Early-stage Central Lung Cancer and Volumetric Modulated Arc Therapy: A Dosimetric Case Study with Literature Review

Background/Aim: In the present article we review on the use of Volumetric Modulated Arc Therapy (VMAT) for a small lung nodule that was centrally located in close proximity to the mediastinal structures. Case Report: An inoperable patient with central, clinical stage IA adenocarcinoma of the right lung was treated with external- beam radiation therapy of 52.5 Gy in 15 factions. A single 360˚ coplanar arc VMAT plan (360-VMAT) was used for treatment and compared to step-and-shoot Intensity Modulation Radiotherapy (IMRT) and a single 180˚ ipsilateral partial arc VMAT plan (180-VMAT). Results: Planning Target Volume (PTV) coverage was not different, and 360-VMAT had the highest dose homogeneity. Both 360- VMAT and 180-VMAT reduced esophageal dose compared to IMRT. While IMRT had the lowest lung dose, all 3 plans achieved acceptable sparing of the lung. 180-VMAT had the highest dose conformity. Both 360-VMAT and 180-VMAT improved esophageal sparing compared to IMRT. Conclusion: Use of VMAT in early-stage, centrally located NSCLC is a promising treatment approach and merits additional investigation. Volumetric Modulated Arc Therapy (VMAT) is a novel technique of rotational radiotherapy that achieves dose modulation by simultaneous variation of arc speed, position of multi-leaf collimator (MLC) leaves and dose rate (1). Planning studies of VMAT for various disease sites have demonstrated favorable dose distribution and short treatment delivery time (2). Definitive external-beam radiation therapy is the primary treatment modality used for patients with non-small cell lung cancer (NSCLC) who are not candidates for surgical