Guidance method for radiation detection

• US 6,331,703 B1
• Filed: 03/12/1999
• Issued: 12/18/2001
• Est. Priority Date: 03/12/1999
• Status: Expired due to Term

• Current Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Original Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Inventors: DiFrancesco, Mark W., Yarnall, Stephen T.
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Gabor, Otilia
• Application Number:
  US09/266,961
• Time in Patent Office: 1,012 Days
• Field of Search: 250/336.1
• US Class Current: 250/336.1
• CPC Class Codes: A61B 6/4057 by using radiation sources located in the interior of the body A61B6/037 takes precedence
• CPC Class Codes: A61B 6/425 using detectors specially adapted to be used in the interior of the body
• CPC Class Codes: A61B 6/4258 for detecting non x-ray radiation, e.g. gamma radiation A61B6/037 takes precedence

Abstract

A non-linear guidance method for radiation detection is described herein wherein a heuristic non-linear radiation detection method is utilized is for the location of sentinel nodes for staging cancer. The method of radiation detection described herein includes the steps of: Generating radiation decay rate counts wherein the counts are a sum of detected radiation decay events over a time interval; loading the counts into an array; summing selected elements of the array to generate a total count and a plurality of candidate counts; comparing the total count to one of the candidate counts to determine whether the one of the candidate counts is statistically different from the total count; using the statistically different one of the candidate counts as an output count rate; and generating an output signal using the output count rate to determine the characteristics of the output signal.

Claims

1. A method of radiation detection comprising the steps of:

a) generating radiation decay rate counts wherein said counts comprise a sum of detection radiation decay evens over a time interval;

b) loading said counts into an array;

c) summing selected elements of said array to generate a total count and a plurality of candidate counts;

d) comparing said total count to one of said candidate counts to determine whether said one of said candidate counts is statistically different from said total count;

e) using said statistically different one of said candidate counts as an output count rate;

f) generating an output signal using said output count rate to determine the characteristics of said output signal;

g) partitioning said plurality of candidate counts into;

a last count value at priority 1;

a sum of the last two count values at priority 2;

a sum of the last four count values at priority 3;

a sum of the last eight count values at priority 4;

said total count at priority 5; and

h) selecting said one said candidate counts as the highest priority count value that is a statistically significant change from priority 5 said total count.

2. A method of radiation detection according to claim 1 wherein said candidate counts are normalized with respect to said total count.

3. A method of radiation detection according to claim 1 wherein said candidate counts are normalized with respect to said total count.

4. A method of radiation detection according to claim 1 wherein said last count value is directly proportional to the count in a first location of said array wherein said first location represents the most recent of said radiation decay rate counts.

5. A method of radiation detecting according to claim 1 wherein said output signal is an audible signal.

6. A method of radiation detection according to claim 5 wherein said audible signal is selected from a plurality of ranges wherein said plurality of ranges cover the entire range of possible count rates expected to be detected.

7. A method of radiation detection according to claim 6 wherein said output signal comprises an audible cue to shift from a first of said plurality of ranges to a second of said plurality of said ranges.

8. A method of locating radio-actively tagged sentinel lymph nodes comprising the steps of:

a) injecting a patient with a radiopharmaceutical;

b) providing a probe for converting radiation decay events into an electrical signal;

c) discriminating said electrical signal from said probe into below threshold radiation decay events and above threshold radiation decay events;

d) counting said above threshold radiation decay events over a plurality of at least 16 discrete time intervals;

e) determining the best estimate of a current count rate by applying a non-linear filtering technique, comprising a heuristic non-linear count rate determination algorithm, to counts within said discrete time intervals; and

f) providing a count rate output;

g) providing an audible signal corresponding to the current count rate output of step f;

h) providing a sound amplitude test and adjustment capability of the audible signal provided in step i.

9. A method of claim 8 wherein said non-linear filtering technique comprises heuristic non-linear count rate determination algorithm.

10. The method of claim 8 further comprising the steps of:

i) partitioning said discrete time intervals into count rates corresponding to;

a last count value at priority 1;

a sum of the last two count values at priority 2;

a sum of the last four count values at priority 3;

a sum of the last eight count values at priority 4;

a sum of the last sixteen count values at priority 5; and

j) updating the count rate of step f as the highest priority count rate that is a statistically significant change from priority 5.

11. The method of claim 10 further comprising the step of:

k) changing the audible signal from step i from a pulsed pitch to a continuous pitch after a predetermined count rate range has been exceeded.