Past and present work practices of European interventional cardiologists in the context of radiation protection of the eye lens-results of the EURALOC study

Trends of occupational exposure to ionizing radiation in Central China for the period 2000-2021

A retrospective analysis of occupational exposure to ionizing radiation from medical uses and industrial uses in the three provinces of Central China from 2000 to 2021 was conducted. The average annual effective dose in medical uses and industrial uses decreased from 2.042 mSv and 2.334 mSv in 2000-2002 to 0.476 mSv and 0.371 mSv in 2021 respectively; the fraction of monitored workers receiving annual dose not exceeding 1 mSv increased from 60.78% and 74.45% in 2000-2002 to 94.20% and 96.85% in 2021 respectively, while receiving annual doses exceeding 20 mSv declined from 1.35% and 1.91% in 2000-2002 to 0.18% and 0.03% in 2021 respectively. The average annual effective dose and NR20 in the period 2000-2021 were relatively high in professional public health institutions (0.955 mSv and 0.004) and hospitals (0.815 mSv and 0.004). In 2021, the average annual effective dose to monitored workers in different occupational categories in medical uses in the three provinces of Central China were in the range of 0.199-0.692 mSv, with interventional radiology received the highest dose and NR20 (0.692 mSv and 0.005); the average annual effective dose ranged from 0.161 to 0.493 mSv in industrial uses, with industrial radiography received the highest dose and NR20 (0.493 mSv and 0.001). Occupational exposure in medical uses and industrial uses declined obviously in Central China, and the groups receiving higher doses are the radiation workers working in hospitals and professional public health institutions, or engaged in interventional radiology, nuclear medicine and industrial radiography, warranting more effective radiation protection measures.

Estimating brain and eye lens dose for the cardiologist in interventional cardiology-are the dose levels of concern?

OBJECTIVES

To establish conversion coefficients (CCs), between mean absorbed dose to the brain and eye lens of the cardiologist and the air kerma-area product, PKA, for a set of projections in cardiac interventional procedures. Furthermore, by taking clinical data into account, a method to estimate the doses per procedure, or annual dose, is presented.

METHODS

Thermoluminescence dosimeters were used together with anthropomorphic phantoms, simulating a cardiologist performing an interventional cardiac procedure, to estimate the CCs for the brain and eye lens dose for nine standard projections, and change in patient size and x-ray spectrum. Additionally, a single CC has been estimated, accounting for each projections fraction of use in the clinic and associated PKA using clinical data from the dose monitoring system in our hospital.

RESULTS

The maximum CCs for the eye lens and segment of the brain, is 5.47 μGy/Gycm2 (left eye lens) and 1.71 μGy/Gycm2 (left brain segment). The corresponding weighted CCs: are 3.39 μGy/Gycm2 and 0.89 μGy/Gycm2, respectively.

CONCLUSIONS

Conversion coefficients have been established under actual scatter conditions, showing higher doses on the left side of the operator. Using modern interventional x-ray equipment, interventional cardiac procedures will not cause high radiation dose levels to the operator when a ceiling mounted shield is used, otherwise there is a risk that the threshold dose values for cataract will be reached.

ADVANCE IN KNOWLEDGE

In addition to the CCs for the different projections, methods for deriving a single CC per cardiac interventional procedure and dose per year were introduced.

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.

Assessment of Occupational Exposure to Eye Lens Dosimetry for Interventional Radiology Workers in China during 2017-2019

