nt Dose: Calculate the volume required for a Y-90 Zeva lin dose [see Dosage and Administration (2.2)]. Withdraw the required volume from the reaction vial. Assay the syringe in the dose calibrator suitable for the measurement of Y-90. The measured dose must be within 10% of the prescribed dose of Y-90 Zeva lin and must not exceed 32 mCi (1184 MBq). Using the supplied labels, record the patient identifier, total activity and volume and the date and time of expiration, and affix these labels to the syringe and shielded unit dose container.
Determine Radiochemical Purity [see Dosage and Administration (2.4)].
Store Yttrium-90 Zeva lin at 2-8°C (36-46°F) until use and administer within 8 hours of radiolabeling. Immediately prior to administration, assay the syringe and contents using a radioactivity calibration system suitable for the measurement of Y-90.
2.4 Procedure for Determining Radiochemical Purity
Use the following procedures for radiolabeling both In-111 Zeva lin and
Y-90 Zeva lin:
Place a small drop of either In-111 Zeva lin or Y-90 Zeva lin at the origin of an ITLC-SG strip.
Place the ITLC-SG strip into a chromatography chamber with the origin at the bottom and the solvent front at the top. Allow the solvent (0.9% NaCl) to migrate at least 5 cm from the bottom of the strip. Remove the strip from the chamber and cut the strip in half. Count each half of the ITLC-SG strip for one minute (CPM) with a suitable counting apparatus.
Calculate the percent RCP as follows:
Repeat the ITLC procedure if the radiochemical purity is <95%. If repeat testing confirms that radiochemical purity is <95%, do not administer the In-111 or Y-90 Zeva lin dose.
2.5 Image Acquisition and Interpretation of Biodistribution
Assess the biodistribution of In-111 Zeva lin by a visual eva luation of whole body planar view anterior and posterior gamma images obtained at 48 - 72 hours after injection. Images at additional time points may be necessary to resolve ambiguities. Acquire whole body anterior/posterior planar images using a large field-of-view gamma camera and medium energy collimators. Suggested gamma camera settings: 256 x 1024 matrix; dual energy photopeaks set at 172 and 247 keV; 15% symmetric window; scan speed of 10 cm/min for the 48-72 hour scan, and 7-10 cm/min for subsequent scans.
Expected Biodistribution
Activity in the blood pool areas (heart, abdomen, neck, and extremities) may be faintly visible.
Moderately high to high uptake in normal liver and spleen.
Moderately low or very low uptake in normal kidneys, urinary bladder, and normal (uninvolved) bowel.
Non-fixed areas within the bowel lumen that change position with time; delayed imaging as described above may be necessary to confirm gastrointestinal clearance.
Focal fixed areas of uptake in the bowel wall (localization to lymphoid aggregates in bowel wall).
Tumor uptake may be visualized however tumor visualization on the In-111 Zeva lin scan is not required for Y-90 Zeva lin therapy.
Altered Biodistribution
The criteria for altered biodistribution are met if any of the following is detected on visual inspection of the required gamma images:
Intense localization of radiotracer in the liver and spleen and bone marrow indicative of reticuloendothelial system uptake.
Increased uptake in normal organs (not involved by tumor) such as:
Diffuse uptake in normal lung more intense than the liver.
Kidneys have greater intensity than the liver on the posterior |
