A method for automatically detecting a region of interest in a 3D image of a mammal characterised by the region of interest corresponding to soft tissue largely or exclusively interior to the mammal rib cage, the method comprising: (i) one of (a) and (b), as follows: (a) automatically determining using a 3D image of a mammal, by a processor of a computing device, a surface distance image comprising intensity values at each of a plurality of points in three dimensions, each of the intensity values corresponding to a distance from a given point in 3D space to the nearest point on the outer surface of the mammal, and applying, by the processor, a threshold to the surface distance image to determine a surface distance mask corresponding to a central region of the mammal body; (b) automatically determining using the 3D image of the mammal, by the processor of the computing device, a body mask corresponding to mammal body, and applying an erosion operation to the body mask to obtain a surface distance mask equivalent; and, (ii) one of (c) and (d), as follows: (c) automatically determining using the 3D image of the mammal, by the processor, a bone distance image comprising intensity values at each of a plurality of points in three dimensions, each of the intensity values of the bone distance image corresponding to a distance from a given point in 3D space to the nearest identified bone tissue of the mammal, and applying, by the processor, a threshold to the bone distance image to determine a bone distance mask corresponding to one or more regions at least a given distance from identified bone tissue of the mammal; (d) automatically determining using the 3D image of the mammal, by the processor, a bone mask corresponding to bone tissue, and applying a dilation operation to the bone mask to obtain a bone distance mask equivalent; and (iii) automatically detecting, by the processor, a region of interest corresponding to soft tissue interior to the mammal rib cage using said (i) one of the surface distance mask and the surface distance mask equivalent, and (ii) said one of the bone distance mask and the bone distance mask equivalent. (i) one of (a) and (b), as follows: (a) automatically determining using a 3D image of a mammal, by a processor of a computing device, a surface distance image comprising intensity values at each of a plurality of points in three dimensions, each of the intensity values corresponding to a distance from a given point in 3D space to the nearest point on the outer surface of the mammal, and applying, by the processor, a threshold to the surface distance image to determine a surface distance mask corresponding to a central region of the mammal body; (b) automatically determining using the 3D image of the mammal, by the processor of the computing device, a body mask corresponding to mammal body, and applying an erosion operation to the body mask to obtain a surface distance mask equivalent; and, (a) automatically determining using a 3D image of a mammal, by a processor of a computing device, a surface distance image comprising intensity values at each of a plurality of points in three dimensions, each of the intensity values corresponding to a distance from a given point in 3D space to the nearest point on the outer surface of the mammal, and applying, by the processor, a threshold to the surface distance image to determine a surface distance mask corresponding to a central region of the mammal body; (b) automatically determining using the 3D image of the mammal, by the processor of the computing device, a body mask corresponding to mammal body, and applying an erosion operation to the body mask to obtain a surface distance mask equivalent; and, (ii) one of (c) and (d), as follows: (c) automatically determining using the 3D image of the mammal, by the processor, a bone distance image comprising intensity values at each of a plurality of points in three dimensions, each of the intensity values of the bone distance image corresponding to a distance from a given point in 3D space to the nearest identified bone tissue of the mammal, and applying, by the processor, a threshold to the bone distance image to determine a bone distance mask corresponding to one or more regions at least a given distance from identified bone tissue of the mammal; (d) automatically determining using the 3D image of the mammal, by the processor, a bone mask corresponding to bone tissue, and applying a dilation operation to the bone mask to obtain a bone distance mask equivalent; and (c) automatically determining using the 3D image of the mammal, by the processor, a bone distance image comprising intensity values at each of a plurality of points in three dimensions, each of the intensity values of the bone distance image corresponding to a distance from a given point in 3D space to the nearest identified bone tissue of the mammal, and applying, by the processor, a threshold to the bone distance image to determine a bone distance mask corresponding to one or more regions at least a given distance from identified bone tissue of the mammal; (d) automatically determining using the 3D image of the mammal, by the processor, a bone mask corresponding to bone tissue, and applying a dilation operation to the bone mask to obtain a bone distance mask equivalent; and (iii) automatically detecting, by the processor, a region of interest corresponding to soft tissue interior to the mammal rib cage using said (i) one of the surface distance mask and the surface distance mask equivalent, and (ii) said one of the bone distance mask and the bone distance mask equivalent.