OCCUPATIONAL DOSE DURING ADULT INTERVENTIONAL CARDIOLOGY: FIRST VALUES WITH PERSONAL ACTIVE DOSIMETERS IN CHILE

OCCUPATIONAL DOSE DURING ADULT INTERVENTIONAL CARDIOLOGY: FIRST VALUES WITH PERSONAL ACTIVE... Abstract The objective of this article is to present initial occupational dose values using digital active personal dosimeters for medical staff during adult interventional cardiology procedures in a public hospital in Chile. Personal dose equivalent Hp(10) over the lead apron of physician, nurse and radiographer were measured during 59 procedures. Mean values of occupational dose Hp(10) per procedure were 47.6, 6.2 and 4.3 μSv for physician, nurse and radiographer, respectively. If no protective tools are used, physician dose can exceed the new eye lens dose limit. INTRODUCTION Patients can receive high doses during fluoroscopically guided cardiology procedures, and some patients may undergo several procedures in a relatively short period of time(1). Dose surveys should be performed in cardiac interventional laboratories as part of a quality assurance programme. The results obtained should be used to compare local practice with that in other centres. Local practice should be investigated if median local dose distribution values exceed guidance levels or fall below action levels(2). It is also known that medical staff (physicians, nurses, radiographers) in cardiac intervention laboratories may receive high radiation doses if radiological protection tools are misused or good operational measures are not applied, and radiation lesions of the eyes may occur after several years of work if several complex procedures are performed per day(1, 3). Interventional cardiologist physicians represent the most important group of medical specialists involved in such practices(4). Scatter radiation levels to medical staff are neither uniform nor symmetrical. Proper use of personal monitoring badges is necessary in interventional cardiology laboratories in order to monitor and audit occupational radiation dose(1). Furthermore, according to the Society of Cardiovascular Angiography and Interventions, the use of personal dose monitors must form part of radiation safety programmes in interventional cardiology laboratories(5). In Chile, occupational exposure monitoring is traditionally implemented with passive dosimeters (film, thermoluminescent and optically stimulated luminescence dosimeters). However, several papers from other regions of the world have concluded that digital active personal dosimeters (APDs) are a useful tool for reducing occupational dose(6–8), informing medical staff of their level of exposure according to their position with respect to the X-ray system and the patient in the interventional cardiology laboratory(9). Besides, papers reporting use of APDs are still non-existent for fluoroscopically guided cardiology procedures in the regions of Latin America and the Caribbean. In light of the above and within the framework of an IAEA regional project in Latin America and the Caribbean (RLA 9075) for optimisation of radiation protection in interventions guided by X-ray imaging, this paper presents the methodology and first results of occupational dose values using APDs for medical staff during adult interventional cardiology procedures in Chile. MATERIALS AND METHODS Angiography system Measurements were performed using a Siemens Axiom Artis dFA angiography system (Siemens Healthcare, Germany) equipped with a flat-panel detector (FPD) and belonging to the cardiology service of the Antofagasta Regional Hospital in Chile. The system was equipped with amorphous silicon detectors of 48 cm in diagonal dimension and a pixel size of 154 μm. It also had a generator of 100 kW at 125 kV. The protocol used for all procedures was Cardio <85 kg, with three fluoroscopy modes (low, medium and high dose), all configured from 7.5 to 30 pulses s−1, and only one acquisition or cine mode, configured from 15 to 30 frames s−1. There were six fields of view: 11, 16, 22, 32, 42 and 48 cm. Additional filters, from 0.1 to 0.9 mm Cu, and virtual collimation were available. Distance from isocentre to floor was 106 cm and focus-to-isocentre distance was 75 cm. The angiography system was characterised using the protocols agreed in the DIMOND and SENTINEL European programmes(10, 11). The kerma-area product (PKA)(12) metre were verified and corresponding calibration factors and attenuation of the table and mattress, allowing for correction of the measured dose quantities included in the patient dose reports. Staff dose Measurements of personal dose equivalent Hp(10)(12) and dose rate were taken using Ray Safe i2, an APD system specifically calibrated to provide real-time insights into radiation exposure(6, 8, 9, 13) during 59 (22 diagnostic and 37 therapeutic) adult interventional cardiology procedures. The dosimeter measures and records X-ray exposure every second and transfers the data wirelessly, via radio, to the real-time display. The study was approved by the ethics committee of the university that conducted the research. Only four dosimeters were used for all procedures. The first three dosimeters (for physician, nurse and radiographer) were used over the lead apron (in addition to the regular passive personal dosimetry), which provides a reasonable estimate of dose delivered to the surface of the unshielded skin and to eye lens(6, 14). The fourth dosimeter was used as a comparison and positioned at the C-arm, at 45° under the table and around ±85 cm from the isocentre, according to Sanchez et al.