Impact of the Ceiling-Mounted Radiation Shielding Position

Summary
The effect of ceiling-mounted radiation shielding on the amount of scattered radiation was evaluated under conditions that simulated obese patients for clinically relevant exposure parameters. The measurements were made in different projections and with different positions of the ceiling mounted armature: without armor; shield closer to the patient; and shield closer to the doctor performing the procedure.

Lead radiation X-ray shielding

The protection provided by the shield was evaluated for cardiology when using the femoral access and for radiology when the doctor performs the procedure in the abdominal area. The results show that the use of ceiling-mounted shields can reduce the scatter radiation dose by 95% in the attending physician’s position. In cardiology, the impact is more pronounced when the left oblique projection is used. In radiology a sharp decrease in right oblique views was observed compared to cardiology. The ceiling mounted screen should be placed as close to the physician as possible. The idea of ​​creating the largest radiation shadow by placing the radiation shield as close to the patient as possible does not provide the operator with as effective radiation shielding as one might think.

1. Introduction
It is widely accepted that exposure to low doses may increase the risk of cancer and, consequently, the scattered radiation produced by patients during fluoroscopy-guided procedures may pose a risk to medical specialists [1]. Physicians who perform interventional procedures in close proximity to patients are exposed to potentially low levels of dispersed doses for an extended period [2], making radiation protection of interventional personnel a major concern [3, 4]. There are practical ways to reduce professional doses to interventional personnel, including the use of protective shields. Protective shielding can be personal (aprons, thyroid shields, and goggles) or it can be part of the X-ray system and its accessories such as ceiling-mounted shield, table-top extending screen, disposable electrodes, or shield placed on patients [5-10]. Doses for both staff and patients can also be reduced by using the modified angiography system settings (image frequency, x-ray field size, spectral filtering, projection, etc.). These are described in [5] and will not be discussed here.

In some situations, properly placed shielding can significantly improve radiation protection for personnel; Fetterly et al. [11] examined the effects of different types of shielding and their influence on protection against diffuse radiation. Fetterly et al. They dealt with the position of the lower, middle and upper body shielding and its influence on protection from scattered radiation. The authors measured doses by simulating procedures performed on angiographic systems, but only in the posteroanterior (PA) view, which is not commonly used in cardiological and sometimes radiological procedures. Doctors use views that include the left anterior oblique (LAO) and right anterior oblique (RAO), often tilted in the cranial (CR) or caudal (CD) directions. In the LAO view, the X-ray beam enters the patient from the right side and in the CR view, the X-ray beam enters from the patient’s lower body towards the head.

In this study, the influence of roof-mounted shielding and its location on the occupational doses of treating physicians due to scattering of radiation from different projections under conditions that simulate exposure during interventional procedures was investigated.

2. Materials and methods
Two angiography systems were chosen for this study, each equipped with a ceiling mounted radiation shield. The first, Artis Q (installed in 2016, Siemens, Erlangen, Germany) has a 25cm flat screen detector and is used for cardiac procedures. Coro_CARE cine mode (dose saving mode) was chosen for the measurement, each cine acquisition is performed for 4 s with a frame rate of 15 fr / s, as used clinically. Exposure parameters were set automatically using the automatic dosage control (ADRC), used in both angiography systems. Exposure parameters were as follows: 86 to 96 kVp, 340 to 780 mA, pulse duration of 5.2 to 9.0 ms, additional filtration of 0.0 mm of Cu, and small and large focus .

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