Direct aperture optimization for online adaptive radiation therapy

被引:30
作者
Mestrovic, Ante [1 ]
Milette, Marie-Pierre
Nichol, Alan
Clark, Brenda G.
Otto, Karl
机构
[1] Univ British Columbia, Vancouver, BC V5Z 1M9, Canada
[2] BC Canc Agcy, Vancouver Ctr, Vancouver, BC V5Z 1M9, Canada
[3] BC Canc Agcy, Ctr So Interior, Kelowna, BC, Canada
[4] BC Canc Agcy, Dept Radiat Oncol, Vancouver, BC, Canada
[5] Ottawa Hosp, Reg Canc Ctr, Ottawa, ON, Canada
基金
欧盟地平线“2020”;
关键词
adaptive radiation therapy (ART); online ART; direct aperture optimization (DAO); accelerated treatment plan adaptation; adaptive radiation delivery (ARD); inter-fractional anatomical deformations; prostate deformations;
D O I
10.1118/1.2719364
中图分类号
R8 [特种医学]; R445 [影像诊断学];
学科分类号
1002 ; 100207 ; 1009 ;
摘要
This paper is the first investigation of using direct aperture optimization (DAO) for online adaptive radiation therapy (ART). A geometrical model representing the anatomy of a typical prostate case was created. To simulate interfractional deformations, four different anatomical deformations were created by systematically deforming the original anatomy by various amounts (0.25, 0.50, 0.75, and 1.00 cm). We describe a series of techniques where the original treatment plan was adapted in order to correct for the deterioration of dose distribution quality caused by the anatomical deformations. We found that the average time needed to adapt the original plan to arrive at a clinically acceptable plan is roughly half of the time needed for a complete plan regeneration, for all four anatomical deformations. Furthermore, through modification of the DAO algorithm the optimization search space was reduced and the plan adaptation was significantly accelerated. For the first anatomical deformation (0.25 cm), the plan adaptation was six times more efficient than the complete plan regeneration. For the 0.50 and 0.75 cm deformations, the optimization efficiency was increased by a factor of roughly 3 compared to the complete plan regeneration. However, for the anatomical deformation of 1.00 cm, the reduction of the optimization search space during plan,adaptation did not result in any efficiency improvement over the original (nonmodified) plan adaptation. The anatomical deformation of 1.00 cm demonstrates the limit of this approach. We propose an innovative approach to online ART in which the plan adaptation and radiation delivery are merged together and performed concurrently-adaptive radiation delivery (ARD). A fundamental advantage of ARD is the fact that radiation delivery can start almost immediately after image acquisition and evaluation. Most of the original plan adaptation is done during the radiation delivery, so the time spent adapting the original plan does not increase the overall time the patient has to spend on the treatment couch. As a consequence, the effective time allotted for plan adaptation is drastically reduced. For the 0.25, 0.5, and 0.75 cm anatomical deformations, the treatment time was increased by only 2, 4, and 6 s, respectively, as compared to no plan adaptation. For the anatomical deformation of 1.0 cm the time increase was substantially larger. The anatomical deformation of 1.0 cm represents an extreme case, which is rarely observed for the prostate, and again demonstrates the limit of this approach. ARD shows great potential for an online adaptive method with minimal extension of treatment time. (c) 2007 American Association of Physicists in Medicine.
引用
收藏
页码:1631 / 1646
页数:16
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