Caren van Roekel

295 Summary FIGURE 3. Timeline. Fifty-two patients of this study underwent two simulation procedures, one with administration of 99m Tc-MAA and one with 166 Ho-scout, as per protocol of the HEPAR I and HEPAR II studies. Fifty-three patients underwent one simulation procedure with administration of 166 Ho-scout. After administration of 166 Ho- scout and the 166 Ho-treatment dose, 166 Ho-SPECT/CT images were made to assess the absorbed dose distribution. In chapter 4, the safety and feasibility of a one-day treatment protocol for 166 Ho-radioembolization was evaluated. It was shown that a large percentage of patients (12%) was excluded from treatment based on findings of the simulation procedures. In another 12% of patients, treatment had to be adjusted. The main reasons for this were extrahepatic deposition of activity, vascular anatomy and suboptimal targeting (the activity distribution within the liver: in the tumors versus the healthy liver parenchyma). Another drawback of this one- day procedure was that many patients (27%) complained of back pain, which was likely due to the long duration of laying supine, inherent to the one-day protocol. Based on these results, a one-day treatment approach should only be considered in a select patient population. 11