[⁹⁰Y]DOTATOC doses based on dosimetry from the patient’s previous injection are used to maximize tumor uptake versus limiting renal toxicity.

All manufacturing operations were conducted under cGMP using a single-use cassette and designed to deliver the final product in approx. 100mL.  Once the dose had been prescribed based on dosimetry, [⁹⁰Y]YCl₃ was ordered. A solution of ascorbate buffer in saline was added to the product vial as diluent and to prevent product radiolysis.  The amount of DOTATOC precursor was scaled to the amount of activity received. The received [⁹⁰Y]YCl₃ was transferred to the reaction vessel (RV) and the vial rinsed with ascorbate buffer.  The RV was heated to 95^oC for 25min.  The reaction mixture was purified by trapping on a C-18 SPE cartridge, then eluted with aq. ethanol and saline into the final product vial (approx. 100mL of [⁹⁰Y]DOTATOC solution).

[⁹⁰Y]DOTATOC was routinely produced in >98% radiochemical purity and >90% radiochemical yield after removal of QC samples. Having the final product in approx. 100mL meant that only a small fraction was removed for QC and the dilution in concert with the presence of approx. 1% ethanol and ascorbate prevented any significant radiolysis. The use of a vial with close to 100mL contents made it easy to make consistently accurate Y-90 measurements.  The adjustment of the amount of precursor used to provide a semi-quantitative way to maintain specific activity did not appear to affect yield.  Only the quantity of [⁹⁰Y]YCl₃ needed to ensure a production safety margin was purchased.

A patient specific dose of [⁹⁰Y]DOTATOC was consistently provided based on the patient's prior dosimetry.  The procedure avoids using excessive amounts of [⁹⁰Y]YCl₃ resulting in reduced costs, limiting exposure and disposal.  The more dilute preparation avoids significant exposure to the administrating technologist, nurses, and accompanying family.