Patent Publication Number: US-2011061662-A1

Title: Apparatus and method to limit exposure of a body area to radiation

Description:
BACKGROUND OF THE INVENTION 
     The subject matter described herein relates generally to an apparatus and method for use in stabilizing a body part of a patient during a medical procedure, such as during radiation therapy and, more specifically, to an apparatus that includes one or more radiation barriers configured to protect at least a portion of an underlying body area from exposure to radiation. 
     Many medical procedures, including surgery and radiographic imaging, require stabilization and/or immobilization of specific body parts. Conventional apparatuses for use in stabilizing the body part during such procedures include padded supports or contoured mattresses. However, conventional apparatuses may not be suitable for stabilizing a patient&#39;s head during the procedure. 
     Radiographic images, such as a computed tomography (CT), a positron emission tomography (PET), or a magnetic resonance imaging (MRI) scan, of a body part are often necessary before performing surgery and are often used during surgery. During such procedures, a patient&#39;s head may be immobilized with an apparatus that includes invasive fixating pins. Although cranial fixation with invasive pins is adequate for some medical procedures, its use may be undesirable for other applications. 
     Further, underlying and/or adjacent structure or tissue, such as teeth, gingiva (gums), periodontal bone, the parotid and sublingual, salivary glands and/or related tissue, may be exposed to undesirable or excessive doses of radiation during such procedures. Exposure to radiation may result in harmful side effects. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one aspect, an apparatus for limiting exposure of an underlying body area of a patient to radiation is provided. The apparatus includes a mask defining a void. The mask is contoured to substantially conform to the underlying body area. A radiation barrier is positionable within the void to facilitate limiting exposure of at least a portion of the underlying body area to radiation. 
     In another aspect, a mask configured to limit exposure of an underlying body area to radiation is provided. The mask includes a sheet of material defining at least one void. The sheet of material is moldable to conform to at least a portion of the underlying body area to be shielded. A radiation barrier is positionable within the at least one void to facilitate limiting exposure of at least a portion of the underlying body area to radiation. 
     In yet another aspect, a method is provided for treating a body area of a patient. The method includes molding a sheet of material to form a mask configured to conform to the body area. The sheet of material defines a void. A radiation barrier is positionable within the void to facilitate limiting exposure of at least a portion of the body area to radiation during treatment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a side view of an apparatus configured to limit exposure of an underlying body area to radiation with a patient&#39;s head oriented in a supine position; 
         FIG. 2  shows a front view of a radiation barrier suitable for use with the apparatus shown in  FIG. 1 ; 
         FIG. 3  shows a top view of an exemplary support frame suitable for use with the apparatus shown in  FIG. 1 ; and 
         FIG. 4  is a procedural flow diagram for an exemplary method for treating a body area of a patient. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The apparatus described herein includes a moldable mask having one or more radiation barriers that are configured to protect teeth, gingiva (gums), periodontal bone, the parotid and sublingual, salivary glands and/or related tissue against harmful side effects of radiation therapy. The radiation barrier may include one or more different radiation shielding materials that are known to protect against radiation, such as lead in sheet form or a composite material that includes a sheet or layer of lead positioned between layers of a suitable plastic material, for example. The radiation barrier may vary in thickness and other physical characteristics depending upon the intensity of radiation required for treatment and/or the patient being treated. 
       FIGS. 1-3  illustrate components of an apparatus  10  for use in stabilizing a body part. Apparatus  10  supports and/or immobilizes a head  12  of a patient  13  during a medical procedure, such as during radiation therapy. However, it should apparent to those skilled in the art that apparatus  10  may be suitably sized, shaped or oriented to support and/or immobilize other body parts, such as the patient&#39;s neck, back, pelvis, or at least a portion of an appendage, or may be positioned within a desired body area, such as on the patient&#39;s breast, chest, back, pelvis or abdomen during the medical procedure. 
     Referring further to  FIG. 1 , in the exemplary embodiment, apparatus  10  stabilizes head  12 , shown by a dashed line, in a supine position. Apparatus  10  may also be configured to stabilize head  12  in a prone position and/or any suitable orientation, as desired. 