ABSTRACT

The eye lens is a sensitive tissue to ionizing radiation and recently has been recognized as more radiosensitive than previously considered. The International Commission on Radiological Protection (ICRP) has recommended a considerable reduction in the equivalent dose limit of eye lens from 150 mSv y -1 to 20 mSv y -1 , averaged over a defined period of 5 y. In this paper, the eye lens dose of interventional radiology workers in China during 2017-2019 is analyzed to understand the current status of eye lens occupational exposure and to provide decision-making suggestions for health supervision departments using data obtained from the National Radiological Health Information Platform in China. A total of 3,026 eye lens dose records of interventional radiology workers were collected. The average annual eye lens dose (AAELD) for interventional radiology workers ranged from 1.07 to 1.51 mSv during 2017-2019 and was 1.44 mSv for all monitored interventional radiology workers, with 2,973 records (98.2%) lower than the public limit of 15 mSv and 33 records (1.1%) exceeding the newly revised occupational eye lens dose limit of 20 mSv y -1 . During the period of 2017-2019, the AAELDs of interventional radiologists (1.61 mSv) and of interventional cardiologists (1.59 mSv) were significantly higher than that of other interventional workers (0.62 mSv); the AAELD of doctors (1.50 mSv) was significantly higher than that of nurses (1.01 mSv); the AAELD of western China (2.00 mSv) was significantly higher than that of eastern (1.11 mSv) and central China (1.27 mSv); and the AAELD of males (1.59 mSv) was significantly higher than that of females (0.84 mSv). The eye lens dose of interventional radiology workers meets the Chinese standard limit of 150 mSv y -1 , while some cases exceed the one recommended by ICRP. The study shows that the interventional radiology workers' eye lens dosimetry data complied with the existing Chinese eye lens dose limits. However, education, training, and supervision of radiation protection also should be strengthened continuously for interventional radiology workers, especially for the interventional radiologists and interventional cardiologists. Significant attention should be paid to the radiation protection of underdeveloped regions in China in future works.

Occupational exposure to physicians working with a Zero-Gravity™ protection system in haemodynamic and electrophysiology labs and the assessment of its performance against a standard ceiling suspended shield

A two centre clinical study was performed to analyse exposure levels of cardiac physicians performing electrophysiology and haemodynamic procedures with the use of state of the art Zero-Gravity™ radiation protective system (ZG). The effectiveness of ZG was compared against the commonly used ceiling suspended lead shield (CSS) in a haemodynamic lab. The operator's exposure was assessed using thermoluminescent dosimeters (TLDs) during both ablation (radiofrequency ablation (RFA) and cryoablation (CRYA)) and angiography and angioplasty procedures (CA/PCI). The dosimeters were placed in multiple body regions: near the left eye, on the left side of the neck, waist and chest, on both hands and ankles during each measurement performed with the use of ZG. In total 29 measurements were performed during 105 procedures. To compare the effectiveness of ZG against CSS an extra 80 measurements were performed with the standard lead apron, thyroid collar and ceiling suspended lead shield during CA/PCI procedures. For ZG, the upper values for the average eye lens and whole body doses per procedure were 4 µSv and 16 µSv for the left eye lens in electrophysiology lab (with additionally used CSS) and haemodynamic lab (without CSS), respectively, and about 10 µSv for the remaining body parts (neck, chest and waist) in both labs. The skin doses to hands and ankles non-protected by the ZG were 5 µSv for the most exposed left finger and left ankle in electrophysiology lab, while in haemodynamic lab 150 µSv and 17 µSv, respectively. The ZG performance was 3 times (p < 0.05) and at least 15 times (p < 0.05) higher for the eye lenses and thoracic region, respectively, compared to CSS (with dosimeters on the apron/collar). However, when only ZG was used slightly higher normalised doses were observed for the left finger compared to CSS (5.88e - 2 Sv/Gym² vs. 4.31 e - 2 Sv/Gym², p = 0.016). The study results indicate that ZG performance is superior to CSS. It can be simultaneously used with the ceiling suspended lead shield to ensure the protection to the hands as long as this is not obstructive for the work.

Body pain - An unheeded personal health hazard in interventional cardiologists: A national online cross-sectional survey study in China

INTRODUCTION

Interventional cardiology procedures (ICPs) have become the mainstay treatments in cardiology diseases and increased rapidly. This study aims to assess the occupational health hazards (OHHs) related to the long-time wearing of lead personal protective equipment and reveal health protection needs in interventional cardiologists.

METHODS AND RESULTS

We invited interventional and non-interventional cardiologists in tertiary hospitals in China to participate in an online cross-sectional survey on their health status, utilization of personal protective equipment (PPE), and personal health protection (PHP) needs. Propensity score methods were used for comparisons of OHHs between the matched interventional and non-interventional cardiologists. Totally, 642 interventional and 402 non-interventional cardiologists completed the survey. The interventional cardiologists had significantly higher incidence of body pain (56.6% vs. 24.2%, p < 0.001), bone and joint disease (21.7% vs. 8.6%, p = 0.001), cataract (3.5% vs. 0%, p = 0.039), and anxiety (8.1% vs. 2.5%, p = 0.029) than the matched non-interventional cardiologists. The risk of back pain was independently associated with female gender, performing percutaneous coronary intervention procedure or ≥ 2 types of ICP, and the personal annual volume of ICPs. Only 3.3% of interventional cardiologists were satisfied with PPE and 83.0% of them complained of physical toll caused by heavy PPE. 90.7% were willing to conduct ICP without radiation exposure.

