Influence of safety glasses, body height and magnification on the occupational eye lens dose during pelvic vascular interventions: a phantom study

Objective By simulating a fluoroscopic-guided vascular intervention, two differently designed radiation safety glasses were compared. The impacts of changing viewing directions and body heights on the eye lens dose were evaluated. Additionally, the effect of variable magnification levels on the arising scattered radiation was determined. Methods A phantom head, replacing the operator’s head, was positioned at different heights and rotated in steps of 20° in the horizontal plane. Thermoluminescent dosimeters (TLD), placed in the left orbit of the phantom, detected eye lens doses under protected and completely exposed conditions. In a second step, radiation dose values with increasing magnification levels were detected by RaySafe i3 dosimeters. Results Changing eye levels and head rotations resulted in a wide range of dose reduction factors (DRF) from 1.1 to 8.5. Increasing the vertical distance between the scattering body and the protective eyewear, DRFs markedly decreased for both glasses. Significant differences between protection glasses were observed. Increasing magnification with consecutively decreasing FOV size variably reduced the dose exposure to the eye lens between 47 and 83%, respectively. Conclusion The safety glasses in the study effectively reduced the dose exposure to the eye lens. However, the extent of the protective effect was significant depending on eye levels and head rotations. This may lead to a false sense of safety for the medical staff. In addition, the application of magnification reduced the quantity of scattering dose significantly. To ensure safe working in the Cath-lab, additional use of protective equipment and the differences in design of protective eyewear should be considered. Key Points • Eye lens dose changes with physical size of the interventionist and viewing direction. • The use of magnification during fluoroscopic-guided interventions reduces scattered radiation.

Protected and unprotected radiation exposure to the eye lens of vascular surgeons during endovascular procedures in hybrid operating rooms

Objective Radiation induced cataract has been observed at lower threshold doses than expected. Therefore, the annual limit for equivalent dose to the eye lens has been reduced from 150 to 20 mSv. We aimed to evaluate radiation exposure to the eye lens of vascular surgeons working in a hybrid operating room before and after a dose reduction program was established. Methods Prospective non-randomized trial with a historic control group. From April – October 2019, radiation exposure to the operator was measured during all endovascular procedures performed in the hybrid operating room using BeOSL Hp(3) eye lens dosimeters placed outside the 0.75mm lead equivalent glasses on the side of the radiation source and behind the lead glasses. Measured values were compared to data from a prospective study performed at the same center in the years of 2012 and 2013 before a dose reduction program had been implemented. Results A total of 181 consecutive patients underwent an endovascular procedure in the hybrid operating room. The mean unprotected eye lens dose of the main operator was 0.119 mSv for EVAR (n = 30), 0.118 mSv for TEVAR (n = 23), 0.312 mSv for more complex aortic procedures (F/BrEVAR; n = 15) and 0.046 mSv for peripheral interventions. Compared to the control period, EVAR had 75% lower, TEVAR 79% lower and more complex aortic procedures 55% lower radiation exposure unprotected eye lens of the operator. The 0.75 mm lead equivalent glasses led to a median reduction of the exposure to the eye lens by the factor 3.43. Behind the lead glasses at the level of the eye lens, radiation exposure exceeding the detection limit of 0.042 mSv was measured only in 22 of 181 cases. There was a significant correlation between DAP between both protected and unprotected eye lens dose (p < 0.0001, r2 = 0.512 and 0.282). DAP correlated significantly with patients’ body mass index, operating time, fluoroscopy time and digital subtraction angiography time. Conclusion The dose reduction program at our institution has led to a relevant reduction of the radiation dose to the head and the eye lens of the main operator in endovascular procedures. With optimum radiation protection measures including a ceiling-mounted shield and 0.75 mm lead equivalent glasses, more than 440 EVARs, 280 TEVARs or 128 FEVARs could be performed per year until the dose limit for the eye lens of 20 mSv would be reached.

Assessment Of Whole Body, Skin and Eye Lens Doses of the Interventional Radiologists At Selected Hospitals in Iran

High radiation doses to the body may lead to the stochastic/deterministic effects of ionizing radiation on the critical organs as well as causing the cataract in eye lens of the clinical staff in interventional radiology. In this study, the received doses of the eyes, skin and whole body of 38 clinical staff including physicians, residents, nurses and radiotechnologists in cardiac angiography departments in three selected hospitals were assessed using personal dosemeters during two bimonthly dosimetry periods. Moreover, the correlation coefficients among the measured dose components including eye lens dose, skin dose and whole body dose equivalent in both area of under and over their lead-apron were calculated for all these occupational groups. The results show that the occupational annual dose values of the clinical staff are below the annual dose limits recommended by International Commission on Radiation Protection. Furthermore, among the measured dose components, the highest correlation coefficient value was obtained between the eye lens dose and personal dose equivalent measured over the lead apron for all the occupational groups.

Applicability of a Commercially Available Active Extremity Dose-Rate Meter to Eye Lens Dose Monitoring

A commercially available active extremity dosemeter is a promising candidate for medical staff aid individual monitoring of the eye lens. We investigated the applicability of the newly developed active extremity dosemeter, which uses a low-energy photon probe, to eye lens dose monitoring by performing a complete characterization of the dosemeters. Performance tests revealed that the active extremity dosemeter would overestimate personal dose equivalent, Hp(3), when the probe is worn close to the lens of the eye of a medial worker without any improvement in the response. Introducing an appropriate filter into the probe for low-energy photon has proven to improve the response. The dosemeter then satisfies the criteria of the personal dosemeter for eye lens dosimetry and can be applicable to individual monitoring of eye lens dose. This article also discusses the applicability of the dosemeter to area monitoring for decision making regarding additional monitoring of the eye lens and the extremities.

Operator’s eye lens dose in computed tomography–guided interventions

Objectives To survey (1) operator’s eye lens doses in typical computed tomography (CT)-guided interventions, (2) correlation between dose length product (DLP) and the operator’s dose, and (3) different ways for estimating the eye lens dose in clinical settings. Methods Doses of 16 radiologists in 164 CT-guided interventional procedures were prospectively measured during a 6-month time period upon radioprotective garments and descriptive statistical outcomes were calculated. The correlations between DLP and measured doses were surveyed. Results On average, the operator’s dose at the eye level (DEL, Hp(0.07)) was 22 μSv per procedure and the personal equivalent dose Hp(10) at the collar level was 21 μSv per procedure. The mean DLP of a procedure was 320 mGy cm, where 54% resulted from the fluoroscopy, the mean exposure time being 18 s. Based on the results, the operator’s DEL could be estimated from DLP using the equation DEL (μSv) = 0.10 μSv/mGy cm × patient fluoro DLP (mGycm) (p < 0.001), and the dose at the collar level (DCL) using the equation DCL (μSv) = 0.12 μSv/mGy cm × patient fluoro DLP (mGy cm) (p < 0.001). In addition, DEL (μSv) = 0.7 × DCL (μSv). Conclusions The eye lens doses in CT-guided interventions are generally low even without protective equipment, and it is unlikely that the recommended annual equivalent dose limit of 20 mSv for the lens of the eye will be exceeded by conducting CT-guided interventions solely. Eye lens dose can be roughly estimated based on either DLP of the procedure or dose measured at the operator’s collar level. Key Points • Eye lens doses in CT-guided operations are generally low. • It is unlikely that the ICRP recommendation of the yearly equivalent dose limit of 20 mSv will be exceeded by conducting CT-guided interventions solely. • Magnitude of eye lens dose can be estimated based on either DLP of the procedure or dose measured at the operator’s collar level.