CA1097440A - X-ray patient support stretcher and method for fabrication - Google Patents
X-ray patient support stretcher and method for fabricationInfo
- Publication number
- CA1097440A CA1097440A CA299,737A CA299737A CA1097440A CA 1097440 A CA1097440 A CA 1097440A CA 299737 A CA299737 A CA 299737A CA 1097440 A CA1097440 A CA 1097440A
- Authority
- CA
- Canada
- Prior art keywords
- fibers
- support stretcher
- stretcher
- radiolucent support
- radiolucent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/04—Positioning of patients; Tiltable beds or the like
- A61B6/0407—Supports, e.g. tables or beds, for the body or parts of the body
- A61B6/0442—Supports, e.g. tables or beds, for the body or parts of the body made of non-metallic materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/40—Shaping or impregnating by compression not applied
- B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
- B29C70/44—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
- A61G1/00—Stretchers
- A61G1/01—Sheets specially adapted for use as or with stretchers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
- B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
- B29C43/10—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies
- B29C43/12—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies using bags surrounding the moulding material or using membranes contacting the moulding material
Abstract
X-RAY PATIENT SUPPORT STRETCHER AND METHOD
FOR FABRICATION
A B S T R A C T
A patient support stretcher for X-ray units is formed by curing a multiple layered composite in situ on a balsa wood core.
The patient support stretcher, although having medium attenuation of X-rays, can be more efficiently fabricated. The balsa wood core allows the multiple layered composite skin containing fiber strengthened polymeric resin, to be concurrently cured and bonded with the balsa wood core.
FOR FABRICATION
A B S T R A C T
A patient support stretcher for X-ray units is formed by curing a multiple layered composite in situ on a balsa wood core.
The patient support stretcher, although having medium attenuation of X-rays, can be more efficiently fabricated. The balsa wood core allows the multiple layered composite skin containing fiber strengthened polymeric resin, to be concurrently cured and bonded with the balsa wood core.
Description
~0~4~) BACKGROUND OF THE INVENTION
The present invention relates to a composite patient support stretcher used to support patients during X-ray examinations, and, more particularly, to a polymeric resin strengthened fibrous shell with a balsa wood core support structure, and a method for forming the same.
The increasing application of X-ray medical procedures in lieu of such invasive techniques as surgery for examination, diagnosis or therapy, and the development of tomographic procedures (wherein X-rays of a predetermined plane section are made) to fulfill objectives which are unobtainable by conventional radiographical procedures'have promoted the usage of accessory X-ray equipment having characteristics particularly suited for a specific application.
In conventional radiology, for example, the patient is subjected to radiation from an X-ray tube acting as a point source. The attenuation o the rays (reduction of power per unit area with distance from the source) through the thickness of the patient's body is recorded on a single film. secause it is desirable to limit the radiation dose (radiation per unit volume of body tissue), it is important to reduce the attenuation attributable to accessory equipment, such as patient support stretchers, which is interposed within the X-ray path, in order to reduce the required source intensity. Thus, a patient support as sho~n in U.S. Patent 3,947,686 in the name Adrainus A. Cooper and Philip M. Leopold, dated March 30, 1976, is described as having low X-ray attenuation (equivalent to 1 mm Al or less), in addition to minimal deflection under load when supported in a cantilevered position. The support therein is formed with a polyurethane foam core and a shell composed of graphite fiber embedded in polyurethane. For convenience the shells may be fabricated from prepregs. Prepregs are pre-engineered, ready to mold combinations of resin and reinforcement. U.S. Patent 3,897,345 in the name Melvin L. Foster, dated July 29, 1975, also describes a patient support designed for low attenuation 10 purposes which is composed of a shell containing graphite or carbon fibers in a plastic resin matrix around and bonded to a rigid polyurethane core. Moreover, British Patent 1435223 in the name Siemens Akt.iengesellschaft, published May 12, 1976, discloses the use of panels composed of cast resin reinforced with carbon fiber material that has a hard foam core sandwiched between the panels in an apparatus for subjecting a patient to X-ray or gamma-ray examination or therapy. The apparatus is characterized as having considerable mechanical strength, and low X-ray and gamma-ray absorption.
