The construction of low mass vertex detectors with a high level of system integration is of great interest for next generation collider experiments. Radiation length images with a sufficient spatial resolution can be used to measure and disentangle complex radiation length ($X$/$X_0$) profiles and contribute to the understanding of vertex detector systems. Beam test experiments with multi GeV particle beams and high resolution tracking telescopes provide an opportunity to obtain precise 2D images of the radiation length of thin planar objects. At the heart of the $X$/$X_0$ imaging is a spatially resolved measurement of the scattering angles of particles traversing the object under study.\\
In order to demonstrate the capabilities of $X$/$X_0$ imaging, a beam test experiment has been conducted. The device under test was a mechanical prototype half-ladder of the Belle II pixel detector (PXD). The measured $X$/$X_0$ image was overlaid with a Geant4 simulation of a PXD half-ladder and excellent agreement was found. As shown here, radiation length imaging of detectors can serve as a method to validate geometry models of complex vertex detectors.