1. An X-ray measuring instrument comprising: an X-ray source that generates X-rays to be irradiated to an object; an X-ray detector that is opposed to the X-ray source with the subject between them and detects X-rays transmitted by the object as measurement data; a filter that is interposed between the X-ray source and the object and regulates an exposure of X-rays to be transmitted; a holding unit that holds the X-ray source and the X-ray detector; a rotating unit that rotates the X-ray source and the X-ray detector about the object; and a control processing unit that computes measurement data items which are detected by the X-ray detector at a plurality of angles with respect to the object rotated by the rotating unit;
wherein, the control processing unit logarithmically converts the measurement data so as to produce projection data, obtains an X-ray absorption coefficient relevant to the filter using the produced projection data, calculates the thickness of the filter by applying a predetermined conversion expression to the obtained X-ray absorption coefficient, obtains a correction coefficient for the produced projection data according to the calculated thickness of the filter, multiplies the projection data by the obtained correction coefficient, computes the projection data, which is multiplied by the correction coefficient, for reconstruction, and thus produces a three-dimensional image.
2. The X-ray measuring instrument according to claim 1,
wherein the control processing unit searches a first conversion lookup table on the basis of the projection data so as to obtain the X-ray absorption of the filter.
3. The X-ray measuring instrument according to claim 1,
wherein the first conversion lookup table is produced in such a manner that: prior to measurement of the object, measurement data is obtained in a state in which the filter is disposed but the object is not placed in position; the measurement data is logarithmically converted in order to produce projection data; a coordinate in a lateral direction in the projection data and a coordinate in a longitudinal direction therein are changed in order to obtain projection data values at respective coordinate pairs; and the relationship between the projection data values of the object and the X-ray absorptions in the filter is defined.
4. The X-ray measuring instrument according to claim 1,
wherein the control processing unit searches a second conversion lookup table on the basis of the projection data so as to obtain the correction coefficient.
5. The X-ray measuring instrument according to claim 1,
wherein the second conversion lookup table is produced in such a manner that: measurement data is obtained in a state in which a filter having a predetermined even thickness is disposed and an arbitrary subject is placed in position; projection data is produced by logarithmically converting the measurement data; projection data of an ideal object providing uniform values for a reconstructed image is defined; a correction coefficient is calculated by dividing the ideal projection data by the projection data of the object; the correction coefficient is obtained relative to a plurality of filters having different thicknesses; and the relationship among the thicknesses of the filters, the projection data items of the object, and the correction coefficients is defined.
6. The X-ray measuring instrument according to claim 1,
wherein for obtaining the X-ray absorptions of the filter, the control processing unit uses projection data produced by averaging projection data items obtained under the same conditions.
7. The X-ray measuring instrument according to claim 2,
wherein for obtaining the X-ray absorptions of the filter, the control processing unit records a coordinate pair in the first conversion table in steps of several points, and calculates an X-ray absorption at an arbitrary coordinate pair by performing interpolation.
8. The X-ray measuring instrument according to claim 2,
wherein for obtaining the X-ray absorption of the filter, the control processing unit holds the second conversion lookup table as a conversion expression according to which an X-ray absorption is calculated using coordinates as variables, and calculates the X-ray absorption according to the conversion expression.
9. The X-ray measuring instrument according to claim 1,
wherein for obtaining the thickness of the filter, the control processing unit uses projection data produced by averaging projection data items obtained under the same conditions.
10. The X-ray measuring instrument according to claim 4,
wherein for obtaining the thickness of the filter, the control processing unit records a coordinate pair in the second conversion lookup table in steps of several points, and calculates an X-ray absorption at an arbitrary coordinate pair by performing interpolation.
11. The X-ray measuring instrument according to claim 4,
wherein for obtaining the thickness of the filter, the control processing unit holds the second conversion lookup table as a conversion expression according to which an X-ray absorption is calculated using coordinates as variables, and calculates the X-ray absorption according to the conversion expression.
12. The X-ray measuring instrument according to claim 1,
wherein the shape of the filter is laterally symmetrical.
13. The X-ray measuring instrument according to claim 1,
wherein the shape in a depth direction of a section of the filter is identical.
14. The X-ray measuring instrument according to claim 1,
wherein the shape of a section of the filter has convex arcs adjoining a concave arc and has straight lines adjoining the respective convex arcs, the tangents at the points of intersections between the concave arc and the convex arcs have the same slope, and the tangents at the points of intersections between the convex arcs and the straight lines have the same slope.
15. The X-ray measuring instrument according to claim 1,
wherein the thickness of the filter varies in the direction of the center axis of rotation of the rotating unit.
