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 (V-5), spinal cord maxi- mum dose (spinal D-max) homogeneity index (HI), and monitor-unit (MU) parameters. RESULTS No statistical difference was shown in RTOG criteria. HI was lower with DCA (p=018) while V-5, spinal D-max and MU were lower with S7F (p=0.007, p=0.001, p<0.001, respectively). With the S7F technique, spinal D-max in small tumors, V-5, spinal D-max and MU in medium tumors, V-5 and MU in large tumors, V5 and spinal D-max in central tumors, and spinal D-max and MU in peripheral tumors were lower. CONCLUSION Spinal D-max, V-5 and MU were better with the S7F technique. Both techniques are appropriate for planning according to RTOG criteria.