Assessment of Uncertainty in Volume Estimation of Non-Static Target: A Phantom Study using Racemosa Wood

Area of Science:

• Medical Physics
• Radiotherapy Research
• Biomaterials Science

Background:

• Accuracy of CT imaging for moving targets in radiotherapy is a significant concern.
• Previous studies often used uniform density lung models, not reflecting clinical complexity.

Purpose of the Study:

• To validate racimosa wood as a lung equivalent material.
• To assess volume estimation uncertainties in CT scans of non-static targets during radiotherapy simulations.

Main Methods:

• Validated racimosa wood as lung equivalent using two methods.
• Acquired CT images of a phantom with wood inserts simulating tumor movement (+/-5mm, +/-15mm, +/-25mm).

Main Results:

• Racimosa wood demonstrated a density range (-850 to -400 HU) comparable to human lungs.
• CT-derived target volume showed overestimation, increasing with movement amplitude (up to 9.5 cm³ vs. true 7.8 cm³).

Conclusions:

• Racimosa wood is a viable, cost-effective lung equivalent for radiotherapy research.
• Movement during CT scanning leads to target volume overestimation, crucial for lung cancer radiotherapy planning.
• The study's methodology closely mimics clinical settings for realistic radiotherapy assessments.