Impact of new X-ray technology on patient dose in pacemaker and implantable cardioverter defibrillator (ICD) implantations
Impact of new X-ray technology on patient dose in pacemaker and implantable cardioverter defibrillator (ICD) implantations
Joris D. van Dijk 0 1 2 3
Jan Paul Ottervanger 0 1 2 3
Peter Paul H. M. Delnoy 0 1 2 3
Martine C. M. Lagerweij 0 1 2 3
Siert Knollema 0 1 2 3
Cornelis H. Slump 0 1 2 3
Pieter L. Jager 0 1 2 3
0 Department of Cardiology, Isala Hospital , Zwolle , The Netherlands
1 MIRA: Institute for Biomedical Technology and Technical Medicine, University of Twente , Enschede , The Netherlands
2 Department of Nuclear Medicine, Isala Hospital , PO Box 10400, 8000 GK Zwolle , The Netherlands
3 Department of Medical Physics, Isala Hospital , Zwolle , The Netherlands
Purpose New X-ray technology providing new image processing techniques may reduce radiation exposure. The aim of this study was to quantify this radiation exposure reduction for patients during pacemaker and implantable cardioverter defibrillator (ICD) implantation. Methods In this retrospective study, 1185 consecutive patients who had undergone de novo pacemaker or ICD implantation during a 2-year period were included. All implantations in the first year were performed using the reference technology (Allura Xper), whereas in the second year, the new X-ray technology (AlluraClarity) was used. Radiation exposure, expressed as the dose area product (DAP), was compared between the two time periods to determine the radiation exposure reduction for pacemaker and ICD implantations without cardiac resynchronization therapy (CRT) and with CRT. Procedure duration and contrast volume were used as measures to compare complexity and image quality. Results The study population consisted of 591 patients who had undergone an implantation using the reference technology, and 594 patients with the new X-ray technology. The two groups did not differ in age, gender, or body mass index. The DAP decreased with 69 % from 16.4 ± 18.5 to 5.2 ± 6.6 Gy cm2 for the non-CRT implantations (p < 0.001). The DAP decreased with 75 % from 72.1 ± 60.0 to 17.8 ± 17.4 Gy cm2 for the CRT implantations (p < 0.001). Nevertheless, procedure duration and contrast volume did not differ when using the new technology (p = 0.09 and p = 0.20, respectively). Conclusions Introduction of new X-ray technology resulted in a radiation exposure reduction of more than 69 % for patients during pacemaker and ICD implantation while image quality was unaffected.
Dose reduction; Imaging; Radiation dose; Pacemaker; Implantable cardioverter defibrillator (ICD)
The use of pacemakers and implantable cardioverter
defibrillator (ICD) has increased sharply over the past decade .
This increase has led to concerns about the long-term health
consequences of the radiation exposure during the
implantation of these devices . Patients and in particular staff can be
exposed to high cumulative doses due to the increasing
complexity and high number of pacemaker and ICD
implantations. Minimizing the radiation exposure while maintaining
an acceptable image quality is therefore essential, especially
for staff performing many procedures every year [3, 4].
New imaging technologies have the potential to decrease
radiation exposure while maintaining image quality. This is
mainly due to ongoing developments in both computational
power and software algorithms . A new X-ray imaging
technology (AlluraClarity), commercially introduced during
in mid-2012, is equipped with the latest image processing
techniques, showed in pre-clinical setting radiation exposure
decreases of between 50 and 85 % . These results were
confirmed for coronary angiography and electrophysiology
procedures in clinical practice [6–8]. However, these results
have not been confirmed for pacemaker and ICD
implantations where different image processing settings and projection
angles are used compared to coronary angiography or
electrophysiological procedures. The aims of this study were to
quantify the reduction in radiation exposure for patients
during pacemaker or ICD implantation using the new
AlluraClarity X-ray technology, and to assess whether image
quality was comparable to that achieved previously.
2.1 Study population
This was a retrospective cohort study. All patients who
underwent de novo implantation of a pacemaker or ICD in
our institution between August 16, 2012 and August 16,
2014 were included. The standard acquisition chain and image
processing (hereafter, referred to as the reference technology,
Allura Xper FD10, Philips Healthcare) were used during all
implantations performed in the first year (<August 16, 2013).