CONCLUSIONS

Body pain was the main OHH in interventional cardiologists likely due to wearing heavy lead PPE for long working hours. Besides training more interventional cardiologists, the adoption of emerging technologies without heavy lead PPE will be a promising way to reduce the OHH burden.

Eye protection in interventional procedures

Data suggest that radiation-induced cataracts may form without a threshold and at low-radiation doses. Staff involved in interventional radiology and cardiology fluoroscopy-guided procedures have the potential to be exposed to radiation levels that may lead to eye lens injury and the occurrence of opacifications have been reported. Estimates of lens dose for various fluoroscopy procedures and predicted annual dosages have been provided in numerous publications. Available tools for eye lens radiation protection include accessory shields, drapes and glasses. While some tools are valuable, others provide limited protection to the eye. Reducing patient radiation dose will also reduce occupational exposure. Significant variability in reported dose measurements indicate dose levels are highly dependent on individual actions and exposure reduction is possible. Further follow-up studies of staff lens opacification are recommended along with eye lens dose measurements under current clinical practice conditions.

Personal dosimeter utilisation among South African interventionalists

Ionising radiation (IR) is increasingly being used in diagnostic and therapeutic procedures and offers increased benefits to patients but poses an increased occupational health risk to operators. The consistent use and monitoring of radiation health care workers' dosimeters is an important part of the process for ensuring adequate monitoring and control of IR in the workplace. There is however often inconsistent dosimeter utilisation among these workers. The aim of this study was to report on the dosimeter utilisation and dosimetry practices in South African interventionalists. We conducted a survey and did in-depth and group interviews to evaluate dosimetry practices and the factors influencing these practices. We used STATA 15 to do a descriptive analysis of the quantitative data. A thematic analysis of the qualitative data was done using a deductive and inductive approach. There were 108 respondents (35 radiologists, 41 adult cardiologists, 32 paediatric cardiologists). The majority overall (65.8%), and in each category were males. The median age was 44 (interquartile range (IQR) 31-66)) and the median years worked with fluoroscopy was 10 years (IQR 1-32). Overall interventionalists (55%) ranked their perceived occupation risk as 2/10. Thirteen per cent of all interventionalists reported never using a personal dosimeter (PD), 58% reported wearing it >70% of the time. Inconsistent and inappropriate use of PDs emerged strongly from the qualitative data. There was poor dosimeter utilisation in this study. Participants were not aware of the role of medical physics departments. Evaluation of dosimetry practices as a means of monitoring and improving radiation safety in the catheterisation laboratory must be improved to create an improved culture of radiation safety and protection.

Challenges in Occupational Dosimetry for Interventional Radiologists

This review presents the challenges met by interventional radiologists in occupational dosimetry. The issues mentioned are derived from the recommendations of the International Commission on Radiological Protection, the CIRSE guidelines on "Occupational radiation protection in interventional radiology" and the requirements of the European directive on Basic Safety Standards. The criteria for a proper use of personal dosimeters and the need to introduce optimization actions in some cases are set out in this review. The pros and cons of the electronic real-time dosimeters are outlined and the potential pitfalls associated with the use of personal dosimeters summarized. The electronic dosimeters, together with the appropriate software, allow an active optimization of the interventional procedures.

Report of IRPA task group on issues and actions taken in response to the change in eye lens dose limit

In 2018, the International Radiation Protection Association (IRPA) established its third task group (TG) on the implementation of the eye lens dose limit. To contribute to sharing experience and raising awareness within the radiation protection community about protection of workers in exposure of the lens of the eye, the TG conducted a questionnaire survey and analysed the responses. This paper provides an overview of the results of the questionnaire.