     In the exemplary embodiment, apparatus  10  includes a mask  14  that is formed from a suitable thermally-activated moldable sheet of material that is heated to a suitable softening temperature that is sufficiently low enough so that the patient can tolerate a direct molding process. The softened sheet is conformed to head  12  and allowed to cool. In this embodiment, mask  14  is formed as a direct molding of head  12  prior to the medical procedure. In the exemplary embodiment, the moldable material is a thin sheet of low temperature thermoplastic material commercially available under the name of Aquaplast™ from WFR/Aquaplast Corporation located in Avondale, Pa. 19311 (USA). In alternative embodiments, mask  14  may be formed from any suitable material or combination of materials including, without limitation, fiberglass, plaster, and/or foam. After proper molding and cooling, mask  14  conforms to a particular patient&#39;s head  12  to provide a personal fit for the support and immobilization of head  12  by apparatus  10 . Mask  14  thus provides a hardened or rigid support structure that is contoured to correspond to the unique features of head  12  and to facilitate supporting and immobilizing head  12  during the medical procedure. As such, mask  14  is contoured to accommodate head  12 . 
     Referring further to  FIGS. 1 and 2 , in the exemplary embodiment, a radiation barrier  16  is positioned within a pocket or void  18  formed in mask  14 . One or more voids  18  may be preformed on or formed within the sheet of material formed during the mask molding process. Radiation barrier  16  is positioned within a corresponding void  18  such that barrier  16  is positioned to facilitate shielding a selected area or portion of the patient&#39;s body, such as on or near the teeth, gingiva, periodontal bone, salivary glands and adjacent body areas. More specifically, barrier  16  is positioned to facilitate protecting desired areas of the patient&#39;s body from direct impingement of radiation used, for example, in radiation therapy, and applied to patient body areas such as the head, neck, and/or thyroid. 
     Radiation barrier  16  includes a radiation shielding material that is suitable for limiting or preventing undesirable radiation from contacting the selected body area and/or that facilitates preventing or limiting undesirable side effects including, without limitation, salivary gland atrophy and xerostomia (dry mouth), demineralization and break down of teeth enamel, stunted undeveloped roots, retarded eruption, and anodontia (missing teeth) in young patients, resorbtion of the alveolar bone and periodontitis (pyohorrea), infected teeth, and osteoradionecrosis. Suitable materials for radiation barrier  16  may include, without limitation, a lead-based material. In one embodiment, radiation barrier  16  is a composite material that includes an inner sheet or layer of lead material that is covered with a suitable material, such as a plastic material, that substantially prevents interaction and/or contact between the lead material and any surrounding tissue. In an alternative embodiment, a layer of fine lead particles is positioned between layers of a suitable material, such as a plastic material. Such suitable materials may include, without limitation, synthetic resins such as methyl methacrylates, synthetic polyamides such as nylon, and silicones for biological use commercially available from Dow Coming Corporation located in Midland, Mich. 48686 (USA). Moreover, radiation barrier  16  may be formed with any suitable shape, configuration, and/or orientation that facilitates radiation barrier  16  being positioned to substantially shield the selected body area from undesirable radiation exposure. In one embodiment, radiation barrier  16  has a thickness of about 1 millimeter (mm) to about 4 mm or, more specifically, about 2.75 mm to about 3.25 mm or, even more specifically, about 3 mm to about 3.10 mm. 
     As illustrated in  FIGS. 1 and 2 , radiation barrier  16  is generally arcuate in shape and is adapted to encompass a lower front portion  20  of head  12 . In the exemplary embodiment, radiation barrier  16  includes rearwardly extended portions  21  that extend over and around a patient&#39;s face  22  substantially from ear  23  to ear  24 , shown in  FIG. 2 , and a lower inwardly directed cap-shaped portion  25 . The dimensions and configuration of radiation barrier  16  enable radiation barrier  16  to substantially cover the extraoral anatomy of the patient&#39;s face  22 , and to substantially shield the parotid, sublingual and salivary glands from undesirable radiation exposure. During certain medical procedures it may not be desirable to include extended portions  21 , such as when X-rays of the glands, for example, are to be taken. 
     In the exemplary embodiment, mask  14  includes a plurality of perforations  26  to facilitate patient comfort and to reduce erythema, as well as provide molding flexibility, if desired. Moreover, in the exemplary embodiment, mask  14  includes a plurality of fiducial markers  28  affixed to it. 