A new X-ray technology (hereafter, referred to as the new
technology, AlluraClarity FD10, Philips Healthcare) was used
in all implantations performed in the second year. The new
Xray equipment has more computational power than
conventional X-ray equipment and therefore features real-time
automatic motion compensation to align moving structures before
averaging. This correction allows averaging over more
consecutive images resulting in an increased temporal noise
reduction. Moreover, the new hardware also allows to average
the intensity of more neighborhood pixels in a single frame
than the conventional systems, improving the spatial noise
reduction. Finally, new imaging algorithms also improve
brightness control and edge and contrast enhancement.
The indication for a pacemaker or ICD implantation was
determined according to the European guidelines at the time of
implantation [9, 10]. Pacemaker and ICD devices from any of
the five major manufacturers (Medtronic Inc, St Jude Medical,
Boston-Scientific, Biotronik, and Sorin Group) were
implanted. All the implants were inserted through a pectoral
incision, and the leads were inserted through the subclavian
vein. The majority of coronary sinus leads was bipolar and
was positioned in the lateral, posterolateral, or posterior region
wherever possible, whereas the anterior and anterolateral
positions were considered suboptimal and avoided if possible.
Fluoroscopic guidance was used to ensure accurate tip
placement. The standard image processing settings for pacemaker
and ICD implantations were used for both reference and new
X-ray technologies, as advised by the vendor, and are shown
in Table 1. This also included the lower radiation exposure
settings when using the new technology. All procedures were
started using the default Blow^ fluoroscopy dose setting and
were increased by the cardiologist from a Blow^ to Bmedium^
and from a Bmedium^ to Bhigh^ exposure rate when clinically
The dose area product (DAP) was measured by the
ionization chambers inside the X-ray systems, and the cumulative
DAP was derived for each procedure. We distinguished
between two types of implantations: the standard pacemaker or
I C D d e v i c e s a n d t h e i m p l a n t a t i o n s w i t h c a r d i a c
resynchronization therapy (CRT), all with biventricular lead
placements. The latter procedure is generally associated with a
higher radiation exposure and use of contrast fluids, possibly
influencing the radiation exposure reduction when
introducing the new technology. The mean DAP was compared
between the two X-ray technologies for both groups to
determine differences in radiation exposure. In addition, the
procedure time and contrast volume were also compared between
the two technologies for both type of implantations as
measures of image quality and procedural complexity. Procedure
time was defined as the total occupation time of the operating
room, including room preparation and the time-out procedure.
Influence of operator experience on the radiation exposure
reduction was assessed. An experienced operator was defined
as an operator performing more than 80 procedures in the
2year period. In addition, we assessed a possible learning curve
for using the new technology by comparing the mean DAP in
the first 3 months after installation of the new technology with
the mean DAP in the last 3 months.
All patient-specific parameters and characteristics for
both the groups were presented as percentages or
mean ± standard deviation (sd), and compared using the
chi-square or unpaired t tests as appropriate, using Stata
software (StataSE 12.0). The radiation exposure,
expressed as the DAP, and procedure time were
compared between the two technologies using a t test, for
both the non-CRT devices and CRT devices. The same
test was used to test for difference in contrast volume
for the CRT devices between both the technologies.
Percentage of procedures performed by experienced
operators was compared between the two technologies
using a t test. Influence of operator experience on the
reduction in radiation exposure was tested using a
twoway ANOVA for the non-CRT and CRT implantations.
The mean radiation exposure in the first 3 months was
compared with the last 3 months for the new
technology by using a t test. The level of statistical significance
was set to 0.05 for all the statistical analyses.
Table 1 Standard fluoroscopic
and cinematographic imaging
settings—including an example
of the tube settings for a typical
patient corresponding to a 20-cm
equivalent water thickness (with a
constant source-to-image receptor
distance of 87 cm, field size of
25 mm without magnification)—
for both the reference technology
(Alura Xper) and new X-ray
± 52.7 min for the CRT implantations) and the new technology
(98.0 ± 47.3 and 154.2 ± 47.2 min for the CRT implantations),
for both the non-CRT and CRT implantations (p = 0.68 and
p = 0.09, respectively), as shown in Fig. 2. The mean volume
of contrast injected during the CRT procedures did not differ
between using the reference technology (75 ± 56 ml) and the
new X-ray technology (83 ± 52 ml, p = 0.20), as shown in
The percentage of procedures performed by experienced
operators did not differ between the two groups. The
nonCRT implantations were performed by experienced operators
using the reference and new technologies in 48 and 46 % of
the cases (p = 0.71). The percentage of the CRT procedures
performed by experienced physician was higher: 60 and 54 %
using the reference and new technologies (p = 0.24). Operator
experience did not influence the reduction in radiation
exposure for the non-CRT implantations (p = 0.87) or for the CRT
implantations (p = 0.08).
