Therapy of hepatocellular carcinoma with 131I-lipiodol: patient dosimetry

Dosimetry in (131)I-lipiodol therapy for hepatocellular carcinoma (HCC) in the hitherto largest existing patient cohort.

38 courses of intra-arterial (131)I-lipiodol therapy with a total activity up to 6.7 GBq were performed in 18 patients with HCC. Liver and tumour volume were measured by computed tomography (CT) and (131)I-activity by scintigraphy on day 3, 6, 14, 28 and 42 after injection. Lipiodol deposition in tumour nodules as shown by CT rendered definite attachment to scintigraphic data possible. The radiation dose in tumour nodules, liver and lungs was calculated according to the MIRD concept and the tumour dose related to pre-therapeutic tumour volume, response and survival.

Mean tumour dose was 23.6 +/- 3.6 Gy (14.2 +/- 2.1 mGy/MBq) with maximal 162 Gy (90.1 mGy/MBq) after one and 274 Gy after three courses. The dose to nontumourous liver was 1.9 +/- 0.2 Gy (1.2 +/- 0.1 mGy/MBq) and the mean dose ratio of tumour / nontumourous liver 11.1 +/- 1.7 (max. 82). The pulmonary dose was 25.9 +/- 1.8 mGy (16.3 +/- 1.2 microGy/MBq) and therefore much lower. There was a reciprocal relation between tumour dose and pretherapeutic tumour volume. Tumour dose had no effect on response or survival.

High radiation doses are particularly in small tumour nodes achievable but not necessarily related to tumour response. The dose of non-tumourous liver and lungs is much lower.