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 CW531Z
Nonimaging Nuclear Medicine Probe of Chest using Indium 111
Nonimag Nucl Med Prob of Chest using Oth Radionuclide
Nonimag Nucl Med Prob of Chest using Technetium 99m