Derivation and application of dose reduction factors for protective eyewear worn in interventional radiology and cardiology

Effect of backscatter radiation on the occupational eye-lens dose

We quantified the level of backscatter radiation generated from physicians' heads using a phantom. We also evaluated the shielding rate of the protective eyewear and optimal placement of the eye-dedicated dosimeter (skin surface or behind the Pb-eyewear). We performed diagnostic X-rays of two head phantoms: Styrofoam (negligible backscatter radiation) and anthropomorphic (included backscatter radiation). Radiophotoluminescence glass dosimeters were used to measure the eye-lens dose, with or without 0.07-mm Pb-equivalent protective eyewear. We used tube voltages of 50, 65 and 80 kV because the scattered radiation has a lower mean energy than the primary X-ray beam. The backscatter radiation accounted for 17.3-22.3% of the eye-lens dose, with the percentage increasing with increasing tube voltage. Furthermore, the shielding rate of the protective eyewear was overestimated, and the eye-lens dose was underestimated when the eye-dedicated dosimeter was placed behind the protective eyewear. We quantified the backscatter radiation generated from physicians' heads. To account for the effect of backscatter radiation, an anthropomorphic, rather than Styrofoam, phantom should be used. Close contact of the dosimeter with the skin surface is essential for accurate evaluation of backscatter radiation from physician's own heads. To assess the eye-lens dose accurately, the dosimeter should be placed near the eye. If the dosimeter is placed behind the lens of the protective eyewear, we recommend using a backscatter radiation calibration factor of 1.2-1.3.

Comparison of shielding effects of over-glasses-type and regular eyewear in terms of occupational eye dose reduction

Given the new recommendations for occupational eye lens doses, various lead glasses have been used to reduce irradiation of interventional radiologists. However, the protection afforded by lead glasses over prescription glasses (thus over-glasses-type eyewear) has not been considered in detail. We used a phantom to compare the protective effects of such eyewear and regular eyewear of 0.07 mm lead-equivalent thickness. The shielding rates behind the eyewear and on the surface of the left eye of an anthropomorphic phantom were calculated. The left eye of the phantom was irradiated at various angles and the shielding effects were evaluated. We measured the radiation dose to the left side of the phantom using RPLDs attached to the left eye and to the surface/back of the left eyewear. Over-glasses-type eyewear afforded good protection against x-rays from the left and below; the average shielding rates on the surface of the left eye ranged from 0.70-0.72. In clinical settings, scattered radiation is incident on physicians' eyes from the left and below, and through any gap in lead glasses. Over-glasses-type eyewear afforded better protection than regular eyewear of the same lead-equivalent thickness at the irradiation angles of concern in clinical settings. Although clinical evaluation is needed, we suggest over-glasses-type Pb eyewear even for physicians who do not wear prescription glasses.

The Effect of a Suspended Radiation Protection System on Occupational Radiation Doses During Infrarenal EVAR Procedures: A Randomised Controlled Study

OBJECTIVE

To compare the protective effect of Zero Gravity (ZG) with conventional radiation protection during endovascular aneurysm repair (EVAR). Secondly, user experience was surveyed with a questionnaire on ergonomics.

METHODS

This was a single centre, prospective, randomised, two arm trial where 71 consecutive elective infrarenal EVAR procedures were randomised into two groups: (1) operator using ZG and assistant using conventional protection (n = 36), and (2) operator and assistant using conventional radiation protection (n = 35). A movable floor unit ZG system consists of a lead shield (1.0 mm Pb equivalent) for the front of the body and 0.5 mm Pb equivalent acrylic shielding for the head and neck. The ZG also includes arm flaps of 0.5 mm Pb equivalent covering the arm up to the elbow. Deep dose equivalent values, Hp(10) were measured with direct ion storage dosimeters (DIS) placed on various anatomical regions of the operator (axilla, chest, abdomen, and lower leg). Personal dose equivalent values, Hp(3) to eye lenses were measured in the operating and assisting surgeon using thermoluminescence dosimeters. The study was registered at the US National Institute of Health #NCT04078165.

RESULTS

Protection with the standard protection was superior in chest (0.0 vs. 0.1 μSv), abdomen (0.0 vs. 0.6 μSv), and lower leg (0.4 vs. 2.2 μSv) (p < .001). On the other hand, the ZG system yielded better shielding for the axilla (1.5 vs. 0.0 μSv) and eyes (6.3 vs. 1.1 μSv) of the operator. The use of ZG hampered the deployment of ancillary shields, which is particularly relevant for protection of the assisting surgeon. Users found ZG more cumbersome than conventional garments, it also impaired communication and reduced field of view.

