X-ray or gamma ray systems or devices – Photographic detector support – Dental
Reexamination Certificate
2002-03-13
2004-06-01
Church, Craig E. (Department: 2882)
X-ray or gamma ray systems or devices
Photographic detector support
Dental
Reexamination Certificate
active
06742928
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to x-ray imaging systems and, more particularly, to a dental x-ray block having a packet support member that is configured to attenuate x-rays.
BACKGROUND OF THE INVENTION
The use of x-rays provides a minimally invasive, yet effective, tool in the diagnosis and treatment of dental conditions. Dental x-rays may be used not only to detect cavities, but also to survey tooth development, to diagnose bone diseases, to evaluate the results of an injury, or to plan orthodontic treatment. These procedures typically are performed by placing a dental x-ray block, including a dental x-ray film packet, into the mouth of a patient and positioning the dental x-ray block adjacent to an area of interest, such as a tooth, within the patient's mouth to be diagnosed and/or treated. An external x-ray source is placed adjacent to and directed toward the area of interest, opposite to the dental x-ray film packet. When activated, the external x-ray source emits a primary x-ray beam, which travels through the area of interest and exposes dental x-ray film within the dental x-ray film packet. After the dental x-ray film has been exposed, the dental x-ray block is removed from the patient's mouth, and the dental x-ray film packet is separated from the dental x-ray block. The dental x-ray film then is extracted from the dental x-ray film packet and developed, producing an x-ray image of the area of interest. Additional x-ray images can be created by repeating the above procedure with other dental x-ray film packets.
The construction of dental x-ray film packets is well-known. A typical dental x-ray film packet includes a single or double sheet of intraoral dental x-ray film as discussed in a book, entitled “Oral Radiology: Principles and Interpretation,” by Drs. Goaz and White. With one or both sides coated with emulsion, the dental x-ray film is light-sensitive and is enclosed within an opaque protective wrapper to prevent exposure of the dental x-ray film to light. The protective wrapper, in turn, is placed within a moisture-resistant wrapper with a thin sheet of lead foil that is disposed between the opaque protective wrapper and the moisture-resistant wrapper. When the dental x-ray film packet is positioned adjacent to the area of interest, the sheet of lead foil attenuates the primary x-ray beam that travels beyond the dental x-ray block and toward tissues within the patient's mouth that are immediately adjacent to the area of interest. Thus, the primary x-ray beam, as attenuated, is less likely to unnecessarily expose the adjacent tissues and be reflected by dense structures, such as teeth or bone, within the adjacent tissues, as backscattered reflections that can result in a secondary exposure of the dental x-ray film.
Similarly, dental x-ray blocks for holding x-ray film packets also generally are well-known. For example, U.S. Pat. No. 1,012,561, issued to Ketcham, describes a mouth packet holder to be used for taking x-rays of teeth. A typical dental x-ray block includes a mouthpiece, which is formed from a soft material, and a packet holder. The packet holder is coupled with the mouthpiece and includes a packet retention section and a packet support member, which extends substantially perpendicularly from the mouthpiece. The packet retention section is configured to receive and engage the dental x-ray film packet, which abuts the packet support member when engaged by the packet retention section. Although the dental x-ray film packet is substantially rigid, the packet support member is configured to support the dental x-ray film packet, holding the dental x-ray film packet flat to prevent image distortion. When the packet holder with the dental x-ray film packet is positioned adjacent to an area of interest within the patient's mouth, the mouthpiece is configured to be engaged by the patient's teeth to secure the dental x-ray film packet in place without causing damage to the patient's teeth.
The use of dental x-ray blocks, however, currently suffers from several critical disadvantages. First, although the lead foil within the dental x-ray film packet serves a useful purpose, lead is highly toxic to humans, and children are particularly susceptible to the effects of lead exposure. Even low levels of lead exposure may gravely impact a child's health and intellectual development by impairing his growth, reducing his attention span, and causing learning disabilities. These effects may be long-term and irreversible. Further, lead does not naturally decompose. Once the air, water, or soil in a geographic region has been contaminated, the lead contamination, unless properly removed, can continue indefinitely, poisoning generations of children. Recognizing these risks, some film packet manufacturers have instituted lead-recycling programs, and environmental protection groups have advocated avoiding unnecessary lead usage and removing existing lead contamination.
Second, the sheet of lead foil is not completely opaque to the primary x-ray beam; instead, the typical sheet of lead foil is configured to attenuate the primary x-ray beam only by approximately fifty percent. Therefore, despite the sheet of lead foil, the use of currently-available dental x-ray blocks still permits unnecessarily exposure of the adjacent tissues to a significant portion of the primary x-ray beam, which also can result in the backscattered reflections from the dense structures in the adjacent tissues. Further, upon reaching the dental x-ray block, the backscattered reflections, like the primary x-ray beam, are only partially attenuated by the sheet of lead foil, creating the secondary exposure of the dental x-ray film. Since the backscattered reflections travel at different angles and generally are too weak to produce a second x-ray image, the secondary exposure cause a gray fog to appear on the dental x-ray film, obscuring the x-ray image.
In view of the foregoing, it is believed that a need exists for an improved dental x-ray block that overcomes the aforementioned obstacles and deficiencies of currently-available dental x-ray blocks.
SUMMARY OF THE INVENTION
The present invention is directed to a dental x-ray block having an attenuation member that is configured to attenuate x-rays. A dental x-ray block in accordance with the present invention comprises a mouthpiece and a packet holder. Being manufactured from a material that is substantially transparent to x-rays, the mouthpiece is configured to be received within a patient's mouth and engaged by the patent's teeth. Coupled with the mouthpiece, the packet holder also is manufactured from a material that is substantially transparent to x-rays and is configured to be received within the patient's mouth. The packet holder is configured to receive and engage a dental x-ray film packet and includes an attenuation member. Being substantially axially aligned with the dental x-ray film packet, the attenuation member is configured to significantly attenuate and/or absorb x-rays, preferably having an x-ray attenuation level in excess of approximately fifty percent.
It will be appreciated that a dental x-ray block in accordance with the present invention may serve to alleviate some of the environmental protection and human health concerns regarding lead exposure. As presently used, dental x-ray film packets include dental x-ray film and a sheet of lead foil for preventing unnecessary x-ray exposure and reducing unwanted x-ray reflections. As a result, a sheet of lead foil presently is produced, and must ultimately be disposed of, for each dental x-ray film packet developed. According to the present invention, the attenuation member within the dental x-ray block performs the same functions as the sheet of lead foil and can avoid the lead disposal concerns by facilitating the elimination of the lead foil from the dental x-ray film packets. Thereby, manufacturers of dental x-ray film packets can curtail the amount of lead used, and the contamination of the environment that r
Church Craig E.
Orrick Herrington & Sutcliffe LLP
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