Sliding Window Imrt and Vmat Optimization

Craft, David; Halabi, Tarek

doi:10.1002/9781118960158.ch14

Cited by 1 publication

(2 citation statements)

References 66 publications

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“…We utilize the VMAT planning and delivery technique called sliding window VMAT . Briefly, this approach subdivides the full VMAT arc into arc sectors, in our case of 10 degrees length.…”

Section: Methodsmentioning

confidence: 99%

“…These leaf trajectories are calculated by a leaf‐sweep algorithm that take a fluence map on matrix format as input, where the rows of the matrix are aligned with the direction of leaf travel. In this setting, the delivery time

t_{r}

for a single matrix row r is given by the leaf‐sweep time plus a sum‐of‐positive‐gradients (SPG) term, according to:

t_{r} = \frac{L_{r}}{s} + \frac{\sum_{b = 1}^{N_{r}} max false(f_{b} - f_{b - 1}, 0 false)}{δ},

where

L_{r}

is the length of row r , s is the maximum leaf speed,

f_{b}

is the fluence delivered to bixel b , and

N_{r}

is the number of bixels in row r . Note that

f_{0} = 0

.…”

Section: Methodsmentioning

confidence: 99%

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Technical Note: Improving VMAT delivery efficiency by optimizing the dynamic collimator trajectory

2019

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Purpose To provide a method for optimizing the multileaf collimator angle trajectory in volumetric modulated arc therapy (VMAT) in order to make VMAT delivery and planning more efficient. Methods Static fluence maps are optimized at a 10‐degree spacing around the patient. Sliding window delivery time of each of these fields is computed for a large set of possible collimator orientations. An optimal trajectory, which selects a collimator angle for each field and assures that the collimator angles do not differ excessively between adjacent fields, is computed by solving a network flow model of a shortest path problem. Results For four clinical cases (two brains, an anal, and a spine), we demonstrate time reductions from 6% to 32% (average: 24%) for the optimal static angle vs the worst static angle. Further reductions from 3% to 17% (average 9%) are achievable when dynamic collimator trajectories are allowed. Conclusions Dynamic collimator trajectories, which can be computed with an efficient linear programming formulation, can improve the efficiency of VMAT delivery.

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“…We utilize the VMAT planning and delivery technique called sliding window VMAT . Briefly, this approach subdivides the full VMAT arc into arc sectors, in our case of 10 degrees length.…”

Section: Methodsmentioning

confidence: 99%