There are several sources where you can find DICOM files of CT brain tumor datasets. Here are a few options:
The Cancer Imaging Archive (TCIA): TCIA is a publicly available resource that provides a large collection of medical images, including CT scans of various types of tumors. You can visit their website at https://www.cancerimagingarchive.net/ and search for specific brain tumor datasets. They offer DICOM files along with associated metadata.
Radiological Society of North America (RSNA): The RSNA hosts the RSNA Clinical Trials Processor (CTP), which is a platform for sharing and exchanging medical images for research purposes. You can explore their database at https://www.rsna.org/ and search for brain tumor datasets. The CTP provides DICOM files that can be downloaded for research purposes.
Research publications and academic institutions: Many research publications and academic institutions share their datasets for research purposes. You can search for specific CT brain tumor datasets in academic journals or university websites. Often, these datasets are accompanied by links or instructions on accessing the DICOM files.
Collaborative platforms and data repositories: Platforms like Kaggle (https://www.kaggle.com/) and GitHub (https://github.com/) host various medical imaging datasets. You can search for CT brain tumor datasets on these platforms, and some datasets may provide DICOM files for download.