Method and Apparatus for Generating Proton Therapy Treatment Planning Images

• US 20130108014A1
• Filed: 10/31/2011
• Published: 05/02/2013
• Est. Priority Date: 10/31/2011
• Status: Active Grant

• Current Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wolfgang Axel Tome
• Inventors: Mackie, Thomas R., Wang, Dongxu, Tom, Wolfgang Axel
• Granted Patent: US 8,897,857 B2
• Time in Patent Office: Days
• US Class Current: 378/21
• CPC Class Codes: A61B 5/4869 Determining body composition
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4258 for detecting non x-ray radiation, e.g. gamma radiation A61B6/037 takes precedence
• CPC Class Codes: A61B 6/50 specially adapted for specific body parts; specially adapted for specific clinical applications
• CPC Class Codes: A61B 6/505 for diagnosis of bone
• CPC Class Codes: A61B 6/5217 extracting a diagnostic or physiological parameter from medical diagnostic data
• CPC Class Codes: A61B 6/544 dependent on patient size
• CPC Class Codes: A61B 6/583 using calibration phantoms
• CPC Class Codes: A61N 2005/1061 using an x-ray imaging system having a separate imaging source
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 5/103 Treatment planning systems
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

A method of producing a patient image indicating proton stopping power of the tissue may employ photon attenuation information converted to proton stopping power. The conversion uses different conversion functions for particular tissue types to account for a strong atomic number dependency in the conversion process. Megavoltage x-rays may be used for improved accuracy.

Claims

1. A program fixed in the non-transient medium and executable on an electronic computer to perform the steps of:

(a) receiving data of a patient based on photon attenuation of x-ray photons passing through patient tissue;

(b) identifying within the tissue at least two tissue types;

(c) converting at least a portion of the photon attenuation data to derived proton stopping-power data using different conversion functions unique to each tissue type; and

(d) producing a treatment control sequence defining proton energies along different paths through the patient tissue using the derived proton stopping power data according to a predefined treatment plan.

2. The program of claim 1 wherein the photon attenuation data provides attenuation of megavoltage photons.

3. The program of claim 1 wherein the photon attenuation data provides attenuation of kilovoltage photons.

4. The program of claim 1 further including the step of receiving partial proton stopping power data of the patient insufficient to reconstruct a tomographic image and wherein step (d) uses the derived proton stopping power data to complete the partial proton stopping power data to reconstruct a tomographic image revealing proton stopping power, and using the tomographic image revealing proton stopping power to produce the treatment control sequence.

5. The program of claim 1 wherein the derived proton stopping power data is sufficient to reconstruct a tomographic image and including the step of using the derived proton stopping power data to reconstruct a tomographic image revealing proton stopping power, and using the tomographic image revealing proton stopping power to produce the treatment control sequence.

6. The program of claim 1 wherein step (c) further includes the step of determining the conversion functions by analyzing the attenuation of x-ray photons along different paths through the patient through different tissue types.

7. The program of claim 6 wherein the analysis mathematically combines attenuation of x-ray photons through different combinations of the different tissue types to isolate an attenuation value for each tissue type.

8. The program of claim 6 wherein the analysis further analyzes attenuation of x-ray photons through a phantom material simulating one tissue type in isolation.

9. The program of claim 8 wherein the phantom is a water phantom representing non-adipose tissue.

10. The program of claim 6 wherein the calibration fits a mathematical function to measured data.

11. The program of claim 1 wherein the tissue types are selected from at least two of the group consisting of adipose tissue, non-adipose tissue, and cortical bone tissue.

12. The program of claim 1 wherein step (b) identifies at least three tissue types.

13. A treatment planning system comprising an electronic computer executing a stored program to:

(a) receive an image of a patient based on photon attenuation data of x-ray photons passing through patient tissue;

(b) identify within the image at least two tissue types;

(c) convert at least a portion of the photon attenuation data to derived proton stopping power data using different conversion functions unique to each tissue type; and

(d) produce a treatment control sequence defining proton energies along different paths through the patient tissue using the derived proton stopping power data.

14. A method of preparing a treatment control sequence for proton radiotherapy comprising the steps of:

(a) obtaining an image of a patient based on photon attenuation data of x-ray photons passing through patient tissue;

(b) identifying within the image at least two tissue types;

(c) converting at least a portion of the photon attenuation data to derived proton stopping power data using different conversion functions unique to each tissue type; and

(d) outputting a treatment control sequence defining proton energies along different paths through the patient tissue using the derived proton stopping power data.

15. The method of claim 14 wherein the photon attenuation data provides attenuation of megavoltage photons.

16. The method of claim 14 wherein the photon attenuation data provides attenuation of kilovoltage photons.

17. The method of claim 14 further including the step of obtaining partial proton stopping power data of the patient insufficient to reconstruct a tomographic image and wherein step (d) uses the derived proton stopping power data to complete the partial proton stopping power data to reconstruct a tomographic image revealing proton stopping power, and using the tomographic image revealing proton stopping power to produce the treatment control sequence.

18. The method of claim 14 wherein the derived proton stopping power data is sufficient to reconstruct a tomographic image and including the step of using the derived proton stopping power data to reconstruct a tomographic image revealing proton stopping power, and using the tomographic image revealing proton stopping power to produce the treatment control sequence.

19. The method of claim 14 wherein the tissue types are selected from at least two of the group consisting of adipose tissue, non-adipose tissue, and cortical bone tissue.

20. The method of claim 14 wherein step (b) identifies at least three tissue types.