DICOM RTPLAN Jaw & MLC Blocking Checker Python Script for Control-Point–Level Dose Point Visibility Analysis

🔍 What this tool does

This Python script analyzes a DICOM RTPLAN to determine whether a dose specification point is geometrically open or blocked by jaws or MLCs, evaluated per control point.

Instead of relying on visual inspection inside the treatment planning system, this tool performs a pure geometry-based check in beam’s-eye view (BEV) — exactly as the beam is delivered by the machine.

For each control point, the script:

• Projects the dose point into BEV coordinates
• Checks whether the point is inside the jaw opening
• Identifies the correct MLC leaf pair using leaf position boundaries
• Determines whether the point is open, blocked, or outside the field

⚙️ Key Features

• ✅ Control-point–level analysis (dynamic delivery aware)
• ✅ Jaw gating before MLC evaluation
• ✅ Automatic leaf pair mapping (supports variable leaf widths)
• ✅ Vendor-agnostic geometry logic
• ✅ Beam’s-eye-view–only evaluation (no TPS display assumptions)
• ✅ Clear debug output for verification and education

🧠 Why this matters

In VMAT and other dynamic techniques, jaw and MLC positions change continuously.

A dose point that appears “inside the field” on a static display may be blocked at certain control points.

This script provides:

• Independent verification logic
• A foundation for automated plan checks
• Insight into what the machine is actually delivering

👩‍⚕️ Who this is for

• Medical physicists
• Physics residents
• QA and plan-check automation developers
• Anyone working with DICOM RTPLAN geometry
• Researchers or educators demonstrating BEV-based checks