Original Article
Impact of New-generation Hybrid Imaging Technology on Radiation Dose during Percutaneous Coronary Interventions and Trans-femoral Aortic Valve Implantations: A comparison with conventional flat-plate angiography

https://doi.org/10.1016/j.hlc.2015.08.023Get rights and content

Background

Technological advancements in newer-generation catheterisation laboratories may reduce patient and occupational radiation exposure.

Methods

We compared fluoroscopy time and dose-area product (DAP) between a Philips Allura X-PER FD20 and Siemens Artis Zeego Hybrid systems for 47 single-vessel percutaneous coronary interventions (PCI) and 35 transcatheter aortic valve implantations (21 Corevalve, 14 Edwards Sapien TAVI) using the FD20, versus 30 PCI and 28 TAVI (15 Corevalve, 13 Sapien) with the Zeego over a 24-month period.

Results

Multivariate analysis revealed that, adjusting for patient weight and fluoroscopy time, DAP (median, interquartile range) was 26% lower for PCI with the Zeego than the FD20 [55.6 (27.0-91.5) vs 77.6 (51.2-129.1) Gy.cm2, P=0.03)] and using tomographic imaging with the Zeego did not increase DAP for TAVI procedures [98.1 (65.9-136.6) vs 112.4 (64.9-156.2) Gy.cm2 (P=NS). Although fluoroscopy times were longer for TAVI procedures than PCI with both systems (23.5-24.4 vs 7.3-9.2mins, p<0.0001), there was a significant difference in DAP between PCI and combined TAVI with the Zeego (55.6 vs 112.4 Gy.cm2, P<0.006) but not with the FD20 (77.6 vs 98.1 Gy.cm2, P=NS).

Conclusion

Specific dose-reducing features of the new-generation system reduced DAP more for PCI than TAVI, as valve replacement procedures use additional cine-acquisition not necessary for PCI.

Introduction

Radiation exposure to staff and patients during cardiac imaging is a major concern, particularly in the cardiac catheterisation laboratory where sequential fluoroscopy and high-dose cine acquisition result in high radiation dosages [1]. Irrespective of the actual dose involved, the risk/benefit ratio to patients strongly favours continued use of diagnostic X-ray imaging techniques [2], and current radiation safety programs encourage reduction in medical radiation exposure by means of staff education, regular monitoring and recording of radiation dose for each procedure, mandatory licensing requirements, following ALARA (As Low As Reasonably Achievable) principles and monitoring personal dosimetry [3], [4]. Nevertheless, radiation exposure in the cardiac catheterisation laboratory is unavoidable, and manufacturers have responded by developing new technology, instrumentation and software aimed at reducing radiation dosage during diagnostic and interventional imaging.

Increasing use of percutaneous treatment for structural heart interventions and for complex coronary artery disease continues to raise concerns regarding the radiation risk posed to patients and attendant healthcare staff, and recent studies have quantified doses generated during various cardiac interventions [5], [6]. Reported levels of fluoroscopy time, dose area product (DAP) and air kerma represent the radiation risk associated with these procedures and may also indicate dosages expected from other structural heart interventions. These studies, however, used fluoroscopic equipment that has since been replaced by a new generation of angiography suites that can potentially improve radiation safety as the new technology becomes more widely distributed.

This study compares differences in case time, fluoroscopy time, dose area product and ±air kerma for percutaneous coronary interventions (PCI) and two types of transcatheter aortic valve implantation (TAVI) between one of the new generation X-ray machines (Artis Zeego, Siemens, Munich) and a previous-generation flat-plate angiography model (Allura X-PER FD20, Philips, Amsterdam, The Netherlands) with flat-plate technology that is still in common use. Transcatheter aortic valve implantation patients received either a Corevalve (Medtronic Inc., Minnesota) or an Edwards Sapien valve (Edwards Lifesciences, Irvine, California).

Section snippets

Study Design

The cardiac catheterisation laboratory operates a Siemens Artis Zeego hybrid system installed in May 2013 and also uses a Philips Allura X-PER FD20 flat-plate angiography system in an adjoining suite. Four experienced interventional cardiologists routinely perform PCI in both suites, while TAVI and other structural heart studies are performed exclusively in the hybrid laboratory. The objective of this study was to determine how effective the new-generation angiography technology is in reducing

Statistical Analysis

Data was tabulated in Microsoft Excel 2010® (Microsoft Corporation, Redmond, USA) and analysed using SAS9.4® (www.sas.com). We compared proportions using the χ2 test. For normally distributed data, results were reported using means and standard deviation, and a two sample t-test to generate comparisons. Data that did not conform to a normal distribution were reported using medians and interquartile ranges, and these were compared using the Wilcoxon Rank Sum test. We performed logarithmic

Results

Informed consent was obtained from a total of 140 patients entered into this study. All procedures were performed by the same group of experienced interventional cardiologists over a total 24-month period preceding and following installation of the new hybrid laboratory. There were 47 single-vessel PCI cases performed using the older FD20, versus 30 PCI using the new Zeego. Collectively, 21 Corevalve TAVI procedures were performed with the FD20 versus 15 with the Zeego, and 14 Edwards TAVI with

Discussion

Dose area product levels (median, interquartile range) were significantly lower for PCI in the Zeego room than in the FD20 room, but despite the added radiation delivered by ACT with the Zeego, there was no difference in DAP levels between the two rooms for combined TAVI procedures. Adjusting for patient weight and fluoroscopy time, the total radiation dose for PCI was 26% less in the Zeego room than in the FD20 room (P=0.02), but there was no difference in DAP between the two rooms for either

Conclusion

A hybrid system can markedly reduce radiation exposure for PCI by having a lower input dose per given field size and by using features like stored fluoroscopy, image fusion and last-image hold. However, in this study, use of the new technology resulted in increased DAP for TAVI, and considerably higher air kerma for Sapien TAVI specifically. We attribute the higher air kerma for Sapien TAVI to greater use of high-dose cine-angiography, including ACT, that is not required at all for PCI, and to

Acknowledgments

There was no financial assistance with this project. The authors thank Drs. Paul Roy, David Baron and David Roy, along with the St. Vincent's Hospital cardiac catheterisation team for their continued commitment to the unit's percutaneous intervention program and also Ms. Julie Murray for preparation of graphics.

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