Effectiveness of a radiation protective device for anesthesiologists and transesophageal echocardiography operators in structural heart disease interventions

Visualization of spatial dose distribution for effective radiation protection education in interventional radiology: obtaining high-accuracy spatial doses

In recent years, eye lens exposure among radiation workers has become a serious concern in medical X-ray fluoroscopy and interventional radiology (IVR), highlighting the need for radiation protection education and training. This study presents a method that can maintain high accuracy when calculating spatial dose distributions obtained via Monte Carlo simulation and establishes another method to three-dimensionally visualize radiation using the obtained calculation results for contributing to effective radiation-protection education in X-ray fluoroscopy and IVR. The Monte Carlo particle and heavy ion transport code system (PHITS, Ver. 3.24) was used for calculating the spatial dose distribution generated by an angiography device. We determined the peak X-ray tube voltage and half value layer using Raysafe X2 to define the X-ray spectrum from the source and calculated the X-ray spectrum from the measured results using an approximation formula developed by Tucker et al. Further, we performed measurements using the "jungle-gym" method under the same conditions as the Monte Carlo calculations for verifying the accuracy of the latter. An optically stimulated luminescence dosimeter (nanoDot dosimeter) was used as the measuring instrument. In addition, we attempted to visualize radiation using ParaView (version 5.12.0-RC2) using the spatial dose distribution confirmed by the above calculations. A comparison of the measured and Monte Carlo calculated spatial dose distributions revealed that some areas showed large errors (12.3 and 24.2%) between the two values. These errors could be attributed to the scattering and absorption of X-rays caused by the jungle gym method, which led to uncertain measurements, and (2) the angular and energy dependencies of the nanoDot dosimetry. These two causes explain the errors in the actual values, and thus, the Monte Carlo calculations proposed in this study can be considered to have high-quality X-ray spectra and high accuracy. We successfully visualized the three-dimensional spatial dose distribution for direct and scattered X-rays separately using the obtained spatial dose distribution. We established a method to verify the accuracy of Monte Carlo calculations performed through the procedures considered in this study. Various three-dimensional spatial dose distributions were obtained with assured accuracy by applying the Monte Carlo calculation (e.g., changing the irradiation angle and adding a protective plate). Effective radiation-protection education can be realized by combining the present method with highly reliable software to visualize dose distributions.

Radiation dose to the eye of physicians during radio frequency catheter ablation: a small-scale study

BACKGROUND

Radio frequency catheter ablation (RFCA), a treatment for arrhythmia, requires a long fluoroscopy time that increases the radiation exposure dose to the physician, particularly to the lens of the eye. It is recommended that a lens-specific dosimeter such as DOSIRIS® is used to measure the dose to the lens.

AIMS

In this study, we investigated whether conventional glass badges can be used as an alternative to lens dosimeters.

METHODS

The doses to the lenses of two physicians (physician A, main operator; physician B, assistant; physician B was further away from the patient than physician A) were measured for 126 RFCA procedures performed over a 6-month period (fluoroscopy rate of 3.0 p/s with use of a ceiling-hanging shield).

RESULTS

The cumulative value measured by a lens dosimeter attached to the inside of Pb glasses (0.07-mm dose equivalent) next to the left eye was 4.7 mSv for physician A, and 0.8 mSv for physician B. The reading on the glass badge worn on the left side of the neck was 4.7 mSv for physician A and 1.3 mSv for physician B. Lens dosimeter and glass badge values showed a good correlation for the left eye and left neck (r = 0.86, p < 0.01).

CONCLUSIONS

We show that glass badges may be a viable alternative to lens-equivalent dosimetry when using low-pulse fluoroscopy and a ceiling-hanging shield.

Concept, Design, and Preclinical Testing of a Remote-Control Robotic System for Transesophageal Echocardiography

Background

Interventional echocardiography (IE) plays a critical role in guiding structural heart interventions. IE specialists face challenges including high radiation exposure and unfavorable ergonomics. To address these issues, a novel remote-control robotic (RCR) system for transesophageal echocardiography (TEE) control has been developed. This study aims to describe the novel RCR system and to assess its performance in bench tests and in vitro models in terms of functionality, image quality, and reproducibility.

