Purpose: Photon-based radiation therapy does currently not play a major role as local ablative treatment for hepatocellular carcinoma (HCC). Carbon ions offer distinct physical and biological advantages. Due to their inverted dose profile and the high local dose deposition within the Bragg peak, precise dose application and sparing of normal tissue is possible. Furthermore, carbon ions have an increased relative biological effectiveness (RBE) compared to photons. Methods and materials:A total of six patients with one or more HCC-lesions were treated with carbon ions delivered by the raster-scanning technique according to our clinical trial protocol. Diagnosis of HCC was confirmed by histology or two different imaging modalities (CT and MRI) according to the AASLD-guidelines. Applied fractionation scheme was 4 × 10 Gy(RBE). Correct dose application was controlled by in-vivo PET measurement of β + −activity in the irradiated tissue shortly after treatment.

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Purpose: 68Ga-FAPI (fibroblast activation protein inhibitor) is a rapidly evolving and highly promising radiotracer for PET/CT imaging, presenting excellent results in a variety of tumor entities, particularly in epithelial carcinomas. This retrospective analysis sought to evaluate the potential and impact of FAPI-PET/CT in rare cancer diseases with respect to improvement in staging and therapy, based on tracer uptake in normal organs and tumors.Material and Methods: 55 patients with rare tumor entities, defined by a prevalence of 1 person out of 2000 or less, received a 68Ga-FAPI-PET/CT scan. 14 women and 41 men (median age 60) were included within the following subgroups: cancer of unknown primary (n=10), head-and-neck-cancer (n=13), gastro-intestinal and biliary-pancreatic cancer (n=17), urinary tract cancer (n=4), neuroendocrine cancer (n=4) and others (n=7). Tracer uptake was quantified by standardized uptake values SUVmax and SUVmean and the tumor-to-background ratio (TBR) was determined (SUVmax tumor/ SUVmean organ). Results: In 20 out of 55 patients the primary tumor was identified and 31 patients presented metastases (n=88), characterized by a high mean SUVmax in primary (10.1) and metastatic lesions (7.6). Highest uptake was observed by liver metastases (n=6) with a mean SUVmax of 9.8 and a high TBR of 8.7, closely followed by peritoneal carcinomatosis (n=16) presenting a mean SUVmax of 9.8 and an excellent TBR of 29.6. In terms of the included subgroups the highest uptake regarding mean SUVmax was determined in gastro-intestinal and biliary-pancreatic cancer with 9.8 followed closely by urinary tract cancer with 9.5 and head-and-neck cancer (9.1). Conclusion Due to excellent tumor visualization and, thereby, sharp contrasts in terms of high TBRs in primary and metastatic lesions in different rare malignancies, 68Ga-FAPI-PET/CT crystallizes as a powerful and valuable imaging tool, particularly with respect to epithelial carcinomas, and therefore an enhancement to standard diagnostics imaging methodologies. The realization of further and prospective studies is of large importance to confirm the potential of FAP-imaging in oncology.