(6) and Vano et al.(8) for to have one value measured as a reference for the scatter dose that intervening staff would receive in normal conditions if they did not use additional protection tools such as ceiling-suspended screen or protective goggles. Statistical calculations for dose values were performed using the SPSS 17 software package(15). Correlations in scatterplots were investigated by calculating the Pearson correlation (R) between PKA and Hp(10) values. RESULTS AND DISCUSSION Dose data Hp(10) for each dosimeter is shown in Table 1. Table 1. Mean, median and range values for Hp(10) values per procedure for physician, nurse, radiographer and C-arm dosimeters and cumulative dose in the period (1 month). Type of procedure  Physician (μSv)  Nurse (μSv)  Radiographer (μSv)  C-arm (μSv)  Mean–median (range)[cumulative dose]  Mean–median (range)[cumulative dose]  Mean–median (range) (range) [cumulative dose]  Mean–median (range) (range) [cumulative dose]  Diagnostic  41.2–20.0  4.1–3.0  4.0–2.5  93.8–60.0  (5.0–200.0) [1524]  (0.1–11.0) [132]  (0.3–21.2) [149]  (10.0–540.0) [3470]  Therapeutic  58.5–20.0  9.4–1.0  4.7–4.3  118.6–105.0  (6.0–510.0) [1286]  (0.2–130.0) [188]  (0.9–17.7) [103]  (30.0–350.0) [2610]  All  47.6–20.0  6.2–2.0  4.3–2.8  103.1–70.0  (5.0–510.0) [2810]  (0.1–130.0) [320]  (0.3–321.2) [251]  (10.0–540.0) [6080]  Type of procedure  Physician (μSv)  Nurse (μSv)  Radiographer (μSv)  C-arm (μSv)  Mean–median (range)[cumulative dose]  Mean–median (range)[cumulative dose]  Mean–median (range) (range) [cumulative dose]  Mean–median (range) (range) [cumulative dose]  Diagnostic  41.2–20.0  4.1–3.0  4.0–2.5  93.8–60.0  (5.0–200.0) [1524]  (0.1–11.0) [132]  (0.3–21.2) [149]  (10.0–540.0) [3470]  Therapeutic  58.5–20.0  9.4–1.0  4.7–4.3  118.6–105.0  (6.0–510.0) [1286]  (0.2–130.0) [188]  (0.9–17.7) [103]  (30.0–350.0) [2610]  All  47.6–20.0  6.2–2.0  4.3–2.8  103.1–70.0  (5.0–510.0) [2810]  (0.1–130.0) [320]  (0.3–321.2) [251]  (10.0–540.0) [6080]  Table 1. Mean, median and range values for Hp(10) values per procedure for physician, nurse, radiographer and C-arm dosimeters and cumulative dose in the period (1 month). Type of procedure  Physician (μSv)  Nurse (μSv)  Radiographer (μSv)  C-arm (μSv)  Mean–median (range)[cumulative dose]  Mean–median (range)[cumulative dose]  Mean–median (range) (range) [cumulative dose]  Mean–median (range) (range) [cumulative dose]  Diagnostic  41.2–20.0  4.1–3.0  4.0–2.5  93.8–60.0  (5.0–200.0) [1524]  (0.1–11.0) [132]  (0.3–21.2) [149]  (10.0–540.0) [3470]  Therapeutic  58.5–20.0  9.4–1.0  4.7–4.3  118.6–105.0  (6.0–510.0) [1286]  (0.2–130.0) [188]  (0.9–17.7) [103]  (30.0–350.0) [2610]  All  47.6–20.0  6.2–2.0  4.3–2.8  103.1–70.0  (5.0–510.0) [2810]  (0.1–130.0) [320]  (0.3–321.2) [251]  (10.0–540.0) [6080]  Type of procedure  Physician (μSv)  Nurse (μSv)  Radiographer (μSv)  C-arm (μSv)  Mean–median (range)[cumulative dose]  Mean–median (range)[cumulative dose]  Mean–median (range) (range) [cumulative dose]  Mean–median (range) (range) [cumulative dose]  Diagnostic  41.2–20.0  4.1–3.0  4.0–2.5  93.8–60.0  (5.0–200.0) [1524]  (0.1–11.0) [132]  (0.3–21.2) [149]  (10.0–540.0) [3470]  Therapeutic  58.5–20.0  9.4–1.0  4.7–4.3  118.6–105.0  (6.0–510.0) [1286]  (0.2–130.0) [188]  (0.9–17.7) [103]  (30.0–350.0) [2610]  All  47.6–20.0  6.2–2.0  4.3–2.8  103.1–70.0  (5.0–510.0) [2810]  (0.1–130.0) [320]  (0.3–321.2) [251]  (10.0–540.0) [6080]  Table 1 shows the results per procedure in terms of occupational dose Hp(10). Values were higher for therapeutic than diagnostic procedures, which is explained because the median values of PKA followed that same trend (52 and 26 Gy cm2, respectively). In this study, the range for personal dose equivalent Hp(10) was between 5.0 and 510.0 μSv with a mean value of 47.6 μSv for the dosimeter used by the physician, from 0.1 to 130.0 μSv with a mean value of 6.2 μSv for the dosimeter used by the nurse and from 0.3 to 321.2 μSv with a mean value of 4.3 μSv for the dosimeter used by the radiographer. According to the ORAMED research project(16), personal dose equivalent Hp(10) measured at physician chest over the apron was 50 μSv. Sanchez et al.