Development of a leakage monitoring system in isolated limb perfusion with portable gamma camera

Abstract

Isolated limb perfusion (ILP) is a method for treating unresectable lesions of limbs in patients with melanoma or sarcoma by using high doses of tumor necrosis factor alpha and melphalan. This high doses can result in high systemic toxicity if there is a drug leak from the isolated circulation of the limb to the systemic. This makes it imperative to monitor the leakage rate (F(%)) during the infusion, currently performed with radiotracers. The objective of this work was to develop a leakage monitoring protocol as accurate as possible to ensure safe ILP. Material and methodWe built a phantom with three compartments (body, limb and precordial area) and a high sensitivity collimator fitted to a portable gamma camera. We simulate ILP with scheduled leaks every 10 min from 1% to 9% (theorical F(%)). We mesured F(%) using two equation: one is the proposed in the literature and another corrected by decay of the radioisotope. We test the optimal radiopharmaceutical doses to minimize the detector dead time error and compare F(%) mesured by both equations regarding the theoretical F(%).The leakage monitoring protocol was used in 17 ILP of 16 patients and an analysis of the recorded data was performed. ResultsWe found significant differences between F(%) mesured using the first equation and theoretical F(%), obtaining results very adjusted to the theorical after applying the decay correction. Conclusionsthe decay correction of the radioisotope is a simple manner to carry out the procedure more safely, reducing the error in the calculation of F(%).