Comparison of volumetric‐modulated arc therapy and dynamic conformal arc treatment planning for cranial stereotactic radiosurgery

The aim was to analyze arc therapy techniques according to the number and position of the brain lesions reported by comparing dynamic noncoplanar conformal arcs (DCA), two coplanar full arcs ([Formula: see text]) with volumetric‐modulated arc therapy (VMAT), multiple noncoplanar partial arcs with VMAT ([Formula: see text]), and two full arcs with VMAT and 10° table rotation ([Formula: see text]). Patients with a single lesion (n = 10), multiple lesions (n = 10) or a single lesion close to organs at risk (n = 5) and previously treated with DCA were selected. For each patient, the DCA treatment was replanned with all VMAT techniques. All DCA plans were compared with VMAT plans and evaluated in regard to the different quality indices and dosimetric parameters. For single lesion, homogeneity index (HI) better results were found for the [Formula: see text] technique ([Formula: see text]) compared with DCA procedure ([Formula: see text]). Concerning conformity index (CI), the [Formula: see text] technique gave higher and better values ([Formula: see text]) compared with those obtained with the DCA technique ([Formula: see text]). DCA improved healthy brain protection ([Formula: see text] vs. [Formula: see text] for [Formula: see text]) and reduced monitor unit numbers ([Formula: see text] MU vs. [Formula: see text] for [Formula: see text]), even if global room occupation was higher. For multiple lesions, VMAT techniques provided better HI (0.16) than DCA ([Formula: see text]). The CI was improved with [Formula: see text] ([Formula: see text] for [Formula: see text] vs. [Formula: see text] for DCA). The [Formula: see text] healthy brain was better protected with DCA ([Formula: see text]). Regarding the MU numbers: [Formula: see text]. For a single lesion close to OAR, [Formula: see text] achieved high degrees of homogeneity ([Formula: see text] vs. [Formula: see text] for DCA) and conformity ([Formula: see text] vs. [Formula: see text] for DCA) while sparing organs at risk ([Formula: see text] vs. [Formula: see text] for DCA, and [Formula: see text] vs. [Formula: see text] for DCA). On the other hand, MU numbers were lower with DCA ([Formula: see text] MU vs. [Formula: see text] MU for [Formula: see text]) even if overall time was inferior with [Formula: see text]. For a single lesion, DCA provide better plan considering low doses to healthy brain even if quality indexes are better for the others techniques. For multiple lesions, [Formula: see text] seems to be the best compromise, due to the ability to deliver a good conformity and homogeneity plan while sparing healthy brain tissue. For a single lesion close to organs at risk, [Formula: see text] is the most appropriate technique. PACS numbers: 87.55. dk, 87.56.bd