A comparative dosimetric evaluation of dynamic conformal arc therapy and volumetric modulated arc therapy for lung stereotactic body radiotherapy

Purpose: This study assesses the viability of utilizing dynamic conformal arc therapy (DCAT) as an alternative to volumetric-modulated arc therapy (VMAT) in stereotactic body radiation therapy (SBRT) for lung cancer, with a focus on four-dimensional computed tomography (4DCT) in free-breathing conditions. Materials and methods: We selected four non-small cell lung cancer (NSCLC) patients who had previously undergone VMAT SBRT and re-planned their treatment using DCAT. We compared the DCAT and VMAT plans based on dose distribution, conformity index (CI), homogeneity index (HI), gradient index (GI), and total monitor units (MUs). Quality assurance (QA) assessments for both plans were conducted using the Octavius 4D system (PTW, Freiburg, Germany). Results: The results showed that CIPaddick was 0.80 f 0.06 and 0.79 f 0.04 (p-value >0.05), HI was 1.16 f 0.03 (p-value <0.05) and 1.07 f 0.02, GI was 3.91 f 0.05 and 3.40 f 0.05 (p-value <0.05), and MU was 1880.42 f 135.19 and 5020.82 f 188.03 for DCAT and VMAT, respectively (p-value <0.05). The average gamma passing rate exceeded 95 % with a 2 %/2 mm criteria. The dose distribution displayed remarkable similarity between DCAT and VMAT. Conclusion: The DCAT technique exhibits the capacity to deliver PTV dose distributions comparable to those achieved with VMAT, while significantly reducing treatment duration.