The shells of the prior art patient support stretchers are typically cured in a mold prior to bonding with the foam cores ;
since application of the shell curing heat may be detrimental to the oam, particularly where polyurethane is used. The shells are subsequently bonded to the core. Thus, a multi-phase labor intensive procedure is required to form the stretchers, that is, separately molding the top shell and the bottom shell; trimming the shells; shaping the core; bonding the core to the bottom shell; and, bonding the top shell to the core-bottom shell combination.
~ -- 2 --10974~0 Case 4183 Since irregularlties in stretcher density can appear as images on conventional radiographic photo-graphs~ allowable density variations are stringently limited in order to preclude interpretation thereof as a tumor.
Recently~ tomographic procedures have been developed to proY1de images that reveal information which may be hidden from vie~ in conven~ional radiographlc diagnosis due to overlap of anatomical ~eatures. In computerized tomography~
for example, an image o~ a cross-sectlonal plane of a specimen ls developed by sequentially directing X-rays through the subject from a p:lurality of dir-ections. In the basic scanning process, a collimated `^
X-ray beam passes through the patient's body (and at ;
some angles through the stretcher), is attenuated to varying degrees, and impinges on a sensor which de-tects the amount of radiation received and electroni-cally converts it to a signal that may be recorded by a computer. Angular rotational movement of the rad~ation source is coordinated with that of the sensor. The patient typically is translated normal to the orbital plane defined by the rotation of the source-sensor pair. The X-ray profiles of each section are processed by the computer which can reconstruct the images that have been accumulated to depict cross sec~lons of the body.
Since tomographic techniques are not as sensitive to density variations as conventlonal radiographic techniques, the stretcher does not require precision density homogenelty~ Moreover3 because the X-ray be~n is well collimated, only the l~g~9~0 seetions being scanned are irradiated and overall dose reeeived for a eomplete sean of the seetion is eomparable to the dosage reeeived from a single eonventional X-ray. Thus, the signifieance of low patient support stretcher attenuation is less eritical than in eonventional radiography. The eombination of these factors is conducive to the use of core materials having medium attenuation but whieh ean be more effieiently fabricated.
SUMMARY OF THE INVENTION
In aeeordanee with the present invention there is provided a radiolucent support stretcher for supporting patients during X-ray examination which comprises: a balsa wood core having a longitudinal axis; a skin, said skin having a plurality of layers of a first composite with oriented fibers bound in a polymerie resin matrix, said plurality of layers being sandwiehed between a seeond eomposite of fiber prepreg impregnated with a polymerie resin; said skin being disposed about and bonded to said balsa wood.
The various features of novelty whieh eharaeteri2e the invention are pointed out with particularity in the claims annexed to and forming a part of this specifieation. For a better understanding of the invention, its operating advantages and speeifie objeets attained by its use, referenee should be had to the accompanying drawings and descriptive matter in which there is illustrated and deseribed a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, forming a part of this specification, and in which reference numerals shown in the drawings designate like or corresponding 109744~ Case 4183 parts throughout the same, Figure 1 is a perspective view of an X-ray scanning unit and X-ray tablej and Figure 2 is a perspective view, partly broken a~ay, of a patient support stretcher made in accordance with the in~entlon.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 illustrates a tomQgraphic X-ray ; ;
scanning unit, generally indicated by reference .
numeral 10, and an X-ray table 11 ha~ing a longi-tudinally extendable radiolucent patlent support stretcher 12. The X-ray scanning un;Lt contalns a scanning apparatus 13 rotatably mounted to a base member 14. The scanning apparatus 13 is pro~ided with an opening 15 of su~icient size to accommodate a patient (not shown) lyin~ prone upon the support stretcher 12.
As is best shown in Figure 2, the patient support stretcher 12 is generally co~posed of a core material 20 to which a skin 21 is adhered. In the referred embodiment, the core material is balsa wood laminate of and the skin is a/multi-layered composite composed of prepregs with fibers in a polymeric resin material.
