Patent Number: 059819642
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view of a typical X-ray procedure table 10 and an embodiment of the adjustable X-ray shield 100 according to the present invention attached thereto. During a catheter procedure, for example, the patient's head rests on the narrow portion 11 of the table 10, while the patient's feet lie toward the wide portion 12 of the table 10. The physician normally stands to the patient's right, near waist level. The shape of the table 10, it is to be understood, may vary from that shown in FIG. 1. The embodiment of the adjustable X-ray shield 100 shown in FIG. 1 includes an adjustable frame assembly 30 attached to the table 10, and a plurality of sheets of radio-opaque shielding material attached thereto, such as sheets 20, 21, 22 and 23 (best shown in FIG. 3). The sheets of radio-opaque material 20, 21, 22 and 23 may include lead or any material suitable for blocking or attenuating radiation of other wavelengths. The sheet of radio-opaque shielding material 20, according to an embodiment of the present invention, is adjustably disposed alongside the procedure table 10, from an adjustable distance above the surface of the table 10 to about the surface of the floor. The sheet of radio-opaque shielding material 22 is adjustably disposed across and above the surface of the table 10, at about the patient's waist level, as the patient (not shown) lays on the table 10. The sheet 22 may have a generally rectangular shape and may include a cutout portion to accommodate the patient's waist or legs. The sheet of radio-opaque shielding material 21 is disposed across the width of the table 10, generally at the level of the patient's waist on the table 10, and spans the distance from just underneath the table 10 to about the surface of the floor. According to the present invention, the sheets of radio-opaque shielding material 20, 21 and 22 at least partially surround the X-ray tube (not shown), which is generally located within the corner formed by the shields 20 and 21. Investigations into the sources of radiation during interventional procedures have revealed that some direct radiation may reach the physician as a result of a less than perfectly collimated X-ray source, and that substantial amounts of radiation are scattered by the table and the patient's body. A substantial portion of this scatter, it has been found, is directed back underneath the table, toward the physician's lower body. The sheet 21, according to the present invention, protects the physician from this X-ray scatter directed back underneath the table by substantially partitioning the X-ray tube from the physician. Another portion of radiation travels through the patient's body, and is scattered thereby, in all directions. It has further been found that, of this scatter, a substantial portion emerges through the patient's hip and thigh region, near the physician. This unexpected finding is addressed in the present invention by providing at least one sheet of radio-opaque material 22 across the patient's hips and waist, at an adjustable distance above the surface of the procedure table 10. The sheet 22, disposed across the width of the table 10, protects the physician from the scatter that originates from the patient's body. In this manner, the physician is further protected against harmful scatter, particularly scatter originating from the table itself and from the patient's body. FIG. 2 shows a side view of the adjustable frame assembly 30 of an embodiment of the adjustable X-ray shield according to the present invention, whereas FIG. 3 shows a perspective elevation view of the adjustable X-ray shield 100. Considering now FIGS. 2 and 3 collectively, the frame assembly 30 of the adjustable X-ray shield 100 includes a main support bar 1 mounted substantially vertically on the table 10 near the patient's waist level. The main support bar 1 extends both above the surface of the table 10 and underneath the table 10. A first transversal support bar 5 is attached to the main support bar 1 just below the table 10. The first transversal support bar 5 extends across the width of the table 10 or across a substantial portion thereof, as best shown in FIG. 3. A second transversal support bar 6 is pivotally mounted to the main support bar 1 above the surface of the table 10 and also extends across the width of the table 10 or a substantial portion thereof, as shown in FIGS. 2 and 3. A first longitudinal bar 7, shown in FIG. 3, is pivotally mounted to the main support bar 1 above the surface of the table 10 and extends along a portion of the length of the table 10 from the main support bar 1 to at least past the patient's chest. As shown in FIG. 3, the first longitudinal support bar 7 may include an articulated joint 32, thereby allowing the physician to swing a portion of the first longitudinal support bar 7 and any attached sheet of radio-opaque shielding material away from the table 10. The first transversal, the second transversal and the first longitudinal support bars 5, 6 and 7 may be made from metal such as stainless steel or aluminum, from a radiolucent material, such as carbon fiber or from a combination thereof. As shown in FIGS. 2 and 3, the second transversal and the first longitudinal bars 6, 7 are pivotally attached to the main support bar 1 by respective clevis joints 9, 8 having respective pivot pins (not shown). Tightening the pivot pins increases the friction in the levis joints 9, 8. The main support bar 1 includes an outer support tube 2 below the table 10, an upper support tube 3 above the table 10 and a telescoping support bar 4 slidingly mounted at least within the upper support tube 3. The telescoping support bar 4 allows the height of the second transversal and first longitudinal support bars 6, 7 and thus of the sheets 20, 22 and 23 to be adjusted above the surface of the table to accommodate the patient's body habitus and to provide optimal radiation attenuation. For applications in which shielding is desired for personnel positioned on the side of the table 10 opposite to the side closest to the first longitudinal support bar 7 (the patient's left side as he or she is laying on the procedure table 10), a second upper support assembly, similar to upper support assembly 3, may be attached