     Mask  14 , in the exemplary embodiment, is formed around the patient&#39;s face  22  to enable subsequent medical procedures to be performed with the patient  13  in a prone position. Mask  14  also includes a cushion  30  that is molded against a back  31  or a side  32  of head  12  for use as a headrest or support. In the exemplary embodiment, cushion  30  is coupled to a support frame  33  with a suitable coupler, such as a clamp  34  and bolts  36 . Alternatively, cushion  30  may be coupled directly to support frame  33  with bolts  36 . Thus, when mask  14  is coupled to a medical procedure table (not shown) using a mounting assembly  40 , head  12  is effectively stabilized without utilizing fixating pins or any other intrusive members. 
     In the exemplary embodiment, mask  14  is removably coupled to support frame  33 . More specifically, in the exemplary embodiment, support frame  33  is substantially rectangular in shape and is sized to create a stable foundation to support head  12 . Support frame  33  may be formed of any suitable material, including without limitation, a plastic or nylon material, such that unnecessary images or artifacts do not appear along with the image of the body part during the radiographic imaging. 
     Support frame  33 , in the exemplary embodiment, includes a plurality of holes  42  for use in removably coupling mask  14  to support frame  33 . Referring to  FIGS. 1 and 2 , in one embodiment, holes  42  are spaced about an outer perimeter  44 , an inner perimeter  46 , a top  48 , and/or a bottom  50  opposing top  48  of support frame  33 . The various locations of holes  42  enable masks  14  having different shapes and/or sizes with head  12  to be positioned or oriented as desired relative to support frame  33 . In one embodiment, holes  42  are configured to receive nylon or plastic bolts  36 . Mounting assembly  40  is also coupled to support frame  33  and is configured such that apparatus  10  may be coupled to a medical procedure table, a radiographic imaging table, or any suitable support structure. 
     Apparatus  10  may be utilized in a method for treating a body part or an area of a patient. Although the method is described herein in reference to a medical procedure related to head  12 , it should be apparent to those skilled in the art that the apparatus and the method may be applied to other body parts or areas as well. Generally, the method involves the use of an apparatus as described above during a radiographic imaging process. 
     With reference to  FIG. 4 , a method for treating a body part or area of a patient is described. The patient is placed into a position that will enable a medical procedure to be performed. For example, the patient may be placed in a prone or supine position or other suitable orientation. A mask is formed  402  to conform to the patient&#39;s head or other body part or area for the procedure to be performed. In one embodiment, the mask is made of a thermally-activated moldable sheet of plastic material that is heated until the sheet of plastic material becomes moldable. The sheet of plastic material is then molded to follow the contours of the head and/or a face of the patient. The sheet of plastic material is cooled to form the rigid mask. In one embodiment, the sheet of plastic material is heated by submerging the sheet of plastic material into a hot water bath. The temperature of the water is high enough to soften the plastic material, and the precise temperature will depend upon the specific plastic material used. For example, when an Aquaplast™ material is utilized to form the mask, the water bath should be between 140° F. and 180° F. Due to the high temperatures involved, the molding process may be delayed until the temperature of the plastic material is tolerable to the patient. 
     During the molding process, facial protrusions, contours, and bony areas such as the nose, cheeks, forehead, and chin are accurately shaped. After molding the mask, the mask may remain on the patient until the mask has adequately cooled. When sufficiently cooled, the plastic material becomes rigid and the mask may be removed from the patient. A radiation barrier is positioned  404  within a void defined by the mask before or during the mask forming process. The radiation barrier is positioned to facilitate limiting exposure of at least a portion of the underlying body area to radiation during treatment. 
     With the mask positioned about the patient&#39;s head, the mask is coupled to the support frame, which is secured to a structure such as a bed or a table. In one embodiment, a cushion is positioned underneath the patient&#39;s head to provide added support and/or immobilization. After stabilizing the patient&#39;s head, a radiographic imaging procedure, such as a computed tomography (CT), positron emission tomography (PET), or magnetic resonance imaging (MRI) scan, may be performed. 
     One or more radiation barriers included in the mask are configured to protect teeth, gingiva (gums), periodontal bone, the parotid and sublingual, salivary glands and/or related tissue against harmful side effects of radiation emitted during the imaging procedure. The radiation barrier may include one or more different radiation shielding materials that are known to protect against radiation, such as lead in sheet form or a composite material that includes a sheet or layer of lead positioned between layers of a suitable plastic material, for example. The radiation barrier may vary in thickness and other physical characteristics depending upon the intensity of radiation required for treatment, the treatment area, and/or the patient being treated. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.