16. The X-ray measuring instrument according to claim 1,
wherein the control processing unit has a correction coefficient obtained from the projection data of an arbitrary subject formed as a water cylinder or an elliptic water cylinder.
17. The X-ray measuring instrument according to claim 1,
wherein the control processing unit selects a correction coefficient from among a plurality of correction coefficients according to a radiographic condition under which the object is radiographed.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for installing a flexible spinal needle assembly, said method comprising:
inserting a distal end of a flexible spinal needle assembly provided through dura mater and into an intrathecal space of a subject, the spinal needle assembly comprising:
a support needle with a non-cutting piercing point at the distal end and a hollow bore; a flexible needle with a tip at the distal end and slidably mounted on and supported by the support needle to expose the piercing point slightly extending beyond the tip in the distal end thereof, the flexible needle having an outside diameter sufficiently small so that upon insertion of the flexible spinal needle assembly and withdrawal of the support needle from the flexible needle permits the dura mater substantially to seal against the outside diameter of the flexible needle; and
removing the support needle from within the flexible needle while maintaining the tip of the flexible needle within the intrathecal space.
2. The method of claim 1, further comprising prior to removing the support needle from within the flexible needle, verifying presence of cerebrospinal fluid in a proximal end of the flexible spinal needle assembly; if no cerebrospinal fluid is observed, further inserting the distal end of the flexible spinal needle assembly through dura mater until the tip is at least in the intrathecal space; and thereafter removing the support needle from within the flexible needle upon observing cerebrospinal fluid presence within the flexible spinal needle assembly.
3. The method of claim 1, wherein inserting the distal end of the flexible spinal needle assembly through dura mater and into the intrathecal space of the subject comprises the outside diameter of the flexible needle being sufficiently small so that upon withdrawal of the flexible needle from dura mater, subsequent to insertion of the flexible spinal needle assembly therethrough, permits the dura mater substantially to reseal a space formerly occupied by the flexible needle.
4. The method of claim 1, wherein the spinal needle assembly further comprises a central stylet slidably mounted in the support needle to prevent the entry of matter through an opening in the distal end of the support needle during inserting, and further comprising prior to removing the support needle from within the flexible needle checking for cerebrospinal fluid at a proximate end of the spinal needle assembly; if no cerebrospinal fluid is observed, replacing the central stylet and further inserting the spinal needle assembly until the tip is in the intrathecal space; and once cerebrospinal fluid is observed, then removing.
5. The method of claim 2, wherein the spinal needle assembly further comprises a central stylet slidably mounted in the support needle to prevent the entry of matter through an opening in the distal end of the support needle during inserting, and further comprising prior to removing the support needle from within the flexible needle checking for cerebrospinal fluid at a proximate end of the spinal needle assembly; if no cerebrospinal fluid is observed, replacing the central stylet and further inserting the spinal needle assembly until the tip is in the intrathecal space; and once cerebrospinal fluid is observed, then removing the support needle and the central stylet.
6. The method of claim 1, wherein removing the support needle from within the flexible needle comprises advancing the flexible needle into the intrathecal space until a proximate end hub of the flexible needle contacts the subject.
7. The method of claim 1, further comprising subsequent to removing the support needle from within the flexible needle checking for the presence of cerebrospinal fluid at a flexible needle hub on a proximate end of the flexible needle.
8. The method of claim 7, further comprising subsequent to removing the support needle from within the flexible needle connecting medical fluid transfer apparatus to the flexible needle hub; and securing the flexible needle hub to the subject.
9. The method of claim 1, further comprising prior to inserting the distal end of the flexible spinal needle assembly through dura mater and into the intrathecal space of the subject, preparing the skin of a patient at an injection site; applying local anesthetic at the injection site; and inserting the distal end of the flexible spinal needle assembly through the prepared injection site.
10. The method of claim 4, wherein checking for cerebrospinal fluid comprises removing the central stylet subsequent to receiving a feedback signal that puncture of the dura mater has occurred.
11. A method for installing a flexible spinal needle assembly, said method comprising:
inserting a distal end of a flexible spinal needle assembly provided through dura mater and into an intrathecal space of a subject, the spinal needle assembly comprising:
a needle body comprising an elongated flexible hollow tube, the flexible needle body configured to be slidably mounted on an exterior of a rigid hollow body of a support needle and having an exposed piercing element of a first end of the support needle protruding from the distal end of the flexible needle selected for entering the dura mater, the hollow tube of the flexible needle has sufficient transverse flexibility relative to the rigid support needle to accommodate patient torso bending movement; and
removing the support needle from within the flexible needle while maintaining the tip of the flexible needle within the intrathecal space.
