Radiation Protection Dosimetry (2015), Vol. 165, No. 1–4, pp. 299 –303 Advance Access publication 15 April 2015
doi:10.1093/rpd/ncv173
ASSESSMENT OF EYE LENS DOSES FOR WORKERS DURING INTERVENTIONAL RADIOLOGY PROCEDURES A. Urboniene*, E. Sadzeviciene and J. Ziliukas Radiation Protection Centre, Kalvariju 153, Vilnius 08221, Lithuania *Corresponding author: [email protected]
INTRODUCTION
MATERIALS AND METHODS
In 2011, the International Commission on Radiological Protection (ICRP) published a statement on tissue reactions(1). For the lens of the eye, the threshold in absorbed dose for radiation-induced cataract is considered to be 0.5 Gy. Based on this new threshold, the ICRP has recommended to reduce an equivalent dose limit for the lens of the eye. After this recommendation, the equivalent dose limit for the lens of the eye was reduced from 150 to 20 mSv y – 1, averaged over a defined period of 5 y, with no annual dose in a single year exceeding 50 mSv(2, 3). In 2013, reduced annual occupational equivalent dose limit to the lens of the eye was adopted in the European legislation(3). This new provision should be adopted in legal acts of all Member States during the period of 4 y. The new dose limit becomes very important for interventional radiology (IR) workers, because this category of workers receives the highest occupational exposure compare with other medical staff. Another alarming factor of the risk for radiation-induced cataract formation is progressively increasing workload of IR workers. According to the annual report of the Lithuanian Hygiene Institute, the number of IR procedures performed since 2008 has increased with about 40 %. The number of IR procedures performed in 2008 was 31 807, 56 300 in 2012 and 49 278 in 2013, while the increase in the number of IR workers was with only about 15 % (188 IR workers in 2008, 218 in 2012 and 222 in 2013). With the increase in IR procedures, the exposure of IR workers also increases. The purpose of this study was to study the current situation of radiation doses to the lens of the eye of IR workers during IR procedures and according to the results to suggest practical recommendations for monitoring of eye lens dose and for use of protective measures.
The assessment of eye lens doses for IR workers was performed using results of routine individual monitoring and measurements done with an eye lens dosemeter introduced recently. The routine individual monitoring of IR workers is performed with two whole-body dosemeters. One of them is used under the protective apron and the other above the protective apron on the left side. Monitoring period for IR workers is 1 month. According to the national legislation(4), the dose to the lens of the eye can be assessed using the dose equivalent Hp(10) measured with the whole-body dosemeter worn above protective apron near the lead collar. The measurements of doses to the lens of the eye were performed with the new eye lens dosemeter used outside the lead glasses. This thermoluminescent dosemeter named EYE-D (Radcard, Poland) was developed during Optimization of Radiation Protection of Medical Staff (ORAMED) project and dedicated for use in routine individual monitoring(5). Eye lens thermoluminescent dosemeters with LiF:Mg,Cu,P-type detectors and whole-body dosemeters with LiF:Mg,Ti-type detectors were used. Dosemeters were prepared and read out with RADOS thermoluminescent dosimetric system. The eye lens dosemeters and the whole-body dosemeters were calibrated for Hp(3) and Hp(10), respectively, in the Radiation Metrology Laboratory of the Radiation and Nuclear Safety Authority (STUK) in Finland. For the calibration, both the types of dosemeters were irradiated with 137Cs on an ISO slab water phantom. The information about IR procedures was collected in two types of protocols. One of them was dedicated for collection of information about the IR procedures and used protective measures and the other for collection of information about IR workers’ workload.
# The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected]
Downloaded from http://rpd.oxfordjournals.org/ at University of Sussex on August 4, 2015
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.
