A case report of image-based dosimetry of bone metastases with Alpharadin (223Ra-dichloride) therapy: inter-fraction variability of absorbed dose and follow-up

• DOI: 10.1007/s12149-015-1044-9
• Publication Date: 2015-11-27T09:31:54Z
• Authors: Massimiliano Pacilio; Guido Ventroni; Bartolomeo Cassano; Pasquale Ialongo; Leda Lorenzon; Elisabetta Di Castro; Federica Recine; Cora N. Sternberg; Lucio Mango
• Keywords: Male; Bone Neoplasms; 3. Good health; Prostatic Neoplasms, Castration-Resistant; 03 medical and health sciences; 0302 clinical medicine; Chlorides; Humans; Dose Fractionation, Radiation; Radiometry; Aged; Follow-Up Studies; Radium

A 70-year-old man affected by bone metastases from castration resistant prostate cancer underwent Alpharadin ((223)Ra-dichloride) therapy (6 administrations of 50 kBq per kg i.v., once every 4 weeks). The inter-fraction variability of the absorbed dose to lesions was evaluated for four injections. Dosimetric assessments were performed following the MIRD approach and a recently published methodology. The mean absorbed dose and standard deviation for 4 lesions [mean (σ %)] were: 434 mGy (15%) and 516 mGy (21%) for the right and left humeral head, 1205 mGy (14%) and 781 mGy (8%) for the right and left glenoid. The estimated total absorbed dose after the whole treatment, considering also the relative-biological effectiveness of alpha particles (RBE = 5), yielded a D RBE range of 13-36 Gy. A good correlation between (99m)Tc and (223)Ra uptake was obtained (R (2) = 0.7613). The tumour-non-tumour (TNT) ratio of 8 lesions (those above, plus 4 additional), monitored by six (99m)Tc-MDP bone scans over a period of about 10 months, evidenced a TNT reduction in two lesions (-42 and -48 %), but in most lesions the TNT remained fairly constant, evidencing that (223)Ra-dichloride therapy tends to prevent further progression of osseous disease, leading to chronicity of the metastatic status.