PET/CT with 2-(3-{1-carboxy-5-[(6-[18F]fluoro-pyridine 3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid demonstrates high specificity and positive predictive value and adds greater value to pel... Background Prostate cancer recurrence is found in up to 40% of men with prior definitive (total prostatectomy or whole-prostate radiation) treatment. Prostate-specific membrane antigen PET agents s...

Purpose Topotecan is a camptothecin analogue with potential advantages over irinotecan for transarterial chemoembolization (TACE) of hepatic colorectal metastases including greater anti-neoplastic activity without enzymatic activation. The purpose of this study was to assess safety and tolerability of topotecan-loaded radiopaque microspheres (ROMTOP) administered by TACE in a rabbit model and to compare the in vitro elution of topotecan from microspheres to irinotecan. Materials and Methods Topotecan was loaded into radiopaque microspheres (70–150 µm, DC Bead LUMI™, Biocompatibles UK Ltd—Boston Scientific Corporation) to the maximum capacity of 80 mg/mL of microspheres. Six healthy New Zealand White rabbits underwent hepatic TACE with ROMTOP under fluoroscopic guidance until angiographic stasis. Assessment of toxicities included regular liver function tests and complete blood counts until euthanasia 28 days post-TACE. In vitro topotecan elution from the microspheres was assessed using an open-loop flow-through system and compared to irinotecan. Results The mean bead volume and topotecan dose delivered were 0.086 mL (0.076–0.105 mL) and 1.99 mg/kg (1.51–2.55 mg/kg), respectively. Aspartate aminotransferase and alanine aminotransferase were elevated post-embolization but resolved within 2 weeks. One rabbit died two days after TACE with pyloric duodenal perforation observed at necropsy, potentially due to non-target embolization. In vitro elution of topotecan from ROMTOP was complete in 10 h compared to 3 h for irinotecan-loaded microspheres. Conclusion Selective embolization with ROMTOP was tolerated at a dose of 2 mg/kg (24 mg/m²) in rabbits. In vitro topotecan elution from microspheres was more prolonged compared to irinotecan.

Transarterial radioembolization (TARE) is an established therapy for primary and secondary hepatic malignancies. Outcomes depend heavily on dosimetry, which has evolved from empirical and body-surface-area methods to partition and voxel-based approaches. This review summarizes current evidence for advanced (personalized) dosimetry across tumor types, highlights emerging dose–response concepts, and outlines practical barriers and implementation strategies. A narrative review of peer-reviewed clinical studies and trials evaluating dosimetry in TARE, with emphasis on hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (iCCA), metastatic colorectal cancer (mCRC), neuroendocrine tumor (NET), and breast cancer liver metastases, was performed with comparison of single-compartment medical internal radiation dosimetry method (MIRD), partition (multicompartment) methods, and voxel-based dosimetry methodologies. Personalized dosimetry improves outcomes in multiple tumor types. A randomized trial in HCC showed superior overall survival with partition-based dosing versus MIRD. In selective HCC treatments, voxel-derived metrics (e.g., D95) correlate with complete pathologic necrosis, suggesting benefit beyond mean dose targets. For iCCA, data associate higher tumor doses with better radiologic response, progression-free survival, and downstaging. In mCRC, voxel-based and threshold analyses link specific tumor and margin doses with metabolic/radiographic response and survival. Smaller series in NET and breast cancer indicate dose–response relationships using advanced dosimetry. Evidence supports broader adoption of advanced dosimetry in TARE. Emerging strategies that ensure adequate coverage of the “coldest” tumor regions and thoughtful particle-load planning may further optimize results. Standardized protocols, prospective validation, and scalable workflows are needed to accelerate implementation.