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 C7631Z
Nonimag Nucl Med Assay of Blood using Oth Radionuclide
Nonimaging Nuclear Medicine Assay of Blood using Cobalt 57
Nonimaging Nuclear Medicine Assay of Blood using Cobalt 58
Nonimaging Nuclear Medicine Assay of Blood using Chromium
Nonimaging Nuclear Medicine Assay of Blood using Indium 111
Nonimag Nucl Med Assay of Blood using Technetium 99m
Nonimaging Nuclear Medicine Assay of Blood using Iodine 125