Comparisons of static 7 field and dynamic conformal arc techniques for stereotactic lung radiotherapy

OBJECTIVES: We aimed to compare dynamic conformal arc (DCA) and static 7 field (S7F) techniques in terms of Radiation Therapy Oncology Group (RTOG) criteria for stereotactic lung radiotherapy. METHODS: Treatment of 33 lung tumors was planned using DCA or S7F techniques, and tumors were allocated into groups according to their volume (small: <25 cc, medium: 25-50 cc, large: >50 cc) and localization (central, peripheral). Plans were compared in terms of lung volume receiving 5 Gy (V5), spinal cord maximum dose (spinal Dmax), homogeneity index (HI), and monitor-unit (MU) parameters. RESULTS: No statistical difference was shown in RTOG criteria. HI was lower with DCA (p=0.018) while V5, spinal Dmax and MU were lower with S7F (p=0.007, p=0.001, p<0.001, respectively). With the S7F technique, spinal Dmax in small tumors, V5, spinal Dmax and MU in medium tumors, V5 and MU in large tumors, V5 and spinal Dmax in central tumors, and spinal Dmax and MU in peripheral tumors were lower. CONCLUSION: Spinal Dmax, V5 and MU were better with the S7F technique. Both techniques are appropriate for planning according to RTOG criteria.