- Email: [email protected]
Radioprotection Measures during the Learning Curve with Hybrid Operating Rooms
Accepted Manuscript Radioprotection Measures During The Learning Curve With Hybrid Operating Rooms L. Fidalgo Domingos, MD, E.M. San Norberto García, MD PhD, D. Gutiérrez Castillo, MD, C. Flota Ruiz, MD, I. Estévez Fernández, MD PhD, C. Vaquero Puerta, MD PhD. PII:
S0890-5096(18)30184-5
DOI:
10.1016/j.avsg.2017.12.010
Reference:
AVSG 3739
To appear in:
Annals of Vascular Surgery
Received Date: 31 August 2017 Revised Date:
7 December 2017
Accepted Date: 17 December 2017
Please cite this article as: Fidalgo Domingos L, San Norberto García E, Gutiérrez Castillo D, Flota Ruiz C, Estévez Fernández I, Vaquero Puerta C, Radioprotection Measures During The Learning Curve With Hybrid Operating Rooms, Annals of Vascular Surgery (2018), doi: 10.1016/j.avsg.2017.12.010. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT 1
RADIOPROTECTION MEASURES DURING THE LEARNING CURVE WITH
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HYBRID OPERATING ROOMS
3 Fidalgo Domingos L, MD; San Norberto García EM, MD PhD; Gutiérrez
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Castillo D, MD; Flota Ruiz C, MD; Estévez Fernández I, MD PhD; Vaquero
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Puerta C MD PhD.
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Department of Angiology and Vascular Surgery,
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Valladolid University Hospital, Spain
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Key
words:
Operating
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Procedures, Ionizing Radiation.
rooms,
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Radiation
Protection,
Endovascular
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There are no sources of financial support or competitive relationships that
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may pertain to the manuscript.
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Address for Correspondence:
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Liliana Fidalgo Domingos, M. D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
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[email protected]
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1
ACCEPTED MANUSCRIPT Enrique M San Norberto García, M.D. Ph.D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
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[email protected]
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31 Diana Gutiérrez Castillo, M.D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
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[email protected]
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Cintia Flota Ruiz, M.D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
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[email protected]
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Isabel Estévez Fernández, M.D. Ph.D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
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[email protected]
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Carlos Vaquero Puerta, M.D. Ph.D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
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[email protected]
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RADIOPROTECTION MEASURES DURING THE LEARNING CURVE WITH
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HYBRID OPERATING ROOMS Abstract
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Background: Endovascular procedures come with a potential risk of radiation
65
hazards both to patients and to the vascular staff. Classically, most
66
endovascular interventions took place in regular operating rooms using a
67
fluoroscopy C-arm unit controlled by a third party. Hybrid operating rooms
68
(HOR) provide an optimal surgical suit with all the qualities of a fixed C-arm
69
device, while allowing the device to be controlled by the surgical team. The
70
latest studies suggest that an operator-controlled system may reduce the
71
radiation dose.
72
The purpose of the present study is to determine the amount of absorbed
73
radiation using a HOR in comparison with a portable C-arm unit and to assess
74
whether the radioprotection awareness of the surgical team influences the
75
radiation exposure. The primary endpoint was the effective dose in miliSievert
76
(mSv) for the surgical team and the average dose-area-product (ADAP) in
77
Gray-meters squared (Gym2) for patients.
78
Methods: The values of absorbed radiation of the surgical team’s dosimeters
79
were collected from January 2015 to May 2016. The HOR was installed in
80
June 2015 and a radioprotection seminar was given in October 2015. The
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HOR issued radiation, measured by the maximum dose-area-product
82
(MDAP), average dose-area-product (ADAP), average dose per procedure
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(AD), maximum dose per procedure per month (MD), maximum fluoroscopy
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time (MFT) average fluoroscopic time (AFT), peak skin dose (PSD) and
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average skin dose (ASD), was collected monthly from September 2015 to July
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ACCEPTED MANUSCRIPT 2016. The timeline was divided into three periods: 5 months pre-HOR (Pre-
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HOR), 5 months after the HOR installation (PreS-HOR) and 5 months after a
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radioprotection seminar (PostS-HOR).
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Results: The average number of procedures per month was 22,55 (±4,9),
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including EVAR/TEVAR, carotid, visceral and upper and lower limb
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endovascular revascularization.
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The average amount of absorbed radiation by the surgeons during PreS-HOR
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was 1,07±0,4mSv, which was higher than the other periods (Pre-HOR
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0,06±0,03mSv, p=0,002; PostS-HOR 0,14±0,09mSv, p=0,000, respectively).
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The ADAP during PreS-HOR was 0,016±0,01Gym2, which was lower than the
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PostS-HOR (0,001±0,002Gym2) (p=0,034). The AD during PreS-HOR was
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0,78±0,3Gy and 0,39±0,3Gy during PostS-HOR (p=0,098). The ASD during
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PreS-HOR was 0,40±0,2Gy and 0,20±0,1Gy during PostS-HOR (p=0,099).
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Conclusions: In our experience, the HOR increases the amount of absorbed
100
radiation for both patients and surgeons. The radioprotection seminars are of
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utmost importance to provide a continued training and optimize the use of
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ionizing radiation while using and HOR. Despite the awareness of the surgical
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team in the radioprotection field, the amount of absorbed radiation using an
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HOR is higher than the one using a C-Arm unit.
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ACCEPTED MANUSCRIPT Introduction
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The first human implant of a fabric-covered stent took place in 1985 by
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Volodos, later in 1990 Parodi performed the first Endovascular Aneurysm
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Repair (EVAR) in the western world, opening a door to an endovascular
113
era[1]. However, with this new technology comes a potential risk of radiation
114
hazards, both to the patient and the vascular staff, and so its use should be
115
ruled by the “as low as reasonably achievable” (ALARA) principle[2].
116
Radiation exposure can lead to deterministic (direct tissue damage) or
117
stochastic effects (gene mutation). Previous studies have shown that up to
118
30% of EVAR procedures require a radiation dosage sufficient to cause
119
deterministic effects[3,4]. Staff radiation dose can be monitored using
120
dosimeters and minimized using various forms of X-ray shielding (led aprons,
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collars and glasses), image processing, shorter pulse duration and smaller
122
focal spot size[5].