A. URBONIENE ET AL.
RESULTS AND DISCUSSION In the period of 2012–2013, routine individual monitoring was performed for 114 IR physicians and 137 IR nurses at 9 Lithuanian hospitals. The maximum annual dose above the lead collar for IR physicians was 87.6 and 93.2 mSv in 2012 and 2013, respectively, and for IR nurses 9.8 and 8.3 mSv in 2012 and 2013, respectively. The average annual dose equivalent Hp(10) measured above the lead apron for IR nurses is about 10 times lower than that for IR physicians. The reason for the
lower doses of IR nurses compared with the doses of IR physicians is because of the different nature of their work. The maximum and average annual Hp(10) measured above the lead apron for IR physicians and IR nurses at 9 Lithuanian hospitals are presented in Figures 1 and 2, respectively. The results from the routine individual monitoring show that doses to IR physicians measured above protective apron can be very high and about 4.5 times exceed the new eye lens dose limit. The routine
Figure 2. Maximum and average annual Hp(10) measured above the lead apron for IR nurses at nine Lithuanian hospitals in 2012– 2013.
300
Downloaded from http://rpd.oxfordjournals.org/ at University of Sussex on August 4, 2015
Figure 1. Maximum and average annual Hp(10) measured above the lead apron for IR physicians at nine Lithuanian hospitals in 2012–2013.
ASSESSMENT OF EYE LENS DOSES FOR WORKERS DURING IR PROCEDURES
The eye lens doses were measured outside the lead glasses, and in cases where the lead glasses were used, the real eye lens dose is lower. Protective measures for the lens of the eye used by IR workers The collective protective measures (mobile or ceiling suspended screens) are installed at every X-ray equipment in fluoroscopy room, but not always used during IR procedure. For that reason, the collective measures against scattered X-ray radiation do not always effectively protect head and eye lens. The use of lead glasses reduces the eye lens dose rate by a factor of 2–10(5 – 7). During the study, the information about measures used for eyes protection was collected. The results showed that 22 % of workers do not use any protective measure (lead glasses or lead screen). The statistics shows (Figure 3) that 76 % of workers’ eyes were protected with lead screens or glasses. Eye glasses were used for 50 % of IR workers, which is higher percentage
Table 1. Results of measured and predicted dose equivalent to the lens of the eye for IR workers. Code of IR worker
Physician 24 30 52 22 59 73 74 61 72 64 69 66 55 56 58 50 71 63 Nurse 70 48 68 49 44 65 53 54 a
Number of IR procedures per month
Fluoroscopy time (min per month)
Lead glasses
Measureda Hp(3) (mSv per month)
82 74 69 58 21 100 155 22 60 27 18 7 12 10 6 17 10 29
386 352 537 364 214 700 1050 126 600 136 112 130 16 21 34 64 158 59
Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No
8.19 7.39 6.62 5.21 5.15 2.83 2.28 2.00 1.96 0.79 0.62 0.43 0.33 0.26 0.23 0.22 0.20 0.01
30 23 15 24 17 18 6 2
162 87 171 134 103 93 23 21
No No No No No No No No
0.48 0.31 0.16 0.12 0.10 0.09 0.05 0.01
Measured with new eye lens dosemeter. Measured with whole-body dosemeter.
