Four-dimensional proton treatment planning for lung tumors

摘要: Purpose: In proton radiotherapy, respiration-induced variations in density lead to changes radiologic path lengths and will possibly result geometric misses. We compared different treatment planning strategies for lung tumors that compensate respiratory motion. Methods Materials: Particle-specific margins were applied standard helical computed tomography (CT) scans as well "representative" CT scans. Margins incorporated beam specific laterally by aperture widening longitudinally compensator smearing. Furthermore, plans using full time-resolved 4D-computed data generated. Results: Four-dimensional guaranteed target coverage throughout a cycle. Use of set resulted underdosing the volume 36% prescribed dose. For representing average positions, can be expected but not guaranteed. comparison this strategy, 4D decreased mean dose up 16% receiving 20 Gy (prescribed 72 Gy) 15%. Conclusion: When three are compared, only guarantees delivery approach results equal or reduced critical structures; even ipsilateral is spared.