123
Classically, most endovascular procedures take place in regular operating
124
rooms (OR) using a fluoroscopy C-arm unit. As a remarkable progress has
125
been made in this field over the past two decades, the classic C-arm has
126
gotten short, with limited precision when it comes to fenestrated grafts or
127
small vessel catheterizations and a limited time of use before overheating [6].
128
Also, there is an increased tendency to perform “hybrid” procedures (partial
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open techniques associated with endovascular interventions) that ideally
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require an interventional suite associated with an operating room, commonly
131
known as a “hybrid operating room” (HOR).
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ACCEPTED MANUSCRIPT The latest studies suggest that a system with an operator-controlled imaging,
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as an HOR, could be capable of reducing the radiation dose when compared
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to the classic C-arm unit[7].
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There are only a few studies that document the effect radiation dosage using
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a regular OR compared to a HOR with very limited inclusion criteria that do
137
not represent the daily activity in a vascular OR.
138
The purpose of the present study is to determine the amount of absorbed
139
radiation using a HOR in comparison with a portable C-arm unit, by both the
140
surgical team and the patient, and to assess whether the radioprotection
141
awareness of the surgical team influences the radiation exposure.
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Materials and Methods
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Objectives and Endpoints
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The primary objective of this study is to determine the amount of absorbed
145
radiation using a HOR in comparison with a portable C-arm unit, by both the
146
surgical team and the patient. The primary endpoint was the effective dose in
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miliSievert (mSv) for the surgical team and the average dose-area-product
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(ADAP) in Gray-meters squared (Gym2) for patients. The secondary
149
endpoints were maximum dose-area-product (MDAP) in Gym2, average (AD)
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and maximum dose per procedure (MD) in Gy, average (ASD) and peak skin
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dose (PSD) in Gy, average (AFT) and maximum fluoroscopy time (MFT) in
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minutes.
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Study Design
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The present study took place in an Angiology and Vascular Surgery
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Department at Valladolid University Hospital, a tertiary referral hospital. A
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radioprotection checklist took place before all interventions. All surgical
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ACCEPTED MANUSCRIPT personnel wore a dosimeter under their lead apron over the chest to all
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endovascular procedures regardless the operating room, and its data was
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collected retrospectively from January 2015 to March 2016. This period of
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time was chosen in order to provide data from both before and after the
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installation of the HOR. The HOR at our institution went in use in June 2015,
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thus all interventions performed before that time were identified as undergoing
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an endovascular procedure using a portable C-arm unit (OEC 9900 Plus
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Mobile C-arm; General Electric Healthcare, Fairfield, CT, USA) in two regular
165
OR simultaneously. After the installation of the HOR (Artis Zeego; Siemens
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Healthcare, Erlangen, Germany) all endovascular procedures took place in
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the new operating suite.
168
Upon the installation of the HOR at our center a dedicated seminar about the
169
Siemens Artis Zeego device was given to all vascular personnel, before it
170
went in use.
171
Data from the all the elective endovascular procedures was recorded by the
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HOR device and collected retrospectively from its installation (June 2015) until
173
March 2016. Since the installation of the HOR, all emergency endovascular
174
interventions took place in a regular operating room with a mobile C-arm unit.
175
Therefore, all emergency endovascular procedures were excluded from the
176
present study.
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Both operating rooms were used to perform several types of endovascular
178
peripheral procedures, such as thoracic and abdominal endovascular
179
aneurysm repair (TEVAR and EVAR, respectively); iliac aneurysms and
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carotid, subclavian, visceral arteries, venous and lower limb angioplasty
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and/or stenting.
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ACCEPTED MANUSCRIPT Ionizing Radiation
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Patient intraoperative radiation dose is measured by the device and can be
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expressed with several parameters such as dose-area-product (DAP) defined
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as the absorbed dose multiplied by the irradiated area and expressed in gray-
186
meters squared (Gym2) (we considered the maximum and the average DAP,
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MDAP and ADAP, respectively); dose per procedure as the total amount of
188
radiation absorbed during an endovascular intervention measured in grays
189
(Gy) (we considered the maximum and the average dose per procedure per
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month, MD and AD, respectively); fluoroscopy time that resumes the total time
191
that fluoroscopy is used during an interventional procedure measured in
192
minutes (we considered the maximum and the average fluoroscopic time, AFT
193
and MFT, respectively); and skin dose (PSD) referring to dose absorbed at
194
any portion of a patient’s skin during a procedure measured in Gy (we
195
considered the peak skin dose and the average skin dose, PSD and ASD,
196
respectively) [4,8-10].
197
Although all surgical personnel had a Second Level Radioprotection
198
Accreditation issued by the Spanish Ministry of Health, Social Services and
199
Equality
200
radioprotection seminar was given to the vascular staff in October 2015. The
201
goal of this seminar was to review all the general radioprotection measures
202
and means to reduce the radiation exposure, as using lead apparel, reducing
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detector-to-patient distance, limiting the fluoroscopy time, moving away of the
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source during digital subtraction angiography, maximal collimation and limiting
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angulations.
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ACCEPTED MANUSCRIPT The timeline was divided in three periods: 5 months pre-HOR (Pre-HOR), 5
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months after the HOR installation (PreS-HOR) and 5 months after a
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radioprotection seminar (PostS-HOR).
209
The variables of primary interest were: absorbed radiation dose by the staff
210
dosimeters and the patient’s intraoperative radiation dose expressed as
211
maximum dose-area-product (MDAP), average dose-area-product per month
212
(ADAP), average dose per procedure per month (AD), maximum dose per
213
procedure (MD), maximum fluoroscopy time (MFT) average fluoroscopic time
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(AFT), peak skin dose (PSD) and average skin dose (ASD).
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Interventional Procedures
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The same consultant vascular team, experienced in endovascular procedures
217
and certified in radioprotection according to the European standards,
218
performed all the interventions.
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Procedures were typically done under general or loco-regional anesthesia.
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The approach type (percutaneous or open) was dictated by the patient’s
221
anatomical and clinical features. Low-dose fluoroscopy and high-dose digital
222
acquisition were used according to the type of intervention. DAP was
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recorded by transmission ionization chambers. The HOR device also
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recorded the screening time automatically, and the time recorded represents
225
the total for low-dose fluoroscopy and high-dose digital acquisition.