to the outer support tube 16. A second longitudinal support bar may then be attached by a clevis joint to the second upper support assembly. When a sheet of radio-opaque shielding material similar to sheet 20 is attached to this second longitudinal support bar, additional shielding on the patient's left side will be obtained. The second upper support assembly, the second longitudinal support bar, the levis joint connecting the two, as well as the sheet of radio-opaque shielding material attached to the second longitudinal support bar are not shown, for clarity, as their structures are similar to their counterparts on the patient's right side. For applications in which it is anticipated that X-ray scatter will be a factor above the level of the second transversal and first longitudinal support bars 6, 7, additional shielding may be required. This may be achieved by means of a ceiling mounted transparent leaded acrylic shield with a 1 millimeter lead equivalency, which is available from, for example, Minex Engineering, Antioch, Calif. As shown in FIG. 2, the first transversal support bar 5 includes a telescoping extender bar 15, allowing the adjustable frame assembly 30 according to the present invention to accommodate procedure tables of varying widths. The X-ray shield according to the present invention may be integral to the procedure table 10. Alternatively, as shown in both FIGS. 2 and 3, the X-ray shield according to the present invention may be removably attached to the table 10 by means of a clamping assembly. Preferably, as in the embodiment shown in FIG. 2, the upper support tube 3 should be removable, allowing the clamping assembly to remain attached to the table 10 at all times, if the adjustable shield according to the present invention is not to be used for a particular case. The clamping assembly may include mounting pads 13 and 14, which mounting pads support the adjustable frame assembly 30 on the table 10. The mounting pads 13 and 14 are placed on opposite sides and across the width of the procedure table 10. The separation between the mounting pads 13 and 14 is adjustable by means of the telescoping extender bar 15 of the first transversal support bar 5. According to one embodiment of the present invention, the clamping assembly includes a bell crank mechanism attached to the first transversal support bar 5 underneath the table 10 to secure the adjustable frame assembly 30 to the table 10. As shown in FIG. 2, the bell crank mechanism may include a pair of rectangular blocks 17, 18 each of which is pivotally attached to one end of a pair of center pivots 24, 25, respectively. The pair of rectangular blocks 17, 18 may be made of hard plastic or from other suitably hard material. The pair of rectangular blocks 17, 18 may be attached to the pair of center pivots 24, 25 by a pair of screws, for example. Likewise, the pair of center pivots 24, 25 may also be pivotally attached to the first transversal support bar 5 by means of screws or other suitable fasteners. Attached to the other end of the center pivots 24, 25 are a pair of threaded cylinders 26, 27, respectively. The threaded cylinders 26, 27 include respective cylinder threads 28, 29. The threaded cylinders 26, 27 are inserted through a threaded bore within the outer support tube 16 and the outer support tube 2 of the main support tube 1. Turning the threaded cylinder heads 31, 32 of the threaded cylinders 26, 27, respectively, causes the rectangular blocks 17, 18 to act like cams on the undersurface of the table 10 and exert a force thereon. The table 10 is then squeezed between the two rectangular blocks 17, 18, catching respective edges of the underside of the table 10. The rectangular blocks 17, 18 also exert a force component toward the mounting pads 14 and 13, respectively, further securing the adjustable frame assembly 30 to the table 10. It is to be noted that the embodiment of the clamping assembly described herein and shown in the referenced figures is but one of many possible embodiments of such a clamping assembly. Indeed, any such clamping assembly that is effective in securing the adjustable frame assembly 30 to the table 10 may be implemented within the context of the present invention. Whichever clamping assembly is implemented, however, must attach the adjustable frame assembly 30 to the table 10 with sufficient strength to allow the frame assembly to securely and safely support the combined weight of at least the sheets of radio-opaque shielding material 20, 21, 22 and 23. As shown in FIG. 3, at least one sheet of radio-opaque shielding material, such as sheets 20, 21, 22 and 23, is attachable to the first transversal support bar 5, the second transversal support bar 6 and the first longitudinal support bar 7. For example, the second transversal support bar 6 may support not only the sheet 22 having the cutout portion therein, but also another sheet of radio-opaque shielding material 23 draped over the patient's pelvic and thigh areas to attenuate scatter therefrom. The sheet 23 may be a rectangular sheet of radio-opaque material and may be attached to the second transversal support 6 adjacently to the main support bar 1. Providing additional shielding, the sheet of radio-opaque material 21 is particularly effective in attenuating X-ray scatter originating from underneath the table, while affording the physician with unobstructed space in which to stand. Such sheet 21 is attached to the first transversal support bar 5 and spans substantially the width of the table 10 from just underneath the table 10 to the floor surface. As shown in FIG. 2, the sheets of radio-opaque shielding material may overlap one another, to provide overlapping coverage along at least the vertical axis of the main support bar 1. Moreover, overlapping coverage may also be indicated on the patient's left side, along the axis of the second upper assembly support bar attached to the outer support tube 16, if the patient's left side is to be shielded. This overlapping coverage provides additional shielding when, for example, the second transversal and the first longitudinal support bars 6, 7 are swung away from their depicted positions. Such repositioning of the radio-opaque sheets may be necessary when the imaging angle is changed during a procedure. Preferably, the