CONCLUSION

Both ZG and conventional radiation protection reduced radiation exposure. Conventional protection allows better manoeuvrability at the price of wider exposure of the upper arm and axilla. ZG indirectly impaired protection of the assistant.

Evaluation of novel radiation protection devices during radiologically guided interventions

BACKGROUND

In radiologically guided interventions, medical practitioners are subjected to radiation exposure, which may lead to radiation-induced diseases. In this study, novel radiation shields for the head and neck were evaluated for their potential to reduce radiation exposure.

METHOD

An anthropomorphic phantom was exposed on its left side to scattered radiation from beneath to simulate the exposure of an operator in a x-ray operating room. Thermoluminescent dosimeters (TLDs) were positioned at different depths in five slices in the phantom, measuring personal dose equivalent. Two different set up situations were evaluated: a head protector designed to reduce radiation in the upper section of the head; and a novel thyroid protector prototype extended in the front and on both sides, designed to reduce radiation in the lower and middle sections of the head. A standard thyroid collar prototype and a ceiling mounted lead glass shield were used as comparisons. Furthermore, the head protector was evaluated in a clinical study in which TLDs were positioned to measure scattered radiation exposure to the heads of operators during endovascular interventions.

RESULTS

The extended thyroid protector reduced the scattered radiation in the throat, chin, and ear slices. Some shielding effect was seen in the brain and skull slices. The head protector showed a shielding effect in the skull slice up to two cm depth where it covered the phantom head. As expected, the ceiling mounted lead glass shield reduced the scattered radiation in all measuring points.

CONCLUSIONS

A ceiling mounted lead glass shield is an effective radiation protection for the head, but in clinical practice, optimal positioning of a ceiling mounted lead shield may not always be possible, particularly during complex cases when radiation protection may be most relevant. Added protection using these novel guards may compliment the shielding effect of the ceiling mounted lead shield. The head protector stand-alone did not provide sufficient protection of the head. The extended thyroid protector stand-alone provided sufficient protection in the lower and middle sections of the head and neck.

Radiation shielding effects of lead equivalent thickness of a radiation protective apron and distance during C-arm fluoroscopy-guided pain interventions: A randomized trial

BACKGROUND

The present study aimed to evaluate the degree of radiation shielding effects according to lead equivalent thickness and distance during C-arm fluoroscopy-guided lumbar interventions.

METHODS

The exposure time and air kerma were recorded using a fluoroscope. The effective dose (ED) was measured with and without the shielding material of the lead apron using 2 dosimeters at 2 positions. According to the lead equivalent thickness of the shielding material and distance from the side of the table, the groups were divided into 4 groups: group 1 (lead equivalent thickness 0.6 mm, distance 0 cm), group 2 (lead equivalent thickness 0.6 mm, distance 5 cm), group 3 (lead equivalent thickness 0.3 mm, distance 0 cm), and group 4 (lead equivalent thickness 0.3 mm, distance 5 cm). Mean differences such as air kerma, exposure time, ED, and ratio of EDs (ED with protector/ED without protector) were analyzed.

RESULTS

A total of 400 cases (100 cases in each group) were collected. The ratio of ED was significantly lower in groups 1 and 2 (9.18 ± 2.78% and 9.56 ± 3.29%, respectively) when compared to that of groups 3 and 4 (21.93 ± 4.19% and 21.53 ± 4.30%, respectively). The reductive effect of a 5-cm distance was 33.3% to 36.1% when comparing the ED between groups 1 and 2 and groups 3 and 4.

CONCLUSIONS

The 0.3- and 0.6-mm lead equivalent thickness protectors have a radiation attenuation effect of 78.1% to 78.5% and 90.4% to 90.8%, respectively. The 5-cm distance from the side of the table reduces radiation exposure by 33.3% to 36.1%.

A practical method for routine eye lens dosimetry of staff in interventional radiology

Hospital staff doing fluoroscopy-guided interventions receive the highest doses and are at risk of exceeding the new occupational eye lens dose limit of 20 mSv. Since the introduction of the new limit in the International Commission on Radiological Protection recommendations different eye lens dose monitoring techniques have been tested on phantoms. This study uses real-life dose data to assess the need for routine eye lens dose monitoring. The correlation of eye lens dose and Hp (10) measured with a whole-body dosemeter above the lead apron was investigated as an alternative to dedicated eye lens dosimetry. A survey taken among the medical personnel allowed to determine the preferred method for measuring eye lens doses in daily practice.

