Update README.md

README.md

@@ -12,6 +12,34 @@ In addition to DRT generation, the framework extends [ITKTwoProjectionRegistrati
 
 Work in progress — requirements and example code to be added.
 
+## Citation
+
+If you use this code or method in your research, please cite the following paper:
+
+> **Giovanni Fattori, Riccardo Via, et al.**  
+> *Topogram and 3DCT geometry calibration for image-guided proton therapy with in-room CT-on-rails*  
+> *Physics and Imaging in Radiation Oncology*, 2025.  
+> [https://doi.org/10.1016/j.phro.2025.100799](https://doi.org/10.1016/j.phro.2025.100799)
+
+<details>
+<summary>BibTeX</summary>
+
+```bibtex
+@article{Fattori2025,
+  author  = {Giovanni Fattori and Riccardo Via and others},
+  title   = {Topogram and 3DCT geometry calibration for image-guided proton therapy with in-room CT-on-rails},
+  journal = {Physics and Imaging in Radiation Oncology},
+  year    = {2025},
+  doi     = {10.1016/j.phro.2025.100799}
+}
+```
+
+</details>
+
+## Requirements
+
+Work in progress — requirements and example code to be added.
+
 ## Contributors
 
 - Giovanni Fattori