Abstract
Purpose: To test the validity of the assumption that passive scatteringproton therapy (PSPT) would benefit more from respiratory motion management techniques of deep‐inspiration breath hold (DIBH) and end‐exhale respiratory gating compared to 3D conformal photonradiotherapy (3DCRT) for early stage lungtumors. Methods: Four‐dimensional and breath‐hold CT scans were acquired for patients with target motion greater than 10mm. Motion‐encompassing (standard) plans were created using target volume contoured on the 4D 10‐phase maximum intensity projection image and 10‐ phase average CT for dose calculations. Respiratory gating was simulated by creating average CT for three exhale phases (T40, 50, 60) for contouring and dose calculation. DIBH plans were simulated from breath‐hold CT scans for contouring and dose calculation. PSPT and 3DCRT plan triplets (standard, gated, BH) were designed by trained dosimetrists using consistent margins and current clinical standards. Plans were normalized to equal target dose coverage in PSPT and 3DCRT. For each patient, mean lungdose (MLD) and V20 of gated and DIBH plans were compared to standard plan. Results: For 3 patients, PSPT gating reduced MLD ranging 6–14% and V20 6–16%. 3DCRT gating reduced MLD ranging 8–19% and V20 7–19%. 3DCRT DIBH reduced MLD between 18–37% and V20 21–38%, while PSPT DIBH plans reduced MLD between 8–33% and V20 8–23%. Conclusions: This planning study showed that 3DCRT showed a larger reduction in MLD and V20 as compared to PSPT in both gating and DIBH. Furthermore, DIBH provided an equal or larger reduction than gating in both modalities. MLD and V20 are inherently lower in PSPT than 3DCRT, but DIBH and gating lead to larger benefits in 3DCRT. One reason that 3DCRT may benefit more than PSPT is due to reduced field sizes sparing tissue throughout the patient in 3DCRT as opposed to savings only throughout the proton beam range in PSPT.
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