Evaluation of a New Real-Time Dosimeter Sensor for Interventional Radiology Staff

In 2011, the International Commission on Radiological Protection (ICRP) recommended a significant reduction in the lens-equivalent radiation dose limit, thus from an average of 150 to 20 mSv/year over 5 years. In recent years, the occupational dose has been rising with the increased sophistication of interventional radiology (IVR); management of IVR staff radiation doses has become more important, making real-time radiation monitoring of such staff desirable. Recently, the i3 real-time occupational exposure monitoring system (based on RaySafeTM) has replaced the conventional i2 system. Here, we compared the i2 and i3 systems in terms of sensitivity (batch uniformity), tube-voltage dependency, dose linearity, dose-rate dependency, and angle dependency. The sensitivity difference (batch uniformity) was approximately 5%, and the tube-voltage dependency was <±20% between 50 and 110 kV. Dose linearity was good (R2 = 1.00); a slight dose-rate dependency (~20%) was evident at very high dose rates (250 mGy/h). The i3 dosimeter showed better performance for the lower radiation detection limit compared with the i2 system. The horizontal and vertical angle dependencies of i3 were superior to those of i2. Thus, i3 sensitivity was higher over a wider angle range compared with i2, aiding the measurement of scattered radiation. Unlike the i2 sensor, the influence of backscattered radiation (i.e., radiation from an angle of 180°) was negligible. Therefore, the i3 system may be more appropriate in areas affected by backscatter. In the future, i3 will facilitate real-time dosimetry and dose management during IVR and other applications.

RELATIONSHIPS BETWEEN TYPES OF PROTECTIVE EYEWEAR AND EYE LENS DOSE WITHIN ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY

In this study, variations in eye lens dose across different types of protective operator eyewear as well as the most appropriate protective methods when conducting endoscopic retrograde cholangiopancreatography were evaluated. The eye lens doses of 10 types of commercially available protective eyewear were compared. The ratio of the measured value near the eye to the measured value at the eye lens position ranged from 0.65 to 5.40 and it varied according to the mounting position of the dosemeter as well as the type of protective eyewear. Thus, the eye lens dose may have been overestimated or underestimated. Regardless of the working conditions, a face shield type of protective eyewear is recommended to reduce the eye lens dose. Moreover, it is preferable to attach a lens dosemeter near the eye to measure and evaluate the eye lens dose.

DOSE MEASUREMENT PRECISION OF AN RPLD-BASED EYE LENS DOSEMETER APPLICABLE TO THE MEDICAL SECTOR

We demonstrate a practical calibration method and its applicability for a commercially available radiophotoluminescence dosemeter (RPLD), i.e. the GD-352M (AGC Techno Glass, Shizuoka, Japan) to eye lens dose monitoring, by performing the calibration according to the ISO recommendations. The calibration was then verified through a series of experiments. For verification of the derived calibration factor (1.21 ± 0.04, k = 1) of the RPLD, we performed standard irradiations in the ISO narrow series X-ray reference fields and the simulation measurements in the actual radiation fields in a hospital. The TLD-based commercially available dosemeters, DOSIRIS™ was also put on the ISO cylinder phantom and the RANDO phantom together with the GD-352M in the verification experiments. The personal dose equivalents Hp(3) obtained from the GD-352M and those obtained from the DOSIRIS™ were in good agreement with each other. Our results demonstrate the proper calibration of a commercially available RPLD that is applicable to the additional monitoring of the lens of the eyes for medical staff.

An investigation into potential improvements in the design of lead glasses for protecting the eyes of interventional cardiologists

The lens of the eye can be damaged by ionising radiation, so individuals whose eyes are exposed to radiation during their work may need to protect their eyes from exposure. Lead glasses are widely available, but there are questions about their efficiency in providing eye protection. In this study, Monte Carlo simulations are used to assess the efficiency of lead glasses in protecting the sensitive volume of the eye lens. Two designs currently available for interventional cardiologists are a wraparound (WA) style and ones with flat frontal lenses with side shielding. These designs were considered together with four modifications that would impact upon their efficiency: changing the lead equivalent thickness, adding lead to the frames, elongating the frontal lenses, and adding a closing shield to the bottom rim. For the eye closest to the source, standard models of lead glasses only decrease the radiation reaching the most sensitive region of the eye lens by 22% or less. Varying the lead thickness between 0.4 mm and 0.75 mm had little influence on the protection provided in the simulation of clinical use, neither did adding lead to the frames. Improved shielding was obtained by elongating the frontal lens, which could reduce radiation reaching the eye lens by up to 76%. Glasses with lenses that had a rim at the base, extending towards the face of the user, also provided better shielding than current models, decreasing the dose by up to 80%. In conclusion, elongating the frontal lens of lead glasses, especially of the WA design, could provide a three-fold increase in shielding efficiency and this is still valid for lenses with 0.4 mm lead equivalence.

