Methods and devices for quantitative analysis of x-ray images
View Patent ↗The present invention relates to network enabled analysis of x-ray images. Also described are devices comprising calibration phantoms; methods of using these devices; methods of formulating databases containing information regarding x-ray images; the databases themselves; and methods of manipulating the information and databases.
1. A method of generating a density calibration curve, comprising the steps of
(a) providing an assembly comprising an x-ray film holder; x-ray film and a wedge-shaped calibration phantom having length (L) and varying thickness (T) along the length:
(b) producing an x-ray image of an anatomical structure, wherein the x-ray image comprises the calibration phantom;
(c) measuring attenuation at a multitude of points in the x-ray image of the calibration phantom, wherein each point is at known distance from a selected part of the phantom;
(d) measuring attenuation of at least one point of known density in the x-ray image of the anatomical structure; and
(e) generating a calibration curve that describes the relationship between attenuation measured in (c) and (d) and material thickness.
2. The method of claim 1 , further comprising the step of translating the calibration curve describing thickness into a curve describing calcium concentration.
3. The method of claim 2 , wherein the calibration phantom comprises aluminum and the calibration curve describes aluminum thickness.
4. A method of generating a reference calibration curve, comprising the step of calculating the average of calibration curves obtained according to the method of claim 1 .
5. The method of claim 1 , wherein the x-ray image is a dental x-ray.
6. The method of claim 1 , wherein the calibration curve is generated in a network environment.
7. A method of diagnosing osteoporosis comprising the step of analyzing an x-ray image obtained by the method of claim 1 , wherein if the bone mineral density is below a reference standard, osteoporosis is diagnosed.
8. A method of treating osteoporosis comprising diagnosing osteoporosis according to the method of claim 7 and administering one or more anti-resorptive agents or one or more anabolic agents.
9. The method of claim 1 , wherein, in step (d), the at least one point of known density in the anatomical structure is in muscle, fat, or air.
10. The method of claim 9 , wherein the fat is subcutaneous fat.
11. A method of generating a density calibration curve, comprising the steps of
(a) providing an assembly comprising an x-ray film holder; x-ray film and a wedge-shaped calibration phantom having length (L) and varying thickness (T) along the length and wherein the thickness of calibration phantom varies non-linearly along its length;
(b) producing an x-ray image of an anatomical structure, wherein the x-ray image comprises the calibration phantom;
(c) providing an expected calibration curve for the non-linear calibration phantom;
(d) measuring attenuation at a multitude of points in the x-ray image of the calibration phantom;
(e) measuring attenuation of at least one point of known density in the x-ray image of the anatomical structure: and
(e) aligning the points measured in steps (d) and (e) with the expected calibration curve generated in step (c), thereby generating a calibration curve for the image.
12. The method of claim 11 , further comprising the step of translating the calibration curve describing thickness into a curve describing calcium concentration.
13. The method of claim 12 , wherein the calibration phantom comprises aluminum and the calibration curve describes aluminum thickness.
14. A method of generating a reference calibration curve, comprising the step of calculating the average of calibration curves obtained according to the method of claim 11 .
15. The method of claim 11 , wherein, in step (e), the at least one point of known density in the anatomical structure is in muscle, fat, or air.
16. The method of claim 15 , wherein the fat is subcutaneous fat.
17. A method of generating a density calibration curve, comprising the steps of
(a) generating a digital x-ray image of an anatomic structure that includes a wedge-shaped calibration phantom having length (L) and varying thickness (T) along the length;
(b) generating an expected calibration curve; and
(c) measuring attenuation at a multitude of points in the x-ray image including the calibration phantom;
(d) measuring attenuation of at least one point of known density in the x-ray image of the anatomical structure: and
(e) aligning the points measured in steps (c) and (d) with the expected calibration curve generated in step (b), thereby generating a calibration curve for the image.
18. The method of claim 17 , further comprising the step of translating the calibration curve describing thickness into a curve describing calcium concentration.
19. The method of claim 18 , wherein the calibration phantom comprises aluminum and the calibration curve describes aluminum thickness.