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General radioprotection tools were used during all procedures. Both operating
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rooms were provided with an architectural shielding built-in the walls as well
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as with ceiling-suspended shields constructed of a transparent leaded plastic
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and equipped-mounted shielding such as drapes suspended from the
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ACCEPTED MANUSCRIPT operating table. All personnel were equipped with thyroid shields, leaded
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eyeglasses and a vest-skirt apron of 0,25mm lead-equivalent.
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Besides the change in the OR and the radioprotection seminar, there was no
233
change in the operative protocol during the study period.
234
Statistical analysis
235
Descriptive statistics were used to present mean values and standard
236
deviation for continuous variables. Means were compared by unpaired two-
237
tailed t-tests or Mann-Whitney U test. P<0.05 was considered significant. All
238
calculations were performed with the SPSS statistical software package
239
(version 20.0; IBM Corporation, Somers, NY, USA).
240
Results
241
From January 2015 to April 2016, 478 patients underwent an elective
242
endovascular procedure. Of these 162 patients had their intervention prior to
243
the HOR (Pre-HOR) and 316 after its installation, 174 during PreS-HOR and
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142 during PostS-HOR periods. The average number of procedures per
245
month was 21(±7) and 22,89(±4,8) during the PreS-HOR and PostS-HOR,
246
respectively, (Table 1, Figure 1).
247
The average amount of absorbed radiation by the surgical team during PreS-
248
HOR was 1,07±1,4mSv, which was significantly higher than the other two
249
periods (Pre-HOR 0,06±0,03mSv, p=0,002; PostS-HOR 0,14±0,09mSv,
250
p=0,000, respectively). Representing 18 times more radiation during the
251
PreS-HOR period then the Pre-HOR period, and 8 times more then the
252
PostS-HOR (Table 2).
253
During the PreS-HOR the maximum dose-area-product (MDAP) was
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0,145(±0,09) Gym2 and the average dose-area-product (ADAP) was
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ACCEPTED MANUSCRIPT 0,016(±0,01) Gym2, showing a significant decrease during the following
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period of PostS-HOR, of 75% with an MDAP of 0,036(±0,02) Gym2 (p=0,004)
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and 62.5% with an ADAP of 0,006(±0,002) Gym2 (p=0,005).
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Although there were no significant differences in terms of average dose per
259
procedure (AD) during PreS-HOR and PostS-HOR, with 0,78±0,3Gy and
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0,39±0,3Gy each (p=0,137); the maximum dose per procedure (MD) was
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approximately 3 times higher during PreS-HOR when compared to PostS-
262
HOR, with 7,20(±3,0) Gy and 2,57(±1,6) Gy during each period (p=0,001).
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The average skin dose (ASD) showed a tendency to decrease during PostS-
264
HOR (0,20±0,1Gy) in comparison to the previous period of PreS-HOR
265
(0,40±0,2Gy), p=0,055; while the peak skin dose (PSD) presented no
266
significant differences during the two periods (PreS-HOR 1,75±0,9Gy and
267
PostS-HOR 1,06±0,9Gy, p=0,363).
268
There were no significant differences in terms of average fluoroscopy time
269
(PreS-HOR 19,78±0,5 minutes and PostS-HOR 19,30±0,1 minutes, p=0,913)
270
or maximum fluoroscopic time (PreS-HOR 84,22±28,5 minutes and PostS-
271
HOR 82,35±35,0 minutes, p=0,946).
272
Discussion
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The use of ionizing radiation to perform endovascular procedures is
274
nowadays inevitable and so are its potential undesirable effects, both to the
275
patient and to the surgical team. Therefore minimizing the radiation dose
276
during interventional procedures is a “win-win” situation, benefiting both the
277
patient and the surgical team. In order to do so, it’s of utter importance
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minimizing the fluoroscopy time as well as the number of fluorographic
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images, use collimation and all available information to plan the interventional
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ACCEPTED MANUSCRIPT procedure. Likewise, the surgical team should have general knowledge of
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safe operating practices in a radiation environment and be equipped with a
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dosimeter and wear protective shielding (leaded aprons, eyewear and thyroid
283
shields)[12].
284
Most endovascular procedures are typically performed under two-dimensional
285
(2D) fluoroscopy imaging, which not only may be insufficient to carry out
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complex interventions, but also imply a higher radiation dose to carry out the
287
procedure. The HOR combines an optimal surgical suit with the advanced
288
imaging capabilities of a fixed system, including more tube power with less
289
overheating issues, flat-panel detectors, customizable x-ray dose levels,
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three-dimensional (3D) acquisition through a C-arm rotation around the
291
patient and preoperative CT angiography (CTA) images fusion. Both 3D
292
acquisition and CTA images can be used as a road map during fluoroscopy,
293
minimizing the radiation dosage per intervention [13-15].
294
Although many authors have compared the amount of radiation exposure
295
using a C-arm portable unit to a HOR during certain types of interventions,
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little work has been done in terms of overall radiation exposure of an
297
interventional suite regular use.
298
The ADAP values found in our study were 16mGym2 and 6mGym2, during
299
PreS-HOR and PostS-HOR respectively, which are comparable to the ones
300
found by Weerakkody et al[16] (15mGym2) and Geijer et al[17] (7,23mGym2).
301
Nonetheless, both studies were performed exclusively with bifurcated EVAR,
302
while our results refer to a much wide range of interventions where EVAR
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represents only 19% of all procedures performed.