(14) reported mean dose per procedure of 46 μSv for physician and 12 μSv for nurse. Personal dose equivalent Hp(10) recorded at operators’ chest level (over the apron) in cardiac catheterisation laboratories can be used to roughly estimate eye lens dose when eye dosimeters are not available and with the C-arm dosimeter located on the lower part of the x-ray tube, in the surroundings of the patient backscatter radiation and with no protection barrier such as a ceiling-suspended screen, information could be obtained on scatter radiation levels in the worst-case geometry. According to Martin(17) the dose in the eyes can be 75% of the dose recorded by the dosimeter placed in chest or thyroid protector. As the study was conducted over the course of a month (59 cardiological procedures) it is also possible to extrapolate from Table 1, that the personal dose equivalent Hp(10) values for physician, nurse, radiographer and C-arm dosimeter for 1 year would be 33.7, 3.9, 3.0 and 73.0 mSv, respectively. For the above, it becomes absolutely necessary the use eyewear protection that reduce the lens dose by a factor of 8–10 from frontal exposures, depending on the eyewear and the quality of the scattered radiation(18, 19). However, according to Sanchez et al.(14) in some circumstances (high workloads and inefficient goggle design), the only use of goggles may not, in absence of a protective screen, be enough to keep eye lens doses under the occupational dose limit. A protective screen correctly positioned can, on the contrary, help reduce eye lens doses and what is more, the dose to the whole brain, head and thyroid gland. Figure 1 shows the correlation between PKA and Hp(10) values for physician, nurse, radiographer and C-arm positions. Figure 1. View largeDownload slide Correlation between kerma-area product and personal dose equivalent Hp(10) for the four dosimeters. Figure 1. View largeDownload slide Correlation between kerma-area product and personal dose equivalent Hp(10) for the four dosimeters. Figure 1 illustrates the correlation of Hp(10) values as a function of PKA for the entire data set. The physician and nurse dosimeter, presented the highest correlation values. However, there was also a moderately positive correlation for the other two dosimeters. Starting from the slopes calculated, the personal dose equivalent Hp(10) for one mean patient dose (53.9 Gy cm2) would be 48 μSv (physician), 5 μSv (nurse), 4 μSv (radiographer) and 103 μSv (C-arm), respectively. With the dosimeter located on the radiographer’s chest, your doses per unit of patient dose was expected to be lower, in comparison with the nurse and physician as the dosimeter was more moved away from the area where patient backscatter was predominant. Depending on the C-arm angle, this reduction may vary(20). In addition, when the ceiling-suspended screen is used, an additional reduction in the slope (physician dose per unit of patient dose) of the order of the screen attenuation factor should be observed. Such screen attenuation factor, depending on the beam quality, could range from 20 to 50 or even higher(19). In our case, it was ~50% (103–48 μSv). A strict policy on the regular use of personal dosimeter should therefore form part of any quality assurance programme in cardiology laboratories. Failure to wear monitoring equipment could represent a breach of the employer’s procedures and/or local regulatory or legislative requirements(1). Unfortunately, Chilean legislation on radiological protection issues still does not consider these programmes. A useful alternative could be an APD system that offers real-time access to staff doses and dose rates alarm within cardiac interventional laboratories(8). This dosimeters are extensively used in Europe and have long been recognised as essential tools for worker dose reduction(21). STUDY LIMITATIONS The limitations of this study were the low number of adult interventional cardiology procedures and that it was performed in the context of a single cardiology service. However, these are merely preliminary results given that the study is currently being conducted in other cardiology services in Chile. CONCLUSIONS Mean values of occupational dose Hp(10) per procedure were 47.6, 6.2, 4.3 and 103.1 μSv for physician, nurse, radiographer and C-arm dosimeters, respectively. If no protective tools are used, physician dose may exceed the new eye lens dose limit. ACKNOWLEDGEMENTS The current work has been carried out under the framework of the International Atomic Energy Agency regional project RLA/9/075, ‘Strengthening National Infrastructure for End-Users to Comply with Regulations and Radiological Protection Requirements’. The authors thank the staff of the Hemodynamic Department, Cardiovascular Service, Antofagasta Regional Hospital, Antofagasta, Chile. MD Bernhard Westerberg, MD Guillermo Illanes, BSC Tomas Aguilar and BSC Rigoberto Choque. C.U. acknowledges the support of the Direction of Research at Tarapaca University, through senior research project No. 7710-14. REFERENCES 1 International Commission on Radiological Protection. Radiological protection in cardiology. Ann. ICRP  42, 1–125, ( 2013) ICRP Publication 120. 