Methods and apparatus for determining distributions of radioactive materials

• US 4,929,832 A
• Filed: 12/27/1988
• Issued: 05/29/1990
• Est. Priority Date: 03/11/1988
• Status: Expired due to Fees

• Current Assignee: Robert S. Ledley
• Original Assignee: Robert S. Ledley
• Inventors: Ledley, Robert S.
• Primary Examiner(s): Howell, Janice A.
• Assistant Examiner(s): Freeman, John C.
• Application Number:
  US07/291,393
• Time in Patent Office: 518 Days
• Field of Search: 250/328, 378/20, 378/57
• US Class Current: 250/328
• CPC Class Codes: G01N 27/44717 Arrangements for investigating the separated zones, e.g. localising zones
• CPC Class Codes: G01T 1/2914 Measurement of spatial distribution of radiation
• CPC Class Codes: G01T 1/2942 using autoradiographic methods

Abstract

A method for determining the distribution of a radioactive material in a medium is provided which comprises the steps of: (a) providing a plurality of radiation detectors at a set of predetermined locations, each of said detectors producing an electrical output indicative of the amount of radioactive material in the vicinity of the detector; (b) moving the medium containing the radioactive material and the plurality of radiation detectors relative to one another so as to position the medium relative to the detectors at each of a set of predetermined positions; and (c) recording the electrical output of each of the detectors at each of the predetermined positions. Apparatus for practicing the method is also provided.

Claims

1. A method for determining the quantitative distribution of bands of a radioactive material spaced lengthwise along a medium which is in the form of a narrow elongated track, said radioactive material comprising a radioactive isotope which emits radiation, said method comprising the steps of:

(a) providing a plurality of identical radiation detectors at a set of predetermined locations spaced along the length of the track, said radiation detectors being arranged in a straight line, said predetermined locations being equally spaced from one another, center-to-center, by a distance D, and each of said detectors producing an electrical output indicative of the amount of radioactive material in each said band in the vicinity of the detector;

(b) moving the medium containing the radioactive material and the plurality of radiation detectors relative to one another in a step-like manner only along a path parallel to the straight line and parallel to the long axis of the track so as to position the medium and radioactive bands relative to the detectors at each of a plurality of predetermined positions which are equally spaced from one another by a distance d, the spacing D between the predetermined locations being several times greater than the spacing d between the predetermined positions, the total relative movement of the medium and the plurality of radiation detectors being equal to the spacing D between the predetermined locations;

(c) simultaneously measuring the amount of radioactive material in each of the bands in the vicinity of each of the detectors after each step at each of the predetermined positions by means of the electrical output produced by the individual detectors; and

(d) recording the electrical output of each of the detectors at each of the predetermined positions to produce simultaneous measurements of the amount of radioactive material in each of the spaced bands along the elongated track.

2. The method of claim 1 wherein the spacing between the predetermined locations is greater than the spacing between the predetermined positions by a factor of 10 or more.

3. The method of claim 1 wherein the relative motion between the plurality of radiation detectors and the medium is achieved by holding the detectors stationary and moving the medium past the detectors.

4. The method of claim 1 including the additional step of providing identical collimating means between the medium and each of the detectors for collimating the radiation emitted by the radioactive material in the medium before said radiation reaches the detectors, each said collimating means forming a rectangular through in front of each of the detectors, the long axis of the rectangle extending across the width of the track so that each detector is primarily responsive to the transverse portion of the track nearest the detector rather than transverse portions of the track ahead or behind the nearest portion.

5. Apparatus for determining the distribution of a radioactive material in a medium which is in the form of a narrow elongated track, said radioactive material comprising a radioactive isotope which emits radiation, said apparatus comprising:

(a) first means for supporting a plurality of identical radiation detectors at a set of predetermined locations spaced along the length of the track, said radiation detectors being arranged in a straight line, said predetermined locations being equally spaced from one another, center to center, by a distance D, and each of said detectors producing an electrical output indicative of the amount of radioactive material in each said band in the vicinity of the detector;

(b) second means for receiving the medium containing the radioactive material;

(c) third means for moving the first and second means relative to one another in a step-like manner only along a path parallel to the straight line and parallel to the long axis of the track so as to position the medium and radioactive bands relative to the detectors at a plurality of predetermined positions which are equally spaced from one another by a distance d, the spacing D between the predetermined locations being several times greater than the spacing d between the predetermined positions, the total relative movement of the first and second means being equal to the spacing D between the predetermined locations; and

(d) fourth means for simultaneously recording the electrical output of each of the detectors after each step at each of the predetermined positions.

6. The apparatus of claim 5 wherein the spacing between the predetermined location is greater than the spacing between the predetermined positions by a factor of 10 or more.

7. The apparatus of claim 5 wherein the first means is stationary and the second means is moved past the first means by the third means.

8. The apparatus of claim 5 wherein the radiation detectors are Geiger-Mueller detector tubes.

9. The apparatus of claim 8 wherein the first means includes identical collimating means for collimating the radiation emitted by the radioactive material in the medium before said radiation reaches the detectors each said collimating means forming a rectangular through in front of each of the detectors, the long axis of the rectangle extending across the width of the track so that each detector is primarily responsive to the transverse portion of the track nearest the detector rather than transverse portions of the track ahead or behind the nearest portion.