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ACCEPTED MANUSCRIPT Peach et al[7] studied 122 patients that underwent an aortic endovascular
305
repair and found a significant decrease on ADAP from 6,9mGym2 to
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4,9mGym2, after the installation of an operator-controlled imaging system,
307
representing a 29% reduction in terms of patient absorbed radiation. Our
308
study showed an overall increase of the absorbed radiation even after the
309
radioprotection seminar. The ADAP suffered a 62.5% reduction after a
310
radioprotection seminar that was given to the surgical staff, defining the
311
radioprotection awareness of the surgical team as a fundamental key to
312
reduce the radiation exposure. During our study the absorbed radiation by the
313
surgeons’ dosimeters, increased up to 18 times after the installation of the
314
new HOR suite. What is more striking is that even though the absorbed
315
radiation dropped following a radioprotection seminar, it has never reached
316
the initial radiation exposure. It is not new that a mobile C-arm reduces the
317
radiation dose compared to a fixed C-arm, this could be due to a better image
318
quality that can be obtained from the new device, at cost of a higher radiation
319
dosage. Our results agree with the work of Guillou et al.[18], who studied two
320
series of patients with peripheral arterial disease treated with an endovascular
321
procedure, either at a HOR or with a mobile C-arm unit, and observed that the
322
HOR with a fixed C-arm offered better image quality at the expense of a
323
higher radiation dose to the patients. Also, Kendrick et al.[19] studied 116
324
endovascular procedures performed with a HOR or with a fixed C-arm unit
325
and concluded that the scattered radiation using a fixed imaging system (like
326
an HOR) is several-fold times higher then with a mobile C-arm unit,
327
suggesting that additional strategies to minimize exposure and occupational
328
risk are needed.
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ACCEPTED MANUSCRIPT In our study, the initial peak of radiation exposure could be related to the
330
installation of the new equipment, which, passed the learning curve, should
331
have been normalized. Instead, it remained higher than the radiation
332
exposure previous to the HOR installation. Nonetheless, the abrupt decrease
333
of absorbed radiation that followed the radioprotection seminar raises
334
concerns about the importance of periodic recertification in radioprotection of
335
the surgical team.
336
Limitations
337
This report involves a single-center experience, with a potential bias existing
338
because of the relatively small number of cases involved.
339
The post-seminar period considered was 6 months; maybe longer intervals
340
could modify the results. So, further investigations need to evaluate the long-
341
term follow-up and radiation dosage.
342
Since the collected data is not related to specific procedures, our results do
343
not allow us to draw a conclusion in terms of radiation issued per procedure.
344
Further studies should be considered to investigate the relationship between
345
procedures and issued radiation, in order to decide which ones should take
346
place at an HOR and which ones could benefit from the mobile C-arm unit.
347
Conclusion
348
In our experience, the HOR increases the amount of absorbed radiation for
349
both patients and surgeons. The radioprotection seminars are of utmost
350
importance to provide a continued training and to optimize the use of ionizing
351
radiation while using and HOR. Despite the awareness of the surgical team in
352
the radioprotection field, the amount of absorbed radiation using an HOR is
353
still higher than the one using a C-Arm unit.
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International Commission on Radiation Units and Measurements. Report 85: Fundamental quantities and units for ionizing radiation. J
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ICRU 2011;11:1–31.
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11.
Smith PH. EC Directive: 97/43/Euratom. Br J Radiol 1998;71:108–8.
388
12.
Miller DL, Vañó E, Bartal G, et al. Occupational Radiation Protection in
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Interventional Radiology: A Joint Guideline of the Cardiovascular and
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Interventional Radiology Society of Europe and the Society of
391
Interventional Radiology. Cardiovasc Intervent Radiol 2009;33:230–9.
393 394
395
13.
Markelj P, Tomaževič D, Likar B, et al. A review of 3D/2D registration
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methods for image-guided interventions. Med Image Anal 2012;16:642– 61.
14.
Stahlberg E, Planert M, Panagiotopoulos N, et al. Pre-operative
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Simulation of the Appropriate C-arm Position Using Computed
397
Tomography
398
Contrast Medium Exposure During EVAR Procedures. European
399
Journal of Vascular and Endovascular Surgery 2017;53:269–74.
Post-processing
Software
Reduces
Radiation
and
17
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15.
de Ruiter QMB, Reitsma JB, Moll FL, et al. Meta-analysis of Cumulative
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Radiation Duration and Dose During EVAR Using Mobile, Fixed, or
402
Fixed/3D Fusion C-Arms. J. Endovasc. Ther. 2016;23:944–56.
during endovascular aneurysm repair. Br J Surg 2008;95:699–702.
404
17.
of abdominal aortic aneurysms. Br J Radiol 2005;78:906–12.
406
407
Geijer H, Larzon T, Popek R, et al. Radiation exposure in stent-grafting
18.
SC
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Weerakkody RA, Walsh SR, Cousins C, et al. Radiation exposure
RI PT
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Guillou M, Maurel B, Necib H, et al. Comparison of Radiation Exposure
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during Endovascular Treatment of Peripheral Arterial Disease with Flat-
409
Panel Detectors on Mobile C-arm versus Fixed Systems. Ann Vasc
410
Surg 2017; 19.
Kendrick
DE,
Miller
CP,
Moorehead PA,
et
al.
Comparative
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occupational radiation exposure between fixed and mobile imaging
413
systems. J. Vasc. Surg. 2016;63:190–7.
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Figure 1: Endovascular procedures performed during the study follow-up. Pre
418
hybrid operating room installation (Pre-HOR), after the HOR installation
419
(PreS-HOR) and after the radioprotection seminar (PostS-HOR).
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420 200
Miscellanea
180
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Venous PTA-Stent Embolization
160
Bypass PTA-Stent
140
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Distal PTA-Stent
120 100 80 60
20 0
423
424 425
Iliac PTA-Stent Renal PTA-Stent Mesenteric PTA-Stent Subclavian PTA-Stent Carotid Stent Complex EVAR Iliac Branch TEVAR EVAR
PostS-HOR
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PreS-HOR
Femoral PTA-Stent
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Popliteal PTA-Stent
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Table 1: Interventions per period of time. During the study period 478
427
procedures were performed, 316 (66,1%) of which took place in the Hybrid
428
Operating Room (HOR).
431
432
433 434
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24 3 2 3 2 2 0 2 35 41 1 14 0 10 1 2 142
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31 1 3 4 7 6 1 3 39 52 5 11 3 4 2 1 174
89 8 7 8 9 13 8 9 103 140 9 37 4 25 3 6 478
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34 4 2 1 0 5 7 4 28 47 3 12 1 11 0 3 162
TOTAL OF PostS-HOR INTERVENTIONS
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EVAR TEVAR Iliac Branch Complex EVAR Carotid Stent Subclavian PTA-Stent Mesenteric PTA-Stent Renal PTA-Stent Iliac PTA-Stent Femoral PTA-Stent Popliteal PTA-Stent Distal PTA-Stent Bypass PTA-Stent Embolization Venous PTA-Stent Miscellanea TOTAL
Pre-HOR
PERIOD PreS-HOR
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ACCEPTED MANUSCRIPT Table 2: Continuous variables analysis.
