A European survey on the regulatory status for the estimation of the effective dose and the equivalent dose to the lens of the eye when radiation protection garments are used

Practical guidelines for personal monitoring and estimation of effective dose and dose to the lens of the eye in interventional procedures

Estimation of effective dose and dose to the lens of the eye for workers involved in interventional procedures is challenging. The interventional procedures in question involve high doses and, due to this, workers need to wear protective garments. As a result, various methodologies have been developed to assess the effective dose and dose to the lens of the eye. In the present study, measurements from four European dosimetry services, over and under protective garments, have been collected and analysed in order to provide practical guidelines based on the routine use of personal dosemeters from staff in interventional workplaces. The advantages and limitations of using one or two dosemeters are discussed.

[Radiation exposure of the eye lens in orthopedics and trauma surgery : A pilot study]

BACKGROUND

On 27 June 2017 the Act on new regulation of the law for the protection against the harmful effects of ionizing radiation was passed. One of the main innovations in daily surgical practice in the now legally stipulated provisions is the lowering of the eye lens dose to 20 mSv/year (§§ 78, 212 Radiation Protection Act, StrlSchG).

MATERIAL AND METHODS

To estimate the level of exposure of the eye lens to ionizing radiation that is to be expected in the course of surgical interventions, the dose that surgeons receive during surgery was determined. For this, the radiation exposure adjacent to the eye lens was measured using a forehead dosimeter while performing surgical interventions over a period of 8 weeks in 2 different operating rooms.

RESULTS

As a result, a mean estimated eye lens radiation dose Hp (3) of 190 µSv could be determined during the 2‑month study period. Thus, the estimated cumulative radiation dose in 1 year of approximately 1.2 mSv was significantly below the threshold of 20 mSv/year.

CONCLUSION

By complying with the common radiation protection measures in the context of operative interventions in orthopedics and trauma surgery, the legal limit value of 20 mSv/year is generally not expected to be exceeded.

Estimation of occupational radiation doses in neuroendovascular procedures

To estimate the mean effective dose per procedure with multiple dosimetry, to calculate the annual effective dose to personnel working in neuroendovascular procedures and compared with methods reported in the literature and with national and international limits. The radiation dose to personnel was monitored in 20 procedures classified as diagnostic or therapeutic. During each procedure, the equivalent dose to eyes, thyroid, under and over the lead apron at chest level, hands, gonads and knees was measured with lithium fluoride thermoluminescent dosimeter chips (TLD-100). Estimations of the annual effective dose from different methods found in literature that use one or two dosimeters and from this work were compared. Also, a comparison was made with the safety limits recommended in national and international regulations. Radiation exposure to eyes, thyroid, gonads and knees is relevant to the effective dose, and therefore to the annual effective dose estimations. Personnel position is important, as the performing physician, who is closer to the patient, received the highest dose measured. In particular, this was observed in the equivalent dose received over the apron. However, the equivalent dose to the right eye was higher for neuroanaesthesiologists than for performing physicians due to their position relative to the patient. In general, effective doses estimated using one- and two-dosimeter methods found in the literature were, respectively, lower and higher than those obtained with the ten-dosimeter method in this work. The annual effective doses to personnel estimated with the multiple dosimetry algorithm ranged from 1.3 to 1.5 mSv y^-1and are within the national and international limits.

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.

Effect of the radiation protective apron on the response of active and passive personal dosemeters used in interventional radiology and cardiology

In fluoroscopy guided interventional procedures, workers use protective garments and often two personal dosemeters, the readings of which are used for the estimation of the effective dose; whereas the dosemeter above the protection can be used for the estimation of the equivalent dose of the lens of the eye. When a protective apron is worn the scattered field that reaches the dosemeter is different from the case where no protection is used; this study analyses the changes in the response of seven passive and eight active personal dosemeters (APDs) when they are placed above a lead or lead equivalent garment for S-Cs and x-ray diagnostic qualities. Monte Carlo simulations are used to support the experimental results. It is found that for passive dosemeters, the influence on the dosemeter's response to the lead or lead equivalent was within the range 15%-38% for the x-ray qualities. This effect is smaller, of the order of 10%, when lead-free garments are used, and much smaller, within 1%-10%, for most of the APDs used in the study. From these results it is concluded that when comparing passive and active dosemeter measurements worn above the protection, a difference of 20%-40% is expected. The effect is small when deriving the effective dose from double dosimetry algorithms, but it can be of major importance when eye lens monitoring is based on the use of the dosemeter worn above the protection.