2 Balter, S., Miller, D., Vano, E., Ortiz, P., Bernardi, G., Cotelo, E., Faulkner, K., Nowonty, R., Padovani, R. and Ramirez, A. A pilot study exploring the possibility of establishing guidance levels in x-ray directed interventional procedures. Med. Phys.  35( 2), 673– 680 ( 2008). Google Scholar CrossRef Search ADS PubMed  3 International Commission on Radiological Protection (ICRP). Avoidance of radiation injuries from medical interventional procedures. Ann. ICRP  30( 2), 7– 67 ( 2000) ICRP Publication 85. CrossRef Search ADS   4 Vano, E. Radiation exposure to cardiologists: how it could be reduced. Heart  89, 1123– 1124 ( 2003). Google Scholar CrossRef Search ADS PubMed  5 Chambers, C. E., Fetterly, K. A., Holzer, R., Lin, P. J., Blankenship, J. C., Balter, S. and Laskey, W. K. Radiation safety program for the cardiac catheterization laboratory. Catheter. Cardiovasc. Interv.  77, 546– 556 ( 2011). Google Scholar CrossRef Search ADS PubMed  6 Sanchez, R., Vano, E., Fernandez, J. M. and Gallego, J. J. Staff radiation doses in a real-time display inside the angiography room. Cardiovasc. Intervent. Radiol.  33, 1210– 1214 ( 2010). Google Scholar CrossRef Search ADS PubMed  7 Muller, M. C., Welle, K., Strauss, A., Naehle, P. C., Pennekamp, P. H., Weber, O. and Burger, C. Real-time dosimetry reduces radiation exposure of orthopaedic surgeons. Orthop. Traumatol. Surg. Res.  100, 947– 951 ( 2014). Google Scholar CrossRef Search ADS PubMed  8 Vano, E., Fernandez, J. M. and Sanchez, R. Occupational dosimetry in real time. Benefits for interventional radiology. Radiat. Meas.  46, 1262– 1265 ( 2011). Google Scholar CrossRef Search ADS   9 Ordiales, J. M., Nogales, J. M., Vano, E., Lopez-Minguez, J. R., Alvarez, F. J., Ramos, J., Martinez, G. and Sanchez, R. M. Occupational dose reduction in cardiac catheterisation laboratory: a randomised trial using a shield drape placed on the patient. Radiat. Prot. Dosim.  174, 255– 261 ( 2017). 10 Faulkner, K., Malone, J., Vano, E., Padovani, R., Busch, H. P., Zoetelief, J. H. and Bosmans, H. The SENTINEL project. Radiat. Prot. Dosim.  129, 3– 5 ( 2008). Google Scholar CrossRef Search ADS   11 Ubeda, C., Vano, E., Miranda, P., Leyton, F., Valenzuela, E. and Oyarzun, C. Radiation dose and image quality for adult interventional cardiology in Chile: a national survey. Radiat. Prot. Dosim.  147, 90– 93 ( 2011). Google Scholar CrossRef Search ADS   12 International Commission on Radiation Units and Measurements (ICRU). Patient dosimetry for X-rays used in medical imaging. ICRU Report 74. J. ICRU  5, 1– 113 ( 2005). 13 Available on http://www.raysafe.com/Home/Products/Staff/RaySafe%20i2#Downloads. (last accessed December 2017). 14 Sánchez, R. M., Vano, E., Fernández, J. M., Pifarré, X., Ordiales, J. M., Rovira, J. J., Carrera, F., Goicolea, J. and Fernández-Ortiz, A Occupational eye lens doses in interventional cardiology. A multicentric study. J. Radiol. Prot.  36, 133– 143 ( 2016). Google Scholar CrossRef Search ADS PubMed  15 Available on www.spss.com (last accessed November 2017). 16 Vanhavere, F. et al.  . Measurements of eye lens doses in interventional radiology and cardiology: final results of the ORAMED project. Radiat. Meas.  46, 1243– 1247 ( 2011). Google Scholar CrossRef Search ADS   17 Martin, C. J. A review of radiology staff doses and dose monitoring requirements. Radiat. Prot. Dosim.  136, 140– 157 ( 2009). Google Scholar CrossRef Search ADS   18 Van Rooijen, B. D., de Haan, M. W., Das, M., Arnoldussen, C. W., de Graaf, R., van Zwam, W. H., Backes, W. H. and Jeukens, C. R. Efficacy of radiation safety glasses in interventional radiology. Cardiovasc. Intervent. Radiol.  37, 1149– 1155 ( 2014). Google Scholar CrossRef Search ADS PubMed  19 Vano, E., Gonzalez, L., Fernandez, J. M. and Haskal, Z. J. Eye lens exposure to radiation in interventional suites: caution is warranted. Radiology  248, 945– 953 ( 2008). Google Scholar CrossRef Search ADS PubMed  20 Vañó, E., Fernández, J. M., Sánchez, R. M. and Dauer, L. T. Realistic approach to estimate lens doses and cataract radiation risk in cardiology when personal dosimeters have not been regularly used. Health Phys.  105, 330– 339 ( 2013). Google Scholar CrossRef Search ADS PubMed  21 Ginjaume, M., Bolognese-Milsztajn, T., Luszik-Bhadra, M., Vanhavere, F., Wahl, W. and Weeks, A. Overview of active personal dosimeters for individual monitoring in the European Union. Radiat. Prot. Dosim.  125, 261– 266 ( 2007). Google Scholar CrossRef Search ADS   © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Radiation Protection Dosimetry Oxford University Press

