Popularized summary Breast cancer is a common disease worldwide, especially in women. Treatments such as surgery or radiotherapy can lead to various complications, such as ‘breast cancer related lymphedema (BCRL)’. In BCRL that the lymphatic network no longer functions as it should. The function of the lymphatic network is to drain excess fluid from our body. When it stops functioning as it should, it leads to swelling in the affected body region. A therapy used to reduce BCRL is called ‘manual lymphatic drainage (MLD)’, performed by physiotherapists. Using specialized hand movements, a pumping effect is created to move fluid to areas where the lymphatic system still functions, making knowledge of its exact location essential for effective treatment. Better knowledge of the lymphatic system location can also make surgery on the lymphatic system and radiotherapy more accurate. The researchers' main goal is to map the lymphatic system to provide this more accurate knowledge of the lymphatic system location, based on observations in human cadavers and on digital 3D reconstructions of the lymphatic network. The lymphatic system is constructed of several lymph vessels containing valves. These valves ensure that the lymph fluid (fluid transported in the lymphatic system) can only flow in 1 direction. The lymphatic system is so small and consists of transparent lymph vessels that it is difficult to visualize. Because of this, the researchers work with a contrast liquid so that the filled lymphatic vessels can be clearly seen, both with the naked eye and on the imaging. This study focuses on finding the best way to inject that contrast liquid into the lymphatic vessels. To test the best way to inject contrast agent into the lymphatic vessels, anatomical specimens are used. A specific method to prepare a study object from part of the human body was developed and pressure tests were performed on the thoracic duct (the biggest lymphatic vessel in the body) to see what pressure settings would be best to fill the lymphatic vessels with contrast liquid. To help with data collection, experiments were also filmed. The findings from this study provided more insight into the best way to inject contrast agent into the lymphatic vessels. These findings can be used to further improve and contribute to lymphatic mapping studies. Accurate lymphatic mapping is relevant for a wide range of healthcare professionals, such as physiotherapists (for MLD), radiotherapists (for precise radiotherapy planning), surgeons (for accurate surgical interventions) and others involved in breast cancer care and post-treatment management.