Fig. 2.

(a) Cherenkoscopy from a 6 MV square ($10\times 10{\mathrm{cm}}^2$) photon beam incident normally on a tissue phantom ($30\times 30\times 4{\mathrm{cm}}^3$) of opaque water equivalent phantom at $\mathrm{SSD}=100\mathrm{cm}$ with delivered dose at $d_{\max }$ varying from 0.5 to 25 cGy. (b) Signal-to-noise ratio of Cherenkov images with fps from 0.68 to 7. (c) Linearity between intensity of Cherenkov emission from the surface and delivered dose is established under these controlled conditions.