OCCUPATIONAL DOSE DURING ADULT INTERVENTIONAL CARDIOLOGY: FIRST VALUES WITH PERSONAL ACTIVE DOSIMETERS IN CHILE

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Abstract

Abstract The objective of this article is to present initial occupational dose values using digital active personal dosimeters for medical staff during adult interventional cardiology procedures in a public hospital in Chile. Personal dose equivalent Hp(10) over the lead apron of physician, nurse and radiographer were measured during 59 procedures. Mean values of occupational dose Hp(10) per procedure were 47.6, 6.2 and 4.3 μSv for physician, nurse and radiographer, respectively. If no protective tools are used, physician dose can exceed the new eye lens dose limit. INTRODUCTION Patients can receive high doses during fluoroscopically guided cardiology procedures, and some patients may undergo several procedures in a relatively short period of time(1). Dose surveys should be performed in cardiac interventional laboratories as part of a quality assurance programme. The results obtained should be used to compare local practice with that in other centres. Local practice should be investigated if median local dose distribution values exceed guidance levels or fall below action levels(2). It is also known that medical staff (physicians, nurses, radiographers) in cardiac intervention laboratories may receive high radiation doses if radiological protection tools are misused or good operational measures are not applied, and radiation lesions of the eyes may occur after several years of work if several complex procedures are performed per day(1, 3). Interventional cardiologist physicians represent the most important group of medical specialists involved in such practices(4). Scatter radiation levels to medical staff are neither uniform nor symmetrical. Proper use of personal monitoring badges is necessary in interventional cardiology laboratories in order to monitor and audit occupational radiation dose(1). Furthermore, according to the Society of Cardiovascular Angiography and Interventions, the use of personal dose monitors must form part of radiation safety programmes in interventional cardiology laboratories(5). In Chile, occupational exposure monitoring is traditionally implemented with passive dosimeters (film, thermoluminescent and optically stimulated luminescence dosimeters). However, several papers from other regions of the world have concluded that digital active personal dosimeters (APDs) are a useful tool for reducing occupational dose(6–8), informing medical staff of their level of exposure according to their position with respect to the X-ray system and the patient in the interventional cardiology laboratory(9). Besides, papers reporting use of APDs are still non-existent for fluoroscopically guided cardiology procedures in the regions of Latin America and the Caribbean. In light of the above and within the framework of an IAEA regional project in Latin America and the Caribbean (RLA 9075) for optimisation of radiation protection in interventions guided by X-ray imaging, this paper presents the methodology and first results of occupational dose values using APDs for medical staff during adult interventional cardiology procedures in Chile. MATERIALS AND METHODS Angiography system Measurements were performed using a Siemens Axiom Artis dFA angiography system (Siemens Healthcare, Germany) equipped with a flat-panel detector (FPD) and belonging to the cardiology service of the Antofagasta Regional Hospital in Chile. The system was equipped with amorphous silicon detectors of 48 cm in diagonal dimension and a pixel size of 154 μm. It also had a generator of 100 kW at 125 kV. The protocol used for all procedures was Cardio <85 kg, with three fluoroscopy modes (low, medium and high dose), all configured from 7.5 to 30 pulses s−1, and only one acquisition or cine mode, configured from 15 to 30 frames s−1. There were six fields of view: 11, 16, 22, 32, 42 and 48 cm. Additional filters, from 0.1 to 0.9 mm Cu, and virtual collimation were available. Distance from isocentre to floor was 106 cm and focus-to-isocentre distance was 75 cm. The angiography system was characterised using the protocols agreed in the DIMOND and SENTINEL European programmes(10, 11). The kerma-area product (PKA)(12) metre were verified and corresponding calibration factors and attenuation of the table and mattress, allowing for correction of the measured dose quantities included in the patient dose reports. Staff dose Measurements of personal dose equivalent Hp(10)(12) and dose rate were taken using Ray Safe i2, an APD system specifically calibrated to provide real-time insights into radiation exposure(6, 8, 9, 13) during 59 (22 diagnostic and 37 therapeutic) adult interventional cardiology procedures. The dosimeter measures and records X-ray exposure every second and transfers the data wirelessly, via radio, to the real-time display. The study was approved by the ethics committee of the university that conducted the research. Only four dosimeters were used for all procedures. The first three dosimeters (for physician, nurse and radiographer) were used over the lead apron (in addition to the regular passive personal dosimetry), which provides a reasonable estimate of dose delivered to the surface of the unshielded skin and to eye lens(6, 14). The fourth dosimeter was used as a comparison and positioned at the C-arm, at 45° under the table and around ±85 cm from the isocentre, according to Sanchez et al.