preferred embodiments of the invention will be described in detail with reference to fig1 - 2 attached hereto . the embodiment shown in fig1 depicts an insertion medical device 10 for dilating internal strictures comprising a tube 12 having requisite flexibility and an enclosed , hollow space 14 substantially filled with crystalline tungsten powder 16 . in the preferred embodiment , the tube 12 is made of a flexible and waterproof material , such as silicone rubber . flexibility is desired because the tube 12 must conform to the curves and tight bends normally found in internal passageways . further , a flexible tube would be most comfortable for the patient . in the past , some esophageal bougies had metal guide wires within the tube for facilitating placement of the tube 12 inside the passageway , and that this caused pain to the patient ; thus , in the preferred embodiment , such wires are omitted . a waterproof material is used because it is desired to keep the internal medical device &# 39 ; s 10 contents dry and separate from the patient &# 39 ; s internal fluids . this prevents accidental toxicity and keeps the device working properly . silicone rubber is used because it provides the necessary flexibility and waterproof properties . also in the preferred embodiment , the tube 12 is tapered at the distal end 20 to facilitate insertion into the internal stricture and has an enclosed , hollow space 14 that extends upwardly towards the proximal end 22 . the enclosed , hollow space 14 will substantially extend the entire length of the tube 12 in order to allow crystalline tungsten powder 16 (“ ctp ”) to be added to provide adequate weight to the flexible tube 12 . further , the enclosed , hollow space 14 will have a resealable opening through which the ctp 16 can be added and contained within the flexible tube 12 . ctp 16 is preferably used to substantially fill the enclosed , hollow space 14 because it has the necessary flow and weight characteristics to permit placement of the insertion medical device 10 while still maintaining sufficient flexibility in the tube 12 . ctp 16 is a crystallized form of tungsten and is not to be confused with regular tungsten powder . ctp particles are approximately 2 to 4 times larger than regular tungsten powder and have a body - centered cubic . further , ctp 16 has a hall flow rate of approximately 6 to 10 seconds / 50 grams in contradistinction to standard tungsten powder that does not exhibit any flow characteristic and cannot be measured using the hall flow test . in addition , ctp 16 has a rougher surface than standard tungsten powder and this prevents the tungsten from clumping or packing together . because of the foregoing , ctp 16 possesses flowability properties not found in standard tungsten powder . because of its flowability , ctp 16 is effective when used by itself . however , if desired , ctp 16 can be suspended in a fluid , such as silicone , in order to vary flowability . ctp 16 has a scott density of approximately 140 to 160 grams / cc and this density has been found to be adequate for providing the necessary weight to the tube 12 in order to enable the user to maneuver the insertion medical device 10 . the density further provides the firmness necessary to enable the physician to push upon the insertion medical device 10 to force open a constricted passageway without a guide wire . ctp 16 is made by an alkaline process where tungsten powder is chemically enlarged . ctp 16 particles are in the shape of crystals and are approximately 40 to 75 microns . this large size is a factor in the ctp &# 39 ; s favorable flow rate . further , when the insertion medical device 10 is bent , the surface of the insertion medical device 10 remains free from creases and this reduces pain to the patient due to the non - clumping properties of the large size crystal . ctp 16 is also non - toxic to humans and makes ctp 16 more desirable for a rupture in the flexible tube 12 will not cause a health concern to the patient . in addition , because ctp 16 is preferably in a solid state , the ctp 16 will not rapidly exit via the rupture and enter the patient &# 39 ; s body , thereby making ctp 16 a desirable product to be used in the insertion medical device 10 . in order to provide an insertion medical device 10 that is capable of dilating strictures deep within a passageway and to accommodate large individuals , the insertion medical device 10 should be at least 30 inches in overall length and have a uniform diameter typically in the range of 0 . 21 inches to 0 . 79 inches . the tip 18 is typically about 6 inches in length , with a rounded end having a diameter of approximately 0 . 19 inches and is tapered so that its outer surface smoothly meets the outer surface of the tube 10 at its distal end 20 . further , the ctp 16 should substantially fill the enclosed , hollow space 14 in order to provide adequate flowability that is necessary throughout the insertion medical device 10 . in the preferred embodiment , the insertion medical device 10 is a bougie . alternatively , ctp 16 can be used with any flexible tube having a hollow chamber in order to provide adequate weight and flowability . the wide array of medical devices that can be produced using ctp 16 includes , but is limited to , feeding tubes and endoscopy instruments . it is envisioned that any instrument that is to be inserted requires adequate weight in order to be inserted within the human body . further , such instrument requires adequate flowability from a non - toxic substance , yet firmness in order to facilitate maneuverability . all these advantages are provided with ctp 16 and this makes ctp 16 versatile and adaptable to a variety of instruments beyond the preferred embodiment . the embodiment shown in fig2 depicts a process 40 for making a bougie 42 substantially filled with ctp 16 for dilating internal strictures . the process comprising : enlarging tungsten powder using an alkaline process to produce ctp 16 at 43 , filtering the ctp 16 through a 200 mesh screen 44 at 45 , again filtering the ctp 16 through a 325 mesh screen 46 at 47 , selecting the ctp 16 not filtered through the 325 mesh screen 46 at 49 , making a first section 48 of silicone rubber having an aperture 50 and an internal , hollow space 14 substantially the entire length of the first section 48 at 51 , substantially filling said first section 48 with the selected ctp 16 that filtered through the 200 mesh screen 44 but not through the 325 mesh screen 46 at 53 , and making a second section 54 of silicone rubber used to mate with and seal said aperture 50 at 55 . in the preferred embodiment , the first section 48 has a tapered tip at the distal end 20 and is made of silicone rubber . the first section 48 also includes an aperture 50 just large enough to allow ctp 16 to pass . the aperture should not exceed 3 . 0 mm and is preferably between 2 . 0 and 2 . 5 mm . this embodiment may be made by any of a number of methods including , but not limited to , injection molding , blow molding , and machining . in the preferred embodiment , the second section 54 is also made of silicone rubber and may be made using the same method as for the first section 48 . the second section 54 will ideally have a diameter equal to the first section 48 and will further comprise a portion that mates with the aperture 50 of the first section 48 . preferably , this mating portion is a male member 58 that has a diameter the same size as or larger than the diameter of the aperture 50 . this will allow a tight fit to properly seal in the ctp 16 and ensure that no ctp 16 will leak out . after filling the first section 48 with ctp 16 , the second section 54 can then seal the aperture 50 permanently . it is preferred to permanently seal the aperture 50 because ctp 16 is not known to break down or decompose prior to the tube 12 being discarded for wear or sanitation purposes . therefore , once a substantial amount of ctp 16 has been filled , there is no need to reopen the aperture 50 . hence , the first and second sections 48 and 54 may be sealed using a non - toxic sealant or other adhesive . other methods of permanently sealing include , but are not limited to , ultrasonic welding , heating , and chemical bonding . it is desirable to make the first and second sections 48 and 54 the same material because identical materials form the strongest bond upon sealing . alternatively , similar materials may be used but this does not produce the strong bond identical materials form .
this invention provides an apparatus and method for an insertion medical device that dilates internal strictures . the insertion medical device includes a flexible dilator having an enclosed , hollow chamber substantially filled with crystalline tungsten powder . more particularly , a bougie is disclosed . the crystalline tungsten powder provides the bougie with improved flowability and performance when placing the bougie in the stricture . in another aspect , the invention provides improved flowability and adequate weight to other medical devices such as feeding tubes and endoscopy instruments .