Patent Number: 059819642
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention pertains to the field of shielding structures for radiation procedure tables. In particular, the present invention pertains to adjustable X-ray shields for procedure tables and adjustable X-ray shielding systems using on-line radiation dosimetry. 2. Description of the Related Art During certain procedures, for example, those involving the insertion of an intravascular catheter (procedures such as atherectomy, balloon angioplasty, stent placement and the like), patients are required to lay prone on an X-ray procedure table. The physician then inserts a guidewire or a catheter device through a small incision, often near the patient's groin, and advances the device through an artery to the target site. To facilitate imaging of the intravascular device during use, the device may include a radio-opaque distal tip to allow the physician to guide the device under fluoroscopic observation to the desired site. During such procedures, the physician controls an X-ray tube, the source of the radiation used to visualize the target arterial site and the intravascular device, using a foot pedal. The X-ray tube is generally located underneath the table surface. The X-ray beam generated by the tube travels through the procedure table and the patient's body. The majority of the photons generated by the X-ray tube are scattered by the cells within the patient's body. A small portion of the generated X-ray beam, however, succeeds in traversing both the procedure table and the patient's body. A portion of the X-ray beam that traverses both the table and the patient's body reaches an image intensifier located above the patient. The image intensifier detects the photons, channels them through a photon multiplier and transfers the resulting intensified image to a display screen, which allows the physician to accurately guide the device. Interventional procedures such as described above often take hours to complete, and may expose the physician and the patient to a significant amount of radiation that may, over time, pose serious health risks. To reduce the physician's exposure to scattered X-ray radiation, a number of protective measures have been implemented. The first of such protective measures is the use of X-ray shields. Several types of X-ray shields have been developed. Lenhart, for example, in U.S. Pat. No. 5,006,718, proposes a shield assembly wherein shielding material extends from the side of the table adjacent the physician to the floor. However, such shield, while affording an unobstructed view of the patient, does not appear to protect the physician from the large amount of radiation scattered from the patient's body and above the level of the table. Other solutions generally involve the use of horizontally disposed strips of radiation shielding material, such as disclosed by Collica et al. in U.S. Pat. No. 3,984,696, or the use of vertically disposed strips of radiation shielding material hung from a position above the patient's body, as disclosed in Lenhart, U.S. Pat. No. 4,581,538 and Stivender et al., U.S. Pat. No. 4,062,518. However, both of these approaches appear to share common disadvantages. The first of these is that the physician's view of the patient, and the patient's view of the physician is severely impaired by the strips of shielding material. The second of these disadvantages appears to be an incomplete shielding of scattered radiation, in that significant portions of the patient's body are directly exposed to the physician. During the interventional X-ray procedure, a significant amount of scatter from these exposed portions may reach the physician, with deleterious health consequences. Moreover, with such conventional X-ray shields, unintended gaps in coverage may occur due to improperly positioned or repositioned shields, unknowingly exposing the physician to greatly increased radiation levels until the gap is discovered, if ever. Indeed, the shield often must be re-positioned during the procedure when the orientation of the X-ray tube is changed to change the imaging angle. Failure to properly reposition the shield thereafter may result in gaps in the shielding material. As X-ray radiation cannot be seen, heard or felt, such gaps may remain undiscovered and may expose the physician and other personnel in the procedure room to needlessly increased radiation levels. The second of such protective measures to protect the physician from unwanted scatter is the so-called lead apron. The lead apron is an article of clothing donned by the physician prior to a catheter procedure. The lead apron generally covers at least the neck including the thyroid, the torso, and the thighs. Leaded eyeglasses may also be worn. The apron is effective in significantly reducing the physician's instantaneous and cumulative exposure to X-ray radiation over time, at least with respect to the areas covered by the apron. In contrast, uncovered areas, such as the physician's hands, arms and lower legs, are protected, if at all, solely by the table's X-ray shield. Common lead aprons are equivalent to a lead barrier of about 0.25 to 0.5 millimeters in