Stereotactic method and apparatus for locating and treating or removing lesions

• US 4,638,798 A
• Filed: 09/10/1980
• Issued: 01/27/1987
• Est. Priority Date: 09/10/1980
• Status: Expired due to Term

• Current Assignee: Gilbert D. Mccann, Shelden C. Hunter
• Original Assignee: Gilbert D. Mccann, Shelden C. Hunter
• Inventors: Shelden, C. Hunter, McCann, Gilbert D.
• Primary Examiner(s): Thaler, Michael H.
• Application Number:
  US06/185,937
• Time in Patent Office: 2,330 Days
• Field of Search: 128/303 B, 128/653, 128/659, 128/660
• US Class Current: 606/130
• CPC Class Codes: A61B 6/501 for diagnosis of the head, e.g. neuroimaging or craniography
• CPC Class Codes: A61B 90/11 with guides for needles or instruments, e.g. arcuate slides or ball joints
• CPC Class Codes: A61B 90/39 Markers, e.g. radio-opaque or breast lesions markers

Abstract

A stereotactic method and apparatus for treating a region of a patient'"'"'s body defines points in the region using a three-dimensional coordinate system with reference to a ring attached to the patient for establishing a reference point for the three-dimensional coordinate system at the center of the ring. The same ring and reference point is then used for stereotactically controlling instruments used to treat the region. The ring is preferably provided with pins extending parallel to the axis of the ring, and equidistant from the center, for precise location of the center and of a base-line scan for correlation between the location of the region to be treated and the control system for treatment of the region. Prior to treatment, a series of noninvasive tomography scans are made through the region and at least part of the pins for determining the coordinates of at least one point of the region selected for the treatment with respect to the center of the ring. All parameters of the system for stereotactic control of instruments used for treatment are then determined with respect to the ring center as a reference point.

Claims

1. In a stereotactic system for treating a region of a patient'"'"'s body, a method for using a tomography scanner for defining a selected point of the region in a three-dimensional coordinate system with reference to a predetermined point of means attached to the patient for establishing a reference point of said coordinate system for accurate control of instruments used to treat said region, comprising the steps of

placing said means on the patient for precise correlation between the location of the region to be treated and the control system for treatment of the region in said three-dimensional coordinate system,

conducting a series of parallel tomography scans through said region to be treated and at least part of said means for determination of three-dimensional coordinates of points in said region of the body of said patient to be treated relative to said reference point of said means,

determining from data of said scan series three-dimensional coordinates with respect to said reference point of said means of at least one point of said region,

determining all parameters of the system for control of instruments used for treatment with respect to said reference means, and

completing the treatment with instruments guided by said control system with reference to said means still attached to said patient,

wherein said reference means is a ring attached to the patient, and said reference point is the center thereof.

2. A method as defined in claim 1 wherein said ring is provided with a plurality of pins extending therefrom in one direction normal to the plane thereof, and said ring is mounted to be parallel to each tomographic scan, said pins extending in the direction of said region, and wherein said tomography scan includes scans through said pins to provide known points relative to the center of said ring for orientation of scan data in determining three-dimensional coordinates with reference to the center of said ring.

3. A method as defined by claim 2 wherein said pins are at least three at positions on said ring of equal radius from said reference center, whereby the coordinates of the center of the ring in two orthogonal axes in the plane of the ring may be computed from scan data by reference to the centers of said pins.

4. A method as defined in claim 3 including additional pins of different known heights, whereby the third coordinate of a base-line scan may be determined from the known heights of the tips of at least two pins, where one pin appears in successive scans and the other pin appears in one scan and disappears in an adjacent scan by adding to the height of the shortest pin half the difference in the known heights of the two pins, or subtracting from the longest pin half the difference in the known heights of the two pins, and a third coordinate for a point in the region to be treated is accurately determined by accumulating the spacing of successive scans of known spacing from said base-line scan to said point, and adding to the accumulated spacings of the scans the third coordinate of said base-line scan.

5. A method as defined in claim 4 wherein said additional pins are positioned on a circle which includes the pins used for establishing the coordinates of the center of the ring, and said additional pins are equally spaced and arranged in order of height, to facilitate identifying the addiional pins in displays of successive scans.

6. A method as defined in claim 5 wherein said additional pins are in sets, each set having a pin of known height diametrically opposite a pin of equal height.

7. A method as defined in claim 1, 2, 3, 4, 5 or 6 wherein the step of determining all control parameters of the system includes

placing said control system on a standard ring similar to the ring on the patient,

adjusting a target with respect to said standard ring at the coordinates of said one point selected for treatment,

adjusting said control system for guidance of instruments to said target along a selected pathway, and

transferring the system thus adjusted to said ring on the patient for stereotactic treatment.

8. In a stereotactic system for treating a region of a patient'"'"'s body reached through a selected pathway to a point in the region using a three-dimensional coordinate system with reference to a ring attached to the patient for establishing a reference point for the three-dimensional coordinate system at the center of said ring, said ring having a plurality of pins of known heights from a plane in said ring, at least some of which differ in height by a known increment and at least three of which are spaced apart at equal radius from the center of said ring, a method of determining three-dimensional coordinates of a point in said region of the patient comprising the steps of

making a series of parallel tomography scans at equal increments of spacing along the axis of said ring, said series extending through said region and at least some of said pins, including said pins at equal radius from said ring center,

displaying said scans and from said scan displays, determining the centers of said pins of equal radius from said ring center, and determining the position of the center in said series of scans as a reference for two-dimensional coordinates in a plane of said ring relative to said ring,

identifying two adjacent scans from said scan displays where two pins of heights that differ by a known increment appear in one scan and only one of said two pins appears in the adjacent scan, and computing the coordinate of one of said scans to be used as a base-line scan from said plane of said ring along the axis of said ring as the height of one of said pins adjusted by half the incremental difference in height of said two pins,

identifying a scan that includes said point from said scan displays, and

determining the third coordinate of said scan that includes said point as the sum of the coordinate of said base-line scan, and the number of equal scan increments from said base-line scan to the scan that includes said point, and determining the remaining two coordinates of said point relative to said reference point at the center of said ring.

9. In a stereotactic system as defined in claim 8 wherein said pins of equal height are spaced around said ring to define a circle, further including the method of checking that the ring is parallel to the scans by observing displays of a series of scans past the end of said pins of equal length to see that all pins of equal length disappear in the display at the same time.