In the preferred embodiment, support rails 22, 23 are appended to the lower side of the patient support oriented parallel to the longitudinal axis of the stretcher 12. The support rails 22, 23 are eceiYed withln channels (not shown~ o~ the X-ray table 11 ~or t~anslating/the stretcher 12 and patient through the openin~ 15 o~ the scannlng apparatus 13.
; Case 4183 7~'~
Other well known means may be used in lieu of the support rails 22, 23 for longitudinally extending the patient support stretcher~ End plates 24 (only one of which is shown~ cover the ends of the core.
The skin 21 includes a plurality of layers of vriented ~ibè~s in polymeric matrices that are sand~iched between a fahric prepreg impregnated with a polymeric resin to form the skin. The polymeric resin used in the skin could be an epoxy or a poly-ester. The fibers could be carbon, graphite or a fiber sold under the trademark Kevlar. For example~
layers o~ Narmco T300~5213, which is an epoxy matrix containing graphite ~ibers, produced by Narmco Materlals, Inc., Costa Mesa, California, were sand-wlched between a prepreg, also made by Narmco, known as 181 style Kevlar 49/5213, which is a prepreg con-tainlng Dupont's Kevlar 49 fiber woven in fabric form and impregnated with an epoxy resin. Kevlar is a high tensile modulus (higher than 8 x 106 psi ~, high tensile ~;
strength (higher than 3.5 x 105 psi~ aramid fiber. An aramid fiber may be described as a manufactured fiber in which the fiber-forming substance is a long-chain synthetic poly~nid in which at least eighty-five percent of the amid link~ges are attached directly to two aromatic rlngs. Some properties of Ke~lar 49 in fabric style 181 are illustrated in Ta~le I.
T A B L E
Density (lb in. 3~ ,047 Tensile Strength (kpsi) 75 ~ensile Modulus (Mpsi~ 4~7 7 G{t~ G
Case 4183 97~
T A B L E I (Cont.) .
Compressive Strength tkpsi) 27 Compresslve Modulus (Mpsi) 4.5 In-plane Shear Strength (kpsi~ 16 In-pl~ne Shear Modulus (~psi~ .3 The skin 21 need not be ~ormed continuously about the core. Moreover? in operation the stresses in the top portion of the patient support will be predominantly tenslle stresses, and those in the bottom of the stretcher compresslve. Hence, in the pre erred embodiment, the skin 21 is for~ed with separate and dist~nct top and bottom lami~ates or skins, each designed with fiber orlentat~ons to accomm_ odate the predominant stresses~ respectively~ in the top and bottom of the stretcher.
~he number o~ layers or plies o~ composite used to form the laminate are determined by the amount of attenuation allowable~ and the required ~trength and stiffness of the resulting patient support stretcher. The use of the fabric containing aramid fibers such as thQse marketed as KeYlar, to surface the composlte results in a scratch resistant patient support surface. Moreover, the fabric increases the strength of the stretcher in the ~idth direction, there-by increasing the stretcher's capability to withstand handling forces during installatiQn and during patient positioning.
Due to the fact that the thermal expansion and contraction of the fabric ls different from that o~ the unidirectional plies the fabric on thee~e side o~ the Case 4183 1~7~0 laminate is needed to make the laminate balanced and sy~metrical, thereby minimizing nonsYmmetrY Of the thermal stresses when the laminate cools off a~ter curing Nonsymmetry of the stresses can cause the delamination of the lamlnate or its separation ~rom the core of both.
Instead of or in combination with the unidirectional graphlte ~ibers~ unidirectlonal aram~d fibers could be used in the topskin where the stresses are predominantly tensile stresses, ~ince the compressive properties of Kevlar ~re substantially less than the tensile properties, the use o~ unidirection~l aramid flbers~is not advantageous in the bottom skin, where the stresses are predomlnantly compressive stresses.
Aramid fiber is less expensive than graphite or carbon, it has approximately the same X-ray attenuation and tensile strength but has a lower elastic modulus.
Use of aramid fibers may therefore be advantageous where large deflections o~ the stretcher are acceptable.
