Development of a New Radiation Shield for the Face and Neck of IVR Physicians

Interventional radiology (IVR) procedures are associated with increased radiation exposure and injury risk. Furthermore, radiation eye injury (i.e., cataract) in IVR staff have also been reported. It is crucial to protect the eyes of IVR physicians from X-ray radiation exposure. Many IVR physicians use protective Pb eyeglasses to reduce occupational eye exposure. However, the shielding effects of Pb eyeglasses are inadequate. We developed a novel shield for the face (including eyes) of IVR physicians. The novel shield consists of a neck and face guard (0.25 mm Pb-equivalent rubber sheet, nonlead protective sheet). The face shield is positioned on the left side of the IVR physician. We assessed the shielding effects of the novel shield using a phantom in the IVR X-ray system; a radiophotoluminescence dosimeter was used to measure the radiation exposure. In this phantom study, the effectiveness of the novel device for protecting against radiation was greater than 80% in almost all measurement situations, including in terms of eye lens exposure. A large amount of scattered radiation reaches the left side of IVR physicians. The novel radiation shield effectively protects the left side of the physician from this scattered radiation. Thus, the device can be used to protect the face and eyes of IVR physicians from occupational radiation exposure. The novel device will be useful for protecting the face (including eyes) of IVR physicians from radiation, and thus could reduce the rate of radiation injury. Based on the positive results of this phantom study, we plan to perform a clinical experiment to further test the utility of this novel radiation shield for IVR physicians.

In 2011, the International Commission on Radiological Protection significantly reduced the limit of occupational exposure of the eyes to radiation, from 150 to 100 mSv/5 years (i.e., 20 mSv/year) [27]. Furthermore, radiation eye injury (i.e., cataract) in IVR staff has also Figure 1 shows the novel radiation shield for IVR physicians. The device consists of a neck guard and face shield designed using a 0.25 mm Pb-equivalent rubber sheet (nonlead protective sheet, Figure 2). Pb-equivalent rubber sheeting is easy to handle and often used in personal protective aprons. The device is lightweight (0.65 kg). The neck guard and face shield are firmly connected and have adequate stability. The face shield was designed to mainly protect the left side of IVR physicians from scattered radiation.  The novel shield consists of a neck guard and face shield, which together comprise a single unit to promote stability and prevent misalignment. The shield is firmly attached behind the neck of the IVR physicians using Velcro to protect them from scattered radiation from the left side. The device consists of a neck guard and face shield designed using a 0.25 mm Pb-equivalent rubber sheet (nonlead protective sheet).

Phantom Study
We conducted a phantom study at Yamagata University Hospital, Japan. Figure 3 displays the experimental setup used to simulate the typical settings for IVR procedures. A digital cine angiography X-ray unit (an "under-tube" X-ray tube system) with a 16-in mode flat-panel detector (FPD) was used. Digital cine acquisitions were performed at 30 frames/s with a total duration of 150 s (30 s × 5). An automatic control system was used to set the X-ray exposure settings (i.e., kilovoltage and milliamperage) ( Table 1). We set the focus-to-image receptor (i.e., FPD) distance to 120 cm, and the height of the patient table to 92 cm. Five standard tube-viewing angles were used to simulate the typical settings for percutaneous coronary intervention (PCI) and cardiac catheterization: posteroanterior (PA), 60 • left anterior oblique (LAO), 30 • right anterior oblique (RAO), 30 • RAO + 30 • caudocranial (cranial), and 60 • LAO + 30 • craniocaudal (caudal).
A trunk phantom (PBU-60) was used to simulate the patient ( Figure 3). A head phantom (THRA1) was used to simulate the IVR physician ( Figure 3); it was placed 70 cm horizontally and 40 cm vertically from the central radiation beam on the patient table. This position is similar to that used by physicians during PCI at our hospital. The height of the head phantom was 165 cm; therefore, the eye of the phantom was approximately 150 cm above the floor. We did not use a ceiling-protecting Pb plate.

Dosimetry
Scattered radiation from the trunk phantom representing the patient was measured using radiophotoluminescence dosimeters (RPLDs; GD-302M), with and without the novel radiation shield. Dose Ace FGD-1000 was used as the measurement/readout system. RPLDs were placed on the surface of the head phantom representing the physician at 24 locations, including the left (No. 3        .

Twenty-f
). The distance between the measurement points was 3 cm.
The background radiation dose was subtracted from the measurements, and the doses were calibrated. The average of three measurements was recorded for each X-ray viewing angle. Based on the doses measured with (D with ) and without (D without ) the novel radiation shield, we calculated the effectiveness of the radiation protection of the shield as: (D without − D with )/D without × 100%. ) of the face. Figure 5 depicts the protective effect of the novel radiation shield. The radiation protection effectiveness of the novel radiation shield was greater than 80% at almost all measurement points, except RAO 30 • , at which the effectiveness was slightly lower. The average radiation protection effectiveness of the novel device for the five viewing angles were 87.5% and 83.6% for the left (No. 3 ) and right (No.