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 CH20YZ
Tomo Nucl Med Imag of R Breast using Thallium 201
Tomo Nucl Med Imag of R Breast using Oth Radionuclide
Tomo Nucl Med Imag of R Breast using Technetium 99m