(6) and Vano et al.(8) for to have one value measured as a reference for the scatter dose that intervening staff would receive in normal conditions if they did not use additional protection tools such as ceiling-suspended screen or protective goggles. Statistical calculations for dose values were performed using the SPSS 17 software package(15). Correlations in scatterplots were investigated by calculating the Pearson correlation (R) between PKA and Hp(10) values. RESULTS AND DISCUSSION Dose data Hp(10) for each dosimeter is shown in Table 1. Table 1. Mean, median and range values for Hp(10) values per procedure for physician, nurse, radiographer and C-arm dosimeters and cumulative dose in the period (1 month). Type of procedure  Physician (μSv)  Nurse (μSv)  Radiographer (μSv)  C-arm (μSv)  Mean–median (range)[cumulative dose]  Mean–median (range)[cumulative dose]  Mean–median (range) (range) [cumulative dose]  Mean–median (range) (range) [cumulative dose]  Diagnostic  41.2–20.0  4.1–3.0  4.0–2.5  93.8–60.0  (5.0–200.0) [1524]  (0.1–11.0) [132]  (0.3–21.2) [149]  (10.0–540.0) [3470]  Therapeutic  58.5–20.0  9.4–1.0  4.7–4.3  118.6–105.0  (6.0–510.0) [1286]  (0.2–130.0) [188]  (0.9–17.7) [103]  (30.0–350.0) [2610]  All  47.6–20.0  6.2–2.0  4.3–2.8  103.1–70.0  (5.0–510.0) [2810]  (0.1–130.0) [320]  (0.3–321.2) [251]  (10.0–540.0) [6080]  Type of procedure  Physician (μSv)  Nurse (μSv)  Radiographer (μSv)  C-arm (μSv)  Mean–median (range)[cumulative dose]  Mean–median (range)[cumulative dose]  Mean–median (range) (range) [cumulative dose]  Mean–median (range) (range) [cumulative dose]  Diagnostic  41.2–20.0  4.1–3.0  4.0–2.5  93.8–60.0  (5.0–200.0) [1524]  (0.1–11.0) [132]  (0.3–21.2) [149]  (10.0–540.0) [3470]  Therapeutic  58.5–20.0  9.4–1.0  4.7–4.3  118.6–105.0  (6.0–510.0) [1286]  (0.2–130.0) [188]  (0.9–17.7) [103]  (30.0–350.0) [2610]  All  47.6–20.0  6.2–2.0  4.3–2.8  103.1–70.0  (5.0–510.0) [2810]  (0.1–130.0) [320]  (0.3–321.2) [251]  (10.0–540.0) [6080]  Table 1. Mean, median and range values for Hp(10) values per procedure for physician, nurse, radiographer and C-arm dosimeters and cumulative dose in the period (1 month). Type of procedure  Physician (μSv)  Nurse (μSv)  Radiographer (μSv)  C-arm (μSv)  Mean–median (range)[cumulative dose]  Mean–median (range)[cumulative dose]  Mean–median (range) (range) [cumulative dose]  Mean–median (range) (range) [cumulative dose]  Diagnostic  41.2–20.0  4.1–3.0  4.0–2.5  93.8–60.0  (5.0–200.0) [1524]  (0.1–11.0) [132]  (0.3–21.2) [149]  (10.0–540.0) [3470]  Therapeutic  58.5–20.0  9.4–1.0  4.7–4.3  118.6–105.0  (6.0–510.0) [1286]  (0.2–130.0) [188]  (0.9–17.7) [103]  (30.0–350.0) [2610]  All  47.6–20.0  6.2–2.0  4.3–2.8  103.1–70.0  (5.0–510.0) [2810]  (0.1–130.0) [320]  (0.3–321.2) [251]  (10.0–540.0) [6080]  Type of procedure  Physician (μSv)  Nurse (μSv)  Radiographer (μSv)  C-arm (μSv)  Mean–median (range)[cumulative dose]  Mean–median (range)[cumulative dose]  Mean–median (range) (range) [cumulative dose]  Mean–median (range) (range) [cumulative dose]  Diagnostic  41.2–20.0  4.1–3.0  4.0–2.5  93.8–60.0  (5.0–200.0) [1524]  (0.1–11.0) [132]  (0.3–21.2) [149]  (10.0–540.0) [3470]  Therapeutic  58.5–20.0  9.4–1.0  4.7–4.3  118.6–105.0  (6.0–510.0) [1286]  (0.2–130.0) [188]  (0.9–17.7) [103]  (30.0–350.0) [2610]  All  47.6–20.0  6.2–2.0  4.3–2.8  103.1–70.0  (5.0–510.0) [2810]  (0.1–130.0) [320]  (0.3–321.2) [251]  (10.0–540.0) [6080]  Table 1 shows the results per procedure in terms of occupational dose Hp(10). Values were higher for therapeutic than diagnostic procedures, which is explained because the median values of PKA followed that same trend (52 and 26 Gy cm2, respectively). In this study, the range for personal dose equivalent Hp(10) was between 5.0 and 510.0 μSv with a mean value of 47.6 μSv for the dosimeter used by the physician, from 0.1 to 130.0 μSv with a mean value of 6.2 μSv for the dosimeter used by the nurse and from 0.3 to 321.2 μSv with a mean value of 4.3 μSv for the dosimeter used by the radiographer. According to the ORAMED research project(16), personal dose equivalent Hp(10) measured at physician chest over the apron was 50 μSv. Sanchez et al.