Whole-body distribution of radioactivity after intraperitoneal administration of32P colloids

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Abstract
The whole-body distribution of radioactivity after i.p. instillation of 32P-labeled chromic hydroxide particles [used for diagnosis of metastasis] was studied in patients operated for early-stage ovarian cancer. Gamma-camera imaging of the abdominal 32P-distribution revealed that the administration procedure was critical for obtaining a homogeneous plating of the radiocolloids on the serosal surface. Dose calculations based on a uniform distribution of 32P in a capillary layer covering the i.p. surface gave an estimated tissue dose of about 30 Gy [gray] per 370 MBq [mega becquerel] of 32P administered. The amount of 32P in peripheral blood increased for 7 days after instillation followed by a continuous decrease. Bone marrow concentration was from 2-5 times as high as that in blood, but the total amounts were too small to give significant radiation doses. Gel chromatography showed that 33% of the activity in blood consisted of high molecular weight material, probably colloids. The remainder of the activity (67%) was attached to material of very low molecular weight, appearing as a consequence of physiological degradation of the colloids.