Fig. 2.

Finite element models of light fluence models were generated using a multi-step process starting with the clinical x-ray CT image of the joint. Figure 2a shows the CT image of the right distal femoral head. There are features in the CT image, such as a narrowed space between the femur and tibia and bony growths at the side of the femur, which indicate advanced osteoarthritis. Figure 2b shows a view of the femur through the same plane of the finite element model, with regions labeled by tissue type. Light blue denotes cartilage, yellow denotes bone, brown denotes marrow, and dark blue denotes the region outside the model. The arrows indicate the approximate position of the illumination (x=51.67, z=178.54 mm) and collection (x=53.17, z=178.01 mm) fibers. The dashed box indicates the subregion of the model shown in Figure 2c and 2d. Figure 2c shows light fluence from the source fiber optic at using the optical properties at 830 nm. Figure 2d shows light fluence from the measurement fiber at is shown using the optical properties at 901.7 nm (corresponding to the vibrational band at 958 cm⁻¹). The colorbar shows the log₁₀ scaled fluence intensities. Larger numbers denote higher transfer efficiency from the fiber optic to the given position in the image.