CT-less electron radiotherapy simulation and planning with a consumer 3D camera.

Area of Science:

• Medical Physics
• Radiation Oncology
• Imaging Technology

Background:

• Electron radiation therapy dose distributions are significantly influenced by irregular patient surface contours.
• Accurate dosimetry is crucial for effective electron beam treatments, particularly for superficial targets.

Purpose of the Study:

• To evaluate the feasibility of using three-dimensional (3D) cameras to capture body surface contours for electron beam dosimetry.
• To assess if 3D camera data can substitute for traditional treatment planning CT scans in electron beam dosimetry.

Main Methods:

• Dosimetry was compared across six electron beam treatment cases using full CT scans, CT scans with Hounsfield Units (HU) overridden to water (simulating 3D camera data), and flat-phantom techniques.
• Spatial accuracy of the 3D camera was assessed by comparing phantom surfaces captured by the camera to those generated by CT.
• Monitor units (MUs) were calculated based on physician-prescribed doses and treatment planning data.

Main Results:

• Calculations using 3D camera data (HU overridden to water) showed an average MU change of 1.3% (SD 1.0%) compared to full CT scans.
• Hotspot dose differences averaged 0.4% (SD 1.9%).
• In-vivo dose measurements closely matched 3D-camera planned doses, outperforming flat-phantom calculations.

Conclusions:

• Three-dimensional cameras can accurately capture irregular body contours for electron beam dosimetry.
• This technology provides a feasible and potentially more accurate alternative to CT scans for electron beam treatment planning.
• The study provides tools and workflow recommendations for clinical implementation of 3D camera technology in radiation oncology.