b
301
Predicted Hp(3) Measuredb Hp(10) (mSv y – 1) (mSv y – 1)
81.9 73.9 49.7 52.1 42.6 28.3 22.8 11.7 19.6 7.9 6.6 4.3 2.6 2.2 1.4 2.2 4.8 0.1 4.5 3.1 1.6 1.2 1.0 0.9 0.5 0.04
78.1 93.2 67.0 57.9 37.2 30.1 27.5 10.9 45.3 30.1 16.4 10.2 1.12 17.2 3.1 14.6 18.5 0.07 7.52 1.03 2.44 2.34 1.72 2.54 3.71 4.03
Downloaded from http://rpd.oxfordjournals.org/ at University of Sussex on August 4, 2015
individual monitoring results show that without any additional optimisation, the new limit to the lens of the eye can be reached and exceeded. In the same period of 2012–2013, doses to the lens of the eyes were measured with the new eye lens dosemeter for 42 IR physicians and 8 IR nurses. The eye lens doses were measured for the IR workers with the highest workloads during a 1-month period. For each case, the information about IR procedure was collected in dedicated protocols, and each protocol was analysed separately. About 20 different IR procedures were registered: coronarography, percutaneous coronary intervention, implantation of biventricular pacemakers, pulmonary vein isolation and others. The highest eye lens dose of 8.2 mSv in a month was measured for an IR cardiologist, who performed 82 IR procedures per month and the total registered fluoroscopy time was about 6.4 h. For an IR nurse, who assisted during IR procedures performed in urology, the maximum eye lens dose of 0.5 mSv per month was measured. The other measurement results are presented in Table 1.
A. URBONIENE ET AL.
compared with the ORAMED study in several European countries, where protective eye glasses were used in around 30–55 %(5). Comparison of Hp(10) and Hp(3)
Estimation of the annual dose equivalent to the lens of the eye For the assessment of the annual dose, the prediction of the annual dose equivalent to the lens of the eye was performed using the following formula: Hp ð3Þann ¼
Figure 3. Statistics of used protective measures during the measurements performed with new eye lens dosemeter.
Hp ð3Þm Tavg 10 tm
ð1Þ
where Hp(3)m is the measured eye lens dose equivalent, Tavg is the average fluoroscopy time per month and tm is the fluoroscopy time for the period of dose measurement. The annual dose to the lens of the eye was estimated with the assumption that the IR worker has 10 working months in a year and the remaining 2 months were used for vacation and trainings. The estimation showed that the lens of the eye of IR physician can be exposed to up to 82 mSv y – 1. It was estimated that 87 % of physicians participating in the study can receive doses to the lens of the eye higher than 10 % of the new eye lens dose limit (Figure 5 and Table 1). Based on the results of the study and with the aim to reduce doses to the lens of
Figure 4. Comparison of personal dose equivalents Hp(3) and Hp(10) measured at the collar level at the same time.
302
Downloaded from http://rpd.oxfordjournals.org/ at University of Sussex on August 4, 2015
During this study, 37 cases were registered when the measurements were performed with two dosemeters (eye lens dosemeter at the level of the eye and wholebody dosemeter at the collar level) at the same time. The measurement results of these two dosemeters were compared (Figure 4). The comparison demonstrated that in eight cases the results are within the measurement uncertainties. In all other cases, the measured Hp(3) was in average 70 % lower than the measured Hp(10). This difference is mainly due to different position of dosemeters. Eye lens dosemeter was positioned farther from the X-ray tube and patient than the whole-body dosemeter.
The difference could also be influenced by different types of detectors. The eye lens dosemeter with LiF:Mg,Cu,P-type detectors and whole-body dosemeters with LiF:Mg,Ti-type detectors were used. These two types of detectors have different energy responses(8), and dosemeters were calibrated for different quantities. Hp(10) and Hp(3) comparison results show that the dose to the lens of the eye can be overestimated if it is assessed with whole-body dosemeter worn outside the lead apron. More accurate results could be obtained when the dose to the lens of the eye is measured using Hp(3) with the dosemeter close to the eye.
ASSESSMENT OF EYE LENS DOSES FOR WORKERS DURING IR PROCEDURES
the eye, the IR workers were advised to use protective lead glasses during all IR procedures. CONCLUSIONS The results of this study showed that without any additional optimisation the new limit to the lens of the eye of IR workers could be reached and exceeded. All IR workers (physicians and nurses) in the fluoroscopy room should use protective lead glasses and lead screens. When the lead glasses are used, the eye lens dosemeter at the level of the eye and whole-body dosemeter at the collar level overestimate the eye lens dose. The IR workers who do not use lead glasses should be monitored with eye lens dosemeters. The assessment of eye lens doses with an eye lens dosemeter calibrated in Hp(3) is more accurate compared with the assessment performed with a whole-body dosemeter measuring Hp(10). REFERENCES 1. International Commission on Radiological protection. Statement on Tissue Reactions. ICRP 4825-3093-1464. ICRP (2011).