Methods

Bench testing and in vitro testing were performed using the RCR system. All tests were performed using the GE 6VT-D TEE probe and the GE Vivid E95.

Results

Key findings include proof of concept through bench testing, remote control of all five degrees of freedom of the TEE probe, and reliable, fast, and accurate reproducibility using automated navigation. The ROB'E Base is securely attached to the operating table, optimizing the footprint in the operating room. The ROB'E Guide accurately performs the forward and backward motion of the flexible portion of the TEE probe, stabilizing the achieved positions and preventing twisting during rotation. The ROB'E RCR system can store and reproduce TEE probe positions and has demonstrated reliable and accurate automated reproducibility in both bench and in vitro tests.

Conclusions

The ROB'E RCR system for TEE overcomes the limitations of conventional IE by using a RCR approach that eliminates the need for the echocardiographer to be physically present in the operating room. Thus, it significantly reduces radiation exposure and demonstrates its capabilities to improve image quality, reproducibility, and overall safety in IE.

Eye Lens Radiation Dose to Nurses during Cardiac Interventional Radiology: An Initial Study

Although interventional radiology (IVR) is preferred over surgical procedures because it is less invasive, it results in increased radiation exposure due to long fluoroscopy times and the need for frequent imaging. Nurses engaged in cardiac IVR receive the highest lens radiation doses among medical workers, after physicians. Hence, it is important to measure the lens exposure of IVR nurses accurately. Very few studies have evaluated IVR nurse lens doses using direct dosimeters. This study was conducted using direct eye dosimeters to determine the occupational eye dose of nurses engaged in cardiac IVR, and to identify simple and accurate methods to evaluate the lens dose received by nurses. Over 6 months, in a catheterization laboratory, we measured the occupational dose to the eyes (3 mm dose equivalent) and neck (0.07 mm dose equivalent) of nurses on the right and left sides. We investigated the relationship between lens and neck doses, and found a significant correlation. Hence, it may be possible to estimate the lens dose from the neck badge dose. We also evaluated the appropriate position (left or right) of eye dosimeters for IVR nurses. Although there was little difference between the mean doses to the right and left eyes, that to the right eye was slightly higher. In addition, we investigated whether it is possible to estimate doses received by IVR nurses from patient dose parameters. There were significant correlations between the measured doses to the neck and lens, and the patient dose parameters (fluoroscopy time and air kerma), implying that these parameters could be used to estimate the lens dose. However, it may be difficult to determine the lens dose of IVR nurses accurately from neck badges or patient dose parameters because of variation in the behaviors of nurses and the procedure type. Therefore, neck doses and patient dose parameters do not correlate well with the radiation eye doses of individual IVR nurses measured by personal eye dosimeters. For IVR nurses with higher eye doses, more accurate measurement of the radiation doses is required. We recommend that a lens dosimeter be worn near the eyes to measure the lens dose to IVR nurses accurately, especially those exposed to relatively high doses.

Body Surface Radiation Exposure in Interventional Echocardiographers During Structural Heart Disease Procedures

Background

The distribution of radiation exposure on the body surface of interventional echocardiographers during structural heart disease (SHD) procedures is unclear.

Objectives

This study estimated and visualized radiation exposure on the body surface of interventional echocardiographers performing transesophageal echocardiography by computer simulations and real-life measurements of radiation exposure during SHD procedures.

Methods

A Monte Carlo simulation was performed to clarify the absorbed dose distribution of radiation on the body surface of interventional echocardiographers. The real-life radiation exposure was measured during 79 consecutive procedures (44 transcatheter edge-to-edge repairs of the mitral valve and 35 transcatheter aortic valve replacements [TAVRs]).

