fig1 to 4 show the exterior and the configuration of the ultrasound measurement device of the present invention . as shown in fig1 to 4 , the ultrasound measurement device is formed from a main body component 10 , a nozzle 20 , a silicone film 30 , an ultrasound probe 40 , a drive mechanism 50 , and water 60 . the main body component 10 is cuboid in appearance , the bottom face of which is rectangular in shape . the main body component 10 holds the water 60 , which transmits ultrasonic waves , and the ultrasound probe 40 in the interior of this hollow shape . the major axis is disposed from the + x direction to the − x direction . in embodiments , the face of the main body component 10 where the nozzle 20 is located will be called the bottom face , the face on the opposite side from the bottom face will be called the top face , and side face in the + y direction will be called the left side face , the side face in the − y direction will be called the right side face , the side face in the + x direction will be called the front face , the side face in the − x direction will be called the rear face , the plane composed of the x axis and the y axis will be called the xy plane , the plane composed of the x axis and the z axis will be called the xz plane , and the plane composed of the y axis and the z axis will be called the yz plane . the bottom face and top face are parallel to the xy plane , and the right side face and left side face are parallel to the xz plane . the interior of the main body component 10 is hollow . the nozzle 20 has a column shape and a hollow shape in appearance . the nozzle 20 touches the approximate center of the bottom face of the main body component 10 . when divided along a plane parallel to the xy plane , the nozzle 20 is composed of two straight parts that are perpendicular to the y axis , and two curved parts that link the ends of the two straight parts . the two straight parts have the same length . the curves are semicircular arcs that protrude in the + x and − x directions . the length of the outer periphery of a cross section of the nozzle 20 is greatest on the bottom face side of the main body component , and decreases in the − z direction . specifically , the nozzle 20 has a shape that is constricted in the − z direction . the nozzle 20 communicates with the main body component 10 in the − z direction via a hollow portion 21 . since the nozzle 20 is integrated with the interior of the main body component 10 by the hollow portion 21 , it holds the water 60 integrally with the main body component 10 . as shown in fig2 , the face of the nozzle 20 in the − z direction is inclined at an angle of θ 1 to the x axis , and as shown in fig3 , is inclined at an angle of φ 1 to the y axis . the silicone film 30 has the same planar shape as the face of the nozzle 20 in the − z direction , and is composed of a material that transmits ultrasonic waves . the silicone film 30 is provided so as to block the face of the nozzle 20 in the − z direction . therefore , the water 60 will not leak out from the face of the nozzle 20 in the − z direction of the main body component 10 . because the face of the nozzle 20 in the − z direction is inclined to the x axis and the y axis , the silicone film 30 is inclined at θ 1 to the x axis as shown in fig2 , and is inclined at φ 1 to the y axis as shown in fig3 . the ultrasound probe 40 has a circular column shape . the face on the − z side of the ultrasound probe 40 is parallel to the bottom face of the main body component 10 . also , the main body component 10 is tall enough that the ultrasound probe 40 does not touch the silicone film 30 or the top face in the interior of the main body component 10 . a transducer 41 is provided on the − z side of the ultrasound probe 40 . the transducer 41 is electrically connected to a signal processor ( not shown ). the transducer 41 sends and receives ultrasonic wave , and outputs electrical signals corresponding to the intensity of the received ultrasonic waves to the signal processor ( not shown ). the drive mechanism 50 passes through the rear face of the main body component 10 and is connected to the ultrasound probe 40 . the drive mechanism 50 moves the ultrasound probe parallel to the x axis . the ultrasound measurement device is configured so that the place to be measured with ultrasound can be moved along the x axis . the ultrasonic waves emitted from the transducer 41 advance through the water 60 perpendicularly to the bottom face of the main body component 10 , and advance obliquely to the silicone film 30 . next , the shape of a knee joint will be described in detail . fig5 a and 6a show the