Abstract:
A radiation-shielding assembly is provided comprising a first member having a tortuous leading edge and a second member having a complementary edge.

Description:
INCORPORATION BY REFERENCE 
       [0001]    The following documents are incorporated herein by reference as if fully set forth: U.S. Provisional Application No. 61/787,702, filed Mar. 15, 2013; and U.S. patent application Ser. No. 14/215,797, filed Mar. 17, 2014. 
     
    
     FIELD OF INVENTION 
       [0002]    This application is generally related to a radiation-shielding sliding assembly. 
       BACKGROUND 
       [0003]    Radiation therapy facilities, especially those involving high energy X radiation or neutron radiation, require particularly thick walls, doors, and barriers. Particle accelerators, such as linear particle accelerators, use electromagnetic fields to propel charged particles, such as electrons, protons, or ions, at high speeds along defined beams. Due to radiation from particle accelerators, particle facilities must be designed and constructed to provide adequate shielding. 
         [0004]    Known radiation therapy facilities are generally constructed as a room housing the source of radiation, with concrete walls, ceilings, and floors that can reach thicknesses of up to 15 feet. In addition, a maze entry is usually used to provide a wing wall to capture scatter radiation. The entrance to a maze entry or direct entry radiation therapy room can include at least one shielded door to further prevent radiation leakage outside of the room. The shielded door for a radiation therapy room can be constructed as a hinged door having a very thick core, for example 20 inches thick, to provide sufficient shielding. Known shielded doors are also extremely heavy, typically 10,000-20,000 lbs for radiation therapy rooms, and cannot be opened and closed quickly. The time that it takes to open and close a hinged shielded door is especially important in radiation therapy rooms where an operator may need to enter and exit the room repeatedly to make adjustments. For example, in medical applications, several rounds of low energy radiation may be used for diagnostic purposes and patient positioning before treating the patient&#39;s tumor with the high energy radiation. After each round of low energy radiation, the operator must either progress down a very long maze corridor leading to the treatment room or alternatively wait for the shielded door to fully open before entering the treatment room to make adjustments to the patient, and then wait for the shielded door to fully close again before starting the next round of low energy radiation testing or high energy radiation treatment. This process can be very time consuming and tiring to the patient. 
         [0005]    Bi-parting sliding doors typically permit shorter opening and closing times compared to hinged doors. Because existing bi-parting sliding doors have a relatively linear leading edge at the seam between both doors, they lack the necessary seal required to prevent radiation leakage. One known method to reduce radiation leakage is to equip one of the bi-parting doors with an astragal at its leading edge to cover the seam between the doors. 
         [0006]    The increased speed of heavy radiation shielded members introduces additional safety concerns especially when objects obstruct the closing path of the sliding members. 
         [0007]    A need exists for a sliding assembly for radiation therapy rooms that provides a sufficient seal to eliminate radiation leakage and improved safety when closing. 
       SUMMARY 
       [0008]    A radiation-shielding movable barrier for a radiation therapy facility is disclosed. The movable barrier includes a first member movable between an open position, and a closed position. The first member comprises a front face, a rear face, a trailing face, and a leading face including a sine-wave shaped leading edge. The first member has a core constructed of high-density or high-Z material having radiation-shielding characteristics. Radiation is defined as at least one of high energy X radiation, neutron radiation, photon radiation, proton radiation, X ray radiation, gamma radiation, or high energy radiation. A second member has a sine-wave shaped edge that is complementary to the sine-wave shaped leading edge of the first member. The second member has a core constructed of high-density or high-Z material having radiation-shielding characteristics. When the first member is in the closed position, the sine-wave shaped leading edge of the first member and the sine-weave shaped edge of the second member interlock to form a tight seal between the first member and the second member to prevent leakage of radiation through the seal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The foregoing summary, as well as the following detailed description of the preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangement shown. 
           [0010]      FIG. 1  is a plan view of a direct entry radiation therapy room equipped with a sliding door assembly. 
           [0011]      FIG. 2A  is a top view of a direct entry radiation therapy room equipped with an embodiment of a bi-parting door assembly having a leading edge in the shape of a sine-wave. 
           [0012]      FIG. 2B  is a top view of an alternative embodiment of the bi-parting door assembly. 
           [0013]      FIG. 2C  is a top view of another alternative embodiment of the bi-parting door assembly. 
           [0014]      FIG. 3  is a top view a single sliding door. 
           [0015]      FIG. 4  is a view of the biparting door assembly of  FIG. 2A  in a closed configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    Certain terminology is used in the following description for convenience only and is not limiting. The words “top,” “bottom,” “inner,” and “outer” designate directions in the drawings to which reference is made. The terminology includes the words specifically noted above, derivatives thereof, and words of similar import. 