sheets 20, 21, 22 and 23 have at least a 1 millimeter lead equivalency rating. The sheets 20, 21, 22 and 23 may be attached to their respective support bars 7, 5, and 6 by any suitable means. Preferably, such attachment means allow the sheets 20, 21, 22 and 23 to be removable from the adjustable frame assembly 30. For example, VELCRO.RTM. hook and loop fasteners may be utilized with good results. The adjustable X-ray shield according to the present invention, as described and illustrated herein, is believed to be highly effective in blocking a substantial portion of scatter from the procedure table 10 itself, as well as from the patient's body. Accordingly, the present invention may allow the physician to dispense with a high lead equivalency (heavy) lead apron, or to dispense with the lead apron altogether. However, to insure the safety of the physician and that of other personnel present in the operating room, it is prudent to monitor the effectiveness of the adjustable shield. Moreover, as the shield must often be reconfigured and moved to accommodate changes in position of the X-ray tube, such monitoring should preferably be substantially constant to insure that the shield is optimally configured at all times to protect the physician from X-ray or other radiation scatter. According to another embodiment of the adjustable shield according to the present invention, at least one of the sheets of radio-opaque shielding material 20, 21, 22 and 23 (as well as those on the patient's left side, if present) includes at least one radiation sensor, such as an X-ray sensor. FIG. 4 shows an embodiment of an adjustable radiation shield according to the present invention, wherein the sheets 20, 21, 22 and 23 include a plurality of X-ray sensors attached thereto. The plurality of X-ray sensors 40 of FIG. 4 form an array of sensors that are connected to a data processing and display device, such as a computer 50 and a display 51. The display 51 is preferably visible to the physician during the interventional procedure, to allow the physician to monitor, in real time, the efficacy and proper deployment of the adjustable shield according to the present invention. The array of sensors 40 may be connected to the data processing and display device via a communication link 45, which may include wires, or may be a wireless communication channel. A plurality of additional sensors 46 (only two of which are shown in FIG. 4) are provided, which may be strategically placed anywhere in the operating room, or may be worn on the physician's or other caregiver's person, to provide a direct reading of the amount of radiation the physician (or other personnel in the room) is receiving and/or has cumulatively received. One of these additional sensors 46 may also be attached to the patient's back or to the table, to measure the patient's entrance dose of X-ray radiation. Although the additional sensors 46 are shown, in FIG. 4, as being attached to the computer 50, they may alternatively be connected to and form an integral part of the array of sensors 40 instead. The sensors 40, 46 may be semiconductor X-ray sensors, such as CdZnTe radiation sensors, available from eV Products, Saxonburg, Pa. The sensors 40 may be attached to the sheets 20, 21, 22 and 23 or may be sewn therein. The data processing and display device preferably allows the physician to view, in real time, his or her instantaneous radiation dose, as well as his or her cumulative radiation dose. Entrance dose data from the sensor attached to the patient's back may also be displayed. Historical radiation data for the physician may be stored within the data processing device 50, and such data may be later accessed and thereafter updated by entering a physician ID code, for example. In this manner, an accurate and timely source of radiation dose data may be acquired and maintained for each physician using the adjustable X-ray shield according to the present invention. According to one embodiment, the display 51 may display a graphical representation of the shield and radiation level indicia adjacent thereto or superimposed thereon. Such indicia may include color, numerical data or other perceptible and intuitive indication of radiation levels. To acquire the relevant radiation data, the sensors 40, 46 may be periodically polled, may generate interrupt signals, or may utilize some other protocol, thereby allowing the data processing and display unit to process and display real time radiation scatter data. Utilizing this real time information, the physician may make timely adjustments to the adjustable shield of the present invention to insure that it is optimally positioned at all times during a procedure. In this manner, the physician forms part of a feedback loop, alternately adjusting the shield and observing the resultant changes in the readings of the sensors 40, 46 on the display 51. Appropriate data acquisition and rendering software should be loaded and running on the computer 50. Should the display unit 51 show that one or more of the semiconductor sensors 40, 46 are registering an unacceptable level of scatter, an alarm may sound and the physician may then make any appropriate adjustments to the shield during the procedure to minimize radiation exposure. While the foregoing detailed description has described several embodiments of this invention, it is to be understood that the above description is illustrative only and not limiting of the disclosed invention. For example, the clamping assembly described herein may be varied to suit the particular procedure table utilized. Other details of the frame assembly or sheets of radio-opaque material may vary from that described and illustrated herein, without, however, departing from the spirit and scope of the present invention. For example, a letter "J" shaped rigid support member may be slid under the patient's right thigh and a sheet of radio-opaque shielding material may be draped thereon, to further protect the physician from scatter directed orthogonally from the patient's thigh. A number of other modifications will no doubt occur to persons of skill in this art. All such modifications, however, should be deemed to fall within the scope of the present invention. Thus, the invention is to be limited only by the claims as set forth below.