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Lung SBRT: Dosimetric and Treatment Time Comparison of Volumetric-Modulated Arc Therapy and Three-Dimensional Conformal Radiotherapy in Clinically Treated Cases

J Han

J Han*, Z Xu , J Baker , A Hsia , S Ryu, Stony Brook Medicine, Stony Brook, NY


SU-F-T-635 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall

To compare three-dimensional conformal radiotherapy (3D CRT) and volumetric-modulated arc therapy (VMAT) in lung stereotactic body radiation therapy (SBRT)

A retrospective study of clinically treated lung SBRT cases treated between 2010 and 2015 at our hospital was performed. All treatment modalities were included in this evaluation (VMAT, 3D CRT, static IMRT, and dynamic conformal arc therapy). However, the majority of treatment modalities were either VMAT or 3D CRT. Treatment times of patients and dosimetric plan quality metrics were compared. Treatment times were calculated based on the time the therapist opened and closed the patient’s treatment plan. This treatment time closely approximates the utilization time of the treatment room. The dosimetric plan quality metrics evaluated include ICRU conformity index, the volume of 105% prescribed dose outside PTV, the ratio of volume of 50% prescribed dose to the volume of PTV, the percentage of maximum dose at 2 cm away from PTV to the prescribed dose, and the V20 (percentage of lung volume receiving 20 Gy or more).

Treatment time comparisons show that on average VMAT has shorter treatment times than 3D CRT. Dose conformity, defined by the ICRU conformity index, and high dose spillage, defined by the volume of 105% dose outside the PTV, is reduced when using VMAT compared to 3D CRT. V20 and intermediate dose spillage/fall-off metrics of VMAT and 3D are not significantly different.

Clinically treated lung SBRT cases indicate VMAT is superior to 3D with regard to shorter treatment times, plan dose conformity, and plan high dose spillage.

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