  We demonstrate the appearance of symmetry protected triplon Dirac modal lines
in the low energy excitation spectrum of a realistic microscopic model of the
geometrically frustrated quantum magnet SrCu2(BO3)2 in its high symmetry phase.
The symmetry-allowed Dzyaloshinskii-Moriya interactions induce dispersive
trilpon bands within the bond-operator formalism that cross linearly over an
extended closed path in the Brillouin zone. Our results establish that the
nodal lines are protected by a $U(1)$-symmetry and robust against perturbations
that preserve this symmetry. In the presence of a longitudinal field, the nodal
loop shrinks and vanishes for a sufficiently strong field.
