\label{fig:ctrdoi-20} The coincidence time resolution is plotted versus the depth of interaction for three configurations of a $2\times2\times20$ mm$^3$ LSO:CeCa scintillator crystal. Wrapped refers to covering all faces except that in contact with the photodetector in PTFE tape. Partially wrapped has only the side faces covered in PTFE tape leaving the face in contact and opposite the photodetector unwrapped. Unwrapped refers to no covering.