I understand that total flux measures photons/s whereas average radiance is measurement of photons/s/cm2/sr. The purpose of the imaging is to follow the cancer growth (cancer cell line tagged with luciferase) in vivo. Based on most publications, such studies usually report total flux instead of average radiance. Given that males and females have slight variation in size, should we take into account the surface area of the mouse when performing analysis and report average radiance instead?
The appropriate measure of tumor burden in bioluminescence imaging is total flux (photons/s), which is average radiance (flux per unit area and unit solid angle) integrated over the region of interest. The size of animal is not relevant for tumor burden, when total flux is reported.
Thanks Roman for the reply. I understand and agree that the size of the animal is irrelevant for tumor burden.
During analysis, the region of interest is gated and this is the area where signal is measured. In that case, by taking total flux, the variation in area is omitted in the analysis. Will it be a fair comparison between each mouse?
You would measure total flux only if you have the same area for ROI for all of your mice. If not, you have to divide by the number of pixels.
Total Flux = the radiance (photons/sec) in each pixel summed or integrated over the ROI area (cm2) x 4π.
Average Radiance = the sum of the radiance from each pixel inside the ROI/number of pixels or super pixels (photons/sec/cm2/sr).
- Badges
- Science topic