Radiation based treatment beam position calibration and verification

1. A phantom comprising:

a phantom body and an X-ray luminescent material, wherein the X-ray luminescent material is at least partially embedded in an outer surface of the phantom body, wherein the phantom body has a cavity, the phantom having a transparency that allows acquiring, using one camera at one location, of an image of an entrance feature of a radiation beam entering the phantom and an exit feature of the radiation beam exiting the phantom, wherein the X-ray luminescent material is a dielectric material comprising water with a fluorescent compound to generate a Cerenkov optical signal in response to a radiation beam incident on the phantom.

2. The phantom of claim 1 , wherein the X-ray luminescent material is an X-ray scintillation material with superficial build-up material.

3. The phantom of claim 1 , wherein:

the phantom body comprises an opaque substrate;

opaqueness of the phantom does not allow acquiring, using one camera at one location, of an image of an entrance feature of a radiation beam entering the phantom and an exit feature of the radiation beam exiting the phantom.

4. The phantom of claim 1 , wherein a pattern of visually identifiable features at relative positions is overlaid on the surface of the phantom.

5. The phantom of claim 4 , wherein the pattern is a checkerboard pattern.

6. A phantom comprising:

phantom body and an X-ray luminescent material, wherein at least a portion of the X-ray luminescent material is embedded in a surface of the phantom body, wherein:

the surface of the phantom body is uniform;

a relationship of optical signal to absorbed source is constant over the surface of the phantom body;

the optical signal is a measurement of a radiation beam incident to the surface; and

the absorbed source is a measurement of absorption of the radiation beam in the phantom.