Dynamic hybrid-phase computed tomography simulation in lung stereotactic body radiotherapy: A feasibility study

Area of Science:

• Medical Imaging
• Radiation Oncology

Background:

• Lung stereotactic body radiation therapy (SBRT) requires precise tumor targeting.
• Current simulation methods may have limitations in accurately defining target volumes during patient motion.

Purpose of the Study:

• To evaluate the feasibility and accuracy of dynamic hybrid-phase computed tomography (CT_DHP) simulation for lung SBRT.
• To compare CT_DHP-derived target volumes with those from cone-beam CT (CBCT).

Main Methods:

• Eighteen non-small-cell lung cancer patients undergoing SBRT were scanned using CT_DHP with immobilization and abdominal compression.
• Internal target volume (ITV) and planning target volume (PTV) were determined.
• Comparison metrics included Boolean "AND" function, volume overlap (VO), Dice similarity coefficient (DSC), and dose-volume histogram analysis.

Main Results:

• CT_DHP demonstrated smaller average ITV and PTV compared to 3D-CBCT (p<0.001).
• High agreement was observed between CT_DHP and CBCT for both ITV and PTV.
• Dose coverage analysis showed that 97.9% of ITV_CBCT received 95% of the prescribed dose, with mean dose at 101.3%.

Conclusions:

• Dynamic hybrid-phase CT simulation is a feasible and effective method for lung SBRT.
• This technique provides accurate target volume delineation with potential for reduced margins.
• CT_DHP offers advantages of adequate margins and fewer simulation phases.