The characteristic properties of balsa wood, the lightest wood commercially available, allow selectlon of a composite and core system that are not adversely a~fected by temperatures detrimental to the foam cores o~ the prior art. Hence, the patient support stretcher 12 m~y be formed by concurrently curing the skin in situ while b~nding to the balsa wood core 20 This eliminates the steps of pre-molding the skin, and subsequently bonding the pre-molded skin to the core.
In order to form the patient support stretcher, a balsa wood core is cut to the desired shape. The wood core iæ sealed typically with a resin component 1097441D Case 4183 which is compatl~le with the polymeri~ resin in the skin prepregs. ~;
In the preferred embodiment, top and bottom support stretcher skins are laid up and cured cQnsecu-tively~ forming lap Joints where they meet on each side of the stretcher. A prepreg consisting of the aramld fiber fabrlc lmpregnated with a polymeric resin is applied to the balsa wood core such that one group (weave) of the interwoven fibers in the fabric is oriented in parallel with the length of the stretcher. Multiple layers of prepregs containing resin with oriented flber aligned parallel to the longitudinal axis of the stretcher are then layered on the stretcher, followed by a final layer of the described aramid fiber prepreg. The components are then sub~ected to conventional vacuum bag molding techniques and cured, in order to cause the plies of composite to laminate and bond to the balsa wood core.
It will be evident to those skilled in the art that additional changes may be made without departing from the scope of the claimed invention.
The present invention relates to a composite patient support stretcher used to support patients during X-ray examinations, and, more particularly, to a polymeric resin strengthened fibrous shell with a balsa wood core support structure, and a method for forming the same.
The increasing application of X-ray medical procedures in lieu of such invasive techniques as surgery for examination, diagnosis or therapy, and the development of tomographic procedures (wherein X-rays of a predetermined plane section are made) to fulfill objectives which are unobtainable by conventional radiographical procedures'have promoted the usage of accessory X-ray equipment having characteristics particularly suited for a specific application.
In conventional radiology, for example, the patient is subjected to radiation from an X-ray tube acting as a point source. The attenuation o the rays (reduction of power per unit area with distance from the source) through the thickness of the patient's body is recorded on a single film. secause it is desirable to limit the radiation dose (radiation per unit volume of body tissue), it is important to reduce the attenuation attributable to accessory equipment, such as patient support stretchers, which is interposed within the X-ray path, in order to reduce the required source intensity. Thus, a patient support as sho~n in U.S. Patent 3,947,686 in the name Adrainus A. Cooper and Philip M. Leopold, dated March 30, 1976, is described as having low X-ray attenuation (equivalent to 1 mm Al or less), in addition to minimal deflection under load when supported in a cantilevered position. The support therein is formed with a polyurethane foam core and a shell composed of graphite fiber embedded in polyurethane. For convenience the shells may be fabricated from prepregs. Prepregs are pre-engineered, ready to mold combinations of resin and reinforcement. U.S. Patent 3,897,345 in the name Melvin L. Foster, dated July 29, 1975, also describes a patient support designed for low attenuation 10 purposes which is composed of a shell containing graphite or carbon fibers in a plastic resin matrix around and bonded to a rigid polyurethane core. Moreover, British Patent 1435223 in the name Siemens Akt.iengesellschaft, published May 12, 1976, discloses the use of panels composed of cast resin reinforced with carbon fiber material that has a hard foam core sandwiched between the panels in an apparatus for subjecting a patient to X-ray or gamma-ray examination or therapy. The apparatus is characterized as having considerable mechanical strength, and low X-ray and gamma-ray absorption.
The shells of the prior art patient support stretchers are typically cured in a mold prior to bonding with the foam cores ;
since application of the shell curing heat may be detrimental to the oam, particularly where polyurethane is used. The shells are subsequently bonded to the core. Thus, a multi-phase labor intensive procedure is required to form the stretchers, that is, separately molding the top shell and the bottom shell; trimming the shells; shaping the core; bonding the core to the bottom shell; and, bonding the top shell to the core-bottom shell combination.