2. International Atomic Energy Agency. Implications for Occupational Radiation Protection of the New Dose Limit for the Lens of the Eye. IAEA-TECDOC-1731. IAEA (2013). 3. Council Directive 2013/59/Euratom of 5 December 2013, laying down basic safety standards for protection against the dangers arising from exposure to ionizing radiation. Official Journal of the European Union. L13 of 17.0157 (2014). 4. Radiation Protection Centre. The Order of Workers Exposure and Workplace Monitoring. Order No. 63, Vilnius (2007). 5. Vanhavere, F. et al. ORAMED: Optimization of Radiation Protection of Medical Staff. EURADOS Report 2012-02, ISSN/2226-8057 Braunschweig (2012). 6. Thornton, R. H., Dauer, L. T., Altamirano, J. P., Alvarado, K. J., St Germain, J. and Solomon, S. B. Comparing strategies for operator eye protection in the interventional radiology suite. J. Vasc. Interv. Radiol. 21(11), 1703– 1707 (2010). 7. Magee, J. S., Martin, C. J., Sandblom, V., Carter, M. J., Almen, A., Cederblad, A., Jonasson, P. and Lundh, C. Derivation and application of dose reduction factors for protective eyewear worn in interventional radiology and cardiology. J. Radiol. Prot. 34(4), 811–823 (2014). 8. Bilski, P. Lithium fluoride: from LiF:Mg,Ti to LiF:Mg, Cu,P. Radiat. Prot. Dosim. 100, 199–206 (2002).
303
Downloaded from http://rpd.oxfordjournals.org/ at University of Sussex on August 4, 2015
Figure 5. Estimated annual dose equivalent to the lens of the eye for IR workers.
doi:10.1093/rpd/ncv173
ASSESSMENT OF EYE LENS DOSES FOR WORKERS DURING INTERVENTIONAL RADIOLOGY PROCEDURES A. Urboniene*, E. Sadzeviciene and J. Ziliukas Radiation Protection Centre, Kalvariju 153, Vilnius 08221, Lithuania *Corresponding author: [email protected]
INTRODUCTION
MATERIALS AND METHODS
In 2011, the International Commission on Radiological Protection (ICRP) published a statement on tissue reactions(1). For the lens of the eye, the threshold in absorbed dose for radiation-induced cataract is considered to be 0.5 Gy. Based on this new threshold, the ICRP has recommended to reduce an equivalent dose limit for the lens of the eye. After this recommendation, the equivalent dose limit for the lens of the eye was reduced from 150 to 20 mSv y – 1, averaged over a defined period of 5 y, with no annual dose in a single year exceeding 50 mSv(2, 3). In 2013, reduced annual occupational equivalent dose limit to the lens of the eye was adopted in the European legislation(3). This new provision should be adopted in legal acts of all Member States during the period of 4 y. The new dose limit becomes very important for interventional radiology (IR) workers, because this category of workers receives the highest occupational exposure compare with other medical staff. Another alarming factor of the risk for radiation-induced cataract formation is progressively increasing workload of IR workers. According to the annual report of the Lithuanian Hygiene Institute, the number of IR procedures performed since 2008 has increased with about 40 %. The number of IR procedures performed in 2008 was 31 807, 56 300 in 2012 and 49 278 in 2013, while the increase in the number of IR workers was with only about 15 % (188 IR workers in 2008, 218 in 2012 and 222 in 2013). With the increase in IR procedures, the exposure of IR workers also increases. The purpose of this study was to study the current situation of radiation doses to the lens of the eye of IR workers during IR procedures and according to the results to suggest practical recommendations for monitoring of eye lens dose and for use of protective measures.
