Inclusion Criteria:  Diagnosis of hepatocellular carcinoma or liver metastases originating from colorectal cancer. At least one lesion of ≥10 mm in the longest diameter on contrast-enhanced MRI or contrast-enhanced CT Patient is eligible for SIRT as determined by the tumour board (in Dutch: MDO) Patient has a life expectancy of 12 weeks or longer Patient has a WHO performance score of 0-2  Exclusion Criteria:  Significant extrahepatic disease (2x sum of diameters of lesions outside the liver > sum of lesions inside the liver) Radiation therapy, chemotherapy or major surgery within 4 weeks before treatment Serum bilirubin > 2.0 x the upper limit of normal ALAT, ASAT, alkaline phosphatase (AF) > 5x the upper limit of normal Glomerular filtration rate (GFR-MDRD) <35 ml/min Leukocytes <4.0 * 109/L or platelet count <60 * 109/L Significant heart disease that in the opinion of the physician increases the risk of ventricular arrhythmia. Pregnancy or breast feeding Disease with increased chance of liver toxicity, such as primary biliary cirrhosis or xeroderma pigmentosum Patients ineligible to undergo MR-imaging (claustrophobia, metal implants, etc) Portal vein thrombosis of the main branch (more distal branches are allowed) Evidence of clinically relevant, untreated grade 3 portal hypertension Untreated, active hepatitis Body weight > 150 kg (because of maximum table load) Severe allergy for i.v. contrast (Iomeron, Dotarem and/or Primovist) Lung shunt > 30 Gy, as calculated using scout dose holmium-166 SPECT/CT Uncorrectable extrahepatic deposition of scout dose activity. Activity in the falciform ligament, portal lymph nodes or gallbladder are accepted.