Abstract
BackgroundThe principle aim of this study is to incorporate 4DCT ventilation imaging into functional treatment planning that preserves high-functioning lung with both double scattering and scanning beam techniques in proton therapy.MethodsEight patients with locally advanced non-small-cell lung cancer were included in this study. Deformable image registration was performed for each patient on their planning 4DCTs and the resultant displacement vector field with Jacobian analysis was used to identify the high-, medium- and low-functional lung regions. Five plans were designed for each patient: a regular photon IMRT vs. anatomic proton plans without consideration of functional ventilation information using double scattering proton therapy (DSPT) and intensity modulated proton therapy (IMPT) vs. functional proton plans with avoidance of high-functional lung using both DSPT and IMPT. Dosimetric parameters were compared in terms of tumor coverage, plan heterogeneity, and avoidance of normal tissues.ResultsOur results showed that both DSPT and IMPT plans gave superior dose advantage to photon IMRTs in sparing low dose regions of the total lung in terms of V5 (volume receiving 5Gy). The functional DSPT only showed marginal benefit in sparing high-functioning lung in terms of V5 or V20 (volume receiving 20Gy) compared to anatomical plans. Yet, the functional planning in IMPT delivery, can further reduce the low dose in high-functioning lung without degrading the PTV dosimetric coverages, compared to anatomical proton planning. Although the doses to some critical organs might increase during functional planning, the necessary constraints were all met.ConclusionsIncorporating 4DCT ventilation imaging into functional proton therapy is feasible. The functional proton plans, in intensity modulated proton delivery, are effective to further preserve high-functioning lung regions without degrading the PTV coverage.
Highlights
The principle aim of this study is to incorporate 4DCT ventilation imaging into functional treatment planning that preserves high-functioning lung with both double scattering and scanning beam techniques in proton therapy
Functional double scattering proton therapy (DSPT) planning showed considerable distortions of the isodose curves around the planning target volume (PTV) compared with anatomical DSPT but the difference was not significant
The total lung volumes receiving over 20 Gy (V20) was comparable between IMRT (38.4%) and DSPT (35.5% for Anatomical double scattering proton treatment (aDSPT), 35.4% for Functional double scattering proton treatment (fDSPT)) but reduced to 24.3% (25.2%) with Anatomical intensity modulated proton treatment (aIMPT)
Summary
The principle aim of this study is to incorporate 4DCT ventilation imaging into functional treatment planning that preserves high-functioning lung with both double scattering and scanning beam techniques in proton therapy. Yorke et al demonstrated that the mean dose to the lower lung was more predictive of toxicity than that to the upper parts [5] These findings suggested a radiation treatment strategy for avoidance of high-functioning lung, which might have the potential to reduce pulmonary toxicity to give possibility for dose-escalation. Previous studies have demonstrated decreasing the radiation dose to highfunctioning lung areas and directing the radiation beams to the parts with perfusion/ventilation defects may help to protect highly functioning lung regions and reduce the incidence and seriousness of radiation pneumonitis (RP) [6,7,8,9,10,11,12]. There are even several on-going clinical trials as NCT02528942, NCT02308709, and NCT02843568 to evaluate the clinical outcome that utilizing functional imaging guided photon radiation to avoid more functional portions of the lung
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
