Lesion volume measurements system
An apparatus for measuring lesion volume, for example, in laboratory animals, provides a mirror box allowing a camera to simultaneously acquire profiles of the lesion along at least two crossing axes from which accurate volume may be approximated at low cost.
1. An apparatus for measuring a volume of a lesion comprising:
a housing providing a lower surface adapted to be positioned and supported at a surface of skin around the lesion with the lesion extending upwardly through a center opening in the lower surface; the lower surface defining a plane of contact;
a camera directed toward the center opening along a camera axis, the camera held by the housing at a predetermined distance from the lower surface;
a first mirror attached to the housing and held at a first angle by the housing;
a second mirror attached to the housing and held at a second angle by the housing; and
a computer executing a program stored in non-transitory memory to receive an image from the camera of side views from the first mirror and second mirror to compute the volume of the lesion;
wherein the first angle and the second angle are such as to direct light received from the lesion and parallel to the plane of contact, to the camera for imaging by the camera;
wherein the image by the camera through the first mirror and the second mirror excludes portions of the lesion below the surface of the skin; and
wherein the computer is configured to compute the volume of the lesion limited to a volume above the skin.
2. The apparatus of claim 1 , wherein the lower edge of the first mirror furthest from the camera and the lower edge of the second mirror furthest from the camera provide a reflecting surface within one-quarter inch of the plane of contact.
3. The apparatus of claim 1 , wherein the image is part of a set of images, wherein the computer is configured to compute the volume of the lesion from an average of the set of images using a sum of a set of slices parallel to the plane of contact at different heights along the lesion and displaced along the camera axis, each slice of the set of slices constrained in width across a first mirror axis and a second mirror axis by a width of the side view from a respective mirror at the height.
4. The apparatus of claim 3 , wherein a constraining width of the set of slices is fit to a closed curve to define a slice perimeter; wherein the closed curve is an ellipse, the first mirror axis and the second mirror axis are perpendicular and define a major axis and minor axis of the ellipse, respectively.
5. The apparatus of claim 1 , further including a display displaying the image from the camera, the image having at least one fiducial mark superimposed on the image of a top view of the lesion extending upwardly through the center opening and adapted to allow alignment of the lesion with the at least one fiducial mark between successive measurements of the lesion by the apparatus.
6. The apparatus of claim 5 , further including at least two fiducial marks to allow both a centering of the lesion within the plane and a predetermined rotational orientation of the lesion about the camera axis.
7. The apparatus of claim 1 , wherein the housing provides an opaque shroud around the central opening and further including a diffuse illuminator positioned to illuminate the lesion extending upwardly through the center opening; wherein the diffuse illuminator is a ring light.
8. The apparatus of claim 1 , further including a third mirror attached to the housing and held at a third angle by the housing; when the third angle of the third mirror is such as to direct light received parallel to the plane of contact to the camera; and wherein the computer receives the image from the camera of side views from the first mirror, second mirror, and third mirror to compute the volume of the lesion.
9. The apparatus of claim 1 , further including a display communicating with the computer to display the image of the lesion together with the computed volume.
10. The apparatus of claim 1 , wherein the computer operates to store a set of successive images taken at different times separated by hours together with volumes of the lesions derived from the set of successive images.
11. The apparatus of claim 10 , wherein the computer provides a video display sequencing through the set of successive set of images.
12. The apparatus of claim 1 , wherein the computer operates to timestamp the image.
13. A method of assessing a volume of a lesion using an instrument having: a housing providing a lower surface adapted to be positioned and supported at a surface of the skin around a lesion with the lesion extending upwardly through a center opening in the lower surface, the lower surface defining a plane of contact; a camera directed toward the center opening along a camera axis, the camera held by the housing at a predetermined distance from the lower surface; a first mirror attached to the housing and held at a first angle by the housing; a second mirror attached to the housing and held at a second angle by the housing wherein the first angle of the first mirror and the second angle of the second mirror is such as to direct light received from the lesion and parallel to the plane of contact, to the camera for imaging by the camera; wherein an image by the camera through the first mirror and the second mirror excludes portions of the lesion below the surface of the skin; and computer executing a program stored in non-transitory memory to receive the image from the camera of side views from the first mirror and the second mirrors to compute the volume of the lesion, the method comprising: (a) positioning the lesion to extend upwardly through the center opening in the lower surface; (b) capturing the side views of only portions of the lesion above the surface of the skin from the first mirror and the second mirror by the computer; and (c) computing the volume of the lesion, limited to a volume above the skin, from the side views and a geometry of the first mirror and the second mirror.
14. The method of claim 13 , including repeating steps (a)-(c) at different times separated by hours to obtain a set of time stamped images.
15. The method of claim 13 , including playing the set of images as a video sequence.
16. The method of claim 13 , including marking the lesion with a lesion mark and aligning the lesion mark with a fiducial mark presented in a camera display of the image.
17. The method of claim 16 , wherein aligning includes at least one of translational and rotational alignment between the fiducial mark and the lesion mark.
18. The method of claim 13 , wherein the image is part of a set of images, and the method further including the step of averaging together the set of images to obtain the volume of the lesion.
19. The method of claim 13 , wherein a number of mirrors is limited to two or three.
20. The method of claim 13 , wherein the computer operates to timestamp the image.