Skip to main content
main-content
Top

Tip

Swipe om te navigeren naar een ander artikel

06-03-2019 | Original Article | Uitgave 6/2019 Open Access

Netherlands Heart Journal 6/2019

Cardiology fellows-in-training are exposed to relatively high levels of radiation in the cath lab compared with staff interventional cardiologists—insights from the RECAP trial

Tijdschrift:
Netherlands Heart Journal > Uitgave 6/2019
Auteurs:
W. Vlastra, B. E. Claessen, M. A. Beijk, K. D. Sjauw, G. J. Streekstra, J. J. Wykrzykowska, M. M. Vis, K. T. Koch, R. J. de Winter, J. J. Piek, J. P. S. Henriques, R. Delewi
What’s new?
  • Since staff interventional cardiologists perform more complex procedures in the catheterisation laboratory compared with cardiology fellows-in-training, they use 74% higher radiation levels (dose area product—DAP), consequently staff interventional cardiologists were exposed to 50% higher levels of actual radiation exposure (E in µSv, measured at chest height).
  • However, after correcting the actual radiation exposure for the amount of used radiation (E/DAP), fellows-in-training were exposed to 34% higher relative radiation exposure levels compared with staff interventional cardiologists.
  • These findings highlight that there should be more attention for radiation safety behaviour during the training of cardiology fellows.

Introduction

Despite the technological developments of the last decades, the profession of an interventional cardiologist is inevitably related to exposure to low-dose radiation. Consequently, interventional cardiologists are at risk for developing radiation-induced diseases such as cataract and left-sided brain tumours [ 1, 2]. The operator’s radiation exposure strongly varies per procedure, depending on patient characteristics, complexity of the performed procedure, and radiation protection equipment [ 3]. However, operator behaviour may possibly be the largest influencer of radiation exposure. We hypothesised that awareness regarding radiation exposure among operators grows as skill and the general experience in the catheterisation laboratory increase. Accordingly, we aimed to investigate the difference in the relative radiation exposure of cardiology fellows-in-training compared with staff interventional cardiologists.

Methods

This is a sub-study of the RECAP trial (NCT03139968), a double-blind, sham-controlled, randomised clinical trial, which evaluated the efficacy of a radiation-absorbing drape (the RADPAD 5100A-O, Worldwide Innovations & Technologies, Inc., Lenexa, Kansas, USA) [ 4]. In this single-centre prospective, all-comer trial, performed between January and May 2017, the real-time operator’s radiation exposure (E in µSv) was measured at chest height with a dosimeter (PDM, DoseAware, Philips Medical Systems, the Netherlands) during 766 diagnostic catheterisations (coronary angiography) and percutaneous coronary interventions (PCI). The patient exposure, representing the amount of radiation administered by the operator per procedure, was also collected (dose area product [DAP] in mGy·cm 2). The primary endpoint of the current sub-analysis was the difference in relative radiation exposure between cardiology fellows-in-training and staff interventional cardiologists. This was defined as the ratio between the primary operator’s radiation exposure (E), and patient’s radiation exposure (DAP), both measured per procedure. The relative radiation exposure (E/DAP), rather than the actual radiation exposure, was chosen in order to correct for the inter-procedural variance in the administered amount of radiation [ 5]. This way it is possible to test the actual operator behaviour rather than the complexity of a procedure. Since interventional procedures are often performed by two operators, the primary operator was defined as the operator that had the closest location to the radiation source, and accordingly received the highest radiation exposure. The study protocol was approved by the Institutional Review Boards of the Amsterdam University Medical Center. Since the current study does not impose interventions on the patient and has no risks or benefits for the patient, informed consent was not required.

