Performance of elastic x-ray shield made by embedding Bi2 O3 particles in porous polyurethane.

BACKGROUND: Many healthcare institutions have guidelines concerning the usage of protective procedures, and various x-ray shields have been used to reduce unwanted radiation exposure to medical staff and patients when using x-rays. Most x-ray shields are in the form of sheets and lack elasticity, which limits their effectiveness in shielding areas with movement, such as the thyroid. To overcome this limitation, we have developed an innovative elastic x-ray shield. PURPOSE: The purpose of this study is to explain the methodology for developing and evaluating a novel elastic x-ray shield with sufficient x-ray shielding ability. Furthermore, valuable knowledge and evaluation indices are derived to assess our shield's performance. METHODS: Our x-ray shield was developed through a process of embedding Bi2 O3 particles into porous polyurethane. Porous polyurethane with a thickness of 10 mm was dipped into a solution of water, metal particles, and chemical agents. Then, it was air-dried to fix the metal particles in the porous polyurethane. Thirteen investigational x-ray shields were fabricated, in which Bi2 O3 particles at various mass thicknesses (ranging from 585 to 2493 g/m2 ) were embedded. To determine the performance of the shielding material, three criteria were evaluated: (1) Dose Reduction Factor ( D R F $DRF$ ), measured using inverse broad beam geometry; (2) uniformity, evaluated from the standard deviation ( S D $SD$ ) of the x-ray image obtained using a clinical x-ray imaging detector; and (3) elasticity, evaluated by a compression test. RESULTS: The elastic shield with small pores, containing 1200 g/m2 of the metal element (Bi), exhibited a well-balanced performance. The D R F $DRF$ was approximately 80% for 70 kV diagnostic x-rays. This shield's elasticity was -0.62 N/mm, a loss of only 30% when compared to porous polyurethane without metal. Although the non-uniformity of the x-ray shield leads to poor shielding ability, it was found that the decrease in the shielding ability can be limited to a maximum of 6% when the shield is manufactured so that the S D $SD$ of the x-ray image of the shield is less than 10%. CONCLUSIONS: It was verified that an elastic x-ray shield that offers an appropriate reduction in radiation exposure can be produced by embedding Bi2 O3 particles into porous polyurethane. Our findings can lead to the development of novel x-ray shielding products that can reduce the physical and mental stress on users.

A novel algorithm for extracting soft-tissue and bone images measured using a photon-counting type X-ray imaging detector with the help of effective atomic number analysis.

Most of the objects targeted for X-ray examination are composed of soft-tissue and bone. We aimed to develop an algorithm for generating X-ray images which can give quantitative information of soft-tissue and bone using an energy-resolving photon-counting type imaging detector. We used polychromatic X-rays for analysis in which both the beam hardening effect and detector response were properly corrected and then succeeded in virtually treating the amount of measured X-ray attenuation as if it were measured using monochromatic X-rays.

Effective atomic number image determination with an energy-resolving photon-counting detector using polychromatic X-ray attenuation by correcting for the beam hardening effect and detector response.

In this study, we propose an effective atomic number (Zeff) determination method based on a photon-counting technique. The proposed method can correct for the beam hardening effect and detector response based on polychromatic X-rays to allow high accuracy material identification. To demonstrate the effectiveness of our method, the procedure was applied to X-ray images acquired by a prototype energy-resolving photon-counting detector and we obtained an Zeff image with accuracy of Zeff ± 0.5 regardless of the mass thickness.