(14) reported mean dose per procedure of 46 μSv for physician and 12 μSv for nurse. Personal dose equivalent Hp(10) recorded at operators’ chest level (over the apron) in cardiac catheterisation laboratories can be used to roughly estimate eye lens dose when eye dosimeters are not available and with the C-arm dosimeter located on the lower part of the x-ray tube, in the surroundings of the patient backscatter radiation and with no protection barrier such as a ceiling-suspended screen, information could be obtained on scatter radiation levels in the worst-case geometry. According to Martin(17) the dose in the eyes can be 75% of the dose recorded by the dosimeter placed in chest or thyroid protector. As the study was conducted over the course of a month (59 cardiological procedures) it is also possible to extrapolate from Table 1, that the personal dose equivalent Hp(10) values for physician, nurse, radiographer and C-arm dosimeter for 1 year would be 33.7, 3.9, 3.0 and 73.0 mSv, respectively. For the above, it becomes absolutely necessary the use eyewear protection that reduce the lens dose by a factor of 8–10 from frontal exposures, depending on the eyewear and the quality of the scattered radiation(18, 19). However, according to Sanchez et al.(14) in some circumstances (high workloads and inefficient goggle design), the only use of goggles may not, in absence of a protective screen, be enough to keep eye lens doses under the occupational dose limit. A protective screen correctly positioned can, on the contrary, help reduce eye lens doses and what is more, the dose to the whole brain, head and thyroid gland. Figure 1 shows the correlation between PKA and Hp(10) values for physician, nurse, radiographer and C-arm positions. Figure 1. View largeDownload slide Correlation between kerma-area product and personal dose equivalent Hp(10) for the four dosimeters. Figure 1. View largeDownload slide Correlation between kerma-area product and personal dose equivalent Hp(10) for the four dosimeters. Figure 1 illustrates the correlation of Hp(10) values as a function of PKA for the entire data set. The physician and nurse dosimeter, presented the highest correlation values. However, there was also a moderately positive correlation for the other two dosimeters. Starting from the slopes calculated, the personal dose equivalent Hp(10) for one mean patient dose (53.9 Gy cm2) would be 48 μSv (physician), 5 μSv (nurse), 4 μSv (radiographer) and 103 μSv (C-arm), respectively. With the dosimeter located on the radiographer’s chest, your doses per unit of patient dose was expected to be lower, in comparison with the nurse and physician as the dosimeter was more moved away from the area where patient backscatter was predominant. Depending on the C-arm angle, this reduction may vary(20). In addition, when the ceiling-suspended screen is used, an additional reduction in the slope (physician dose per unit of patient dose) of the order of the screen attenuation factor should be observed. Such screen attenuation factor, depending on the beam quality, could range from 20 to 50 or even higher(19). In our case, it was ~50% (103–48 μSv). A strict policy on the regular use of personal dosimeter should therefore form part of any quality assurance programme in cardiology laboratories. Failure to wear monitoring equipment could represent a breach of the employer’s procedures and/or local regulatory or legislative requirements(1). Unfortunately, Chilean legislation on radiological protection issues still does not consider these programmes. A useful alternative could be an APD system that offers real-time access to staff doses and dose rates alarm within cardiac interventional laboratories(8). This dosimeters are extensively used in Europe and have long been recognised as essential tools for worker dose reduction(21). STUDY LIMITATIONS The limitations of this study were the low number of adult interventional cardiology procedures and that it was performed in the context of a single cardiology service. However, these are merely preliminary results given that the study is currently being conducted in other cardiology services in Chile. CONCLUSIONS Mean values of occupational dose Hp(10) per procedure were 47.6, 6.2, 4.3 and 103.1 μSv for physician, nurse, radiographer and C-arm dosimeters, respectively. If no protective tools are used, physician dose may exceed the new eye lens dose limit. ACKNOWLEDGEMENTS The current work has been carried out under the framework of the International Atomic Energy Agency regional project RLA/9/075, ‘Strengthening National Infrastructure for End-Users to Comply with Regulations and Radiological Protection Requirements’. The authors thank the staff of the Hemodynamic Department, Cardiovascular Service, Antofagasta Regional Hospital, Antofagasta, Chile. MD Bernhard Westerberg, MD Guillermo Illanes, BSC Tomas Aguilar and BSC Rigoberto Choque. C.U. acknowledges the support of the Direction of Research at Tarapaca University, through senior research project No. 7710-14. REFERENCES 1 International Commission on Radiological Protection. Radiological protection in cardiology. Ann. ICRP  42, 1–125, ( 2013) ICRP Publication 120. 