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README.md

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+# Lu-177 Dosimetry Tool (Two-Time-Point Fitting)
+
+This open-source web application calculates **Time-Integrated Activity (TIA)** based on **two post-treatment SPECT/CT time points** using a **mono-exponential washout model**.
+
+## 👨‍⚕️ Purpose
+The tool is designed for simplified, patient-specific dosimetry of **Lutetium-177–PSMA therapy** in individuals diagnosed with **metastatic castration-resistant prostate cancer (mCRPC)**. Its goal is to enable reliable dose estimation without complex imaging protocols.
+
+## 📈 How It Works
+Users provide:
+- Two SPECT imaging time points (in hours)
+- Corresponding activity measurements (in MBq)
+
+The tool automatically:
+- Fits a mono-exponential time–activity curve
+- Calculates:
+  - Washout rate (_k_)
+  - Initial activity (_A₀_)
+  - Time-Integrated Activity (_TIA = A₀ / k_)
+- Displays results clearly and instantly
+
+## 🧠 Model Used
 
 ## 💻 Technology Stack
 - Python 3