METHOD AND APPARATUS FOR TREATMENT PLANNING USING IMPLANTED RADIOACTIVE SEEDS

• US 20080242914A1
• Filed: 05/21/2004
• Published: 10/02/2008
• Est. Priority Date: 05/22/2003
• Status: Active Grant

• Current Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Inventors: Thomadsen, Bruce R., Henderson, Douglass L., Yoo, Sua, Kowalok, Michael E.
• Granted Patent: US 7,442,162 B2
• Time in Patent Office: Days
• US Class Current: 600/1
• CPC Class Codes: A61N 5/1027 Interstitial radiation therapy
• CPC Class Codes: A61N 5/103 Treatment planning systems

Abstract

A pre-computed sensitivity function providing ex ante assessment of optimal placement of a single radioactive seed, is used for sequential placement of multiple radioactive seeds. The location of each successive seed may also be constrained by an exclusion function omitting areas in the target receiving a pre-defined dose from the preexisting seeds. This technique makes possible optimization of additional dimensions of treatment planning including using a different number of needles and using mixed seed types.

Claims

1. A method of treatment planning for placement of radioactive seeds in a tumor in a region of a body comprising the steps of:

(a) determining a desired dose pattern within the region of the body;

(b) pre-calculating a preferred ranking of seed locations for a range of locations within the region of the body based on dose patterns produced by at least one seed moved throughout the range of different locations in a target region;

(c) after step (b) and prior to placement of the seeds in a patient, determining the location of the seeds for a treatment plan by sequentially placing seeds at planning locations according to the preferred ranking of seed locations; and

(d) outputting a proposed treatment plan providing planning locations of the sequentially located seeds for use in surgical implantation of the seeds.

2. The method of claim 1 wherein the pre-calculated preferred ranking of seed locations assesses a relative dose to tumorous and non-tumorous tissue of the dose pattern produced by seeds over a range of different locations in a target region.

3. The method of claim 2 wherein the preferred ranking of seed locations is a ratio of an average dose measured over the tumorous tissue to an average dose measured over the non-tumorous tissue produced by seeds at a range of different locations in a target region.

4. The method of claim 1 wherein the location of seeds does not change after the seeds are first sequentially located.

5. The method of claim 1 wherein each seed is sequentially located according to the pre-calculated preferred ranking of seed locations outside of a zone around previously placed seeds.

6. The method of claim 5 wherein the zone about previously placed seeds is reduced as additional seeds are located.

7. The method of claim 1 wherein the preferred ranking of seed locations is three-dimensional and the seeds are placed variably in three dimensions.

8. The method of claim 1 wherein step (c) continues to sequentially locate seeds until a computed dose from the located seeds matches the desired dose pattern within a predetermined criterion.

9. The method of claim 1 further including the step of:

(e) repeating steps (c) for seed locations constrained along an increasing number of needle tracks up to a predetermined limit;

wherein the step (d) outputs a proposed treatment plan having a fewest number of needle tracks less than the predetermined number of needle tracks where a computed dose from the located seeds matches the desired dose pattern within a predetermined criterion.

10. The method of claim 9 wherein step (c) locates seeds according to the preferred ranking of seed locations adding needle tracks if necessary until the predetermined limit of needle tracks is reached and then locates seeds only along established needle tracks.

11. The method of claim 10 wherein each seed is placed sequentially according to the pre-calculated preferred ranking of seed locations outside of a zone around previously placed seeds and;

wherein different zones are used for locating seeds before and after the increasing number of needle tracks is reached.

12. The method of claim 1 further including the step of:

(e) repeating steps (c) for two different types of seeds having different dose patterns starting with a first seed type and proceeding to a second seed type.

13. The method of claim 12 wherein the first seed type has a substantially different dose pattern than the second seed type.

14. The method of claim 13 wherein each first seed type is placed sequentially according to the pre-calculated preferred ranking of seed locations outside of a first zone around previously placed first seed types and second seed types are placed only after no more first seed types can be placed outside of the first zones.