Results

During the 4‑month study period of the RECAP trial, staff interventional cardiologists were the primary operator during 637 coronary procedures, whereas cardiology fellows-in-training were the primary operator in 129 procedures. The mean patient age was 67 ± 11 years, 70% was male and the mean body mass index (BMI) was 27.7 ± 5.0. Most patient characteristics, including BMI, were comparable among patients treated by staff cardiologists or fellows-in-training (Tab.  1). As expected, staff interventional cardiologists more often performed relatively complex procedures compared with cardiology fellows-in-training. There was a trend towards a higher number of patients presenting with STEMI treated by staff cardiologists compared with cardiology fellows-in-training (8% vs 4%, p = 0.08). Also, staff interventional cardiologists more frequently performed PCI compared with cardiology fellows-in-training (55% vs 35%, P < 0.001). Additionally, interventional cardiologists more frequently performed PCI of chronic total occlusions (CTO) (5% vs 1%, p = 0.02). The performance of these relatively complex procedures by staff interventional cardiologists resulted in a 74% higher use of radiation compared with fellows-in-training (DAP, Fig.  1a). Consequently, staff interventional cardiologists were exposed to 50% higher levels of actual radiation exposure compared with cardiology fellows-in-training (E, Fig.  1b). However, when correcting for the complexity of the procedure, by evaluating the relative operator exposure (E/DAP), fellows-in-training were exposed to a 34% higher relative exposure compared with staff interventional cardiologists (Fig.  1c, p = 0.03).
Table 1
Patient and procedural characteristics
 
staff cardiologists
fellows-in-training
p-value
( n = 637)
( n = 129)
demographics
age (years)
 67 ± 12
 67 ± 10
 0.48
male gender
440 (69)
 92 (71)
 0.61
medical history
BMI
 27.6 ± 5.0
 28.0 ± 4.9
 0.44
previous myocardial infarction
169 (27)
 25 (20)
 0.08
previous PCI
187 (30)
 35 (27)
 0.60
previous bypass surgery
 55 (9)
 11 (9)
 0.98
risk factors
diabetes mellitus
156 (25)
 30 (24)
 0.73
known hypertension
367 (60)
 63 (50)
 0.04
family history of CAD
322 (56)
 68 (56)
 0.99
hypercholesterolaemia
282 (48)
 48 (39)
 0.06
current cigarette smoking
122 (21)
 26 (21)
 0.99
presentation
STEMI
 53 (8)
  5 (4)
 0.08
NSTEMI/UA
124 (20)
 22 (17)
 0.53
stable CAD
366 (58)
 79 (61)
 0.43
other a
 94 (15)
 23 (18)
 0.38
procedural characteristics
radial access
497 (78)
109 (85)
 0.10
PCI
349 (55)
 45 (35)
<0.001
lesions treated per PCI
  1.44 ± 0.67
  1.26 ± 0.50
 0.12
location of treated lesion: LM or LAD
162 (54)
 22 (58)
 0.61
location of treated lesion: CX
 90 (30)
  9 (24)
 0.44
location of treated lesion: RCA
105 (35)
 10 (26)
 0.31
PCI of chronic total occlusion
 34 (5)
  1 (1)
 0.02
iFR/FFR only b
 46 (7)
 15 (12)
 0.09
Skin-to-Skin time (min)
 47.1 ± 27.0
 45.5 ± 21.8
 0.55
Data are number (%) or mean ± SD
BMI body mass index, PCI percutaneous coronary intervention, CAD coronary artery disease, STEMI ST-elevation myocardial infarction, NSTEMI non-ST-elevation myocardial infarction, UA unstable angina, LM left main coronary artery, LAD left anterior descending coronary artery, CX circumflex artery, RCA right coronary artery, iFR/FFR instantaneous wave-free ratio/fractional flow reserve
aHeart failure, pre transplantation, pre-valve replacement
bWithout PCI

