  The Worldline Quantum Field Theory (WQFT) has proven to be an efficient tool
for calculating observables in gravitational wave physics. In contrast to other
QFT-based techniques in the realm of gravitational wave physics, it makes the
classical limit very apparent. However, a natural question remains: How does it
relate to ordinary quantum field theories that we know from particle physics?
This question will be addressed by extending existing approaches to a
description including spin. Furthermore, it will be explicitly shown that the
WQFT can retain quantum contributions by summing up infinite towers of
worldline loops.
