Wolfram Alpha has Thorium-215 as decaying to Radium-211 by alpha emission Th-215 on Wolfram Alpha. However, it is possible that some nuclei would be the product of reactions leaving them with excess energy, which would cause them to decay by gamma emission.
In such a case the formula would be:
The "m" in the equation means "metastable" indicating that the nucleus has excess energy. That energy is converted into a gamma photon as indicated in the equation.