Radiation Protection of the Eye Lens in Fluoroscopy-guided Interventional Procedures

The medical staff involved in fluoroscopy-guided procedures are at potential risks of radiation-induced cataract. Therefore, proper monitoring of the lens doses is critical, and radiation protection should be provided to the maximum extent that is reasonably achievable. The collar dosimeter is necessary to avoid underestimation of the lens dose, and the third dosimeter behind the protective eyewear would be helpful for those who are likely to exceed the dose limit. The reduction of the patient doses will correspondingly reduce the staff doses. Proper placement of the ceiling-mounted shields and minimization of the face-to-glass gap are the keys to effective shielding. The optimization of procedures and devices that help maintain a distance from the irradiated area and to prevent the looking-up posture will substantially reduce the lens dose.

Radiation safety for pain physicians: principles and recommendations

C-arm fluoroscopy is a useful tool for interventional pain management. However, with the increasing use of C-arm fluoroscopy, the risk of accumulated radiation exposure is a significant concern for pain physicians. Therefore, efforts are needed to reduce radiation exposure. There are three types of radiation exposure sources: (1) the primary X-ray beam, (2) scattered radiation, and (3) leakage from the X-ray tube. The major radiation exposure risk for most medical staff members is scattered radiation, the amount of which is affected by many factors. Pain physicians can reduce their radiation exposure by use of several effective methods, which utilize the following main principles: reducing the exposure time, increasing the distance from the radiation source, and radiation shielding. Some methods reduce not only the pain physician's but also the patient's radiation exposure. Taking images with collimation and minimal use of magnification are ways to reduce the intensity of the primary X-ray beam and the amount of scattered radiation. It is also important to carefully select the C-arm fluoroscopy mode, such as pulsed mode or low-dose mode, for ensuring the physician's and patient's radiation safety. Pain physicians should practice these principles and also be aware of the annual permissible radiation dose as well as checking their radiation exposure. This article aimed to review the literature on radiation safety in relation to C-arm fluoroscopy and provide recommendations to pain physicians during C-arm fluoroscopy-guided interventional pain management.

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.

Occupational radiation exposure to the lens of the eye in interventional radiology

INTRODUCTION

Cataract formation is a tissue reaction effected by radiation exposure. The purpose of this study was to evaluate the occupational exposure to the lens of the eye of interventional radiologists (IR's) and interventional radiology staff, with and without lead glasses.

METHODS

Ethical approval was provided by the hospital research and ethics committee. A prospective cohort study was performed over 1 year, doses recorded, lifetime dose (estimated at working 5 days in angiography, for 30 years) was estimated and dose compared to current guidelines. Thermoluminescent dosimeters (TLDs; Landauer, Glenwood, USA) Hp(3) were placed on both the exterior and interior side of the personal lead glasses worn by three interventional radiologists and two radiographers. They were monitored during all procedures performed within 1 year. Lead glasses (AttenuTech^® Microlite^® , Florida, USA) with specifications were 0.75 mm lead equivalent front shield, and Side shield 0.3 mm Pb equivalent. A control TLD was placed in the storage location of the lead glasses when not in use. Yearly dose was measured and lifetime dose was calculated from the data obtained. Calculation of dose received per day(s) spent performing procedures for both annual and lifetime exposure was performed. In addition a record of occurrence of splashes on glasses was made after each case.

RESULTS

Eye doses without protection were double the recommended limits for both annual and lifetime dose. For interventional radiologists working between 3 and 4 or more days in the lab per week, annual dose thresholds would be exceeded (20 mSv/year averaged over 5 years, no more than 50 mSv in 1 year). If interventional radiologists worked between 3 and 4 or more days in the lab, lifetime dose thresholds would be exceeded (500 mSv lifetime dose). Lead glasses reduced radiation exposure by an average of 79%. If lead glasses were worn no interventional radiologists would exceed annual or lifetime dose thresholds to the eyes even if working 5 days per week as the primary operator. Radiographers would not exceed annual or lifetime dose thresholds even without lead glasses. Splash incidents occurred for all interventional radiologists and one radiographer.

CONCLUSION

The use of lead glasses even in this small study resulted in a decreased dose of radiation to the lens of the eye. Regular use of radiation protection eyewear will reduce eye dose for primary proceduralists to well below yearly and lifetime thresholds.

