Thank you for your question regarding CMS129v13 Prostate Cancer: Avoidance of Overuse of Bone Scan for Staging Low Risk Prostate Cancer Patients. CMS129v13 has a denominator exception for “documentation of reason(s) for performing a bone scan.” In this case, a patient having a bone scan ordered by someone other than the reporting clinician qualifies for that denominator exception. Patients with a denominator exception are excluded from the measure denominator and do not affect an eligible clinician’s scoring on the measure.