The Isotope 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 D721DZ
Stereotactic Gamma Beam Radiosurgery of Thymus
Stereotactic Other Photon Radiosurgery of Thymus
Stereotactic Particulate Radiosurgery of Thymus