METHOD FOR COMPUTING PATIENT RADIATION DOSE IN COMPUTED TOMOGRAPHY

• US 20080292055A1
• Filed: 05/19/2008
• Published: 11/27/2008
• Est. Priority Date: 11/21/2005
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Boone, John M.
• Granted Patent: US 7,627,079 B2
• Time in Patent Office: Days
• US Class Current: 378/97
• CPC Class Codes: G01T 1/02 Dosimeters G01T1/15 takes precedence
• CPC Class Codes: G01T 1/2985 In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis); using external radiation sources A61B6/02
• CPC Class Codes: Y10S 378/901 Computer tomography program or processor

Abstract

A system and method are disclosed for computing a radiation dose delivered to a patient during a computed tomography (CT) scan of the patient. The CT image dataset generated during the scan of the patient, and one or more parameters relating to a x-ray source are used to calculate the radiation dose delivered to the patient as a function of the CT image data set and the one or more parameters of the x-ray source. The radiation dose is generally found by calculating a primary x-ray dose distribution and scattered x-ray dose distribution from the CT image dataset and taking the sum of the primary x-ray dose distribution and scattered x-ray dose distribution.

Claims

1. A method for determining a radiation dose delivered to a patient during a computed tomography (CT) scan of the patient, comprising:

subjecting a patient to an x-ray beam from an x-ray source;

determining a primary x-ray radiation level from the x-ray beam;

determining a scattered x-ray radiation level from the x-ray beam; and

calculating a radiation dose delivered to the patient based on the primary x-ray radiation level and scattered x-ray radiation level.

2. A method as recited in claim 1:

wherein the primary x-ray radiation level comprises the deposition of energy in the patient from x-ray photons which have their original trajectory from the x-ray source; and

wherein the scattered x-ray radiation level comprises the deposition of energy in tissues from x-ray photons which have been scattered within the patient and out of line from their original trajectory from the x-ray source.

3. A method as recited in claim 1, wherein determining the primary x-ray radiation level comprises calculating a primary dose distribution from CT scan image data generated during the CT scan of the patient.

4. A method as recited in claim 3, wherein the CT scan image data is scaled down prior to calculating the primary dose distribution.

5. A method as recited in claim 3, further comprising:

inputting properties of the x-ray source;

wherein said properties are used to calculate the primary dose distribution.

6. A method as recited in claim 5:

wherein one of said properties comprises a mA modulation scheme of the x-ray source; and

wherein the mA modulation scheme is used to compute the radiation dose delivered to the patient.

7. A method as recited in claim 6;

wherein the mA modulation scheme is derived from the CT scan image data to compute the radiation dose delivered to the patient.

8. A method as recited in claim 3, wherein determining the scattered x-ray radiation level comprises calculating a scattered dose distribution from the CT scan image data and the primary dose distribution.

9. A method as recited in claim 8;

further comprising;

determining a secondary scattered x-ray radiation level from the scattered dose distribution and the CT scan image data.

10. A method as recited in claim 1, further comprising:

determining a boundary of an organ of the patient; and

calculating an average radiation dose delivered to the organ based on the determined boundary and the calculated radiation dose.

11. A method as recited in claim 10, further comprising:

applying a weight factor to the average dose to calculate an effective dose to the organ.

12. A method as recited in claim 3, further comprising:

generating a CT dose distribution map from the calculated radiation dose;

wherein the CT dose distribution map correlates to the CT scan image data.

13. A method as recited in claim 11, further comprising:

including one or more of the radiation dose, average radiation dose, or effective dose as part of a DICOM header for a CT image of the patient.

14. A method as recited in claim 1, wherein reconstruction software and hardware of the x-ray source is used to calculate the radiation dose.

15. A method for computing a radiation dose delivered to a patient during a computed tomography (CT) scan of the patient, comprising:

generating a CT image dataset of a region of the patient;

determining one or more parameters relating to a x-ray source used to generate the CT image dataset; and

calculating the radiation dose delivered to the patient as a function of the CT image data set and the one or more parameters of the x-ray source.