2 Balter, S., Miller, D., Vano, E., Ortiz, P., Bernardi, G., Cotelo, E., Faulkner, K., Nowonty, R., Padovani, R. and Ramirez, A. A pilot study exploring the possibility of establishing guidance levels in x-ray directed interventional procedures. Med. Phys.  35( 2), 673– 680 ( 2008). Google Scholar CrossRef Search ADS PubMed  3 International Commission on Radiological Protection (ICRP). Avoidance of radiation injuries from medical interventional procedures. Ann. ICRP  30( 2), 7– 67 ( 2000) ICRP Publication 85. CrossRef Search ADS   4 Vano, E. Radiation exposure to cardiologists: how it could be reduced. Heart  89, 1123– 1124 ( 2003). Google Scholar CrossRef Search ADS PubMed  5 Chambers, C. E., Fetterly, K. A., Holzer, R., Lin, P. J., Blankenship, J. C., Balter, S. and Laskey, W. K. Radiation safety program for the cardiac catheterization laboratory. Catheter. Cardiovasc. Interv.  77, 546– 556 ( 2011). Google Scholar CrossRef Search ADS PubMed  6 Sanchez, R., Vano, E., Fernandez, J. M. and Gallego, J. J. Staff radiation doses in a real-time display inside the angiography room. Cardiovasc. Intervent. Radiol.  33, 1210– 1214 ( 2010). Google Scholar CrossRef Search ADS PubMed  7 Muller, M. C., Welle, K., Strauss, A., Naehle, P. C., Pennekamp, P. H., Weber, O. and Burger, C. Real-time dosimetry reduces radiation exposure of orthopaedic surgeons. Orthop. Traumatol. Surg. Res.  100, 947– 951 ( 2014). Google Scholar CrossRef Search ADS PubMed  8 Vano, E., Fernandez, J. M. and Sanchez, R. Occupational dosimetry in real time. Benefits for interventional radiology. Radiat. Meas.  46, 1262– 1265 ( 2011). Google Scholar CrossRef Search ADS   9 Ordiales, J. M., Nogales, J. M., Vano, E., Lopez-Minguez, J. R., Alvarez, F. J., Ramos, J., Martinez, G. and Sanchez, R. M. Occupational dose reduction in cardiac catheterisation laboratory: a randomised trial using a shield drape placed on the patient. Radiat. Prot. Dosim.  174, 255– 261 ( 2017). 10 Faulkner, K., Malone, J., Vano, E., Padovani, R., Busch, H. P., Zoetelief, J. H. and Bosmans, H. The SENTINEL project. Radiat. Prot. Dosim.  129, 3– 5 ( 2008). Google Scholar CrossRef Search ADS   11 Ubeda, C., Vano, E., Miranda, P., Leyton, F., Valenzuela, E. and Oyarzun, C. Radiation dose and image quality for adult interventional cardiology in Chile: a national survey. Radiat. Prot. Dosim.  147, 90– 93 ( 2011). Google Scholar CrossRef Search ADS   12 International Commission on Radiation Units and Measurements (ICRU). Patient dosimetry for X-rays used in medical imaging. ICRU Report 74. J. ICRU  5, 1– 113 ( 2005). 13 Available on http://www.raysafe.com/Home/Products/Staff/RaySafe%20i2#Downloads. (last accessed December 2017). 14 Sánchez, R. M., Vano, E., Fernández, J. M., Pifarré, X., Ordiales, J. M., Rovira, J. J., Carrera, F., Goicolea, J. and Fernández-Ortiz, A Occupational eye lens doses in interventional cardiology. A multicentric study. J. Radiol. Prot.  36, 133– 143 ( 2016). Google Scholar CrossRef Search ADS PubMed  15 Available on www.spss.com (last accessed November 2017). 16 Vanhavere, F. et al.  . Measurements of eye lens doses in interventional radiology and cardiology: final results of the ORAMED project. Radiat. Meas.  46, 1243– 1247 ( 2011). Google Scholar CrossRef Search ADS   17 Martin, C. J. A review of radiology staff doses and dose monitoring requirements. Radiat. Prot. Dosim.  136, 140– 157 ( 2009). Google Scholar CrossRef Search ADS   18 Van Rooijen, B. D., de Haan, M. W., Das, M., Arnoldussen, C. W., de Graaf, R., van Zwam, W. H., Backes, W. H. and Jeukens, C. R. Efficacy of radiation safety glasses in interventional radiology. Cardiovasc. Intervent. Radiol.  37, 1149– 1155 ( 2014). Google Scholar CrossRef Search ADS PubMed  19 Vano, E., Gonzalez, L., Fernandez, J. M. and Haskal, Z. J. Eye lens exposure to radiation in interventional suites: caution is warranted. Radiology  248, 945– 953 ( 2008). Google Scholar CrossRef Search ADS PubMed  20 Vañó, E., Fernández, J. M., Sánchez, R. M. and Dauer, L. T. Realistic approach to estimate lens doses and cataract radiation risk in cardiology when personal dosimeters have not been regularly used. Health Phys.  105, 330– 339 ( 2013). Google Scholar CrossRef Search ADS PubMed  21 Ginjaume, M., Bolognese-Milsztajn, T., Luszik-Bhadra, M., Vanhavere, F., Wahl, W. and Weeks, A. Overview of active personal dosimeters for individual monitoring in the European Union. Radiat. Prot. Dosim.  125, 261– 266 ( 2007). Google Scholar CrossRef Search ADS   © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

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Radiation Protection DosimetryOxford University Press

Published: May 11, 2018

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