Yttrium-90 Radioembolization: A Comprehensive Clinical and Radiopharmaceutical Review

Section 1: Yttrium-90: Isotopic Properties and Therapeutic Rationale

Yttrium-90 (Y-90), a radioactive isotope of the element yttrium, has emerged as a cornerstone in the field of interventional oncology, particularly for the treatment of hepatic malignancies. Its therapeutic efficacy is rooted in a unique combination of radiochemical properties and a sophisticated, targeted delivery mechanism. This section details the fundamental characteristics of the Y-90 isotope and the biological rationale underpinning its use in the advanced radiotherapeutic procedure known as transarterial radioembolization (TARE), or selective internal radiation therapy (SIRT).

1.1 Radiochemical Profile of Yttrium-90

The suitability of Yttrium-90 for locoregional cancer therapy is not coincidental; its physical properties are exceptionally well-matched for delivering a potent, localized, and temporally contained radiation dose. It is a pure beta (${\beta}^{-}$) particle emitter, a critical characteristic that defines its therapeutic action.[1] During its decay process, Y-90 transforms into the stable, non-radioactive isotope Zirconium-90 ($^{90}$Zr).[1] This decay is characterized by the emission of high-energy electrons with a maximum energy of 2.28 MeV and a potent average energy of approximately 0.93 MeV.[1]