Inverse planning for intensity-modulated arc therapy using direct aperture optimization

Earl, M.; Shepard, David; Naqvi, S; Li, X A; Yu, C

doi:10.1088/0031-9155/48/8/309

Cited by 151 publications

(96 citation statements)

References 18 publications

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“…Traditional forward based treatment planning has been supplemented by inverse planning, which uses dose optimization techniques including intensity modulated radiotherapy (IMRT)1 and volumetric modulated arc therapy (VMAT),2, 3 to satisfy user specified criteria. To achieve the appropriate target coverage and respect the dose constraint criteria for organs at risk, both IMRT and VMAT use many irregularly shaped fields defined by multileaf collimators (MLCs).…”

Section: Introductionmentioning

confidence: 99%

Agility MLC transmission optimization in the Monaco treatment planning system

Roche

Crane

Powers

et al. 2018

J Applied Clin Med Phys

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The Monaco Monte Carlo treatment planning system uses three‐beam model components to achieve accuracy in dose calculation. These components include a virtual source model (VSM), transmission probability filters (TPFs), and an x‐ray voxel Monte Carlo (XVMC) engine to calculate the dose in the patient. The aim of this study was to assess the TPF component of the Monaco TPS and optimize the TPF parameters using measurements from an Elekta linear accelerator with an Agility™ multileaf collimator (MLC). The optimization began with all TPF parameters set to their default value. The function of each TPF parameter was characterized and a value was selected that best replicated measurements with the Agility™ MLC. Both vendor provided fields and a set of additional test fields were used to create a rigorous systematic process, which can be used to optimize the TPF parameters. It was found that adjustment of the TPF parameters based on this process resulted in improved point dose measurements and improved 3D gamma analysis pass rates with Octavius 4D. All plans calculated with the optimized beam model had a gamma pass rate of > 95% using criteria of 2% global dose/2 mm distance‐to‐agreement, while some plans calculated with the default beam model had pass rates as low as 88.4%. For measured point doses, the improvement was particularly noticeable in the low‐dose regions of the clinical plans. In these regions, the average difference from the planned dose reduced from 4.4 ± 4.5% to 0.9 ± 2.7% with a coverage factor (k = 2) using the optimized beam model. A step‐by‐step optimization guide is provided at the end of this study to assist in the optimization of the TPF parameters in the Monaco TPS. Although it is possible to achieve good clinical results by randomly selecting TPF parameter values, it is recommended that the optimization process outlined in this study is followed so that the transmission through the TPF is characterized appropriately.

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Section: Introductionmentioning

confidence: 99%

Agility MLC transmission optimization in the Monaco treatment planning system

Roche

Crane

Powers

et al. 2018

J Applied Clin Med Phys

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“…( 1 ) It allows simultaneous variation of dose rate, gantry speed, and multileaf collimator (MLC) segments. ( 2 ) The technique promises some dosimetric benefits ( 3 ) together with reduced treatment times ( 1 , 2 , 4 – 6 ) which, in turn, may have significant radiobiological impact. ( 7 – 9 ) …”

Section: Introductionmentioning

confidence: 99%

The effect of gantry spacing resolution on plan quality in a single modulated arc optimization

Mihaylov

Curran

Sternick

2011

J Applied Clin Med Phys

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Volumetric‐modulated arc technique (VMAT) is an efficient form of IMRT delivery. It is advantageous over conventional IMRT in terms of treatment delivery time. This study investigates the relation between the number of segments and plan quality in VMAT optimization for a single modulated arc. Five prostate, five lung, and five head‐and‐neck (HN) patient plans were studied retrospectively. For each case, four VMAT plans were generated. The plans differed only in the number of control points used in the optimization process. The control points were spaced 2°, 3°, 4°, and 6° apart, respectively. All of the optimization parameters were the same among the four schemes. The 2° spacing plan was used as a reference to which the other three plans were compared. The plan quality was assessed by comparison of dose indices (DIs) and generalized equivalent uniform doses (gEUDs) for targets and critical structures. All optimization schemes generated clinically acceptable plans. The differences between the majority of reference and compared DIs and gEUDs were within 3%. DIs and gEUDs which differed in excess of 3% corresponded to dose levels well below the organ tolerances. The DI and the gEUD differences increased with an increase in plan complexity from prostates to HNs. Optimization with gantry spacing resolution of 4° seems to be a very balanced alternative between plan quality and plan complexity.PACS number: 87.55.de

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“…This method requires a large number of arcs, with the consequence of a long delivery time [25]. (c) direct aperture optimization (DAO), a recently presented method with no leaf-sequencing requirement [9,20]. DAO optimizes the shapes and the weights of the apertures directly, without previous fluence optimization.…”

Section: Introductionmentioning

confidence: 99%

“…Applied to step and shoot, IMRT is capable to create conformal plans. However, its application to IMAT has not yet been successful, because the IMAT constraints make it more difficult to find an optimal solution [9]. The application of DAO to IMAT is very promising.…”

Section: Introductionmentioning

confidence: 99%