~ -- 2 --10974~0 Case 4183 Since irregularlties in stretcher density can appear as images on conventional radiographic photo-graphs~ allowable density variations are stringently limited in order to preclude interpretation thereof as a tumor.
Recently~ tomographic procedures have been developed to proY1de images that reveal information which may be hidden from vie~ in conven~ional radiographlc diagnosis due to overlap of anatomical ~eatures. In computerized tomography~
for example, an image o~ a cross-sectlonal plane of a specimen ls developed by sequentially directing X-rays through the subject from a p:lurality of dir-ections. In the basic scanning process, a collimated `^
X-ray beam passes through the patient's body (and at ;
some angles through the stretcher), is attenuated to varying degrees, and impinges on a sensor which de-tects the amount of radiation received and electroni-cally converts it to a signal that may be recorded by a computer. Angular rotational movement of the rad~ation source is coordinated with that of the sensor. The patient typically is translated normal to the orbital plane defined by the rotation of the source-sensor pair. The X-ray profiles of each section are processed by the computer which can reconstruct the images that have been accumulated to depict cross sec~lons of the body.
Since tomographic techniques are not as sensitive to density variations as conventlonal radiographic techniques, the stretcher does not require precision density homogenelty~ Moreover3 because the X-ray be~n is well collimated, only the l~g~9~0 seetions being scanned are irradiated and overall dose reeeived for a eomplete sean of the seetion is eomparable to the dosage reeeived from a single eonventional X-ray. Thus, the signifieance of low patient support stretcher attenuation is less eritical than in eonventional radiography. The eombination of these factors is conducive to the use of core materials having medium attenuation but whieh ean be more effieiently fabricated.
SUMMARY OF THE INVENTION
In aeeordanee with the present invention there is provided a radiolucent support stretcher for supporting patients during X-ray examination which comprises: a balsa wood core having a longitudinal axis; a skin, said skin having a plurality of layers of a first composite with oriented fibers bound in a polymerie resin matrix, said plurality of layers being sandwiehed between a seeond eomposite of fiber prepreg impregnated with a polymerie resin; said skin being disposed about and bonded to said balsa wood.
The various features of novelty whieh eharaeteri2e the invention are pointed out with particularity in the claims annexed to and forming a part of this specifieation. For a better understanding of the invention, its operating advantages and speeifie objeets attained by its use, referenee should be had to the accompanying drawings and descriptive matter in which there is illustrated and deseribed a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, forming a part of this specification, and in which reference numerals shown in the drawings designate like or corresponding 109744~ Case 4183 parts throughout the same, Figure 1 is a perspective view of an X-ray scanning unit and X-ray tablej and Figure 2 is a perspective view, partly broken a~ay, of a patient support stretcher made in accordance with the in~entlon.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 illustrates a tomQgraphic X-ray ; ;
scanning unit, generally indicated by reference .
numeral 10, and an X-ray table 11 ha~ing a longi-tudinally extendable radiolucent patlent support stretcher 12. The X-ray scanning un;Lt contalns a scanning apparatus 13 rotatably mounted to a base member 14. The scanning apparatus 13 is pro~ided with an opening 15 of su~icient size to accommodate a patient (not shown) lyin~ prone upon the support stretcher 12.
As is best shown in Figure 2, the patient support stretcher 12 is generally co~posed of a core material 20 to which a skin 21 is adhered. In the referred embodiment, the core material is balsa wood laminate of and the skin is a/multi-layered composite composed of prepregs with fibers in a polymeric resin material.
In the preferred embodiment, support rails 22, 23 are appended to the lower side of the patient support oriented parallel to the longitudinal axis of the stretcher 12. The support rails 22, 23 are eceiYed withln channels (not shown~ o~ the X-ray table 11 ~or t~anslating/the stretcher 12 and patient through the openin~ 15 o~ the scannlng apparatus 13.
; Case 4183 7~'~
Other well known means may be used in lieu of the support rails 22, 23 for longitudinally extending the patient support stretcher~ End plates 24 (only one of which is shown~ cover the ends of the core.