A learning curve using the new technology was absent
comparing the mean radiation exposure in the first 3 months
and the last 3 months for the non-CRT implantations
(p = 0.15). However, the radiation exposure decreased from
18.1 ± 16.8 to 12.7 ± 10.5 Gy cm2 for the CRT implantations
after 9 months (p = 0.04).
Reference technology (n = 591)
New technology (n = 594)
A total of 1185 patients were included in this study.
The baseline characteristics are summarized in Table 2.
The study population consisted of 591 patients who
underwent implantation using the reference technology,
and 594 patients on whom the new X-ray technology
was used. Both the groups were comparable regarding
age, gender, body weight, body mass index, and
percentage of ICD implantations.
The percentage of CRT implantations differed between the
two patient groups. The percentage of patients who received a
CRT device was 31 % (183) using the reference technology
versus 39 % (230) using the new technology (p = 0.005). For
the non-CRT implantations, the mean cumulative radiation
exposure reduction was 69 % when using the new X-ray
technology, as shown in Fig. 1. The mean DAP decreased during
these procedures from 16.4 ± 18.5 to 5.2 ± 6.6 Gy cm2
(p < 0.001). The radiation exposure reduction when
implanting CRT devices was 75 %. The mean DAP decreased
from 72.1 ± 60.0 to 17.8 ± 17.4 Gy cm2 for these implantations
(p < 0.001).
Despite these reductions, the procedure time did not differ
between using the reference technology (96.6 ± 47 and 162.6
Table 2 Demographics of all the
patients included in the study who
underwent pacemaker or ICD
implantation using either the
reference or the new X-ray
Data are presented as mean ± standard deviation, or as percentages
Fig. 1 Boxplot showing the radiation exposure—expressed as the dose
area product—during pacemaker or ICD implantation for the non-cardiac
resynchronization therapy devices (CRT) (a) and CRT devices (b) when
using either the reference (n = 591) or new X-ray technology (n = 594).
In this study, we have shown that the use of the new X-ray
technology, with its new processing algorithms and hardware,
reduces the average used radiation exposure for patients by
over 69 % during both pacemaker and ICD implantations.
Despite this radical reduction, the procedure time and used
contrast volume, both indirect measures of image quality,
did not change.
The observed reduction in radiation exposure is in the same
range as the reductions reported by previous studies. One
study assessing the exposure reduction in complex
electrophysiologic procedures reported a dose reduction of 40 %
without compromising image quality . Another study
reported an exposure reduction of 75 % in coronary
Radiation exposure decreased with 69 % for the non-CRT and 75 % for
the CRT implantations (p < 0.001). Outlier values, defined as 1.5 times
the interquartile range, are not shown
angiography procedures while maintaining image quality
. In addition, a large retrospective study reported an
exposure reduction of 66 % when using fluoroscopy and
cineangiography in coronary angiography and percutaneous
interventions . Moreover, Söderman et al. reported an
exposure reduction of 60 % in neuroradiology and interventional
neuroradiology when using both fluoroscopy and digital
subtraction angiography . However, the same group reported
a reduction of 75 % when only using digital subtraction
angiography, indicating a smaller reduction when using only
fluoroscopy . This is in agreement with the reported exposure
reduction of 83 % in iliac artery digital subtraction
angiography procedures .
It seems that in these studies, the reported radiation
exposure reduction is higher using digital subtraction angiography
Fig. 2 Boxplots showing the procedure time for the non-cardiac resynchronization therapy (CRT) devices (p = 0.68) (a) and CRT devices (p = 0.09) (b)
when using the reference or the new X-ray technology. Outlier values, defined as 1.5 times the interquartile range, are not shown
Fig. 3 Boxplot showing the volume of injected contrast used during
implantation of the CRT devices when using the reference or the new
X-ray technology (p = 0.20). Outlier values, defined as 1.5 times the
interquartile range, are not shown
in comparison to that achieved with fluoroscopy and/or
cinematography. The variation in the radiation exposure reduction
using fluoroscopy and/or cineangiography is probably mainly
due to the variation in image processing settings. For each
procedure, the optimal combination of the four main image
processing technologies incorporated in the new technology is
used: real-time pixel shift, motion compensation, noise
reduction, and image enhancement . This should provide the
optimal image quality for each procedure, and these different
settings will most probably influence the reduction in
radiation exposure, explaining the differences between studies.