         [0017]      FIG. 1  shows a direct entry radiation therapy room  2  equipped with a sliding door assembly  10 . The direct entry radiation therapy room  2  can be a particle facility, proton facility, linear accelerator room, or any other radiation therapy room that can involve high energy radiation, such as high energy X radiation, neutron radiation, proton radiation, X-ray radiation, or the like. Due to the high costs associated with constructing modular radiation facilities, maximizing space within the facility radiation therapy room  2  is desirable. The sliding door assembly  10  is positioned outside an existing entryway  30  formed in a wall  42 , such as a shielded wall of the radiation therapy room  2 , in order to maximize space within the radiation therapy room. 
         [0018]      FIG. 2A  shows an embodiment of a bi-parting door assembly  10  according to the present invention in an open position.  FIG. 4  shows the bi-parting door assembly  10  of  FIG. 2A  in a closed configuration showing the seam  11  formed by the doors  12 ,  13 . The bi-parting door assembly  10  is positioned outside the entryway  30  and includes two doors  12 ,  13 , a door frame  14 , a track  15 , and a drive assembly  16 . The doors  12 ,  13  and door frame  14  define a passageway  60  therebetween. The two doors  12 ,  13  are of sufficient thickness to shield radiation from leaking out of the particle facility, and each door  12 ,  13  preferably has a thickness of approximately 12 inches to 60 inches, and more preferably has a thickness of 20 inches to 50 inches. In one embodiment, each door  12 ,  13  has a thickness of approximately 49 inches. In another embodiment, each door  12 ,  13  has a thickness of approximately 25 inches. Each door  12 ,  13  preferably weighs approximately 12,000 lbs. to 65,000 lbs., and more preferably weighs 20,000 lbs. to 60,000 lbs. In one embodiment, each door  12 ,  13  weighs approximately 20,000 lbs. In another embodiment, each door  12 ,  13  weighs approximately 60,000 lbs. The doors  12 ,  13  preferably consist of a core constructed of high-density material adapted to reflect, attenuate, or capture charged particles, such as that described in U.S. patent application Ser. No. 13/060,157 and PCT Application Nos. PCT/US2011/036934, which are incorporated by reference as if fully set forth herein. The core of the doors  12 ,  13  can be comprised of a high-density concrete. In an embodiment, the core of the doors  12 ,  13  preferably have a density between 200 to 400 pounds per cubic foot, and more preferably have a density of 250 pounds per cubic foot. In another embodiment, the core of the doors  12 ,  13  preferably have a density of 313 pounds per cubic foot. The core of the doors  12 ,  13  can be formed from a high-Z material, i.e. a material with a high atomic number and number of protons, such as, for example and without limitation, lead, steel, and tungsten. In another embodiment, the core of the doors  12 ,  13  can be formed from boron or lithium based materials, which are suitable for capturing neutron particles and byproduct radiation. In another embodiment, the core of the doors  12 ,  13  can be formed from a metallic aggregate material that can include high-Z materials, such as, for example and without limitation, iron, lead, steel, and tungsten. High-Z target materials which could be used in the core of the doors  12 ,  13  include but are not limited to copper, aluminum, titanium, and brass. The core of the doors  12 ,  13  can include a material having high-Z aggregates, high hydrogen content, and/or a high macroscopic neutron cross-section to capture byproduct radiation. Such a material can include, but is not limited to, boron, lithium, cadmium, steel, and carbon. The core of the doors  12 ,  13  can include any combination of the materials described above, and can include a plurality of layers of any combination of the materials described above. 
         [0019]    The outer surface of the doors  12 ,  13  are preferably constructed of carbon steel plate face panels and a minimum ½ inch thick edge banding along the top, bottom, and trailing edge of the door. The outer surface of the doors  12 ,  13  can be coated and finished with any suitable material including plastic, wood or metal laminates. 
         [0020]    The leading edge of each of the bi-parting doors  12 ,  13  preferably have complementary tortuous paths to prevent radiation leakage when the doors  12 ,  13  are closed. The tortuous paths extend the length of the doors  12 ,  13  in a direction perpendicular to the seam  11  formed between the two doors  12 ,  13  when the doors  12 ,  13  are closed. 
         [0021]    As shown in  FIG. 2A . the leading edges of the bi-parting doors  12 ,  13  can include complementary sine-wave shaped edges  126 ,  127 . Alternatively, as shown in  FIG. 2B , the leading edges of the bi-parting doors  12 ,  13  can include triangular interlocking shaped edges  226 ,  227 . As shown in  FIG. 2C , the leading edges of the bi-parting doors  12 ,  13  can also include interlocking curved edges  326 ,  327 . Any shape of the leading edges is sufficient so long as the leading edges form a tortuous path in a direction that is perpendicular to the seam  11  between the doors  12 ,  13  to prevent radiation leakage. Due to the tortuous path of the leading edge of the doors  12 ,  13 , astragals are not necessary as are typically required with straight edge doors. 