RADIATION DOSES TO THE EYE LENS AND FOREHEAD OF INTERVENTIONAL RADIOLOGISTS: HOW HIGH AND ON WHAT GROUNDS?

The aim of the study was to measure and evaluate the radiation dose to the eye lens and forehead of interventional radiologists (IRs). The study included 96 procedures (lower-limb percutaneous transluminal angioplasties, embolisations/chemoembolisations and vertebroplasties) performed by 6 IRs. A set of seven thermoluminescence dosemeters was allocated to each physician. The highest dose per procedure was found for the left eye lens of the primary operator in vertebroplasties (1576 μSv). Left and right eye doses were linearly correlated to left and right forehead doses, respectively. A workload-based estimation of the annual dose to participating IRs revealed that the occupational dose limit for the eye lens can be easily exceeded. The left eye dose of ΙRs must be routinely monitored on a personalised basis. Τhe left eye dose measurement provides a reliable assessment of the ipsilateral forehead dose, along with valid estimations for the right eye and right forehead doses.

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.

Occupational eye dose to medical staff in various interventional cardiologic procedures: is the need for lead goggles the same in all groups of radiation workers?

Considering the increased use of interventional cardiologic procedures and concern about irradiation to the eyes, it is necessary to measure eye dose in radiation workers. The assessment of eye dose using collar dose is a routine but inaccurate method. Therefore this study was designed to measure eye dose in the radiation workers of various interventional cardiologic procedures. In this study eye dose was measured for left and right eyes in three groups of radiation workers in angiography ward of Afshar hospital in various procedures using TLD. Measurements were done separately for cardiologists, nurses and radio-technologists in 100 procedures. The nurses functioned as surgical assistants and were usually close to the table. The correlation of staff dose to exposure parameters was also investigated. Eye dose in physicians were higher than other staff in all procedures. Also the left eye dose was considerably higher than right one, especially for physicians. The median equivalent dose per procedure of left eye for physicians, nurses and radio-technologists were 7.4, 3.6, 1.4 µSv (PCI) and 3.2, 3.1, 1.3 µSv (Adhoc) and 3.2, 1.7, 1.1 µSv (CA), respectively. The annual left eye equivalent dose with (without) using lead goggles were 2.4 (15.3), 1.4 (2.2), 1.0 (1.1) mSv for physicians, nurses and radio-technologists, respectively. There were also a positive correlation between eye dose and KAP for procedures without lead goggles. The lead goggles showed lower protection effects for radio-technologists than other staff. Only 30% of physicians received a dose higher than 1/3 of the ICRP annual dose limit, therefor only physician eye dose should be monitored in catheterization labs.

A study of the underestimation of eye lens dose with current eye dosemeters for interventional clinicians wearing lead glasses

The reduction in the occupational dose limit of the eye lens has created the need for optimising eye protection and dose assessment, in particular for interventional clinicians. Lead glasses are one of the protection tools for shielding the eyes, but assessing the eye lens dose when these are in place remains challenging. In this study, we evaluated the impact of the position of H _p (3) dosemeters on the estimated eye lens dose when lead glasses are used in interventional settings. Using the Monte Carlo method (MCNPX), an interventional cardiology setup was simulated for two models of lead glasses, five beam projections and two patient access routes. H _p (3) dosemeters were placed at several positions on the operator and the obtained dose was compared to the dose to the sensitive part of the eye lens (H _lens). Furthermore, to reproduce an experimental setup, a reference dosemeter, H _p (3)_ref, was placed on the surface of the eye. The dose measured by H _p (3)_ref was, on average, only 60% of H _lens. Dosemeters placed on the glasses, under their shielding, underestimated H _lens for all parameters considered, by from 10% up to 90%. Conversely, dosemeters placed on the head or on the glasses, over their shielding, overestimated H _lens, on average, up to 60%. The presence or lack of side shielding in lead glasses affected mostly dosemeters placed on the forehead, at the left side. Results suggest that both use of a correction factor of 0.5 to account for the presence of lead glasses in doses measured outside their shielding and placing an eye lens dosemeter immediately beneath the lenses of lead glasses may lead to the underestimation of the eye lens dose. Most suitable positions for eye lens dose assessment were on the skin, unshielded by the glasses or close to the eye, with no correction to the dose measured.

