BACKGROUND OF THE INVENTION

Field of the Invention

The invention generally relates to nanocomposite materials suitable for radiation shielding. The invention further relates to methods for producing and using nanocomposite materials as shielding from ionizing radiation, particularly that used for radiology.

Background

Diagnostic radiology is a field of medicine where radiologists use non-invasive imaging scans to diagnose patients. Radiology uses techniques such as X-ray imaging in detecting and diagnosing diseases and injuries, managing the care of patients, and guiding many other forms of medical treatment. It is very important to have a periodic evaluation of doses and image quality in order to optimize the radiation protection of patients. The lowest dose of radiation possible is used to avoid or at least minimize the exposure of the patients while still achieving a diagnostic or therapeutic objective. Furthermore, it is a priority of diagnostic radiology to limit exposure of patients to radiation not only for the sake of protecting them, but to protect the radiologist, too. Awareness of radiological protection of the patients also provides occupational protection. Thus, hazardous ionizing radiation is a vital issue that requires significant actions and equipment for protection of workers and patients at medical centers.

Design of radiation shielding must consider of the problems with shielding materials before selecting the appropriate material to be used for shielding. The problems range from minor to complex ones where there might be severe side effects from the use of inappropriate shielding materials in medical radiation procedure rooms. These problems can be considered in terms of shielding performances with different shielding materials. In general, shielding materials do not totally absorb x- and gamma radiation, but the thickness of the shield can significantly reduce the radiation penetration. Constant monitoring of the dose rate is required to verify shielding performance of any material. Materials selection can be optimized when selection is made in conjunction with the requirements of a specific task, thus providing the greatest potential for weight or cost savings. The choice of materials requires consideration of a variety factors, including nuclear interaction, chemical interaction, heat transfer, structural characteristics, other physical properties, and economics, which must all be applied in a strictly monitored analysis.

Radiation exposure is of increasing concern to the scientific community owing to its growing applications ranging from power generation to medical uses. Ionizing radiation has significant roles in diagnostics and radiotherapy. Therefore, the benefits of using ionizing radiation for medical purposes supersede its potential risks to the human health. In this regard, there is need for radiation protection practices to ensure the radiation exposure to the occupational radiation exposure is regulated or kept as low as reasonably achievable (ALARA). To comply with the ALARA safety principle, the choice of shielding materials plays a significant role. A commonly used radiation shielding material to protect patients, radiation workers and the general public is simply a concrete wall. However, this traditional shielding material has several shortcomings, such as occupying unnecessary space and being completely opaque. Therefore, there is a need for flexible shielding materials with promising potential to protect the patient, radiation workers and members of the public from the harmful effects of radiation. In view of the above, there are already numerous efforts by scientific community to replace the use of concrete as shielding with polyester shielding materials including nanocomposite materials.

Nanocomposite materials are defined as materials consisting two or more nanoparticles components of different chemical and physical properties in which the resultant materials may exhibit a unique characteristic different from the individual component. Furthermore, the nanocomposites are typically developed to obtain stronger, less expensive and lighter materials, as compared to traditional materials, such as lead or concrete. The most common nanocomposites materials employed by numerous studies, with a view to replace the traditional shields, are polymer and glass composites. In particular, the physical properties of polymers make these materials more suitable because the polymer compositions are easy to modify through simple preparation techniques. Moreover, to improve the effectiveness of radiation shielding of polymers, they can be doped with heavy metals such as MoO3, WO3, PbO and Bi2O3. For example, many studies reported that addition of Bi2O3improves the shielding properties of the polymer due to its known gamma-ray shielding characteristics. In addition to these advantageous physical properties, polymers also exhibit high density, non-toxicity and ease of fabrication.

Advantageous properties of the polymer composite, such as the ease of preparation, durability, low density and other properties make polyester composites good shielding materials against ionized medical radiation. However, polyester composites are not sufficient on their own to stop high energy photons, for instance photons of gamma rays and x-rays. Various polyester composites are known, however, very few have been shown to be adequate for radiation protection, particularly protection from high energy photons. Therefore, a need exists for improved polyesters as shielding materials.

SUMMARY OF THE INVENTION

The invention is a nanocomposite material for shielding radiation from an x-ray and/or gamma radiation beam, comprising a polyester polymer and lead oxide (Pb3O4) nanopowder, wherein the lead oxide is present at a concentration of 10% to 50% by weight, and wherein the nanocomposite material is formed into a shape suitable for shielding and attenuating exposure from the x-ray and/or gamma radiation beam. In one embodiment, the nanocomposite material of claim1, wherein the lead oxide concentration is in the range of 30% to 40%. In another embodiment, the nanocomposite material of claim1, wherein the lead oxide concentration is 40%.

In one embodiment, the invention is a lead oxide/polyester nanocomposite material that is a sheet or plate. The sheet or plate may be joined to other sheets or plates to form an open surround or box around a device, a target, a medical instrument, a practitioner, a patient and/or a region or body part of a patient. The open surround or box may be two-sided, three-sided, or four-sided. In another embodiment, the invention can be applied to an existing structure or device.

In another embodiment, the invention is a method of fabricating a nanocomposite material for shielding radiation from an x-ray and/or gamma radiation beam, comprising the steps of

preparing a solution of a polyester polymer in acetone with continuous stirring for at least 30 minutes to initiate polymerization,

adding lead oxide (Pb3O4) nanopowder to obtain a concentration in the range of 10% to 40% by weight with continuous stirring until obtaining homogeneous solution,

adding cobalt octoate as an accelerator to obtain a concentration of approximately 5% by weight and

mixing for 5 minutes or until all components are homogenized, transferring the mixture into a plastic solid form of the desired size and shape, and

allowing the mixture to air-dry and cure.

In one embodiment of the method, the lead oxide concentration is in the range of 30% to 40%. In another embodiment, the lead oxide concentration is 40%.

In yet another embodiment, the invention is a method of using a nanocomposite material for shielding radiation from an x-ray beam at diagnostic radiation energy levels and/or gamma radiation beam, comprising the steps of:

fabricating the nanocomposite material from a mixture of a polyester polymer and lead oxide (Pb3O4) nanopowder, wherein the lead oxide is present at a concentration of 10% to 40% by weight, and casting the mixture in a mold suitable for forming a nanocomposite shield,

positioning the nanocomposite shield in a location that provides shielding and attenuation of radiation from an x-ray and/or gamma radiation beam. The invention is particularly appropriate for use in a medical setting, wherein the x-ray and/or gamma radiation beam comprises a diagnostic or therapeutic procedure. The application of the nanocomposite shield may be designed to protect a practitioner, a patient undergoing a treatment, or both. The application may also be designed to protect other individuals who may be in the area of the medical treatment, either as a participant or a bystander who might otherwise be subject to stray radiation.

Other features and advantages of the present invention will be set forth in the description of invention that follows, and in part will be apparent from the description or may be learned by practice of the invention. The invention will be realized and attained by the compositions and methods particularly pointed out in the written description and claims hereof.

