Type-based market taxonomy distinguishes the physical characteristics and regulatory pathways that shape procurement and pricing. Alpha-emitters (e.g., Ra-223, Ac-225) command premium pricing owing to high linear-energy transfer and short tissue range, translating into potent cytotoxicity amid minimal myelosuppression; they represent 24 % of 2023 global sales but >35 % of forecast value growth. Beta-emitters remain the volume anchor at 66 % share, leveraging long-standing logistics for I-131, Y-90, and Lu-177 while benefiting from generator-based hub production. Brachytherapy isotopes (primarily I-125, Pd-103, Cs-131) contribute 10 %, embedded in hospital radiation-oncology departments; their market is constrained by capital equipment requirements and a shift toward external-beam alternatives, yet still delivers steady demand from prostate and ocular melanoma clinics seeking precise, high-dose local control.