[Mid-ventilation position planning: optimal model for dose distribution in lung tumour]

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy

Background:

• Accurate lung tumor dose distribution is crucial for effective radiotherapy.
• Standard 3D-CT scans do not account for respiratory motion, leading to inaccurate dose estimations.
• 4D-CT scans integrate tumor motion during breathing, providing vital data on tumor movement, internal tumor volume (ITV), and motion-weighted average position (MVP).

Observation:

• This study compared 3D and 4D-CT based dose distributions for a lung carcinoma case.
• Non-rigid registration was employed to estimate cumulative dose based on ITV and MVP concepts.
• 4D dose estimation for the gross tumor volume (GTV) showed similar results for both MVP and ITV models.

Findings:

• The MVP model provided superior sparing of healthy lung tissue compared to the ITV model.
• The improved therapeutic index with the MVP model allowed for an approximate 11% increase in the total radiation dose.
• This dose escalation reached 96 Gy with the MVP model, compared to 86 Gy for the ITV model, while respecting dose constraints for organs at risk.

Implications:

• The MVP approach in 4D-CT based radiotherapy planning can enhance treatment efficacy for lung tumors.
• This method allows for dose escalation, potentially improving outcomes for lung cancer patients.
• Further clinical studies with larger patient cohorts are warranted to validate these findings.