Conclusions

In conclusion, in the current study cardiology fellows-in-training were exposed to significantly higher radiation levels than staff interventional cardiologists during catheterisation procedures, when corrected for complexity. We hypothesise that cardiology fellows-in-training are exposed to higher radiation exposure than staff interventional cardiologists for two reasons. Firstly, fellows-in-training, in their eagerness to learn, are often preoccupied with their patient’s health, potentially forgetting to protect their own health by maintaining appropriate distance from the scatter radiation source during the moments of fluoroscopy, and forgetting to optimise collimation settings. Secondly, we hypothesise that fellows-in-training, more than their mentors feel the need to make additional recordings to secure themselves of a successful procedure, increasing total fluoroscopy time. In the current study there was a trend to fellows-in-training more frequently performing procedures through the radial artery compared with staff cardiologists (85% vs 78%, p = 0.10). The performance of more radial procedures could have reduced the distance between the fellow-in-training and the radiation source, increasing the radiation exposure. However, in the current study radial artery access was not related to a higher relative radiation exposure ( p = 0.16). Moreover, during radial procedures, the left radial artery was used in a minority of the procedures, both by cardiology fellows-in-training and staff interventional cardiologists (8% vs 11%, p = 0.45).
There are several strategies to reduce the radiation exposure of cardiology fellows-in-training. Firstly, the total radiation use can be reduced using modern X‑ray systems. In accordance with the ALARA principle (As Low As Reasonably Achievable), the appropriate ratio between optimal image quality and radiation dose is optimised using modern X‑ray systems that combine real-time image noise reduction algorithms with shorter X‑ray pulses and smaller focal spots. The procedures in the current study were performed using multiple catheterisation rooms equipped with either the newer Philips AlluraClarity FD10 (including noise reduction technology) or the Philips Allura Xper FD10 (Philips Medical Systems, the Netherlands). In the current analysis we corrected for the use of these two different systems. Interestingly, the radiation use was 65% lower during diagnostic angiograms performed using the AlluraClarity X‑ray system. Likewise, the operator radiation exposure was 63% lower (both p < 0.001). These findings are in accordance with an earlier study that showed a 50% reduction of the operator exposure, and importantly without a reduction in image quality [ 6]. Likewise, additional shielding measures can be used to reduce the radiation exposure of fellows-in-training. Radiation-absorbing drapes reduce radiation exposure with 20% [ 4], leaded glasses reduce scatter radiation to the eye with a factor of 5 to 10 [ 7], but are often reported as being uncomfortable [ 8]. Moreover, protective caps considerably reduce cranial radiation exposure [ 9].
Nevertheless, the higher radiation exposure of fellows-in-training in the current study was the consequence of operator behaviour and therefore could and should be adjusted. We strongly recommend that during training of cardiology fellows, there should be more attention for radiation safety behaviour, this includes appropriate distance from the scatter radiation source during fluoroscopy. In a randomised controlled trial the use of real-time dosimetry considerably reduced the operator’s radiation exposure [ 10], accordingly real-time dosimeters could provide aid during the training of cardiology fellows. Cardiology fellows-in-training should not only be evaluated by their seniors on their PCI successes but also on their radiation safety behaviour. Because if the mentors won’t protect their pupil’s health, who will?

Acknowledgements

We would like to acknowledge and thank all interventional cardiologists and catheterisation laboratory nurses for contributing to the current trial, especially J.H.W. de Groot-Hagenaars.

Funding

The Heart Center of the AMC received unrestricted grants From Philips and Worldwide Innovations & Technologies. The used dosimeters were provided by Philips. Philips did not have any involvement in the designing of the study, study procedures, collection, and analysis of data or formation of this manuscript.

Conflict of interest

W. Vlastra, B.E. Claessen, M.A. Beijk, K.D. Sjauw, G.J. Streekstra, J.J. Wykrzykowska, M.M. Vis, K.T. Koch, R.J. de Winter, J.J. Piek, J.P.S. Henriques and R. Delewi report no relationships that could be construed as a conflict of interest.
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://​creativecommons.​org/​licenses/​by/​4.​0/​), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Onze productaanbevelingen

Netherlands Heart Journal

Het Netherlands Heart Journal wordt uitgegeven in samenwerking met de Nederlandse Vereniging voor Cardiologie en de Nederlandse Hartstichting. Het tijdschrift is Engelstalig en wordt gratis beschikbaa ...

Literatuur
Over dit artikel

Andere artikelen Uitgave 6/2019

Netherlands Heart Journal 6/2019 Naar de uitgave