Dual-gated volumetric modulated arc therapy

Radiation Oncology

Lei Xing¹  Sarah Geneser¹  Huanmei Wu²  Junqing Wu³  Benjamin Fahimian¹ 

[1] Department of Radiation Oncology, Stanford University, Stanford, CA, USA;Purdue School of Engineering and Technology, Indiana University School of Informatics, IUPUI, Indianapolis, IN, USA;School of Health Sciences, Purdue University, West Lafayette, IN, USA

关键词: SBRT;    VMAT;    IGRT;    Dual gating;   

Others  :  1151273
DOI  :  10.1186/1748-717X-9-209

 received in 2013-10-30, accepted in 2014-08-29,  发布年份 2014

【 摘 要 】

Background

Gated Volumetric Modulated Arc Therapy (VMAT) is an emerging radiation therapy modality for treatment of tumors affected by respiratory motion. However, gating significantly prolongs the treatment time, as delivery is only activated during a single respiratory phase. To enhance the efficiency of gated VMAT delivery, a novel dual-gated VMAT (DG-VMAT) technique, in which delivery is executed at both exhale and inhale phases in a given arc rotation, is developed and experimentally evaluated.

Methods

Arc delivery at two phases is realized by sequentially interleaving control points consisting of MUs, MLC sequences, and angles of VMAT plans generated at the exhale and inhale phases. Dual-gated delivery is initiated when a respiration gating signal enters the exhale window; when the exhale delivery concludes, the beam turns off and the gantry rolls back to the starting position for the inhale window. The process is then repeated until both inhale and exhale arcs are fully delivered. DG-VMAT plan delivery accuracy was assessed using a pinpoint chamber and diode array phantom undergoing programmed motion.

Results

DG-VMAT delivery was experimentally implemented through custom XML scripting in Varian’s TrueBeam™ STx Developer Mode. Relative to single gated delivery at exhale, the treatment time was improved by 95.5% for a sinusoidal breathing pattern. The pinpoint chamber dose measurement agreed with the calculated dose within 0.7%. For the DG-VMAT delivery, 97.5% of the diode array measurements passed the 3%/3 mm gamma criterion.

Conclusions

The feasibility of DG-VMAT delivery scheme has been experimentally demonstrated for the first time. By leveraging the stability and natural pauses that occur at end-inspiration and end-exhalation, DG-VMAT provides a practical method for enhancing gated delivery efficiency by up to a factor of two.

【 授权许可】

   
2014 Fahimian et al.; licensee BioMed Central Ltd.

【 图 表 】

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