15. The method of claim 12 wherein the first seed type has a directional asymmetrical dose pattern and the second seed type has a symmetrical dose pattern.

16. The method of claim 15 wherein the first seed types are placed preferentially near boundaries of the target region.

17. A method of intraoperative real-time treatment planning comprising the steps of:

(a) positioning a patient for treatment;

(b) obtaining treatment images to determining a desired dose pattern within a region of the patient as positioned;

(c) pre-calculating a preferred ranking of seed locations for a range of locations within the region of the body based on each location'"'"'s contribution to that dose pattern and indicating preferential seed locations for the purpose of producing that dose pattern within the region of the patient before seed locations have been determined;

(d) placing a plurality of seeds in a predefined target region at locations according to the pre-calculated preferred ranking of seed locations; and

(e) implanting the seeds in the patient without repositioning the patient from step (a).

18. Treatment planning software for a placement of radioactive seeds in a tumor in a region of a body, the planning software embodied on a tangible computer-readable medium and executing on an electronic computer to:

(a) determine a desired dose pattern within the region of the body;

(b) pre-calculating a preferred ranking of seed locations for a range of locations within the region of the body based on dose patterns produced by at least one seed moved throughout the range of different locations in a target region;

(c) after step (b) and prior to placement of the seeds in a patient, determining the location of the seeds for a treatment plan by sequentially placing seeds at planning locations according to the preferred ranking of seed locations; and

(d) outputting a proposed treatment plan providing locations of the sequentially located seeds for use in surgical implantation of the seeds.

19. The software of claim 18 wherein the preferred ranking of seed locations assesses a relative dose to tumorous and non-tumorous tissue of the dose pattern produced by seeds at a range of different locations in a target region.

20. The software of claim 19 wherein the preferred ranking of seed locations is a ratio of an average dose measured over the tumorous tissue to an average dose measured over the non-tumorous tissue produced by seeds at a range of different locations in a target region.

21. The software of claim 18 wherein the location of seeds does not change after the seeds are first located.

22. The software of claim 18 wherein each seed is located according to the pre-calculated preferred ranking of seed locations and outside of a zone around previously placed seeds.

23. The software of claim 22 wherein the zone about previously placed seeds is reduced as additional seeds are located.

24. The software of claim 18 wherein the preferred ranking of seed locations is three-dimensional and the seeds are placed variably in three dimensions.

25. The software of claim 18 wherein step (c) continues to locate seeds until a computed dose from the located seeds matches the desired dose pattern within a predetermined criterion.

26. The software of claim 18 further including the software step of:

(e) repeating steps (c) for seed locations constrained along an increasing number of needle tracks up to a predetermined limit;

wherein the step (d) outputs a proposed treatment plan having a fewest number of needle tracks less than the predetermined number of needle tracks where a computed dose from the located seeds matches the desired dose pattern within a predetermined criterion.

27. The software of claim 26 wherein step (c) locates seeds according to the preferred ranking of seed locations adding needle tracks if necessary until the predetermined limit is reached and then locates seeds only along established needle tracks.

28. The software of claim 27 wherein each seed is placed sequentially according to the pre-calculated preferred ranking of seed locations outside of a zone around previously placed seeds, and;

wherein different zones are used for locating seeds before and after the increasing number of needle tracks is reached.

29. The software of claim 18 further including the software step of:

(e) repeating steps (c) for two different types of seeds having different dose patterns starting with first seeds of the first type and proceeding to second seeds of the second type.

30. The software of claim 29 wherein the first seeds have a larger dose pattern than the second seeds.

31. The software of claim 30 wherein each first seed is placed sequentially according to the pre-calculated preferred ranking of seed locations outside of a first zone around previously placed first seeds and second seeds are placed only after no more first seeds can be placed outside of the first zones.

32. The software of claim 29 wherein the first seeds have a directionally asymmetrical dose pattern and the second seeds have a directionally symmetrical dose pattern.

33. The software of claim 32 wherein the first seeds are placed preferentially near boundaries of the target region.