ADAP (Gym2)
0,649
1,07 (±1,4)
0,14 (±0,09)
0,000
0,145 (±0,09) 0,016 (±0,01) 0,78 (±0,3) 7,20 (±3,0) 0,40 (±02) 1,75 (±0,9) 19,78 (±0,5) 84,22 (±28,5)
0,036 (±0,02) 0,006 (±0,002) 0,39 (±0,3) 2,57 (±1,6) 0,20 (±0,1) 1,06 (±0,9) 19,30 (±0,1) 82,35 (±35,0)
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AD (Gy) MD (Gy) ASD (Gy) PSD (Gy) AFT (minutes) MFT (minutes)
p
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Average number of procedures (per month) Average amount of radiation absorbed by the surgical team (mSv) MDAP (Gym2)
PERIOD PreS-HOR PostS-HOR 21 (±7) 22,89(±4,8)
0,005
0,137 0,001 0,055 0,363 0,913 0,946
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0,004
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S0890-5096(18)30184-5
DOI:
10.1016/j.avsg.2017.12.010
Reference:
AVSG 3739
To appear in:
Annals of Vascular Surgery
Received Date: 31 August 2017 Revised Date:
7 December 2017
Accepted Date: 17 December 2017
Please cite this article as: Fidalgo Domingos L, San Norberto García E, Gutiérrez Castillo D, Flota Ruiz C, Estévez Fernández I, Vaquero Puerta C, Radioprotection Measures During The Learning Curve With Hybrid Operating Rooms, Annals of Vascular Surgery (2018), doi: 10.1016/j.avsg.2017.12.010. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT 1
RADIOPROTECTION MEASURES DURING THE LEARNING CURVE WITH
2
HYBRID OPERATING ROOMS
3 Fidalgo Domingos L, MD; San Norberto García EM, MD PhD; Gutiérrez
5
Castillo D, MD; Flota Ruiz C, MD; Estévez Fernández I, MD PhD; Vaquero
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Puerta C MD PhD.
7
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Department of Angiology and Vascular Surgery,
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Valladolid University Hospital, Spain
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Key
words:
Operating
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Procedures, Ionizing Radiation.
rooms,
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Radiation
Protection,
Endovascular
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There are no sources of financial support or competitive relationships that
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may pertain to the manuscript.
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Address for Correspondence:
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Liliana Fidalgo Domingos, M. D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
24
[email protected]
25
1
ACCEPTED MANUSCRIPT Enrique M San Norberto García, M.D. Ph.D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
30
[email protected]
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31 Diana Gutiérrez Castillo, M.D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
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[email protected]
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Cintia Flota Ruiz, M.D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
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[email protected]
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Isabel Estévez Fernández, M.D. Ph.D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
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[email protected]
49 50
Carlos Vaquero Puerta, M.D. Ph.D.
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Department of Angiology and Vascular Surgery, Valladolid University
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Hospital, Spain
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Calle Ramón y Cajal nº3, 47003. Valladolid. Spain. 0034-983420000.
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[email protected]
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RADIOPROTECTION MEASURES DURING THE LEARNING CURVE WITH
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HYBRID OPERATING ROOMS Abstract
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Background: Endovascular procedures come with a potential risk of radiation
65
hazards both to patients and to the vascular staff. Classically, most
66
endovascular interventions took place in regular operating rooms using a
67
fluoroscopy C-arm unit controlled by a third party. Hybrid operating rooms
68
(HOR) provide an optimal surgical suit with all the qualities of a fixed C-arm
69
device, while allowing the device to be controlled by the surgical team. The
70
latest studies suggest that an operator-controlled system may reduce the
71
radiation dose.
72
The purpose of the present study is to determine the amount of absorbed
73
radiation using a HOR in comparison with a portable C-arm unit and to assess
74
whether the radioprotection awareness of the surgical team influences the
75
radiation exposure. The primary endpoint was the effective dose in miliSievert
76
(mSv) for the surgical team and the average dose-area-product (ADAP) in
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Gray-meters squared (Gym2) for patients.
78
Methods: The values of absorbed radiation of the surgical team’s dosimeters
79
were collected from January 2015 to May 2016. The HOR was installed in
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June 2015 and a radioprotection seminar was given in October 2015. The
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HOR issued radiation, measured by the maximum dose-area-product
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(MDAP), average dose-area-product (ADAP), average dose per procedure
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(AD), maximum dose per procedure per month (MD), maximum fluoroscopy
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time (MFT) average fluoroscopic time (AFT), peak skin dose (PSD) and
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average skin dose (ASD), was collected monthly from September 2015 to July
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ACCEPTED MANUSCRIPT 2016. The timeline was divided into three periods: 5 months pre-HOR (Pre-
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HOR), 5 months after the HOR installation (PreS-HOR) and 5 months after a
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radioprotection seminar (PostS-HOR).
89
Results: The average number of procedures per month was 22,55 (±4,9),
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including EVAR/TEVAR, carotid, visceral and upper and lower limb
91
endovascular revascularization.
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The average amount of absorbed radiation by the surgeons during PreS-HOR
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was 1,07±0,4mSv, which was higher than the other periods (Pre-HOR
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0,06±0,03mSv, p=0,002; PostS-HOR 0,14±0,09mSv, p=0,000, respectively).
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The ADAP during PreS-HOR was 0,016±0,01Gym2, which was lower than the
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PostS-HOR (0,001±0,002Gym2) (p=0,034). The AD during PreS-HOR was
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0,78±0,3Gy and 0,39±0,3Gy during PostS-HOR (p=0,098). The ASD during
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PreS-HOR was 0,40±0,2Gy and 0,20±0,1Gy during PostS-HOR (p=0,099).
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Conclusions: In our experience, the HOR increases the amount of absorbed
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radiation for both patients and surgeons. The radioprotection seminars are of
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utmost importance to provide a continued training and optimize the use of
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ionizing radiation while using and HOR. Despite the awareness of the surgical
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team in the radioprotection field, the amount of absorbed radiation using an
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HOR is higher than the one using a C-Arm unit.