The skin 21 includes a plurality of layers of vriented ~ibè~s in polymeric matrices that are sand~iched between a fahric prepreg impregnated with a polymeric resin to form the skin. The polymeric resin used in the skin could be an epoxy or a poly-ester. The fibers could be carbon, graphite or a fiber sold under the trademark Kevlar. For example~
layers o~ Narmco T300~5213, which is an epoxy matrix containing graphite ~ibers, produced by Narmco Materlals, Inc., Costa Mesa, California, were sand-wlched between a prepreg, also made by Narmco, known as 181 style Kevlar 49/5213, which is a prepreg con-tainlng Dupont's Kevlar 49 fiber woven in fabric form and impregnated with an epoxy resin. Kevlar is a high tensile modulus (higher than 8 x 106 psi ~, high tensile ~;
strength (higher than 3.5 x 105 psi~ aramid fiber. An aramid fiber may be described as a manufactured fiber in which the fiber-forming substance is a long-chain synthetic poly~nid in which at least eighty-five percent of the amid link~ges are attached directly to two aromatic rlngs. Some properties of Ke~lar 49 in fabric style 181 are illustrated in Ta~le I.
T A B L E
Density (lb in. 3~ ,047 Tensile Strength (kpsi) 75 ~ensile Modulus (Mpsi~ 4~7 7 G{t~ G
Case 4183 97~
T A B L E I (Cont.) .
Compressive Strength tkpsi) 27 Compresslve Modulus (Mpsi) 4.5 In-plane Shear Strength (kpsi~ 16 In-pl~ne Shear Modulus (~psi~ .3 The skin 21 need not be ~ormed continuously about the core. Moreover? in operation the stresses in the top portion of the patient support will be predominantly tenslle stresses, and those in the bottom of the stretcher compresslve. Hence, in the pre erred embodiment, the skin 21 is for~ed with separate and dist~nct top and bottom lami~ates or skins, each designed with fiber orlentat~ons to accomm_ odate the predominant stresses~ respectively~ in the top and bottom of the stretcher.
~he number o~ layers or plies o~ composite used to form the laminate are determined by the amount of attenuation allowable~ and the required ~trength and stiffness of the resulting patient support stretcher. The use of the fabric containing aramid fibers such as thQse marketed as KeYlar, to surface the composlte results in a scratch resistant patient support surface. Moreover, the fabric increases the strength of the stretcher in the ~idth direction, there-by increasing the stretcher's capability to withstand handling forces during installatiQn and during patient positioning.
Due to the fact that the thermal expansion and contraction of the fabric ls different from that o~ the unidirectional plies the fabric on thee~e side o~ the Case 4183 1~7~0 laminate is needed to make the laminate balanced and sy~metrical, thereby minimizing nonsYmmetrY Of the thermal stresses when the laminate cools off a~ter curing Nonsymmetry of the stresses can cause the delamination of the lamlnate or its separation ~rom the core of both.
Instead of or in combination with the unidirectional graphlte ~ibers~ unidirectlonal aram~d fibers could be used in the topskin where the stresses are predominantly tensile stresses, ~ince the compressive properties of Kevlar ~re substantially less than the tensile properties, the use o~ unidirection~l aramid flbers~is not advantageous in the bottom skin, where the stresses are predomlnantly compressive stresses.
Aramid fiber is less expensive than graphite or carbon, it has approximately the same X-ray attenuation and tensile strength but has a lower elastic modulus.
Use of aramid fibers may therefore be advantageous where large deflections o~ the stretcher are acceptable.
The characteristic properties of balsa wood, the lightest wood commercially available, allow selectlon of a composite and core system that are not adversely a~fected by temperatures detrimental to the foam cores o~ the prior art. Hence, the patient support stretcher 12 m~y be formed by concurrently curing the skin in situ while b~nding to the balsa wood core 20 This eliminates the steps of pre-molding the skin, and subsequently bonding the pre-molded skin to the core.