12. The method of claim 11, further comprising prior to removing the support needle from within the flexible needle, verifying presence of cerebrospinal fluid in a proximal end of the flexible spinal needle assembly; if no cerebrospinal fluid is observed, further inserting the distal end of the flexible spinal needle assembly through dura mater until a tip of the distal end of the flexible needle is protruding into the intrathecal space; and thereafter removing the support needle from within the flexible needle upon observing cerebrospinal fluid presence within the flexible spinal needle assembly.
13. The method of claim 11, wherein inserting the distal end of the flexible spinal needle assembly through dura mater and into the intrathecal space of the subject comprises an outside diameter of the flexible needle being sufficiently small so that upon withdrawal of the flexible needle from dura mater, subsequent to insertion of the flexible spinal needle assembly therethrough, permits the dura mater substantially to reseal a space formerly occupied by the flexible needle.
14. The method of claim 11, wherein the spinal needle assembly further comprises a central stylet slidably mounted in the support needle to prevent entry of matter through an exposed opening in the distal end of the support needle during inserting, and further comprising prior to removing the support needle from within the flexible needle checking for cerebrospinal fluid at a proximate end of the spinal needle assembly; if no cerebrospinal fluid is observed, replacing the central stylet and further inserting the spinal needle assembly until a tip of the flexible needle is located within the intrathecal space; and once cerebrospinal fluid is observed, then removing the support needle from within the flexible needle.
15. The method of claim 11, wherein removing the support needle from within the flexible needle further comprises advancing the flexible needle into the intrathecal space until a proximate end hub of the flexible needle contacts the subject and then removing the support needle from within the flexible needle.
16. The method of claim 11, further comprising securing a hub end of the flexible needle to a patient’s skin with an intermediary adhesive element for unobtrusive use.
17. A method for installing a flexible spinal needle assembly, the method comprising:
providing a flexible spinal needle assembly having: a support needle with a hollow core and a piercing point at a distal end, the support needle having a proximal end with a support hub and an opening to allow flow from a point near the distal end thereof to the proximal end; a flexible needle, having a proximal end with a flexible needle hub, slidably mounted on the support needle to expose the piercing point, the flexible needle having an outside diameter sufficiently small so that withdrawal of the flexible needle from dura mater, subsequent to insertion of the flexible spinal needle assembly therethrough, permits the dura mater substantially to reseal a space formerly occupied by the flexible needle; wherein the flexible needle hub and the support hub are configured to form a locking interference therebetween; and a central stylet slidably mounted in the support needle to prevent the entry of matter through the opening;
removing the central stylet subsequent to receiving a feedback signal that puncture of the dura mater has occurred;
checking for cerebrospinal fluid at the support hub;
if no cerebrospinal fluid is observed, replacing the central stylet and further inserting the assembly until the tip is an intrathecal space; and
removing the support needle and checking for the presence of cerebrospinal fluid at the flexible needle hub.
18. The method of claim 17, further comprising once cerebrospinal is observed, unlocking the support hub and the flexible needle hub, and while holding the support needle stationary, advancing the flexible needle until the flexible needle hub contacts the skin.
19. The method of claim 18, further comprising connecting medical fluid transfer apparatus to the flexible needle hub; and securing the flexible needle hub to the skin.
20. A method for installing a flexible spinal needle assembly, the method comprising:
providing a flexible spinal needle assembly having: a support needle with a piercing point at a distal end, the support needle having a proximal end with a support hub and an opening to allow flow from a point near the distal end thereof to the proximal end; a flexible needle, having a proximal end with a flexible needle hub, slidably mounted on the support needle to expose the piercing point, the flexible needle having an outside diameter sufficiently small so that withdrawal of the flexible needle from dura mater, subsequent to insertion of the flexible spinal needle assembly therethrough, permits the dura mater substantially to reseal a space formerly occupied by the flexible needle; wherein the flexible needle hub and the support hub are configured to form a locking interference therebetween; and a central stylet slidably mounted in the support needle to prevent the entry of matter through the opening;
using a spinal needle technique to prepare skin of a patient at an injection site, apply local anesthetic, and insert a tip of the flexible spinal needle assembly, the tip comprising the piercing point;
removing the central stylet subsequent to receiving a feedback signal that puncture of the dura mater has occurred;
checking for cerebrospinal fluid at the support hub;
if no cerebrospinal fluid is observed, replacing the central stylet and further inserting the assembly until the tip is an intrathecal space;
once cerebrospinal is observed, unlocking the support hub and the flexible needle hub, and while holding the support needle stationary, advancing the flexible needle until the flexible needle hub contacts the skin;
removing the support needle and checking for the presence of cerebrospinal fluid at the flexible needle hub;
connecting medical fluid transfer apparatus to the flexible needle hub; and
securing the flexible needle hub to the skin.