Results

The simulation demonstrated high-dose exposure areas (>20 μGy/h) in the right half of the body, especially the waist and lower body, in all fluoroscopic directions caused by scattered radiation from the bottom edge of the patient bed. High-dose exposure occurred when obtaining posterior-anterior and cusp-overlap views. The real-life exposure measurements were consistent with the simulation estimates: interventional echocardiographers were more exposed to radiation at their waist in transcatheter edge-to-edge repair than in TAVR procedures (median 0.334 μSv/mGy vs 0.053 μSv/mGy; P < 0.001) and in TAVR with self-expanding valves than in those with balloon-expandable valves (median 0.067 μSv/mGy vs 0.039 μSv/mGy; P < 0.01) when the posterior-anterior or the right anterior oblique angle fluoroscopic directions were used.

Conclusions

During SHD procedures, the right waist and lower body of interventional echocardiographers were exposed to high radiation doses. Exposure dose varied between different C-arm projections. Interventional echocardiographers, especially young women, should be educated regarding radiation exposure during these procedures. (The development of radiation protection shield for catheter-based treatment of structural heart disease [for echocardiologists and anesthesiologists]; UMIN000046478).

Comparison of Radiation Exposure Among Interventional Echocardiographers, Interventional Cardiologists, and Sonographers During Percutaneous Structural Heart Interventions

Importance

Transesophageal echocardiography during percutaneous left atrial appendage closure (LAAO) and transcatheter edge-to-edge mitral valve repair (TEER) require an interventional echocardiographer to stand near the radiation source and patient, the primary source of scatter radiation. Despite previous work demonstrating high radiation exposure for interventional cardiologists performing percutaneous coronary and structural heart interventions, similar data for interventional echocardiographers are lacking.

Objective

To assess whether interventional echocardiographers are exposed to greater radiation doses than interventional cardiologists and sonographers during structural heart procedures.

Design, Setting, and Participants

In this single-center cross-sectional study, radiation doses were collected from interventional echocardiographers, interventional cardiologists, and sonographers at a quaternary care center during 30 sequential LAAO and 30 sequential TEER procedures from July 1, 2016, to January 31, 2018. Participants and study personnel were blinded to radiation doses through data analysis (January 1, 2020, to October 12, 2021).

Exposures

Occupation defined as interventional echocardiographers, interventional cardiologists, and sonographers.

Main Outcomes and Measures

Measured personal dose equivalents per case were recorded using real-time radiation dosimeters.

Results

A total of 60 (30 TEER and 30 LAAO) procedures were performed in 60 patients (mean [SD] age, 79 [8] years; 32 [53.3%] male) with a high cardiovascular risk factor burden. The median radiation dose per case was higher for interventional echocardiographers (10.6 μSv; IQR, 4.2-22.4 μSv) than for interventional cardiologists (2.1 μSv; IQR, 0.2-8.3 μSv; P < .001). During TEER, interventional echocardiographers received a median radiation dose of 10.5 μSv (IQR, 3.1-20.5 μSv), which was higher than the median radiation dose received by interventional cardiologists (0.9 μSv; IQR, 0.1-12.2 μSv; P < .001). During LAAO procedures, the median radiation dose was 10.6 μSv (IQR, 5.8-24.1 μSv) among interventional echocardiographers and 3.5 (IQR, 1.3-6.3 μSv) among interventional cardiologists (P < .001). Compared with interventional echocardiographers, sonographers exhibited low median radiation doses during both LAAO (0.2 μSv; IQR, 0.0-1.6 μSv; P < .001) and TEER (0.0 μSv; IQR, 0.0-0.1 μSv; P < .001).

Conclusions and Relevance

In this cross-sectional study, interventional echocardiographers were exposed to higher radiation doses than interventional cardiologists during LAAO and TEER procedures, whereas sonographers demonstrated comparatively lower radiation doses. Higher radiation doses indicate a previously underappreciated occupational risk faced by interventional echocardiographers, which has implications for the rapidly expanding structural heart team.