Caren van Roekel

248 Chapter 9 The agreement between the 166 Ho-scout and 166 Ho-therapy dose distribution in our study was high and in line with a previous study (26). These results support the use of 166 Ho-scout for treatment planning. Surprisingly, the agreement with the anti-reflux catheter at a tumor level, was worse compared with a standard microcatheter. The mechanical pressure of the anti-reflux catheter on the vascular wall may have caused a larger variation in flow between the administration of 166 Ho-scout and 166 Ho-therapy. CONCLUSION In this study, no differences in post-treatment T/N activity concentration ratio, tumor- and parenchymal-absorbed dose and infusion efficiency were found between the use of an anti-reflux catheter and a standard microcatheter in mCRC patients treated with 166 Ho-radioembolization.