The assessment of eye lens doses for IR workers was performed using results of routine individual monitoring and measurements done with an eye lens dosemeter introduced recently. The routine individual monitoring of IR workers is performed with two whole-body dosemeters. One of them is used under the protective apron and the other above the protective apron on the left side. Monitoring period for IR workers is 1 month. According to the national legislation(4), the dose to the lens of the eye can be assessed using the dose equivalent Hp(10) measured with the whole-body dosemeter worn above protective apron near the lead collar. The measurements of doses to the lens of the eye were performed with the new eye lens dosemeter used outside the lead glasses. This thermoluminescent dosemeter named EYE-D (Radcard, Poland) was developed during Optimization of Radiation Protection of Medical Staff (ORAMED) project and dedicated for use in routine individual monitoring(5). Eye lens thermoluminescent dosemeters with LiF:Mg,Cu,P-type detectors and whole-body dosemeters with LiF:Mg,Ti-type detectors were used. Dosemeters were prepared and read out with RADOS thermoluminescent dosimetric system. The eye lens dosemeters and the whole-body dosemeters were calibrated for Hp(3) and Hp(10), respectively, in the Radiation Metrology Laboratory of the Radiation and Nuclear Safety Authority (STUK) in Finland. For the calibration, both the types of dosemeters were irradiated with 137Cs on an ISO slab water phantom. The information about IR procedures was collected in two types of protocols. One of them was dedicated for collection of information about the IR procedures and used protective measures and the other for collection of information about IR workers’ workload.
# The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected]
Downloaded from http://rpd.oxfordjournals.org/ at University of Sussex on August 4, 2015
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.
A. URBONIENE ET AL.
RESULTS AND DISCUSSION In the period of 2012–2013, routine individual monitoring was performed for 114 IR physicians and 137 IR nurses at 9 Lithuanian hospitals. The maximum annual dose above the lead collar for IR physicians was 87.6 and 93.2 mSv in 2012 and 2013, respectively, and for IR nurses 9.8 and 8.3 mSv in 2012 and 2013, respectively. The average annual dose equivalent Hp(10) measured above the lead apron for IR nurses is about 10 times lower than that for IR physicians. The reason for the
lower doses of IR nurses compared with the doses of IR physicians is because of the different nature of their work. The maximum and average annual Hp(10) measured above the lead apron for IR physicians and IR nurses at 9 Lithuanian hospitals are presented in Figures 1 and 2, respectively. The results from the routine individual monitoring show that doses to IR physicians measured above protective apron can be very high and about 4.5 times exceed the new eye lens dose limit. The routine
Figure 2. Maximum and average annual Hp(10) measured above the lead apron for IR nurses at nine Lithuanian hospitals in 2012– 2013.
300
Downloaded from http://rpd.oxfordjournals.org/ at University of Sussex on August 4, 2015
Figure 1. Maximum and average annual Hp(10) measured above the lead apron for IR physicians at nine Lithuanian hospitals in 2012–2013.