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The first human implant of a fabric-covered stent took place in 1985 by
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Volodos, later in 1990 Parodi performed the first Endovascular Aneurysm
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Repair (EVAR) in the western world, opening a door to an endovascular
113
era[1]. However, with this new technology comes a potential risk of radiation
114
hazards, both to the patient and the vascular staff, and so its use should be
115
ruled by the “as low as reasonably achievable” (ALARA) principle[2].
116
Radiation exposure can lead to deterministic (direct tissue damage) or
117
stochastic effects (gene mutation). Previous studies have shown that up to
118
30% of EVAR procedures require a radiation dosage sufficient to cause
119
deterministic effects[3,4]. Staff radiation dose can be monitored using
120
dosimeters and minimized using various forms of X-ray shielding (led aprons,
121
collars and glasses), image processing, shorter pulse duration and smaller
122
focal spot size[5].
123
Classically, most endovascular procedures take place in regular operating
124
rooms (OR) using a fluoroscopy C-arm unit. As a remarkable progress has
125
been made in this field over the past two decades, the classic C-arm has
126
gotten short, with limited precision when it comes to fenestrated grafts or
127
small vessel catheterizations and a limited time of use before overheating [6].
128
Also, there is an increased tendency to perform “hybrid” procedures (partial
129
open techniques associated with endovascular interventions) that ideally
130
require an interventional suite associated with an operating room, commonly
131
known as a “hybrid operating room” (HOR).
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ACCEPTED MANUSCRIPT The latest studies suggest that a system with an operator-controlled imaging,
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as an HOR, could be capable of reducing the radiation dose when compared
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to the classic C-arm unit[7].
135
There are only a few studies that document the effect radiation dosage using
136
a regular OR compared to a HOR with very limited inclusion criteria that do
137
not represent the daily activity in a vascular OR.
138
The purpose of the present study is to determine the amount of absorbed
139
radiation using a HOR in comparison with a portable C-arm unit, by both the
140
surgical team and the patient, and to assess whether the radioprotection
141
awareness of the surgical team influences the radiation exposure.
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Materials and Methods
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Objectives and Endpoints
144
The primary objective of this study is to determine the amount of absorbed
145
radiation using a HOR in comparison with a portable C-arm unit, by both the
146
surgical team and the patient. The primary endpoint was the effective dose in
147
miliSievert (mSv) for the surgical team and the average dose-area-product
148
(ADAP) in Gray-meters squared (Gym2) for patients. The secondary
149
endpoints were maximum dose-area-product (MDAP) in Gym2, average (AD)
150
and maximum dose per procedure (MD) in Gy, average (ASD) and peak skin
151
dose (PSD) in Gy, average (AFT) and maximum fluoroscopy time (MFT) in
152
minutes.
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Study Design
154
The present study took place in an Angiology and Vascular Surgery
155
Department at Valladolid University Hospital, a tertiary referral hospital. A
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radioprotection checklist took place before all interventions. All surgical
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ACCEPTED MANUSCRIPT personnel wore a dosimeter under their lead apron over the chest to all
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endovascular procedures regardless the operating room, and its data was
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collected retrospectively from January 2015 to March 2016. This period of
160
time was chosen in order to provide data from both before and after the
161
installation of the HOR. The HOR at our institution went in use in June 2015,
162
thus all interventions performed before that time were identified as undergoing
163
an endovascular procedure using a portable C-arm unit (OEC 9900 Plus
164
Mobile C-arm; General Electric Healthcare, Fairfield, CT, USA) in two regular
165
OR simultaneously. After the installation of the HOR (Artis Zeego; Siemens
166
Healthcare, Erlangen, Germany) all endovascular procedures took place in
167
the new operating suite.
168
Upon the installation of the HOR at our center a dedicated seminar about the
169
Siemens Artis Zeego device was given to all vascular personnel, before it
170
went in use.
171
Data from the all the elective endovascular procedures was recorded by the
172
HOR device and collected retrospectively from its installation (June 2015) until
173
March 2016. Since the installation of the HOR, all emergency endovascular
174
interventions took place in a regular operating room with a mobile C-arm unit.
175
Therefore, all emergency endovascular procedures were excluded from the
176
present study.
177
Both operating rooms were used to perform several types of endovascular
178
peripheral procedures, such as thoracic and abdominal endovascular
179
aneurysm repair (TEVAR and EVAR, respectively); iliac aneurysms and
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carotid, subclavian, visceral arteries, venous and lower limb angioplasty
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and/or stenting.
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ACCEPTED MANUSCRIPT Ionizing Radiation
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Patient intraoperative radiation dose is measured by the device and can be
184
expressed with several parameters such as dose-area-product (DAP) defined
185
as the absorbed dose multiplied by the irradiated area and expressed in gray-
186
meters squared (Gym2) (we considered the maximum and the average DAP,
187
MDAP and ADAP, respectively); dose per procedure as the total amount of
188
radiation absorbed during an endovascular intervention measured in grays
189
(Gy) (we considered the maximum and the average dose per procedure per
190
month, MD and AD, respectively); fluoroscopy time that resumes the total time
191
that fluoroscopy is used during an interventional procedure measured in
192
minutes (we considered the maximum and the average fluoroscopic time, AFT
193
and MFT, respectively); and skin dose (PSD) referring to dose absorbed at
194
any portion of a patient’s skin during a procedure measured in Gy (we
195
considered the peak skin dose and the average skin dose, PSD and ASD,
196
respectively) [4,8-10].
197
Although all surgical personnel had a Second Level Radioprotection
198
Accreditation issued by the Spanish Ministry of Health, Social Services and
199
Equality
200
radioprotection seminar was given to the vascular staff in October 2015. The
201
goal of this seminar was to review all the general radioprotection measures
202
and means to reduce the radiation exposure, as using lead apparel, reducing
203
detector-to-patient distance, limiting the fluoroscopy time, moving away of the
204
source during digital subtraction angiography, maximal collimation and limiting
205
angulations.
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to
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97/43/EURATOM
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ACCEPTED MANUSCRIPT The timeline was divided in three periods: 5 months pre-HOR (Pre-HOR), 5
207
months after the HOR installation (PreS-HOR) and 5 months after a
208
radioprotection seminar (PostS-HOR).