thickness. However, such protection, while effective, does not come without discomfort to the physician. Indeed, such lead aprons commonly weigh about fifteen to twenty pounds. As the physician may be required to bend over the patient for periods of time often measured in hours, a significant proportion of the weight of the lead apron may be borne by the physician's lower back, shoulder and neck area. Supporting such weight can, over time, cause intense lower back, neck and shoulder pain, particularly for those suffering from already weakened backs. What is needed, therefore, is an X-ray shield for an X-ray procedure table that more effectively protects the physician from X-ray scatter. What is also needed is an X-ray procedure shield for an X-ray procedure table that is highly effective in attenuating X-ray scatter while affording the physician a relatively unobstructed view of the patient during the X-ray procedure. What is also needed is an X-ray shield that is sufficiently effective in attenuating radiation to allow the physician to wear a lighter apron (e.g. one having a lower lead equivalency rating) or to allow the physician to safely forego wearing a lead apron or other uncomfortable protective gear altogether. Also needed are means for insuring, at all times, the proper positioning of the X-ray shield to achieve the greatest possible attenuation of radiation. SUMMARY OF THE INVENTION In accordance with the above-described objects and those that will be mentioned and will become apparent below, the adjustable X-ray shield for an X-ray procedure table, according to an embodiment of the present invention comprises: a main support bar mounted substantially vertically on the table near a patient's waist level, the main support bar extending above and below a surface of the table; PA1 a first transversal support bar, the first transversal support bar being attached to the main support bar just below the table and extending substantially across a width of the table; PA1 a second transversal support bar, the second transversal support bar being pivotally mounted to the main support bar above the table and extending substantially across a width of the table; and PA1 a first longitudinal support bar, the first longitudinal support bar being pivotally mounted to the main support bar above the table and extending along a length of the table past the patient's chest level. PA1 a pair of center pivots, each attached near respective ends of the first transversal support bar; a pair of rectangular blocks, each pivotally attached to respective ends of each of the center pivots closest to an underside of the table; and a pair of threaded cylinders, each attached to respective other ends of each of the center pivots and disposed within respective threaded through bores in each of the main support bar and outer support tube. Tightening the pair of threaded cylinders within the threaded through bores causes the pair of rectangular blocks to exert a force on the table to secure the X-ray shield thereto. PA1 a main support bar, mountable substantially vertically on the table near a patient's waist level, such that the main support bar extends above and below a surface of the table; PA1 a first transversal support bar, attachable to the main support bar just below the table to extend substantially across a width of the table; PA1 a second transversal support bar, pivotally mountable to the main support bar above the table to extend across a width of the table; PA1 a first longitudinal support bar, pivotally mountable to the main support bar above the table to extend along a length of the table past the patient's chest level; and PA1 at least one sheet of radio-opaque shielding material attachable to at least one of the first transversal support bar, the second transversal support bar and the first longitudinal support bar. PA1 a first sheet of radio-opaque shielding material adjustably disposed alongside the procedure table, from a distance above a surface of the table to a floor surface; PA1 a second sheet of radio-opaque shielding material adjustably disposed across and above the surface of the table at a level of a patient's waist; and PA1 a third sheet of radio-opaque shielding material disposed across a width of the table from just underneath the table to about the floor surface, the first, second and third sheets of radio-opaque shielding material being supported by an adjustable frame assembly attached to the table. According to other exemplary embodiments, at least one sheet of radio-opaque shielding material is attachable to the first transversal support bar, the second transversal support bar and/or the first longitudinal support bar. The main support bar may include an outer support tube portion below the table; an upper support tube portion above the table; and a telescoping support bar slidingly mounted at least within the upper support tube, the telescoping support bar allowing adjustment of a height of the second transversal and first longitudinal support bars above the surface of the table. The first transversal support bar may include a telescoping extender bar to accommodate X-ray procedure tables of varying widths. The first longitudinal