Medical imaging has made major advances in recent years, offering increasingly effective ways to detect and treat disease. At the same time, the work has become more expensive and more demanding, while the number of specialists has not increased at the same pace. This leads to high costs, workplace stress, and a risk of declining quality. As a result, there is a growing search for smart solutions to organize the work more efficiently.
In the training of nuclear medicine and radiology, the Netherlands is leading the way with an innovative program that combines both fields. This integrated training allows residents to develop a broader perspective and better prepares them for modern technologies. It brings clear benefits, such as improved collaboration and efficiency. However, concerns remain, including limited time for in-depth training, research, and international recognition. In addition, fewer residents are choosing certain pathways within this field, partly due to uncertainty about future job prospects.
Labor market research shows that hospitals are seeking broadly trained specialists with additional skills, such as research, teaching, and digital expertise. This aligns well with the goals of the new training program.
In addition, residents often have limited knowledge of the costs of medical imaging, despite frequently requesting these examinations. At the same time, they express concern about rising healthcare costs and a strong desire for better education on this topic.
Finally, the use of reading room assistants for practical tasks has been shown to save time and reduce pressure. This allows residents to focus more on their core responsibilities, lowering stress levels and ultimately improving the quality of care.

This thesis explores new applications of nuclear imaging and therapy in patients with hepatocellular carcinoma (HCC) and neuroendocrine tumors (NET). These diseases are often detected late, making curative therapy not always possible. Developments in positron emission tomography (PET) and radionuclide therapy have led to new nuclear agents. The aim of this thesis is to provide insight into several new applications of current and new tracers in the diagnosis and treatment of HCC and NET.

One of the investigated tracers is 18F-DOPA, which is currently used for NET tumors that are negative on 68Ga-labeled somatostatin analog (SSA) PET scans. Our study confirms the equivalent detection of 18F-DOPA in tumor detection compared to 68Ga-SSAs. Selective internal radiation therapy (SIRT) uses yttrium-90 radioactive resin spheres that are intravascularly injected into the liver. Higher than usual dosages (>120 Gy) appear to lead to better results in tumor reduction and the effects not only seem to be greater but also longer lasting.

Furthermore, we demonstrated that 11C-Choline and 18F-FDG together find more tumors that are relevant for clinical decision-making in patients suspected of HCC recurrence. The thesis also offers two prospective study protocols, namely a comparison of 68Ga-DOTA-TOC with the new somatostatin tracer 18F-SiTATE in NET and a comparison of ablation with SIRT as a bridge strategy in liver transplantation.

These results suggest that broader use of 18F-DOPA in PET diagnosis of NET is possible and that higher tumor-targeted dosages in SIRT can lead to better treatment.

The most specific and sensitive imaging modality for visualizing and measuring human (patho)physiology in vivo is Positron Emission Tomography (PET). PET is a firmly established biomedical imaging modality with applications in routine clinical diagnostic imaging, but also in research, including clinical trials. Over the past years, PET technology development brought new innovative PET systems to the commercial market: silicon photomultiplier (SiPM)-based or ‘digital’ PET systems, and large axial field-of-view or ‘total body’ PET systems. This thesis describes the technical performance characteristics of these new PET technologies and, in addition, associated optimization of image quality and activity administration is reported. Furthermore, clinical implications and future perspectives regarding these innovations in the field of nuclear medicine and molecular imaging and other medical disciplines are discussed.

The aim of this thesis was to investigate the role of imaging in the management of PTLD, with focus on [18F]FDG PET/CT. Additionally, we set out to explore new diagnostic methods with potential for clinical translation. In Part I (chapters 2-7), we reviewed the published literature on the role of different imaging modalities in PTLD and evaluated the diagnostic performance of [18F]FDG PET/CT for PTLD lesion detection in adults and children. Furthermore, we explored the role of [18F]FDG PET/CT semiquantification in PTLD for lesion classification and prognostication. In Part II (chapters 8-10) we proceeded to explore new avenues of research including: radiomics, identification of radiotracers adjunct to [18F]FDG and cfDNA analysis.