Radiation protection knowledge and practices in interventional cardiologists practicing in Africa: a cross sectional survey

We conducted a survey of doctors working in the cardiac catheterisation laboratories in Africa on their knowledge, attitude and practice with respect to radiation protection. Of seventy-two respondents contacted, 61 (84.7%) completed the questionnaire. Twenty-eight, (45.9%) were younger than 45 years. Thirty-seven, (60.6%) had less than 10 years of experience in the laboratory. Only 28 (45.9%) had undertaken radiation protection training. Fifty-eight, (95.1%) consistently used lead aprons. Forty-seven, (77%) reported consistently using thyroid shields. Ten (16.4%) consistently used radiation protection eyeglasses, whilst 36 (59%) never used them. Thermoluminescent Dosimeter badges were consistently used in 23 (37.7%). Forty-two, (68.9%) reported having ceiling mounted lead/acrylic shields. Level of radiation exposure in the most recent one year was ≤2 mSv in 14, between 2 and 20 mSv in 8 and between 20 and 30 mSv in 2, whilst 33 did not know their dose readings. The use of basic radiation protection tools as well as the knowledge and measurement of radiation exposure among interventional cardiologists working in Africa is low. The unavailability of some of the protective tools and a knowledge gap in terms of radiation protection and monitoring of self-exposure were some of the reasons for suboptimal self-protection against ionising radiation among our respondents. We suggest that initiatives be taken by all stakeholders to train this group of medical professionals in basic radiation protection to avoid unnecessary exposure to themselves, co-workers and patients.

Angular dependence of shielding effect of radiation protective eyewear for radiation protection of crystalline lens

Radiation protective (RP) eyewear effectively protects crystalline lenses from radiation exposure. A drawback of RP eyewear is the angular dependence of the shielding effect, which results from the design of the eyewear. In this study, 21 models of RP eyewear with different designs and lead equivalences were assessed. Each piece of RP eyewear was hung on a Styrofoam phantom that imitated the head, and a 0.125-cc ionization chamber dosimeter was placed at the position of the crystalline lens. The differences in angular dependence of the shielding effect were evaluated by changing the irradiation angle, and parameters that improved the angular dependence of the shielding effect-sufficient lead equivalence, large coverage design, and minimum gap between the crystalline lens and the RP eyewear-were identified. Thus, the findings highlight the importance of selecting RP eyewear according to the angular distribution and the nature of radiation exposure in the workplace for radiation workers.

OPTIMIZATION OF A RADIOPHOTOLUMINESCENT GLASS DOSEMETER FOR OCCUPATIONAL EYE LENS DOSIMETRY IN INTERVENTIONAL RADIOLOGY/CARDIOLOGY

Hospital based workers that perform interventional radiology are at risk of reaching the eye lens dose limit of 20 mSv/y. These workers are exposed to the radiation scattered by the patient, which creates a complex field, with low radiation energy reaching the eyes of the medical staff from wide angles. Therefore, the dosemeter used in the assessment of the eye lens dose of interventional radiologists needs to respond accurately in such conditions. In this study, the angular response of a commercially available radiophotoluminescent glass dosemeter, GD-352M, was optimized via Monte Carlo simulations, aiming at its use as eye lens dosemeter in interventional radiology. The improved dosemeter was manufactured and then characterized in terms of Hp(3), the quantity recommended for eye lens dosimetry. Its response was compared to the IEC 62387:2012 requirements for Hp(3) and to requirements proposed specifically for eye lens dosemeters used in interventional radiology. The improved dosemeter meets the IEC 62387:2012 requirements for energy and angular response for Hp(3) and also shows good agreement with the more strict requisites proposed for eye lens dosemeters to be used in interventional radiology.

RESULTS FROM A NEW METHOD TO ASSESS THE OCCUPATIONAL LENS DOSE IN INTERVENTIONAL RADIOLOGY

Interventional radiology procedures have always been of particular concern because of the potential high dose to the workers. Special attention has recently been given to the lens dose: in 2011 the ICRP issued the recommendation 'Statement on Tissue Reactions' where a new limit of 20 mSv in a year, averaged over defined periods of 5 years, is given. Due to the impossibility of measuring the dose directly on the eye, there is not still a general consensus on a standardized methodology to assess the lens dose, which should be at the same time reliable, robust and simple to implement in practice. The procedure described here aims to assess the lens dose using the Hp(0.07) equivalent dose measured with a dosimeter worn at chest level above the lead apron, through a correlation with the total KAP per procedure and considering the type of the protection tools used during each procedure: glasses (with lateral shields), ceiling screen, both or neither of them and the frequency of their use.

