There is no such thing as a photon. Light, and all radiation, is made of of beams. Those beams produce wavelengths of various length depending on the frequency of the radiation.

Those beams are not made up of particles.

 

Those beams can transmit enough energy to particles that they pass through to cause a myriad of effects on the particles.

 

Those beams have no mass.

 

Particles have to have boundaries. No matter what shape the particle has the boundary separates it from other particles.

 

The boundary and what is inside of it have to have mass.

 

Radioactive substances break apart. The particle is emitting radiation. The breaking apart releases radiation. The radiation is not the particle it is the energy wave being released.