interior of a joint when a right knee has been bent at least 90 degrees . fig5 a is a cross section of the right knee as seen from the inside out . fig6 a is a view of the right knee as seen from the trunk side toward the feet . fig5 b and 6b show the relation between the outer skin and the surface of the cartilage when the right knee is bent at least 90 degrees . in fig5 a and 5b , the + x side is the foot side , and the − x side is the trunk side . in fig6 a and 6b , the + y side is the inside of the right knee , and the − y side is the outside of the right knee . in fig5 a , 5 b , 6 a , and 6 b , the + z side is the front side of the knee , and the − z side is the back side of the knee . of the knee joint cartilage 71 on the foot side of the thigh bone 73 , a load portion 72 is the portion subjected to the greatest load . the surface of the load portion 72 is exposed under the skin when the knee is bent , making measurement easier . the cartilage adjacent skin 75 is the portion of the outer skin 70 that is adjacent to the surface of the load portion 72 . the cartilage adjacent skin 75 is inclined with respect to the surface of the load portion 72 . more specifically , as shown in fig5 b , the cartilage adjacent skin 75 is inclined at an angle θ 2 with respect to the surface of the load portion 72 in the xz plane . as shown in fig6 b , the cartilage adjacent skin 75 is inclined at an angle φ 2 with respect to the surface of the load portion 72 in the yz plane . therefore , it ultrasonic wave should happen to be perpendicularly incident on the cartilage adjacent skin 75 , the ultrasonic wave will not be perpendicularly incident on the surface of the load portion 72 , and will not be reflected perpendicularly by the surface of the load portion 72 . fig7 shows the position of the knee joint and the ultrasound measurement device when the ultrasound measurement device of the present invention is brought into contact with a right knee that has been bent at 120 degrees . fig7 is a view of the right knee as seen from the inside out . in fig7 , the + x side is the foot side , while the − x side is the trunk side . the + z side is the front side of the knee , and the − z side is the back side of the knee . the silicone film 30 is used by being placed in contact with the cartilage adjacent skin 75 so as to form a single plane , and parallel to the cartilage adjacent skin 75 . the bottom face of the main body component 10 is parallel to the xy plane . the silicone film 30 and the cartilage adjacent skin 75 are inclined at the angle θ 1 with respect to the x axis ( the bottom face of the main body component 10 ). the silicone film 30 and the cartilage adjacent skin 75 are inclined at the angle θ 2 in the xz plane with respect to the surface of the load portion 72 . since the angle θ 1 is set to be the substantially same as the angle θ 2 , the surface of the load portion 72 is substantially parallel to the x axis ( the bottom face of the main body component 10 ). thus , the user can make the bottom face of the main body component 10 parallel to the surface of the load portion 72 in the xz plane merely by placing the ultrasound measurement device of the present invention against the cartilage adjacent skin 75 . the ultrasonic waves emitted from the transducer 41 are transmitted through the silicone film 30 , the cartilage adjacent skin 75 , and the soft tissue , in that order , and then reach the load portion 72 . in the xz plane , the angle at which the ultrasonic waves advance is perpendicular to the surface of the load portion 72 because the surface of the load portion 72 and the bottom face of the main body component 10 are parallel . fig8 is a view of the ultrasound measurement device and the right knee shown in fig7 as seen from the trunk side toward the foot side of the patient . the − y side is the outside of the right knee , while the + y side is the inside of the right knee . the bottom face of the main body component 10 and the silicone film 30 and cartilage adjacent skin 75 are inclined at the angle φ 1 with respect to the y axis ( the bottom face of the main body component 10 ). the silicone film 30 and the cartilage adjacent skin 75 are inclined at the φ 2 in the yz plane with respect to the surface of the load portion 72 . since the angle φ 1 is set to be substantially the same as the angle φ 2 , the surface of the load portion 72 is substantially parallel to the y axis ( the bottom face of the main body component 10 ). thus , the user can make the bottom face of the main body component 10 parallel to the surface of the load portion 72 in the yz plane merely by placing the ultrasound measurement