209
The variables of primary interest were: absorbed radiation dose by the staff
210
dosimeters and the patient’s intraoperative radiation dose expressed as
211
maximum dose-area-product (MDAP), average dose-area-product per month
212
(ADAP), average dose per procedure per month (AD), maximum dose per
213
procedure (MD), maximum fluoroscopy time (MFT) average fluoroscopic time
214
(AFT), peak skin dose (PSD) and average skin dose (ASD).
215
Interventional Procedures
216
The same consultant vascular team, experienced in endovascular procedures
217
and certified in radioprotection according to the European standards,
218
performed all the interventions.
219
Procedures were typically done under general or loco-regional anesthesia.
220
The approach type (percutaneous or open) was dictated by the patient’s
221
anatomical and clinical features. Low-dose fluoroscopy and high-dose digital
222
acquisition were used according to the type of intervention. DAP was
223
recorded by transmission ionization chambers. The HOR device also
224
recorded the screening time automatically, and the time recorded represents
225
the total for low-dose fluoroscopy and high-dose digital acquisition.
226
General radioprotection tools were used during all procedures. Both operating
227
rooms were provided with an architectural shielding built-in the walls as well
228
as with ceiling-suspended shields constructed of a transparent leaded plastic
229
and equipped-mounted shielding such as drapes suspended from the
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ACCEPTED MANUSCRIPT operating table. All personnel were equipped with thyroid shields, leaded
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eyeglasses and a vest-skirt apron of 0,25mm lead-equivalent.
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Besides the change in the OR and the radioprotection seminar, there was no
233
change in the operative protocol during the study period.
234
Statistical analysis
235
Descriptive statistics were used to present mean values and standard
236
deviation for continuous variables. Means were compared by unpaired two-
237
tailed t-tests or Mann-Whitney U test. P<0.05 was considered significant. All
238
calculations were performed with the SPSS statistical software package
239
(version 20.0; IBM Corporation, Somers, NY, USA).
240
Results
241
From January 2015 to April 2016, 478 patients underwent an elective
242
endovascular procedure. Of these 162 patients had their intervention prior to
243
the HOR (Pre-HOR) and 316 after its installation, 174 during PreS-HOR and
244
142 during PostS-HOR periods. The average number of procedures per
245
month was 21(±7) and 22,89(±4,8) during the PreS-HOR and PostS-HOR,
246
respectively, (Table 1, Figure 1).
247
The average amount of absorbed radiation by the surgical team during PreS-
248
HOR was 1,07±1,4mSv, which was significantly higher than the other two
249
periods (Pre-HOR 0,06±0,03mSv, p=0,002; PostS-HOR 0,14±0,09mSv,
250
p=0,000, respectively). Representing 18 times more radiation during the
251
PreS-HOR period then the Pre-HOR period, and 8 times more then the
252
PostS-HOR (Table 2).
253
During the PreS-HOR the maximum dose-area-product (MDAP) was
254
0,145(±0,09) Gym2 and the average dose-area-product (ADAP) was
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256
period of PostS-HOR, of 75% with an MDAP of 0,036(±0,02) Gym2 (p=0,004)
257
and 62.5% with an ADAP of 0,006(±0,002) Gym2 (p=0,005).
258
Although there were no significant differences in terms of average dose per
259
procedure (AD) during PreS-HOR and PostS-HOR, with 0,78±0,3Gy and
260
0,39±0,3Gy each (p=0,137); the maximum dose per procedure (MD) was
261
approximately 3 times higher during PreS-HOR when compared to PostS-
262
HOR, with 7,20(±3,0) Gy and 2,57(±1,6) Gy during each period (p=0,001).
263
The average skin dose (ASD) showed a tendency to decrease during PostS-
264
HOR (0,20±0,1Gy) in comparison to the previous period of PreS-HOR
265
(0,40±0,2Gy), p=0,055; while the peak skin dose (PSD) presented no
266
significant differences during the two periods (PreS-HOR 1,75±0,9Gy and
267
PostS-HOR 1,06±0,9Gy, p=0,363).
268
There were no significant differences in terms of average fluoroscopy time
269
(PreS-HOR 19,78±0,5 minutes and PostS-HOR 19,30±0,1 minutes, p=0,913)
270
or maximum fluoroscopic time (PreS-HOR 84,22±28,5 minutes and PostS-
271
HOR 82,35±35,0 minutes, p=0,946).
272
Discussion
273
The use of ionizing radiation to perform endovascular procedures is
274
nowadays inevitable and so are its potential undesirable effects, both to the
275
patient and to the surgical team. Therefore minimizing the radiation dose
276
during interventional procedures is a “win-win” situation, benefiting both the
277
patient and the surgical team. In order to do so, it’s of utter importance
278
minimizing the fluoroscopy time as well as the number of fluorographic
279
images, use collimation and all available information to plan the interventional
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281
safe operating practices in a radiation environment and be equipped with a
282
dosimeter and wear protective shielding (leaded aprons, eyewear and thyroid
283
shields)[12].
284
Most endovascular procedures are typically performed under two-dimensional
285
(2D) fluoroscopy imaging, which not only may be insufficient to carry out
286
complex interventions, but also imply a higher radiation dose to carry out the
287
procedure. The HOR combines an optimal surgical suit with the advanced
288
imaging capabilities of a fixed system, including more tube power with less
289
overheating issues, flat-panel detectors, customizable x-ray dose levels,
290
three-dimensional (3D) acquisition through a C-arm rotation around the
291
patient and preoperative CT angiography (CTA) images fusion. Both 3D
292
acquisition and CTA images can be used as a road map during fluoroscopy,
293
minimizing the radiation dosage per intervention [13-15].
294
Although many authors have compared the amount of radiation exposure
295
using a C-arm portable unit to a HOR during certain types of interventions,
296
little work has been done in terms of overall radiation exposure of an
297
interventional suite regular use.
298
The ADAP values found in our study were 16mGym2 and 6mGym2, during
299
PreS-HOR and PostS-HOR respectively, which are comparable to the ones
300
found by Weerakkody et al[16] (15mGym2) and Geijer et al[17] (7,23mGym2).
