation measurements for CIED implantation procedures with RSS vs without RSS.
Average CIED procedures time was 73 minutes without RSS usage vs 76 minutes with RSS and average X-ray time was 10 minutes without RSS vs 7 minutes with RSS, with no statistical difference between the groups for both parameters (Figure 3).
Table II shows the usage level per type of CIED procedure. Overall, 72% of total radiation time in the RSS group had RSS fully deployed and 16% of radiation time had RSS in Hover mode (total of 88% usage level of RSS). The full deployment was higher in the CRT procedures (80%) vs the PPM/ICD procedures (70%).
As shown in Table I, for all CIED procedures and for all the 5 sensors, the radiation with the system was statistically significantly lower than the radiation without the system. Overall, there was 83% reduction in radiation with RSS use (59%-92% for the different sensors, Table III).
Table V and Figure 6 shows radiation reduction per procedure type and per sensor location. Sensor 4 showed relatively low radiation reduction for CRT implantations and sensor 3 showed relatively low radiation reductions for PPM/ICD implantations -in those areas where the implanting physician was outside RSS shielding area.
Supplementary Figures 3 and 4 describe the distribution of ablations and CIED procedures in both study and control groups according to gender and average BMI. There was no significant difference in the composition of the groups regarding these parameters. We also looked at the distribution of electrophysiologists per procedure there was no difference in the relative participation of different physicians between the study group and control group.
Supplementary Figure 5 shows a correlation between the increase in RSS usage and reduction of radiation exposure.
Five physicians and 4 other medical staff filled the feedback questionnaires. Supplementary Figure 6 shows that all physicians ranked RSS as very safe (average score 5.6 out of 6), comfortable to use (6), simple operation (5.6) and workflow integration (5.4), with no added time of procedure (5.6).
The RSS is a novel robotic radiation shielding system that provides full-body protection to all medical personnel during fluoroscopy-guided procedures. We found that for both CIED procedures and ablation procedures and through the measurements of all 5 sensors, the radiation with RSS was significantly lower than the radiation without RSS. The results of this prospective trial in a real-world clinical environment are consistent with the first-in-men real world results published previously11 that showed mean radiation rate reduction above 90% for all sensor locations in both catheterization and EP procedures. Our current study showed that medical staff is pleased and would be happy to adopt this new technology. The use of the system does not add significant time to the procedure with no change in X-ray times. There were no problems or inconvenience in using intraprocedural TEE or general anesthesia simultaneously with RSS. In these cases, the faceguard was removed and the flow of the procedure was going on smoothly.
Our current study was aimed to measure radiation exposure per specific EP and CIED procedures using more sensitive sensors than the previous study11 in a large number of procedures done beyond the learning curve of the operators, and employ a controlled study design.
For ablation procedures with RSS usage level 70% and above, and for all the 5 sensors, there was 87% reduction in radiation with RSS use (76%-97% for the different sensors) vs without RSS. Overall, there was 95% average usage level for ablation procedures (78% fully deployed and 17% Hover mode). We did not use the system fully due to: learning curve of some of the operators and personal choice during specific cases. Thus, RSS during ablation procedures reduced full body radiation in 87% and has the potential to reduce it in 90% under 100% usage. For complex ablations with Carto 3D-mapping system, there were no disturbances of RSS to the signal recordings, the accuracy and the navigation of the Carto system. However, RSS’s lower robotic extendable shield assembled on the C-arm around the X-ray tube could not fully extend due to the presence of the magnet of the Carto system attached below the table. Thus, sensor 5 demonstrated relatively lower rate of radiation reduction during Carto procedures.
During the CIED procedures we had to accommodate and establish a new RSS deployment mode for the upper shield in order to uncover the upper chest surgical field and to have a direct visualization of the CIED pocket. Thus, only at the beginning of the procedure, if X-ray was needed for vascular puncture, the upper shield was not deployed (“access mode”). The lower shield was always fully deployed. During the rest of the procedure only one upper segment, the one facing the implanting physician (out of 5 upper shield segments), remained retracted to allow access to the surgical field (“modified RSS deployment mode”). Again, the lower shield was always fully deployed. Despite these accommodations, during CIED procedures, RSS reduced full body radiation in 82.7% under 88% averaged usage level, and has the potential to reduce it in 87% under 100% usage. Thus, higher usage level brings higher reduction rates. These favorable results of RSS advantage in CIED procedures, may fill a gap that exists in the field of electrophysiology regarding using convenient protecting measures from radiation exposure during implantations.
During CRT procedures there were lower radiation reduction rates measured on sensor 4 (which reflect lower body of the operators) despite over 80% full deployment of RSS. Possible explanations may be the small number of CRT procedures in the study group, or the location of the operator during the procedure: during CRT implantations the operators usually use 35 ° LAO angle of the C-arm and are forced to stand closer to the patient’s head, where lower protective measures lack. In contract, during CRT procedures the upper sensors (especially #3) had excellent radiation reduction rates (even higher than in pacemakers/ICD implantations). Thus, in CRT procedures with RSS the implanting physician probably should pay closer attention to his location relative to the patient and the protective measures.
Reducing high radiation exposure during medical procedures has been the principal task of many professional societies and advisory groups.4,5,12,13
In light of our results, RSS has the potential to improve medical team safety by offering radiation reduction to all interventional staff in the EP laboratory. It provides radiation reduction to the entire body and appears to integrate smoothly into the clinical workflow. It has a significant role in areas where current convenient protective solutions are scarce (such as during CIED implantations). It is recommended, however, to maintain existing standard shielding until additional clinical data is available. Future studies will probably measure radiation exposure under the lead aprons in order to test the feasibility of wearing thin lead aprons while using RSS.
There were only few CRT procedures in the study group with RSS. The number of Carto procedures in the study group was also low. Thus, the data from these procedures can be unrepresentative to make any conclusions regarding the true yield of RSS during these procedures. Future studies will hopefully fill this gap.
For both CIED procedures and ablation procedures the radiation with RSS was statistically significantly lower than the radiation without RSS installed. Higher usage level brings higher reduction rates. There is a high-level of integration in the clinical workflow, as well as safety profile for all types of EP procedures.
Thus, RSS may have an important role in full-body protection and whole-team protection from scattered radiation during EP and CIED procedures. Until more data is available to show elimination of radiation by RSS, it is recommended to maintain existing standard shielding.
Current standard radiation protection fails to fully protect the interventional cardiology personnel from scattered radiation, leaving the head, hands and feet exposed. A novel robotic radiation protection device (RSS) was developed to provide a full-body protection to all medical personnel by encapsulating the imaging beam and blocking scattered radiation. Our study shows that for both CIED and ablation procedures the radiation with RSS is significantly lower than the radiation without RSS installed. Higher usage level brings higher reduction rates. There is a high-level of integration in the clinical workflow, as well as safety profile for all types of EP procedures.
References