CORRELATION OF EYE LENS DOSES AND PERSONAL DOSE EQUIVALENT MEASURED ON THE ARM OF INTERVENTIONAL CARDIOLOGISTS FOR A RETROSPECTIVE ASSESSMENT OF DOSES TO OPERATORS' EYE LENS

Coefficients converting the readings of the whole body dosemeter worn on the left arm to eye lens doses were determined by analysing the correlations between Hp(10) and Hp(3) values. Doses were measured on a phantom for specific C-arm projections typically used during CA/PCI procedures. In order to estimate the cumulative eye lens doses, conversion coefficients were then applied to the dose records of interventional cardiologists collected in the database of dosimetry service between the years 1995 and 2009. The Hp(10) to Hp(3) conversion coefficients are 0.29 (CV = 34%) and 0.17 (CV = 42%) for left and right eye lens, respectively. However, they can vary from one laboratory to another depending on working technique. From among 61 interventional cardiologists, none exceeded the threshold dose of 0.5 Gy for eye lens opacities. However, 44% of interventional cardiologists were likely to exceed the annual limit of 20 mSv for the most exposed eye at least once in the analysed time period.

OCCUPATIONAL EYE LENS DOSE ESTIMATED USING WHOLE-BODY DOSEMETER IN INTERVENTIONAL CARDIOLOGY AND RADIOLOGY: A MONTE CARLO STUDY

Medical personnel performing interventional procedures in cardiology and radiology is considered to be a professional group exposed to high doses of ionizing radiation. Reduction of the eye lens dose limit made its assessment in the interventional procedures one of the most challenging topics. The objective of this work is to assess eye lens doses based on the whole-body doses using methods of computational dosimetry. Assessment included different C-arm orientations (PA, LAO and RAO), tube voltages (80 -110 kV) and efficiency of different combinations of protective equipment used in interventional procedures. Center position at the height of the thyroid gives best estimate of eye lens dose, with spreads of 11% (13%), 13% (17%) and 14% (13%) for the left (right) eye lens. The conversion factors of 1.03 (0.83), 1.28 (1.06) and 1.36 (1.06) to convert whole body to eye lens dose were derived for positions of first operator, nurse and radiographer, respectively. The eye lens dose reduction factors for different combinations of applied protective equipment are 178, 5 and 6, respectively.

Radiation Dose to the Eye Lens Through Radiological Imaging Procedures at the Surgical Workplace During Trauma Surgery

Background: Due to the drastic reduction of the eye lens dose limit from 150 mSv per year to 20 mSv per year since 2018, the prospective investigation of the estimated dose of the eye lens by radiological imaging procedures at the surgical site during trauma surgery in the daily work process was carried out. This was also necessary because, as experience shows, with changes in surgical techniques, there are also changes in the use of radiological procedures, and thus an up-to-date inventory can provide valuable information for the assessment of occupationally induced radiation exposure of surgical personnel under the current conditions. Methods: The eye lens radiation exposure was measured over three months for five trauma surgeons, four hand surgeons and four surgical assistants with personalized LPS-TLD-TD 07 partial body dosimeters Hp (0.07). A reference dosimeter was deposited at the surgery changing room. The dosimeters were sent to the LPS (Landesanstalt für Personendosimetrie und Strahlenschutzausbildung) measuring institute (National Institute for Personal Dosimetry and Radiation Protection Training, Berlin) for evaluation after 3 months. The duration of the operation, occupation (assistant, surgeon, etc.), type of surgery (procedure, diagnosis), designation of the X-ray unit, total duration of radiation exposure per operation and dose area product per operation were recorded. Results: Both the evaluation of the dosimeters by the trauma surgeons and the evaluation of the dosimeters by the hand surgeons and the surgical assistants revealed no significant radiation exposure of the eye lens in comparison to the respective measured reference dosimeters. Conclusions: Despite the drastic reduction of the eye lens dose limit from 150 mSv per year to 20 mSv per year, the limit for orthopedic, trauma and hand surgery operations is well below the limit in this setting.

