The Qualifier None is identified by letter "Z" and occupies the 6th position in the ICD10-PCS procedure code structure.
Below a selection of ICD 10 PCS codes related to C51BYZ
Planar Nucl Med Imag R Low Extrem Vein w Oth Radionuclide
Planar Nucl Med Imag R Low Extrem Vein w Technetium 99m