AN ASSESSMENT OF THE DOSE REDUCTION OF COMMERCIALLY AVAILABLE LEAD PROTECTIVE GLASSES FOR INTERVENTIONAL RADIOLOGY STAFF

In light of the proposal from the International Commission on Radiological Protection for a lowered eye dose limit, now adopted by a European Union Council Directive, lead glasses may be required for some staff in interventional radiology to ensure that occupational exposure is as low as reasonably practicable. To investigate the lens protection offered from various models of lead glasses exposed to X-rays coming from a source to the left and below, calibrated radiochromic film was positioned in the lens area of a head phantom. When the source-to-eye angles were large, the dose reduction factors (the ratio of eye dose without protection to dose with protection) to the right lens area were much lower than to the left lens area, particularly with smaller-lensed glasses, due to gaps in protection between the face and the glasses. The results of this study reiterate the importance of employers providing eyewear based on the morphology of, and fit to, individual workers' faces.

EYE LENS DOSIMETRY FOR FLUOROSCOPICALLY GUIDED CLINICAL PROCEDURES: PRACTICAL APPROACHES TO PROTECTION AND DOSE MONITORING

Doses to the eye lenses of clinicians undertaking fluoroscopically guided procedures can exceed the dose annual limit of 20 mSv, so optimisation of radiation protection is essential. Ceiling-suspended shields and disposable radiation absorbing pads can reduce eye dose by factors of 2-7. Lead glasses that shield against exposures from the side can lower doses by 2.5-4.5 times. Training in effective use of protective devices is an essential element in achieving good protection and acceptable eye doses. Effective methods for dose monitoring are required to identify protection issues. Dosemeters worn adjacent to the eye provide the better option for interventional clinicians, but an unprotected dosemeter worn at the neck will give an indication of eye dose that is adequate for most interventional staff. Potential requirements for protective devices and dose monitoring can be determined from risk assessments using generic values for dose linked to examination workload.

The effectiveness of lead glasses in reducing the doses to eye lenses during cardiac implantation procedures performed using x-ray tubes above the patient table

The dose reduction factors (DRF) for different types of lead glasses and C-arm units with x-ray tubes placed above the patient table were calculated from the results of measurements by loose thermoluminescent dosimeters (TLDs) and EYE-D dosimeters using a Rando phantom. The DRF values were analysed for different positions of routine dosimeters worn outside lead eyewear and confronted with DRFs calculated as the ratio of the dose equivalent to the eye measured with and without the eyewear. Moreover, for eye lens dosimeters designed to be worn behind lead glasses, multiplicative factors for various positions of dosimeter were derived in order to account for the differences between the doses measured on the inner side of the glasses and the dose equivalent to the eye lens. The DRFs calculated for the position of a routine dosimeter worn outside lead glasses on the band near the left eye lens are 5.6 and 5.7 for goggles and metallic glasses, respectively, while the DRFs calculated as the ratio of doses to the eyes measured with and without the eyewear are 10.2 and 9.9, respectively. Therefore, for dosimeters routinely used outside lead eyewear, the DRF calculated for the position of the dosimeter should be used. Otherwise, we can anticipate an almost two-fold underestimation of the doses. When the dosimeter is worn behind lead glasses, up to two-fold differences between the dose equivalent to the eye lens and the dose measured at the inner side of the glasses were observed depending on the dosimeter position.

The impact of various protective tools on the dose reduction in the eye lens in an interventional cardiology-clinical study

The aim of the study was to check, in clinical practice, the potential for the dose reduction of lead eyewear and a ceiling-suspended shield used to protect the eye lens of physicians working in interventional cardiology. To this end, for the lead eyewear, the dose reduction factors were derived to correct the readings from a dosimeter used routinely outside the glasses. Four types of lead eyewear with attached loose thermoluminescent dosimeters and EYE-D dosimeters were worn by physicians in two clinical centres, for two-month periods, during coronary angiography (CA), percutaneous coronary intervention (PCI), and pacemaker procedures. In order to analyse, separately, how a ceiling-suspended lead screen absorbs the scattered radiation, a series of measurements was carried out during single CA/PCI procedures performed with and without the protection. The lead eyewear may reduce the doses to the eye closest to the x-ray tube by a factor between 1.1 and 3.4, depending on its model and the physician's position. The effectiveness of the eyewear may, however, vary-even for the same model and physician-almost twofold between different working periods. The ceiling-suspended shield decreases the doses in clinical practice by a factor of 2.3. The annual eye lens doses without the eyewear estimated from routine measurements are high-above or close to the new eye lens dose limit established by the recent EU Basic Safety Standards, even though the ceiling-suspended shield was used. Therefore, to comply with the new dose limit that is set in the Directive, protection of the eyes of physicians with high workloads might require the use of both the eyewear and the ceiling-suspended shield.