ASSESSMENT OF EYE LENS DOSES FOR WORKERS DURING IR PROCEDURES
The eye lens doses were measured outside the lead glasses, and in cases where the lead glasses were used, the real eye lens dose is lower. Protective measures for the lens of the eye used by IR workers The collective protective measures (mobile or ceiling suspended screens) are installed at every X-ray equipment in fluoroscopy room, but not always used during IR procedure. For that reason, the collective measures against scattered X-ray radiation do not always effectively protect head and eye lens. The use of lead glasses reduces the eye lens dose rate by a factor of 2–10(5 – 7). During the study, the information about measures used for eyes protection was collected. The results showed that 22 % of workers do not use any protective measure (lead glasses or lead screen). The statistics shows (Figure 3) that 76 % of workers’ eyes were protected with lead screens or glasses. Eye glasses were used for 50 % of IR workers, which is higher percentage
Table 1. Results of measured and predicted dose equivalent to the lens of the eye for IR workers. Code of IR worker
Physician 24 30 52 22 59 73 74 61 72 64 69 66 55 56 58 50 71 63 Nurse 70 48 68 49 44 65 53 54 a
Number of IR procedures per month
Fluoroscopy time (min per month)
Lead glasses
Measureda Hp(3) (mSv per month)
82 74 69 58 21 100 155 22 60 27 18 7 12 10 6 17 10 29
386 352 537 364 214 700 1050 126 600 136 112 130 16 21 34 64 158 59
Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No
8.19 7.39 6.62 5.21 5.15 2.83 2.28 2.00 1.96 0.79 0.62 0.43 0.33 0.26 0.23 0.22 0.20 0.01
30 23 15 24 17 18 6 2
162 87 171 134 103 93 23 21
No No No No No No No No
0.48 0.31 0.16 0.12 0.10 0.09 0.05 0.01
Measured with new eye lens dosemeter. Measured with whole-body dosemeter.
b
301
Predicted Hp(3) Measuredb Hp(10) (mSv y – 1) (mSv y – 1)
81.9 73.9 49.7 52.1 42.6 28.3 22.8 11.7 19.6 7.9 6.6 4.3 2.6 2.2 1.4 2.2 4.8 0.1 4.5 3.1 1.6 1.2 1.0 0.9 0.5 0.04
78.1 93.2 67.0 57.9 37.2 30.1 27.5 10.9 45.3 30.1 16.4 10.2 1.12 17.2 3.1 14.6 18.5 0.07 7.52 1.03 2.44 2.34 1.72 2.54 3.71 4.03
Downloaded from http://rpd.oxfordjournals.org/ at University of Sussex on August 4, 2015
individual monitoring results show that without any additional optimisation, the new limit to the lens of the eye can be reached and exceeded. In the same period of 2012–2013, doses to the lens of the eyes were measured with the new eye lens dosemeter for 42 IR physicians and 8 IR nurses. The eye lens doses were measured for the IR workers with the highest workloads during a 1-month period. For each case, the information about IR procedure was collected in dedicated protocols, and each protocol was analysed separately. About 20 different IR procedures were registered: coronarography, percutaneous coronary intervention, implantation of biventricular pacemakers, pulmonary vein isolation and others. The highest eye lens dose of 8.2 mSv in a month was measured for an IR cardiologist, who performed 82 IR procedures per month and the total registered fluoroscopy time was about 6.4 h. For an IR nurse, who assisted during IR procedures performed in urology, the maximum eye lens dose of 0.5 mSv per month was measured. The other measurement results are presented in Table 1.
A. URBONIENE ET AL.
compared with the ORAMED study in several European countries, where protective eye glasses were used in around 30–55 %(5). Comparison of Hp(10) and Hp(3)
Estimation of the annual dose equivalent to the lens of the eye For the assessment of the annual dose, the prediction of the annual dose equivalent to the lens of the eye was performed using the following formula: Hp ð3Þann ¼
Figure 3. Statistics of used protective measures during the measurements performed with new eye lens dosemeter.
Hp ð3Þm Tavg 10 tm
ð1Þ
where Hp(3)m is the measured eye lens dose equivalent, Tavg is the average fluoroscopy time per month and tm is the fluoroscopy time for the period of dose measurement. The annual dose to the lens of the eye was estimated with the assumption that the IR worker has 10 working months in a year and the remaining 2 months were used for vacation and trainings. The estimation showed that the lens of the eye of IR physician can be exposed to up to 82 mSv y – 1. It was estimated that 87 % of physicians participating in the study can receive doses to the lens of the eye higher than 10 % of the new eye lens dose limit (Figure 5 and Table 1). Based on the results of the study and with the aim to reduce doses to the lens of
Figure 4. Comparison of personal dose equivalents Hp(3) and Hp(10) measured at the collar level at the same time.
