Optimization of collimator trajectory in volumetric modulated arc therapy: Development and evaluation for paraspinal SBRT Journal Article
| Authors: | Zhang, P.; Happersett, L.; Yang, Y.; Yamada, Y.; Mageras, G.; Hunt, M. |
| Article Title: | Optimization of collimator trajectory in volumetric modulated arc therapy: Development and evaluation for paraspinal SBRT |
| Abstract: | Purpose: To develop a collimator trajectory optimization paradigm for volumetric modulated arc therapy (VMAT) and evaluate this technique in paraspinal stereotactic body radiation therapy (SBRT). Method and Materials: We propose a novel VMAT paradigm, Coll-VMAT, which integrates collimator rotation with synchronized gantry rotation, multileaf collimator (MLC) motion, and dose-rate modulation. At each gantry angle a principal component analysis (PCA) is applied to calculate the primary cord orientation. The collimator angle is then aligned so that MLC travel is parallel to the PCA-derived direction. An in-house VMAT optimization follows the geometry-based collimator trajectory optimization to obtain the optimal MLC position and monitor units (MU) at each gantry angle. A treatment planning study of five paraspinal SBRT patients compared Coll-VMAT to standard VMAT (fixed collimator angle) and static field IMRT plans. Plan evaluation statistics included planning target volume (PTV) V95%, PTV-D95%, cord-D05%, and total beam-on time. Results: Variation of collimator angle in Coll-VMAT plans ranges from 26° to 54°, with a median of 40°. Patient-averaged PTV V95% (94.6% Coll-VMAT vs. 92.1% VMAT and 93.3% IMRT) and D95% (22.5 Gy vs. 21.4 Gy and 22.0 Gy, respectively) are highest with Coll-VMAT, and cord D05% (9.8 Gy vs. 10.0 Gy and 11.7 Gy) is lowest. Total beam-on time with Coll-VMAT (5,164 MU) is comparable to standard VMAT (4,868 MU) and substantially lower than IMRT (13,283 MU). Conclusion: Collimator trajectory optimization-based VMAT provides an additional degree of freedom that can improve target coverage and cord sparing of paraspinal SBRT plans compared with standard VMAT and IMRT approaches. © 2010 Elsevier Inc. All rights reserved. |
| Keywords: | clinical article; controlled study; intensity modulated radiation therapy; treatment planning; radiotherapy; algorithms; physical therapy; radiotherapy, intensity-modulated; tumor burden; spinal cord; spinal neoplasms; radiation injuries; intermethod comparison; collimator; radiotherapy planning, computer-assisted; radiation beam; stereotactic body radiation therapy; sbrt; standards; optimization; volumetric modulated arc therapy; cavity resonators; process optimization; principal component analysis; paraspinal; gantry angles; monitor units; multileaf collimators; on time; plan evaluation; planning target volumes; rotation; trajectory optimization; degree of freedom; dose-rate; static fields; target coverage; aerodynamics; trajectories; optical instruments; volumetric modulated radiation therapy; technology, radiologic |
| Journal Title: | International Journal of Radiation Oncology, Biology, Physics |
| Volume: | 77 |
| Issue: | 2 |
| ISSN: | 0360-3016 |
| Publisher: | Elsevier Inc. |
| Date Published: | 2010-06-01 |
| Start Page: | 591 |
| End Page: | 599 |
| Language: | English |
| DOI: | 10.1016/j.ijrobp.2009.08.056 |
| PUBMED: | 20171809 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 5" - "Export Date: 20 April 2011" - "CODEN: IOBPD" - "Source: Scopus" |
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