  The Di{\'o}si-Penrose model is explored in a relativistic context.
Relativistic effects were considered within a recently proposed Grave de
Peralta approach [L. Grave de Peralta, {\em Results Phys.} {\bf 18} (2020)
103318], which parametrize the Schr{\"o}dinger-like hamiltonian so as to impose
that the average kinetic energy of the system coincide with its relativistic
kinetic energy. As a case of study, the method is applied to a particle in a
box with good results. In the Di{\'o}si-Penrose model we observed that the
width of a quantum matter field confined by its own gravitational field [L.
Di{\'o}si, {\em Phys. Lett}. {\bf 105A} (1984) 199], sharply drop to zero for a
mass of the order of the Planck mass, indicating a breakdown of the model at
the Planck scale.