         [0022]    In an alternate embodiment shown in  FIG. 3 , the door assembly  10  can consist of a single sliding door  412 . The single sliding door  412  has a leading edge  426  with a tortuous path, which can include, but is not limited, to the tortuous paths shown in  FIGS. 2A, 2B, and 2C . A fixed member  422 , such as, and without limitation, a panel or fixed door, is preferably secured to the wall  42  outside of the radiation therapy room  2  and includes an edge  427  having a complementary tortuous path to the leading edge  426  on the single door  412 . 
         [0023]    Highly efficient hinged shielded doors used in direct entry radiation therapy rooms take approximately 10-12 seconds to move from an open position to a closed position, and vice-versa. The bi-parting door assembly  10  of the present application can move from an open position to a closed position in approximately 5-6 seconds, which reduces the waiting time for a treatment technician to move in and out of the room. 
         [0024]    A drive assembly  16  drives the bi-parting doors  12 ,  13  or single door  412  between an open and closed configuration. The drive assembly  16  can include any suitable driving mechanism. Preferably, the drive assembly  16  includes magnets to magnetically propel the doors  12 ,  13  along a track  15  preferable having a linear shape. Because the doors  12 ,  13  are magnetically propelled, there are fewer mechanical problems related to gears and drive systems. Due to the lack of moving parts in the drive assembly  16 , the overall failure rate of the sliding door assembly  10  is reduced. Alternatively, a track support mechanism having guidance rollers can be used to opening and closing the doors  12 ,  13 . 
         [0025]    The width of the passageway  60  to the radiation therapy room  2  when the sliding door assembly  10  is open may vary depending on the type of room the sliding door assembly  10  is used in, but should at least be suitable for a person to walk through, for example approximately 36-46 inches wide. In research or medical particle facilities, the passageway  60  may be wider to accommodate equipment to be moved in and out of the room, such as wheel chairs, stretchers, and lab equipment. In addition, the sliding door or doors  12 ,  13  can be removable in order to create additional space to move equipment in and out of the room. 
         [0026]    To prevent the sliding door assembly  10  from closing when a person or object is in the passageway  60 , a sensor  18  may be arranged to detect whether an object is in the passageway  60 . A sensor  18  may be placed in the floor, ceiling, or in the area adjacent to the sliding door assembly  10  to detect when a person or object is approaching the passageway  60 . Preferably, a plurality of sensors are used to enhance accuracy. The sensor  18  may be, for example and without limitation, a pressure sensor arranged in the floor of the sliding door assembly  10 , an ultrasonic presence detecting sensor, or an infra-red light sensor. The sensor  18  may be configured to relay signals to a control system  40  which includes a programmable touch screen interface and is electrically connected to the drive assembly  16  to control operation of the sliding door assembly  10 . When the sensor  18  detects a person or object in the passageway  60 , the control system  40  prevents the drive assembly  16  from moving the door or doors  12 ,  13 . 
         [0027]    A secondary sliding door assembly  34  comprised or one or more sliding panels  32  can be positioned exterior to the sliding door assembly  10  as an additional safety precaution against the sliding door assembly  10  closing on a person or object in the passageway  60 . The panel or panels  32  are preferably made of a thin, lightweight material, such as plastic or plexiglass. The panel or panels  32  can be operated to close before the sliding door assembly  10 . The panel or panels  32  can be driven by either the same drive assembly  16  or a separate drive assembly as the sliding door assembly  10 . The panels  32  are prevented from closing if the sensor  18  detects an object or person within the detection area. 
         [0028]    The sliding door assembly  10  preferably operates on a 220 volt, three-phase, 30 amp power supply with low voltage wiring to the drive assembly  16 , control system  40 , sensor  18 , and any other electronic components. In the event of a power failure, the magnetic propulsion drive assembly  16  would fail. The sliding door assembly  10  includes a manual operation mode wherein at least one of the doors  12 ,  13  and the panel  32  can manually open and close under their own power or by a battery back-up system. 
         [0029]    While a sliding door assembly has been described herein, one of ordinary skill in the art would also recognize that the sliding door assembly could also be modified for use as a window. As shown in  FIG. 4 , a window  48  can be positioned in the wall  42  for an operator or other person to view the radiation therapy room. The window  48  includes a similar single sliding panel or bi-parting sliding panels, track, and drive assembly as described herein with respect to the sliding door assembly. 
         [0030]    While various methods, configurations, and features of the present invention have been described above and shown in the drawings, one of ordinary skill in the art will appreciate from this disclosure that any combination of the above features can be used without departing from the scope of the present invention. It is also recognized by those skilled in the art that changes may be made to the above described methods and embodiments without departing from the broad inventive concept thereof.