Effective reduction of scatter radiation for operator and assistant during coronary procedures with a suspended radiation protection system in a per-procedure live-dosimetry analysis
Authors: Brandt M C , Prinz E , Wintersteller W , Schernthaner C , Hammerer M , Kraus J , Danmayr F , Strohmer B , Pretsch I , Lichtenauer M , Motloch L J , Hoppe U C , Nairz O 
Published: October 2021

Abstract

Background
Interventional cardiologists (IC) are exposed to the highest doses of radiation compared to all other medical specialties. Although head and eyes are exposed to a significant dose of scatter radiation (SCR), precise per-procedure data is sparse. Recently, the EU guidelines for maximum eye lens SCR doses have been reduced from 150 mSv to 20 mSv per year. A ceiling suspended operator radiation protection system has shown additional benefits for SCR protection in radiologic interventional procedures.

Purpose
To study the impact of the ZG system on IC and sterile assistant (SA) SCR exposure when used in addition to the current standard of X-ray protection (SXP) in unselected all-comers cardiologic procedures.

Methods
IC and SA were equipped with Unfors RaySafe i3 live-dosimeters at prespecified locations. 181 consecutive cardiac procedures were recorded, in which either both IC and SA were using SXP (lead apron, thyroid shield) or the IC was using the ZG system and the SA was wearing SXP. In all procedures a suspended lead shield, patient lead cover and an adjustable lead side-shield were present. Diagnostic angiographies (DA) and interventions (PCI) were grouped separately. Within both groups, the IC's and SA's SCR doses were compared.

Results
SCR doses were recorded in 100 DA and 81 PCI procedures. Compared to SXP, the use of the ZG device reduced the average SCR doses per procedure of the IC recorded at the left lateral head from 5.18±1.11 μSv to 0.60±0.07 μSv in DA (−88%; n=49/49, p&lt;0.0001) and from 19.64±3.36 μSv to 1.05±0.28 μSv for PCI (−95%; n=54/23, p=0.0006). The IC's average frontal dose at eye level was reduced from 1.38±0.33 μSv to 0.36±0.04 μSv in DA (−74%; n=50/50, p=0.0033) and from 3.33±0.53 μSv to 0.88±0.20 μSv in PCI (−74%; n=55/25, p=0.0031). Consistently, the dose recorded immediately under the IC's left shoulder were reduced from 34.14±7.79 μSv to 1.59±0.32 μSv in DA (−95%; n=39/40, p=0.0001) and from 71.77±10.77 μSv to 3.95±0.83 μSv in PCI (−94%; n=44/23, p=0.0001). Furthermore, when the IC used the ZG system, the average SCR dose recorded at the SA's head was reduced from 4.32±0.98 μSv to 2.11±0.28 μSv in DA (−51%, n=45/49, p=0.027) and from 18.55±2.69 μSv to 6.93±1.93 μSv in PCI (−63%, n=54/24, p=0.0078). With the exception of the IC frontal dose, all SCR dose effects remained significant after correction for total radiation time (μSv/s) and dose-area product (μSv/Gy·cm2). Procedure duration, contrast use and patient radiation dose were not affected by ZG use.

Conclusions
In a representative all-comers cohort of cardiac procedures, the ZG X-ray protection system demonstrated an impressive potential for SCR reduction in critical anatomical areas - even in a state-of-the-art cath-lab inventory with multiple SCR reduction measures already in place. Remarkably, the protective effect also included the sterile assistant at the table wearing SXP.

Funding Acknowledgement
Type of funding sources: None.