In order to form the patient support stretcher, a balsa wood core is cut to the desired shape. The wood core iæ sealed typically with a resin component 1097441D Case 4183 which is compatl~le with the polymeri~ resin in the skin prepregs. ~;
In the preferred embodiment, top and bottom support stretcher skins are laid up and cured cQnsecu-tively~ forming lap Joints where they meet on each side of the stretcher. A prepreg consisting of the aramld fiber fabrlc lmpregnated with a polymeric resin is applied to the balsa wood core such that one group (weave) of the interwoven fibers in the fabric is oriented in parallel with the length of the stretcher. Multiple layers of prepregs containing resin with oriented flber aligned parallel to the longitudinal axis of the stretcher are then layered on the stretcher, followed by a final layer of the described aramid fiber prepreg. The components are then sub~ected to conventional vacuum bag molding techniques and cured, in order to cause the plies of composite to laminate and bond to the balsa wood core.
It will be evident to those skilled in the art that additional changes may be made without departing from the scope of the claimed invention.
Claims (19)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A radiolucent support stretcher for supporting patients during X-ray examination which comprises: a balsa wood core having a longitudinal axis; a skin, said skin having a plurality of layers of a first composite with oriented fibers bound in a polymeric re-sin matrix, said plurality of layers being sandwiched between a second composite of fiber prepreg impregnated with a polymeric re-sin; said skin being disposed about and bonded to said balsa wood.
2. A radiolucent support stretcher as defined in claim 1, fur-ther comprising means for translating said support stretcher.
3. A radiolucent support stretcher as defined in claim 1, wherein said fiber prepreg includes aramid fibers.
4. A radiolucent support stretcher as defined in claim 3, wherein said aramid fibers are woven in fabric form.
5. A radiolucent support stretcher as defined in claim 4, wherein said oriented fibers are oriented parallel to said longitu-dinal axis.
6. A radiolucent support stretcher as defined in claim 5, wherein said polymeric resin is an epoxy.
7. A radiolucent support stretcher as defined in claim 6, wherein said layers of fibers include graphite fibers.
8. A radiolucent support stretcher as defined in claim 6, wherein said layers of fibers include carbon fibers.
9. A radiolucent support stretcher as defined in claim 6, wherein said layers of fibers include aramid fibers.
10. A radiolucent support stretcher as defined in claim 5, wherein said polymeric resin is a polyester.
11. A radiolucent support stretcher as defined in claim 10, wherein said layers of fibers include graphite fibers.
12. A radiolucent support stretcher as defined in claim 10, wherein said layers of fibers include carbon fibers.
13. A radiolucent support stretcher as defined in claim 10, wherein said layers of fibers include aramid fibers.
14. A radiolucent support stretcher as defined in claim 1 or 2, wherein said skin includes a top skin bonded to the top of said balsa wood core and a bottom skin bonded to the bottom of said bal-sa wood core.
15. A radiolucent support stretcher as defined in claim 14, wherein said fiber prepreg is woven in fabric form.
16. A radiolucent stretcher as defined in claim 15, wherein said oriented fibers in said top skin, one group of interwoven fi-bers in said fabric form of said fiber prepreg in said top skin, and said oriented fibers in said first composite of said bottom skin are all oriented parallel to said longitudinal axis.
17. A radiolucent support stretcher as defined in claim 16, wherein said polymeric resin in said first and second composites is selected from the group consisting of epoxy and polyester.
18. A radiolucent support stretcher as defined in claim 17, wherein said fibers in said first and second composites are selected from the group consisting of aramid, graphite and carbon.