302
Downloaded from http://rpd.oxfordjournals.org/ at University of Sussex on August 4, 2015
During this study, 37 cases were registered when the measurements were performed with two dosemeters (eye lens dosemeter at the level of the eye and wholebody dosemeter at the collar level) at the same time. The measurement results of these two dosemeters were compared (Figure 4). The comparison demonstrated that in eight cases the results are within the measurement uncertainties. In all other cases, the measured Hp(3) was in average 70 % lower than the measured Hp(10). This difference is mainly due to different position of dosemeters. Eye lens dosemeter was positioned farther from the X-ray tube and patient than the whole-body dosemeter.
The difference could also be influenced by different types of detectors. The eye lens dosemeter with LiF:Mg,Cu,P-type detectors and whole-body dosemeters with LiF:Mg,Ti-type detectors were used. These two types of detectors have different energy responses(8), and dosemeters were calibrated for different quantities. Hp(10) and Hp(3) comparison results show that the dose to the lens of the eye can be overestimated if it is assessed with whole-body dosemeter worn outside the lead apron. More accurate results could be obtained when the dose to the lens of the eye is measured using Hp(3) with the dosemeter close to the eye.
ASSESSMENT OF EYE LENS DOSES FOR WORKERS DURING IR PROCEDURES
the eye, the IR workers were advised to use protective lead glasses during all IR procedures. CONCLUSIONS The results of this study showed that without any additional optimisation the new limit to the lens of the eye of IR workers could be reached and exceeded. All IR workers (physicians and nurses) in the fluoroscopy room should use protective lead glasses and lead screens. When the lead glasses are used, the eye lens dosemeter at the level of the eye and whole-body dosemeter at the collar level overestimate the eye lens dose. The IR workers who do not use lead glasses should be monitored with eye lens dosemeters. The assessment of eye lens doses with an eye lens dosemeter calibrated in Hp(3) is more accurate compared with the assessment performed with a whole-body dosemeter measuring Hp(10). REFERENCES 1. International Commission on Radiological protection. Statement on Tissue Reactions. ICRP 4825-3093-1464. ICRP (2011).
2. International Atomic Energy Agency. Implications for Occupational Radiation Protection of the New Dose Limit for the Lens of the Eye. IAEA-TECDOC-1731. IAEA (2013). 3. Council Directive 2013/59/Euratom of 5 December 2013, laying down basic safety standards for protection against the dangers arising from exposure to ionizing radiation. Official Journal of the European Union. L13 of 17.0157 (2014). 4. Radiation Protection Centre. The Order of Workers Exposure and Workplace Monitoring. Order No. 63, Vilnius (2007). 5. Vanhavere, F. et al. ORAMED: Optimization of Radiation Protection of Medical Staff. EURADOS Report 2012-02, ISSN/2226-8057 Braunschweig (2012). 6. Thornton, R. H., Dauer, L. T., Altamirano, J. P., Alvarado, K. J., St Germain, J. and Solomon, S. B. Comparing strategies for operator eye protection in the interventional radiology suite. J. Vasc. Interv. Radiol. 21(11), 1703– 1707 (2010). 7. Magee, J. S., Martin, C. J., Sandblom, V., Carter, M. J., Almen, A., Cederblad, A., Jonasson, P. and Lundh, C. Derivation and application of dose reduction factors for protective eyewear worn in interventional radiology and cardiology. J. Radiol. Prot. 34(4), 811–823 (2014). 8. Bilski, P. Lithium fluoride: from LiF:Mg,Ti to LiF:Mg, Cu,P. Radiat. Prot. Dosim. 100, 199–206 (2002).
303
Downloaded from http://rpd.oxfordjournals.org/ at University of Sussex on August 4, 2015
Figure 5. Estimated annual dose equivalent to the lens of the eye for IR workers.
