Dose distribution analysis in stereotactic body radiotherapy using dynamic conformal multiple arc therapy.

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Dynamic conformal multiple arc therapy (DCMAT) has been utilized for stereotactic body radiotherapy (SBRT) since 2001.
• Assessing the consistency of DCMAT in SBRT is crucial for treatment efficacy and safety.

Purpose of the Study:

• To investigate the consistency of DCMAT for SBRT using dose-volume histogram (DVH) analysis.
• To evaluate the dosimetric parameters of DCMAT in the treatment of peripheral lung tumors.

Main Methods:

• Fifty patients with peripheral lung tumors underwent SBRT using DCMAT.
• Treatment planning involved a superposition algorithm with a prescribed dose of 50 Gy in five fractions.
• Dose-volume histogram analysis was employed to assess the planning target volume (PTV) and surrounding normal lung tissue.

Main Results:

• The median dose covering 95% of the PTV was 50.27 Gy, consistent with the prescribed dose.
• Excellent conformity (median index 1.73) and homogeneity (median index 1.41) were achieved.
• The median volume of lung receiving ≥20 Gy (V(20)) was 4.2%, with correlations found between V(20) and tumor size/PTV to normal lung volume ratio.

Conclusions:

• DCMAT is a feasible and reproducible method for SBRT delivery in lung cancer.
• High conformity and accurate PTV dose coverage were achieved.
• V(20) can be predicted based on tumor diameter and normal lung volume, aiding in treatment planning.