¹⁸⁸W/¹⁸⁸Re Generator System and Its Therapeutic Applications

Abstract

The 188 Re radioisotope represents a useful radioisotope for the preparation of radiopharmaceuticals for therapeutic applications, particularly because of its favorable nuclear properties. The nuclide decay pattern is through the emission of a principle beta particle having 2.12 MeV maximum energy, which is enough to penetrate and destroy abnormal tissues, and principle gamma rays (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:msub><mml:mrow><mml:mi>E</mml:mi></mml:mrow><mml:mrow><mml:mi>γ</mml:mi></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mn>155</mml:mn></mml:math> keV), which can efficiently be used for imaging and calculations of radiation dose. 188 Re may be conveniently produced by 188 W/ 188 Re generator systems. The challenges related to the double neutron capture reaction route to provide only modest yield of the parent 188 W radionuclide indeed have been one of the major issues about the use of 188 Re in nuclear medicine. Since the specific activity of 188 W used in the generator is relatively low (&lt;185 GBq/g), the eluted<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mrow><mml:msup><mml:mrow><mml:mrow><mml:mtext>Re</mml:mtext></mml:mrow><mml:mrow><mml:mn>188</mml:mn></mml:mrow><mml:msub><mml:mrow><mml:mtext>O</mml:mtext></mml:mrow><mml:mrow><mml:mn mathvariant="normal">4</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>can have a low radioactive concentration, often ineffective for radiopharmaceutical preparation. However, several efficient postelution concentration techniques have been developed, which yield clinically useful<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mrow><mml:msup><mml:mrow><mml:mrow><mml:mtext>Re</mml:mtext></mml:mrow><mml:mrow><mml:mn>188</mml:mn></mml:mrow><mml:msub><mml:mrow><mml:mtext>O</mml:mtext></mml:mrow><mml:mrow><mml:mn mathvariant="normal">4</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>solutions. This review summarizes the technologies developed for the preparation of 188 W/ 188 Re generators, postelution concentration of the 188 Re perrhenate eluate, and a brief discussion of new chemical strategies available for the very high yield preparation of 188 Re radiopharmaceuticals.