19. A radiolucent support stretcher as defined in claim 18, wherein the same ploymeric resin is used in said first composite and in said second composite.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/829,401 US4145612A (en) | 1977-08-31 | 1977-08-31 | X-ray patient support stretcher and method for fabrication |
| US829,401 | 1977-08-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1097440A true CA1097440A (en) | 1981-03-10 |
Family
ID=25254440
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA299,737A Expired CA1097440A (en) | 1977-08-31 | 1978-03-23 | X-ray patient support stretcher and method for fabrication |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4145612A (en) |
| CA (1) | CA1097440A (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4252594A (en) * | 1977-08-31 | 1981-02-24 | The Babcock & Wilcox Company | X-ray patient support stretcher and method for fabrication |
| US4698837A (en) * | 1985-03-11 | 1987-10-06 | Amatech Corporation | Armboard mounting assembly |
| US4912787A (en) * | 1987-03-30 | 1990-04-03 | Beta Medical Products | Hydraulic stretcher device |
| US4926457A (en) * | 1988-01-29 | 1990-05-15 | Hill-Rom Company, Inc. | Radiolucent hospital bed surface |
| DE3833594A1 (en) * | 1988-10-03 | 1990-04-05 | Philips Patentverwaltung | PATIENT TABLE FOR DIAGNOSTIC DEVICES |
| EP0777440B1 (en) * | 1995-05-23 | 2005-01-19 | Patrik Dr. Rogalla | Device for computer tomography transillumination for treatment |
| US6456684B1 (en) * | 1999-07-23 | 2002-09-24 | Inki Mun | Surgical scanning system and process for use thereof |
| US6499158B1 (en) | 2000-10-30 | 2002-12-31 | Steris, Inc. | Surgical table top and accessory clamp used thereon |
| US7020917B1 (en) | 2001-03-12 | 2006-04-04 | Steris Corporation | Radiolucent surgical table with low shadow accessory interface profile |
| US6598275B1 (en) | 2001-03-12 | 2003-07-29 | Steris, Inc. | Low shadow radiolucent surgical table, clamp systems, and accessories therefore |
| US6782571B1 (en) * | 2001-11-30 | 2004-08-31 | Ge Medical Systems | Patient transport system for multiple imaging systems |
| US6902320B2 (en) * | 2002-10-03 | 2005-06-07 | Analogic Corporation | Patient table with cantilevered radiolucent pallet |
| US7484253B1 (en) | 2003-05-27 | 2009-02-03 | Qfix Systems, Llc | Patient support element for radiation therapy that reduces skin radiation burn |
| US8020227B2 (en) * | 2003-10-16 | 2011-09-20 | Calypso Medical Technologies, Inc. | Patient support systems for use with radiation therapy systems and other applications |
| US7131769B2 (en) * | 2004-12-16 | 2006-11-07 | Octostop Inc. | Stretcher with dedicated multi-functional removable floating patient support platform |
| EP1850756B1 (en) * | 2005-02-08 | 2015-01-21 | QFix Systems LLC | A rigid patient support element for low patient skin damage when used in a radiation therapy environment |
| WO2009032927A1 (en) * | 2007-09-04 | 2009-03-12 | Tomotherapy Incorporated | Patient support device |
| US8176584B2 (en) * | 2008-08-29 | 2012-05-15 | Hill-Rom Services, Inc. | Patient-support apparatus with movable top |
| WO2010144039A1 (en) * | 2009-06-08 | 2010-12-16 | Oncolog Medical Qa Ab | Table top for radiation therapy |
| CN105027227B (en) | 2013-02-26 | 2017-09-08 | 安科锐公司 | Electromagnetically actuated multi-diaphragm collimator |
| DE102014222061A1 (en) * | 2014-10-29 | 2016-05-04 | Siemens Aktiengesellschaft | Lying board and patient bed for medical imaging procedures |
| CN105030435B (en) * | 2015-07-23 | 2017-08-15 | 浙江贝欧复合材料制造有限公司 | A kind of preparation method of stretcher cross bar |
| US10555707B2 (en) | 2016-11-22 | 2020-02-11 | General Electric Compamny | Patient support system and method for medical imaging |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA985433A (en) * | 1973-07-20 | 1976-03-09 | Melvin L. Foster | High strength low attenuation couch top |
| US3947686A (en) * | 1974-04-25 | 1976-03-30 | The Babcock & Wilcox Co. | Graphite composite X-ray transparent patient support |
-
1977
- 1977-08-31 US US05/829,401 patent/US4145612A/en not_active Expired - Lifetime
-
1978
- 1978-03-23 CA CA299,737A patent/CA1097440A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4145612A (en) | 1979-03-20 |
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