Occupational dose constraints for the lens of the eye for interventional radiologists and interventional cardiologists in the UK

The International Commission on Radiological Protection (ICRP) has recommended a 20 mSv year(-1) dose limit for the lens of the eye, which has been adopted in the European Union Basic Safety Standards. Interventional radiologists (IRs) and interventional cardiologists (ICs) are likely to be affected by this. The effects of radiation in the lens are somewhat uncertain, and the ICRP explicitly recommend optimization. Occupational dose constraints are part of the optimization process and define a level of dose which ought to be achievable in a well-managed practice. This commentary calls on the professional bodies to review a need for national constraints to guide local decisions. Consideration is given to developing such constraints using maximum expected doses in high-workload facilities with good radiation protection practices and application of a factor allowing for attenuation by lead glasses (LG). Doses are based on a Public Health England survey of eye dose in the UK. Maximum expected doses for ICs are approximately 21 mSv year(-1), neglecting LG. However, the extent of IR exposure is not yet fully known, and further evidence is required before conclusions are drawn. A Health and Safety Laboratory review of LG established a conservative dose reduction factor of 3 for models available in 2012. Application of this factor provides a dose constraint of 7 mSv year(-1) to the eye for ICs. To achieve this constraint, those employers with the most exposed ICs will have to provide and ensure the correct use of a ceiling-suspended eye shield and LG.

Measurement of occupational doses of ionising radiation to the lens of the eyes of interventional radiologists

Currently, there exists no standardised method for monitoring radiation doses to the eye lens. This investigation aimed to determine the optimum method for monitoring the eye doses for interventional radiologists. Three interventional radiologists were issued with a series of dosimeters to wear during their routine work. These dosimeters were worn at defined positions on the body and the absorbed dose to each position was measured. It was confirmed that the dose received to the thyroid collar followed an apparently well-defined relationship to the dose recorded on the forehead, which is representative of the dose to the lens of the eye. It was also confirmed that, as hypothesised, the dose to the left eye was universally greater than to the right, although by varying factors. It was concluded that the use of dosimeters attached to the inside arms of protective eyewear is the optimum solution for eye lens dosimetry. It was also concluded that, when used with a dose conversion factor which corroborates existing literature, dosimeters attached to the outside of a thyroid collar yield sufficiently accurate results for use in routine dosimetry programmes.

Assessment of eye lens doses for workers during interventional radiology procedures

The assessment of eye lens doses for workers during interventional radiology (IR) procedures was performed using a new eye lens dosemeter. In parallel, the results of routine individual monitoring were analysed and compared with the results obtained from measurements with a new eye lens dosemeter. The eye lens doses were assessed using Hp(3) measured at the level of the eyes and were compared with Hp(10) measured with the whole-body dosemeter above the lead collar. The information about use of protective measures, the number of performed interventional procedures per month and their fluoroscopy time was also collected. The assessment of doses to the lens of the eye was done for 50 IR workers at 9 Lithuanian hospitals for the period of 2012-2013. If the use of lead glasses is not taken into account, the estimated maximum annual dose equivalent to the lens of the eye was 82 mSv.

On the feasibility of utilizing active personal dosimeters worn on the chest to estimate occupational eye lens dose in x-ray angiography

The International Commission on Radiological Protection (ICRP) has recommended that the occupational dose limit to the eye lens be substantially reduced. To ensure compliance with these recommendations, monitoring of the occupational eye lens dose is essential in certain hospital work environments. For assessment of the eye lens dose it is recommended to use a supplementary dosimeter placed at a position adjacent to the eye(s). Wearing a dosimeter at eye level can, however, be impractical and distributing and managing additional dosimeters over long periods of time is cumbersome and costly for large clinical sites. An attractive alternative is to utilize active personal dosimeters (APDs), which are routinely used by clinical staff for real-time monitoring of the personal dose equivalent rate (H(p)(10)). In this work, a formalism for the determination of eye lens dose from the response of such APD's worn on the chest is proposed and evaluated. The evaluation is based on both phantom and clinical measurements performed in an x-ray angiography suite for interventional cardiology. The main results show that the eye lens dose to the primary operator and to the assisting clinical staff can be conservatively estimated from the APD response as D(eye)(conductor) = 2.0 APD chest and D(eye)(assisting) = 1.0 APD chest, respectively. However, care should be exercised for particularly short assisting staff and if radiation protection shields are misused. These concerns can be greatly mitigated if the clinical staff are provided with adequate radiation protection training.