Dosimetric dependence of ocular structures on eye size and shape for external radiation fields of electrons, photons, and neutrons

The dosimetric dependence of ocular structures on eye size and shape was investigated within the standard ICRP Publication 116 irradiation geometries. A realistic transport geometry was constructed by inserting a scalable and deformable stylised eye model developed in our previous study within the head of the ICRP Publication 110 adult male reference computational phantom. Beam irradiations of external electrons, photons, and neutrons on this phantom were simulated using the Monte Carlo radiation transport code PHITS in the geometries of AP, RLAT, PA and ROT. Absorbed doses in ocular structures such as ciliary body, retina, and optic nerves were computed as well as that in lens. A clear dosimetric dependence of ocular structures on eye size and shape was observed for external electrons while only a small dependence was seen for external photons and neutrons. Difference of the tendency was attributed to their depth-dose distributions where spread dose distributions were created by photons and neutrons while more concentrated distributions were created by external electrons.

Influences of operator head posture and protective eyewear on eye lens doses in interventional radiology: A Monte Carlo Study

PURPOSE

To quantify the effects of operator head posture and different types of protective eyewear on the eye lens dose to operators in interventional radiology (IR).

METHODS

A deformable computational human phantom, Rensselaer Polytechnic Institute (RPI) Adult Male, consisting of a high-resolution eye model, was used to simulate a radiologist who is performing an interventional radiology procedure. The radiologist phantom was deformed to a set of different head postures. Three different protective eyewear models were incorporated into the posture-deformed radiologist phantom. The eye lens dose of the radiologist was calculated using the Monte Carlo code, MCNP. Effects of the radiologist's head posture and different types of protective eyewear on eye lens doses were studied. The relationship between efficacy of protective eyewear and the radiologist's head posture was investigated. Effects of other parameters on efficacy of protective eyewear were also studied, including the angular position of the radiologist, the gap between the eyewear and the face of the radiologist, and the lead equivalent thickness.

RESULTS

The dose to both lenses decreased by 80% as the head posture moved from looking downward to looking upward. Sports wrap glasses were found to reduce doses further than the other two studied models. The efficacy of eyewear was found to be related to radiologist's head posture as well. When the radiologist was looking up, the protective eyewear almost provided no protection to both lenses. Other factors such as the face-to-eyewear distance and the lead equivalent thickness were also found to have an impact on the efficacy of protective eyewear. The dose reduction factor (DRF), defined as the ratio of the dose to the lens without protection to that with protection, decreased from 4.25 to 1.07 as the face-to-eyewear distance increased. The DRF almost doubled when the lead equivalent thickness increased from 0.07 to 0.35 mm. However, further increase in lead equivalent thickness showed little improvement in dose reduction.

CONCLUSION

The radiologist's head posture has a significant influence on the eye lens dose in IR. Sports wrap protective eyewear which conforms to the curve of the face is essential for the radiation protection of the eye lens. However, the radiologist's head posture and other exposure parameters should be considered when evaluating the protection of the radiologist's eyes.

Strategies to optimise occupational radiation protection in interventional cardiology using simultaneous registration of patient and staff doses

The International Commission on Radiological Protection recommends that occupational protection and patient protection be managed in an integrated approach. This paper describes the experience and the initial results of a system able to register and to process simultaneously staff and patient doses in interventional cardiology and the practical use of this system in the optimisation of occupational exposure. The system used simultaneously collects and manages patient and staff doses for all radiation events. The personal electronic dosimeters worn over the protective apron of health professionals working inside catheterisation laboratories can send (wireless) doses and dose rate values to an X-hub and provide the operators inside the catheterisation rooms with real-time information. Individual and global reports for all the health professionals may be periodically obtained from the system to help with the optimisation. The results for eight cardiologists, one fellow and four nurses for a total of 2468 interventional cardiology procedures and 3207 occupational dose values collected over one year are presented here. Annual doses Hp(10) measured over the apron for cardiologists ranged from 0.3 to 6.3 mSv. For the cardiologist, the ratio between occupational doses (over the apron) and patient doses ranged from 0.05 to 0.23 μSv Gy^-1 cm^-2, with a mean value of 0.12 μSv Gy^-1 cm^-2. The system allows defining optimisation strategies by comparing the results between the different operators while considering the workload and complexity of the procedures (based on the total Kerma Area Product managed by the different operators). The registration of the date and time of the occupational radiation doses allows auditing the use of the personal dosimeters worn by the various operators.