The mean DAP measured in this study using the reference
technology is comparable to typical values in literature. The
DAP for the non-CRT devices in this study, 16.4 Gy cm2, was
even lower than that for the typical value as reported by
Heidbuchel et al.: 4 mSv, corresponding to a DAP of
20 Gy cm2 . The same tendency was observed for CRT
devices with a mean DAP of 72.1 Gy cm2 in this study in
comparison to the typical values of 110 Gy cm2 (22 mSv) as
mentioned in the practical guide to reduce radiation dose .
Beside the AlluraClarity system (Philips Healthcare),
which is described in this study, the other major vendors also
introduced new angiographic systems last years, focused on
dose reduction while maintaining or increasing image quality
(GE Healthcare, IGS 730 and IGS 740; Siemens, Artis Q.zen;
and Toshiba, Infinix Elite). However, only one conference
proceeding has been published so far describing a dose
reduction in clinical practice. They reported a radiation exposure
reduction of 55 % using Artis Q.zen technology .
Moreover, Christopoulos et al. performed a bench test with
an anthropomorphic phantom comparing the radiation dose of
the new AlluraClarity system with three other fluoroscopy
systems . They compared the DAP and showed that the
new technique resulted DAP reductions of 74, 69, and 48 % in
comparison to the Innova IGS (GE Healthcare), Artis One
(Siemens), and Integris Allura FD20 (Philips), respectively.
Yet their study did not include the new techniques from the
other two main vendors. It is therefore still unknown how the
new technologies of the other vendors compare in cardiac
procedures to the technology evaluated in this study.
Introduction of the new technology improves the radiation
safety for both patients and staff in the operating rooms.
Despite the relatively low radiation exposure associated with
ICD and pacemaker implantations using the new technology,
procedures still should be performed in accordance with the as
low as reasonably achievable (ALARA) principle and should
be in compliance with the latest procedure indications as
stated in the guidelines. Further refinement of standard procedure
settings, such as decreasing fluoroscopy frame rates or cine
acquisitions, introduction of body weight depending exposure
protocols, and increasing the awareness of the patients’ dose
associated with the various projection angles, could help in
further minimizing the required radiation exposure .
Moreover, introduction non-fluoroscopic mapping systems
using electromagnetic guidance could result in additional dose
Several assumptions underpinned this study. First, we used
a retrospective study design. However, we expect this
influence to be minimal due to the consecutive nature of the
inclusion, the large number of patients as well as the fact that no
additional radiation exposure reduction measures were
introduced during the inclusion period. Second, only indirect
measures of image quality—procedure time and contrast
volume—were assessed. Yet both indirect measures were
identical between both the technologies for the non-CRT and CRT
implantations. In addition, operators were able to manually
increase the fluoroscopy dose setting to ensure that a sufficient
image quality was obtained for all the patients. Third, the
observed radiation exposure reduction is not only due to the
new image processing technologies. The new technology also
allows storage of the fluoroscopy and cineangiography
acquisitions. The ability to replay these acquisitions during the
procedures obviates the need to subject the patient to additional
radiation. Although we were not able to quantify the possible
decrease in fluoroscopy time or cineangiography acquisitions
as these are not routinely recorded, we can reasonably assume
this storage function also contributed to the observed radiation
exposure reduction. Fourth, regional hospitals refer patients
with complex anatomy and pathology to our tertiary hospital.
This higher patient complexity results in the use of higher
volumes of contrast fluids and increased procedure times.
However, used contrast volume and procedure complexity
were comparable between the two periods, and the higher
procedure complexity was therefore not expected to influence
the outcomes. Final, the effect of the new X-ray technology on
the staff radiation dose was not assessed as no additional
dosage or exposure measurements were registered for individual
procedures directly at the staff. However, it can reasonably be
assumed that the staff radiation dose, caused by scattered
radiation, is proportional to the patient dose, as shown
previously . Hence, we can assume that the lower patient radiation
exposure will also result in a comparable dose reduction for
Introduction of new X-ray technology resulted in radiation
e x p o s u r e r e d u c t i o n s o f 6 9 % i n t h e n o n - c a r d i a c
resynchronization therapeutic cardiac pacemaker and ICD
implantations and 75 % in the cardiac resynchronization
therapeutic device implantations while image quality was
Acknowledgments The authors thank Hans Lafeber and Sonja Nijhoff
at the Isala Hospital for their help with the data collection.
Compliance with ethical standards
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