support bar may comprise an articulated joint. The adjustable X-ray shield may further comprise a first sheet of shielding material attached to the first transversal support bar that substantially spans the width of the table from an underside thereof to a floor surface. A second sheet of radio-opaque shielding material may be attached to the second transversal support bar adjacent the main support bar, the second sheet shielding material draping alongside the patient's pelvic and thigh areas to attenuate X-ray scatter therefrom. A third sheet of radio-opaque shielding material may be attached at least to the second transversal support bar, the third sheet of shielding material being of a generally rectangular shape and having a cutout portion for the patient's waist. The sheets of radio-opaque shielding material may provide overlapping coverage along the vertical axis of the main support bar. The main, first transversal, second transversal and first longitudinal support bars may be formed of metal and/or a radiolucent material. The radiolucent material may be a carbon fiber material. According to other embodiments, the X-ray shield may be removably secured to the table by means of a clamping assembly. The clamping assembly may comprise at least two mounting pads to be positioned on the table surface and a bell crank mechanism attached underneath the table surface to the first transversal support bar. A first end of the first transversal support bar may be attached to the main support bar and a second end thereof may be attached to an outer support tube. The bell crank mechanism may comprise: According to still further embodiments, the second transversal and first longitudinal support bars may be pivotally attached to the main support bar by respective clevis joints having respective pivot pins. In that case, tightening the respective pivot pins increases the friction in the respective clevis joints. A first end of the first transversal support bar may be attached to the main support bar and a second end thereof may be attached to an outer support tube and the X-ray shield may further comprise a second longitudinal support bar attached to the outer support tube such that the second longitudinal support bar is parallel to the first longitudinal support bar and disposed on an opposite side of the table; and a further sheet of radio-opaque shielding material attached to the second longitudinal support bar, to attenuate X-ray scatter on the opposite side of the table. According to another embodiment, at least one of the sheets of radio-opaque shielding material may comprise one or more radiation sensors. One or more of the sensors may be a semiconductor X-ray sensor, such as a Cadmium-Zinc-Telluride (CdZnTe) sensor in communication with a data processing and display device. A plurality of X-ray sensors may be attached to each of the one or more sheets of radio-opaque shielding material, to form an array of X-ray sensors, the array of sensors being connected to a data processing and display device to allow real time monitoring of X-ray radiation from the X-ray shield. One or more of the sensors may be attachable to the patient's back or to the table, to measure the patient's entrance dose of radiation. Moreover, one or more of the sensors may be attachable to a person other than the patient, such as the physician and/or other care givers, to measure scatter received by that person during a procedure on the patient. According to another embodiment, the present invention is a kit for an adjustable X-ray shield for a procedure table, comprising: According to another embodiment of the kit according to the present invention, the sheet or sheets of radio-opaque shielding material may comprise at least one X-ray sensor attached thereto. According to a further embodiment, the present invention is an X-ray shield for a procedure table, comprising: According to a still further embodiment, a procedure table radiation shield having on-line radiation dosimetry according to the present invention comprises a plurality of sheets of radio-opaque shielding material adjustably disposed on a frame assembly so as to protect a physician from radiation scatter during a radiation procedure, at least one of the plurality of sheets of radio-opaque shielding material including at least one radiation sensor. According to further embodiments, the array of radiation sensors may include at least one X-ray sensor, which may be a semiconductor X-ray sensor. Such a semiconductor X-ray sensor may be a CdZnTe sensor. The radiation sensor or sensors may be connectable to a data processing and display apparatus via a communication channel to allow the physician to view real time radiation readings from the display apparatus and to adjust a position of the plurality of sheets of radio-opaque shielding material in response to the readings to minimize exposure to radiation scatter during a radiation procedure. One or more of the radiation sensors may be attached to one of the sheets of radio-opaque shielding material and one or more of the radiation sensors may be adapted to be positioned anywhere within the procedure room or on a person within the procedure room.