301
Nonetheless, both studies were performed exclusively with bifurcated EVAR,
302
while our results refer to a much wide range of interventions where EVAR
303
represents only 19% of all procedures performed.
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305
repair and found a significant decrease on ADAP from 6,9mGym2 to
306
4,9mGym2, after the installation of an operator-controlled imaging system,
307
representing a 29% reduction in terms of patient absorbed radiation. Our
308
study showed an overall increase of the absorbed radiation even after the
309
radioprotection seminar. The ADAP suffered a 62.5% reduction after a
310
radioprotection seminar that was given to the surgical staff, defining the
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radioprotection awareness of the surgical team as a fundamental key to
312
reduce the radiation exposure. During our study the absorbed radiation by the
313
surgeons’ dosimeters, increased up to 18 times after the installation of the
314
new HOR suite. What is more striking is that even though the absorbed
315
radiation dropped following a radioprotection seminar, it has never reached
316
the initial radiation exposure. It is not new that a mobile C-arm reduces the
317
radiation dose compared to a fixed C-arm, this could be due to a better image
318
quality that can be obtained from the new device, at cost of a higher radiation
319
dosage. Our results agree with the work of Guillou et al.[18], who studied two
320
series of patients with peripheral arterial disease treated with an endovascular
321
procedure, either at a HOR or with a mobile C-arm unit, and observed that the
322
HOR with a fixed C-arm offered better image quality at the expense of a
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higher radiation dose to the patients. Also, Kendrick et al.[19] studied 116
324
endovascular procedures performed with a HOR or with a fixed C-arm unit
325
and concluded that the scattered radiation using a fixed imaging system (like
326
an HOR) is several-fold times higher then with a mobile C-arm unit,
327
suggesting that additional strategies to minimize exposure and occupational
328
risk are needed.
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ACCEPTED MANUSCRIPT In our study, the initial peak of radiation exposure could be related to the
330
installation of the new equipment, which, passed the learning curve, should
331
have been normalized. Instead, it remained higher than the radiation
332
exposure previous to the HOR installation. Nonetheless, the abrupt decrease
333
of absorbed radiation that followed the radioprotection seminar raises
334
concerns about the importance of periodic recertification in radioprotection of
335
the surgical team.
336
Limitations
337
This report involves a single-center experience, with a potential bias existing
338
because of the relatively small number of cases involved.
339
The post-seminar period considered was 6 months; maybe longer intervals
340
could modify the results. So, further investigations need to evaluate the long-
341
term follow-up and radiation dosage.
342
Since the collected data is not related to specific procedures, our results do
343
not allow us to draw a conclusion in terms of radiation issued per procedure.
344
Further studies should be considered to investigate the relationship between
345
procedures and issued radiation, in order to decide which ones should take
346
place at an HOR and which ones could benefit from the mobile C-arm unit.
347
Conclusion
348
In our experience, the HOR increases the amount of absorbed radiation for
349
both patients and surgeons. The radioprotection seminars are of utmost
350
importance to provide a continued training and to optimize the use of ionizing
351
radiation while using and HOR. Despite the awareness of the surgical team in
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the radioprotection field, the amount of absorbed radiation using an HOR is
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still higher than the one using a C-Arm unit.
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ACCEPTED MANUSCRIPT Tables and Figures
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Figure 1: Endovascular procedures performed during the study follow-up. Pre
418
hybrid operating room installation (Pre-HOR), after the HOR installation
419
(PreS-HOR) and after the radioprotection seminar (PostS-HOR).
RI PT
416
420 200
Miscellanea
180
SC
Venous PTA-Stent Embolization
160
Bypass PTA-Stent
140
M AN U
Distal PTA-Stent
120 100 80 60
20 0
423
424 425
Iliac PTA-Stent Renal PTA-Stent Mesenteric PTA-Stent Subclavian PTA-Stent Carotid Stent Complex EVAR Iliac Branch TEVAR EVAR
PostS-HOR
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PreS-HOR
Femoral PTA-Stent
EP
Pre-HOR
421
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40
Popliteal PTA-Stent
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Table 1: Interventions per period of time. During the study period 478
427
procedures were performed, 316 (66,1%) of which took place in the Hybrid
428
Operating Room (HOR).
431
432
433 434
SC
24 3 2 3 2 2 0 2 35 41 1 14 0 10 1 2 142
M AN U
31 1 3 4 7 6 1 3 39 52 5 11 3 4 2 1 174
89 8 7 8 9 13 8 9 103 140 9 37 4 25 3 6 478
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34 4 2 1 0 5 7 4 28 47 3 12 1 11 0 3 162
TOTAL OF PostS-HOR INTERVENTIONS
EP
EVAR TEVAR Iliac Branch Complex EVAR Carotid Stent Subclavian PTA-Stent Mesenteric PTA-Stent Renal PTA-Stent Iliac PTA-Stent Femoral PTA-Stent Popliteal PTA-Stent Distal PTA-Stent Bypass PTA-Stent Embolization Venous PTA-Stent Miscellanea TOTAL
Pre-HOR
PERIOD PreS-HOR
TE D
PROCEDURE
RI PT
429
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ACCEPTED MANUSCRIPT Table 2: Continuous variables analysis.
ADAP (Gym2)
0,649
1,07 (±1,4)
0,14 (±0,09)
0,000
0,145 (±0,09) 0,016 (±0,01) 0,78 (±0,3) 7,20 (±3,0) 0,40 (±02) 1,75 (±0,9) 19,78 (±0,5) 84,22 (±28,5)
0,036 (±0,02) 0,006 (±0,002) 0,39 (±0,3) 2,57 (±1,6) 0,20 (±0,1) 1,06 (±0,9) 19,30 (±0,1) 82,35 (±35,0)
M AN U
AD (Gy) MD (Gy) ASD (Gy) PSD (Gy) AFT (minutes) MFT (minutes)
p
RI PT
Average number of procedures (per month) Average amount of radiation absorbed by the surgical team (mSv) MDAP (Gym2)
PERIOD PreS-HOR PostS-HOR 21 (±7) 22,89(±4,8)
0,005
0,137 0,001 0,055 0,363 0,913 0,946
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EP
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437
0,004
SC
435 436
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