Attenuation assessment of medical protective eyewear: the AVEN experience

How direct measurements of worker eyes with a Scheimpflug camera can affect lensdose coefficients in interventional radiology

The 2013/59/Euratom Directive reduced the occupational exposure limits for the lens. Since it has become crucial to estimate the dose absorbed by the lens, we have studied the individual variability of exposed workers' ocular conformations with respect to the data estimated from their personal dosimetry. The anterior eye conformations of 45 exposed workers were acquired using Scheimpflug imaging and classified according to their sight conditions (emmetropia, myopia or hypermetropia). Three eye models were computed, with two lens reconstructions, and implemented in an interventional radiology scenario using Monte Carlo code. The models were dosimetrically analysed by simulating setup A, a theoretical monoenergetic and isotropic photon source (10-150 keV) and setup B, a more realistic interventional setting with an angiographic x-ray unit (50, 75, 100 kV peak). Scheimpflug imaging provided an average anterior chamber depth of (6.4 ± 0.5) mm and a lens depth of (3.9 ± 0.3) mm, together with a reconstructed equatorial lens length of (7.1-10.1) mm. Using these data for model reconstruction, dose coefficients (DCs) were simulated for all ocular structures. Regardless of the eye model used, the DCs showed a similar trend with radiation energy, which highlighted that for the same energy and setup, no significant dependence on ocular morphology and workers' visual conditions was observed. The maximum difference obtained did not exceed 1% for all eye models or structures analysed. Therefore, the individual variabilities of worker ocular anatomy do not require any additional correction, compared to the personal dosimetry data measured with a dedicated lens dosimeter. To estimate the dose absorbed by the other eye structures, it is, instead, essential to know the spectrum of the source that has generated the irradiation, since there are differences between monoenergetic sources and more realistic angiographic units.

Occupational eye lens dose in endoscopic retrograde cholangiopancreatography using a dedicated eye lens dosimeter

Increased x-ray exposure to physicians' eye lenses during radiology procedures is a significant concern. In this study, x-ray exposure to the eye was measured using an anthropomorphic head phantom, with and without radiation-protective devices, to examine the dose of x-ray radiation that physicians are exposed to during endoscopic retrograde cholangiopancreatography (ERCP). X-ray exposure of the eye was measured using novel dedicated direct eye lens dosimeters that could specifically measureH_p(3) during the ERCP procedure. The spatial dose in the height direction of the physician was measured using an ionization chamber dosimeter. Eye dosimeters were attached inside and outside the lead (Pb) glasses attached to the head of the human phantom to demonstrate its protective effect. Irradiation from the system lasted for 30 min. When the overcouch x-ray tube system is used, the cumulative radiation dose over the 30 min x-ray fluoroscopy time, without the use of radiation-protective devices, to the left and right eyes was 3.7 and 1.5 mSv, respectively. This dose was estimated to be the dose to the lens per therapeutic ERCP examination. With radiation-protective glasses, the dose reduced to 1.8 and 1.0 mSv for the left and right eye, respectively. The results of our study indicated that radiation exposure to the eye was reduced by up to 80.0% using Pb glasses and by 96.8% using radiation-protective curtains. Our study indicates that a physician's maximum radiation exposure to the eyes during an ERCP procedure may be above the level recommended by the International Commission on Radiological Protection when the physician does not use radiation-protective devices. The eyewear, which is larger and fitted more closely to the face, provided a better protection effect even with a low lead equivalence, demonstrating that the shape of eyewear is important for protective function.

Review of experimental estimates for the protection afforded by eyewear for interventional x-ray staff

This paper attempts to systematise all published experimental results for the dose reduction factor (DRF) offered by leaded eyewear on clinicians performing interventional procedures. We aim to present a comprehensive analysis of the issue and a comparison of the various equipment models at different exposure geometries. The main purpose of the paper is, however, to clarify the best choice for the DRF within the possible diverse contexts and approaches to eye lens dose assessment. Evidence has been obtained that the lowest estimates of DRF are associated with larger scatter incidence angles and that, except for the slightly better performance exhibited by wraparound eyeglasses, there is no real distinction between the DRFs for the different equipment categories. The dataset as a whole confirms that, when measurements for the concerned eyewear model and irradiation conditions are unattainable, assuming DRF = 2 represents an adequately conservative choice. Nonetheless, this value includes only 17% of all results from the literature, whereas their histogram follows a distribution skewed towards higher values, represented by a median equal to 5. Therefore, if more realistic dose reconstructions are necessary, such as for purposes of epidemiological investigations or compensation decisions, the adoption of this central tendency index appears to be more reasonable. The complexity of characterising the DRF behaviour as a function of the various exposure factors reinforces the consideration of a statistical approach to eye lens dose assessment as a viable alternative. In this perspective, assuming for DRF a lognormal distribution with parameters [Formula: see text] and [Formula: see text] which has been verified to satisfactorily approximate the literature data distribution, should be deemed to be an appropriate option.

Performances of a protector against scattered radiation during intraoperative use of a C-arm fluoroscope

The scattered radiation protector for mobile x-ray systems, Creative Valuable Protector-2, has been recently developed. However, there have been no studies investigating the effects of this device. We aim to investigate the effects of the scattered radiation protector on the equivalent doses from scattered radiation delivered to radiosensitive organs while simulating spine surgery using a C-arm fluoroscope. Chest and rando phantoms were used to simulate a patient and a surgeon in this study. The equivalent dose from scattered radiation to radiosensitive organs was measured in four different situations according to the use of the scattered radiation protector and the C-arm configuration. To compare the quality of the images with and without the scattered radiation protector, an acryl step phantom with five steps was used, and the contrast resolution of each step was calculated. The equivalent dose from the scattered radiation to the surgeon's eye, thyroid, and gonad decreased significantly by using the scattered radiation protector for both the Posteroanterior (PA) (p  <  0.001) and Anteroposterior (AP) (p  <  0.001) C-arm configurations. The installation of the scattered radiation protector also reduced the direct radiation dose to the chest phantom. A scattered map showed that scattered radiation doses decreased by approximately 50% for the PA configuration and 75% for the AP configuration by using the scattered radiation protector. Before and after installation of the scattered radiation protector, the contrast resolution of each adjacent step area was 0.025-0.404 and 0.216-0.421. The scattered radiation protector was effective in reducing not only the equivalent dose from scattered radiation to the surgeon's radiosensitive organs, but also the direct radiation dose to the patient. This was all achieved without decreasing the quality of the C-arm fluoroscopic images.