device of the present invention against the cartilage adjacent skin 75 . the ultrasonic waves emitted from the transducer 41 advance perpendicular to the surface of the load portion 72 because the bottom face of the main body component 10 and the surface of the load portion 72 are parallel in the yz plane . as discussed above , with the ultrasound measurement device of the present invention , the angle at which the ultrasonic waves advance can be made perpendicular to the surface of the load portion 72 of the knee cartilage . since the acoustic impedance in soft tissue is different from the acoustic impedance in the knee joint cartilage 71 , the ultrasonic waves that reach the surface of the load portion 72 are reflected by the surface of the load portion 72 . the reflected waves face the opposite direction from the direction in which the ultrasonic waves come out of the transducer 41 . therefore , the reflected waves reach the transducer 41 in the shortest distance from the surface of the load portion 72 . the angle at which the ultrasonic waves advance with respect to the surface of the load portion 72 in fig7 will be perpendicular as long as the surface of the load portion 72 is flat , even if the ultrasound probe 40 is moved along the x axis by the drive mechanism 50 . therefore , the ultrasound measurement device of the present invention can measure ultrasonic waves by using the drive mechanism 50 to continuously move the surface of the load portion 72 in parallel along the x axis . the angles θ 1 and φ 1 of the ultrasound measurement device of the present invention preferably match up perfectly with the angles θ 2 and φ 2 . however , the angles θ 2 and φ 2 may have some variance , depending on the patient . the user will need to make fine adjustments to the angle of the ultrasound probe 40 when measuring a patient in which the angles θ 2 and φ 2 vary greatly in proportion to the average values for the patient . in view of this , in addition to the ultrasound measurement device shown in fig1 to 4 , an ultrasound measurement device that further comprises a silicone rubber piece 80 as an elastic body will now be discussed . in fig9 , those components that are the same as in fig1 to 4 will not be described again . fig9 a is a cross section along the xy plane of the ultrasound measurement device equipped with the silicone rubber piece 80 , fig9 b is a cross section along the yz plane , and fig9 c is a bottom view . the silicone rubber piece 80 is provided between the silicone film 30 and the portion of the nozzle 20 that is in contact with the silicone film 30 . as shown in fig9 c , the silicone rubber piece 80 has the same shape as the cross sectional view of the nozzle 20 . the silicone rubber piece 80 has a ring shape that goes around the edge of the nozzle 20 and is joined on the − z side of the edge of the nozzle 20 . the silicone film 30 is joined to the silicone rubber piece 80 on the opposite side (− z side ) of the silicone rubber piece 80 from the edge of the nozzle 20 . the silicone rubber piece 80 deforms when integrally pressed against the ultrasound measurement device by the user when the silicone film 30 is brought into contact with the cartilage adjacent skin 75 . the extent to which the silicone rubber piece 80 deforms varies with an adjustment in which the user increases the force pressing on the + x side over the force pressing on the − x side , for example . in fig9 a , for instance , if the pressing force in the − z direction on the − x side of the silicone rubber piece 80 is increased over the pressing force in the − z direction on the + x side , the − x side is compressed more along the z axis than the portion on the + x side . the angle θ 1 then becomes greater than before the pressing force was increased . thus , the user can make fine adjustments to the angles θ 1 and φ 1 by pressing on and deforming the silicone rubber piece 80 . also , if the nozzle 20 is made of metal , because the silicone rubber piece 80 is compressed when pressed against the patient , the local pressure on the biological surface is dispersed , which reduces the damage to the biological surface and alleviates the burden on the patient . as discussed above , with the ultrasound measurement device of the present invention , which comprises the silicone rubber piece 80 , the angles θ 1 and φ 1 can be finely adjusted to match the shape of the patient &# 39 ; s knee joint , and even though the angles θ 2 and φ 2 vary depending on the patient , the angle at which the ultrasonic waves advance can be made perpendicular to the surface of the load portion 72 . in the above example , the main body component 