16. A method as recited in claim 15, wherein calculating the radiation dose delivered to the patient comprises:

calculating a primary x-ray dose distribution from the CT image dataset;

calculating a scattered x-ray dose distribution from the CT image dataset; and

calculating the radiation dose delivered to the patient based on said primary x-ray dose distribution and scattered x-ray dose distribution.

17. A method as recited in claim 15, wherein the CT image dataset is scaled down prior to calculating the radiation dose.

18. A method as recited in claim 15:

wherein determining one or more parameters comprises determining a mA modulation scheme of the x-ray source.

19. A method as recited in claim 16, wherein the mA modulation scheme is derived from the CT image dataset.

20. A method as recited in claim 16, wherein the scattered x-ray dose distribution is calculated as a function of the CT image dataset and the primary x-ray dose distribution.

21. A method as recited in claim 16, further comprising:

determining a secondary scattered x-ray dose distribution from the scattered x-ray dose distribution and the CT image dataset.

22. A method as recited in claim 15, further comprising:

calculating an average radiation dose for a specific CT image in the CT image dataset.

23. A method as recited in claim 22, further comprising:

including average radiation dose for a specific CT image in the DICOM header of the CT image.

24. A method as recited in claim 15, further comprising:

determining a boundary of an organ of the patient; and

calculating an average radiation dose delivered to the organ based on the determined boundary and the calculated radiation dose.

25. A method as recited in claim 24, further comprising:

applying a weight factor to the average dose to calculate an effective dose to the organ.

26. A method as recited in claim 15, further comprising:

generating a CT dose distribution map from the calculated radiation dose;

wherein the CT dose distribution map correlates to the CT image dataset.

27. A method as recited in claim 24, further comprising:

including one or more of the radiation dose, average radiation dose, or effective dose as part of a DICOM header for a CT image of the CT image dataset.

28. A method as recited in claim 15, wherein the radiation dose is calculated with a PACS system.

29. A method for computing a radiation dose delivered to a patient during a computed tomography (CT) scan of the patient, comprising:

generating a CT image dataset of a region of the patient;

determining one or more parameters relating to a x-ray source used to generate the CT image dataset;

calculating a primary x-ray dose distribution as a function of the CT image dataset and the one or more parameters relating to a x-ray source;

calculating a scattered x-ray dose distribution as a function of the primary x-ray dose distribution; and

computing the radiation dose delivered to the patient based on the primary x-ray dose distribution and scattered x-ray dose distribution.

30. A method as recited in claim 29, further comprising:

calculating an average radiation dose for a specific CT image in the CT image dataset.

31. A method as recited in claim 30, further comprising:

including the average radiation dose for a specific CT image in the DICOM header of the CT image.

32. A method as recited in claim 29, further comprising:

determining a boundary of an organ of the patient; and

calculating an average radiation dose delivered to the organ based on the determined boundary and the calculated radiation dose.

33. A method as recited in claim 32, further comprising:

applying a weight factor to the average dose to calculate an effective dose to the organ.

34. A method as recited in claim 32, wherein the average radiation dose is calculated for one or more of the following anatomical features:

fetal dose, eye orbit dose, thyroid dose, bones, blood forming elements, spleen, liver, bladder, brain, gonads (male or female), breast (left or right), pancreas, kidney (left or right), adrenal (left or right).

35. A method as recited in claim 29, further comprising:

determining a boundary of a pathological entity of the patient; and

calculating an average radiation dose delivered to the pathological entity based on the determined boundary and the calculated radiation dose.

36. A method as recited in claim 29, further comprising:

determining a boundary of a man-made entity in the patient; and

calculating an average radiation dose delivered to the man-made entity based on the determined boundary and the calculated radiation dose.

37. A method as recited in claim 29, further comprising:

computing an external radiation dose delivered to the patient outside the scanned volume of the CT dataset by extrapolating the calculating radiation dose to other regions of the patient'"'"'s body.