CPT code 77334 covers the professional work involved in designing, developing, and constructing custom devices that facilitate accurate therapeutic radiation delivery and protect adjacent healthy tissues. These patient-specific devices—such as custom immobilization systems, shielding blocks, and applicators—play a critical role in precision radiation therapy and can directly affect treatment accuracy and safety. Nationally, the code is relevant to radiation oncology providers, hospital outpatient departments, and payers managing high-cost oncology care. Key payers in typical analyses include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. This publication provides a concise overview of CPT code 77334, outlining clinical context and service settings, common payer coverage considerations, and how the code fits into radiation therapy service lines. Readers will learn what the code represents, where and how the service is typically delivered, and which major payers commonly address coverage and billing for custom radiation devices. Data not available in the input will be noted where applicable.