10 and the nozzle 20 are configured integrally , but the configuration may allow the nozzle 20 to be replaced . if the nozzle 20 and the silicone film 30 are replaced , then threaded holes are made in the bottom face of the main body component 10 , for example , and the nozzle 20 and the silicone film 30 are attached to the main body component 10 with screws . the user can join the nozzle 20 and the main body component 10 together with screws and thereby attach the nozzle 20 and the silicone film 30 to the main body component 10 . therefore , the user can replace the nozzle 20 to match the shape of the patient &# 39 ; s knee joint , and can make the advance angle of the ultrasonic waves perpendicular to the surface of the load portion 72 . in the above example , the face of the nozzle 20 in the − z direction had a flat shape composed of two straight parts and two curved parts , but this shape is not the only option . for example , the nozzle 20 can be a three - dimensional shape that matches the three - dimensional shape of the patient &# 39 ; s knee , which will allow the angle in which the ultrasonic waves advance to be made perpendicular to the surface of the load portion 72 more accurately . the drive mechanism 50 moves the ultrasound probe 40 parallel to the x axis , but the direction is not limited to the x axis . the drive mechanism 50 can also move the ultrasound probe 40 parallel to the y axis . in this case , the ultrasound measurement device can continuously measure the flat shape of the surface of the load portion 72 . furthermore , the drive mechanism 50 can move in the z axis direction . in this case , even if the soft tissue is thick and the cartilage adjacent skin 75 is farther away from the surface of the load portion 72 , the user can still move the probe in the z axis direction and thereby adjust the focal depth of the emitted ultrasonic waves , so that the ultrasonic waves are emitted properly . in the above example , scanning by mechanical drive was used , but it is also possible for numerous transducer elements to be arranged in an array . with the ultrasound measurement device of the present invention , if the ultrasound probe is configured with numerous transducer elements arranged in an array , then ultrasonic waves can be sent and received all at once even without successive scanning by mechanical drive . therefore , the user can measure cartilage in a knee joint in a short time , which means that the patient does not have to suffer through a prolonged measurement . fig1 is a flowchart of a method for measuring knee joint cartilage using the ultrasound measurement device of the present invention . when the ultrasound measurement device receives a command to start measurement ( s 11 ), the ultrasound probe 40 emits ultrasonic waves toward the cartilage in the knee joint ( s 12 ). the ultrasound probe 40 then receives the ultrasonic waves reflected by the load portion 72 ( s 13 ). when ultrasonic waves are sent and received at other measurement positions by scanning ( yes in s 14 ), the drive mechanism 50 moves the ultrasound probe 40 ( s 15 ). the flow then returns to step s 12 , and measurements are successively made at different positions . once measurement is finished at all of the measurement positions ( no in s 14 ), the ultrasound measurement is ended . as discussed above , the ultrasound measurement method of the present invention allows cartilage to be properly measured by having ultrasonic waves be perpendicularly incident on the surface of the load portion 72 of the knee joint cartilage 71 , and successively scanning .
the ultrasound measurement instrument of the present invention comprises a main body component having a polyhedral shape ; a nozzle that is provided in one plane of the main body component , the nozzle and communicating with the main body component via a hollow portion ; and a contact component blocking off a face of the nozzle on the opposite side from the main body component in a flat shape such that ultrasonic waves are transmitted . the contact component is inclined with respect to a first axis that is parallel to the plane of the polyhedral body in which the nozzle is provided , and to a second axis that is perpendicular to the first axis and is parallel to the plane . a cartilage surface is inclined with respect to a biological surface , and the contact component is inclined by the same degree in the inclination direction thereof . therefore , the ultrasonic waves emitted perpendicular to the face of the main body component where the nozzle is located pass through the contact component and proceed perpendicular to the cartilage surface .