Rotational IMRT delivery using a digital linear accelerator in very high dose rate ‘burst mode’

Salter, Bill J.; Sarkar, Vikren; Wang, Brian; Shukla, H; Szegedi, M; Rassiah‐Szegedi, P

doi:10.1088/0031-9155/56/7/002

Cited by 28 publications

(22 citation statements)

References 19 publications

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“…Multiple groups have published 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 on the use of modulated arcs in the treatment of cancer in varying sites and they have shown that the technique is able to achieve dose distributions that are typically equivalent to those from static gantry IMRT plans, but that can be delivered with much higher efficiency. As already described in literature, 12 , 13 , 14 Siemens' mARC uses the Burst Mode approach for treatment delivery, wherein segment dose is “burst” in at very high dose rates, over very short gantry angles. Because treatment planning systems typically approximate an arc delivery as a series of static beams, the Burst Mode approach should, theoretically, cause the delivered dose to more closely approach the calculated distribution from the treatment planning system.…”

Section: Introductionmentioning

confidence: 99%

Planning for mARC treatments with the Eclipse treatment planning system

Sarkar

Huang

Rassiah‐Szegedi

et al. 2015

J Applied Clin Med Phys

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While modulated arc (mARC) capabilities have been available on Siemens linear accelerators for almost two years now, there was, until recently, only one treatment planning system capable of planning these treatments. The Eclipse treatment planning system now offers a module that can plan for mARC treatments. The purpose of this work was to test the module to determine whether it is capable of creating clinically acceptable plans. A total of 23 plans were created for various clinical sites and all plans delivered without anomaly. The average 3%/3 mm gamma pass rate for the plans was 98.0%, with a standard deviation of 1.7%. For a total of 14 plans, an equivalent static gantry IMRT plan was also created to compare delivery time. In all but two cases, the mARC plans delivered significantly faster than the static gantry plan. We have confirmed the successful creation of mARC plans that are deliverable with high fidelity on an ARTISTE linear accelerator, thus demonstrating the successful implementation of the Eclipse mARC module.PACS numbers: 87.55.D‐, 87.55.ne, 87.57.uq,

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Section: Introductionmentioning

confidence: 99%

Planning for mARC treatments with the Eclipse treatment planning system

Sarkar

Huang

Rassiah‐Szegedi

et al. 2015

J Applied Clin Med Phys

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“…Recently, a rotational IMRT (rIMRT) using burst mode was introduced that delivers step‐and‐shoot in a rotational manner. It turns off the beam during MLC motion 35 , 36 . Using index‐dose optimization, a head and neck case for rIMRT plan was retrospectively studied using the proposed DAO.…”

Section: Resultsmentioning

confidence: 99%

Direct aperture optimization using an inverse form of back‐projection

Zhu

Cullip

Tracton

et al. 2014

J Applied Clin Med Phys

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Direct aperture optimization (DAO) has been used to produce high dosimetric quality intensity‐modulated radiotherapy (IMRT) treatment plans with fast treatment delivery by directly modeling the multileaf collimator segment shapes and weights. To improve plan quality and reduce treatment time for our in‐house treatment planning system, we implemented a new DAO approach without using a global objective function (GFO). An index concept is introduced as an inverse form of back‐projection used in the CT multiplicative algebraic reconstruction technique (MART). The index, introduced for IMRT optimization in this work, is analogous to the multiplicand in MART. The index is defined as the ratio of the optima over the current. It is assigned to each voxel and beamlet to optimize the fluence map. The indices for beamlets and segments are used to optimize multileaf collimator (MLC) segment shapes and segment weights, respectively. Preliminary data show that without sacrificing dosimetric quality, the implementation of the DAO reduced average IMRT treatment time from 13 min to 8 min for the prostate, and from 15 min to 9 min for the head and neck using our in‐house treatment planning system PlanUNC. The DAO approach has also shown promise in optimizing rotational IMRT with burst mode in a head and neck test case.PACS number: 87.55.D‐

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“…The new system is capable of delivering a wide array of clinically relevant treatment plans, and it was found that delivery times are significantly short. 25 The time saved from all these factors can be utilized to add extra beams or intensity modulation to achieve a more conformal dose distribution. We note that, practically, it is possible to incorporate dose delivery time formularized by Eq.…”

Section: Discussionmentioning

confidence: 99%

Bridging the gap between IMRT and VMAT: Dense angularly sampled and sparse intensity modulated radiation therapy

2011

Medical Physics

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Purpose: To propose an alternative radiation therapy (RT) planning and delivery scheme with optimal angular beam sampling and intrabeam modulation for improved dose distribution while maintaining high delivery efficiency. Methods: In the proposed approach, coined as dense angularly sampled and sparse intensity modulated RT (DASSIM-RT), a large number of beam angles are used to increase the angular sampling, leading to potentially more conformal dose distributions as compared to conventional IMRT. At the same time, intensity modulation of the incident beams is simplified to eliminate the dispensable segments, compensating the increase in delivery time caused by the increased number of beams and facilitating the plan delivery. In a sense, the proposed approach shifts and transforms, in an optimal fashion, some of the beam segments in conventional IMRT to the added beams. For newly available digital accelerators, the DASSIM-RT delivery can be made very efficient by concatenating the beams so that they can be delivered sequentially without operator's intervention. Different from VMAT, the level of intensity modulation in DASSIS-RT is field specific and optimized to meet the need of each beam direction. Three clinical cases (a head and neck (HN) case, a pancreas case, and a lung case) are used to evaluate the proposed RT scheme. DASSIM-RT, VMAT, and conventional IMRT plans are compared quantitatively in terms of the conformality index (CI) and delivery efficiency. Results: Plan quality improves generally with the number and intensity modulation of the incident beams. For a fixed number of beams or fixed level of intensity modulation, the improvement saturates after the intensity modulation or number of beams reaches to a certain level. An interplay between the two variables is observed and the saturation point depends on the values of both variables. For all the cases studied here, the CI of DASSIM-RT with 15 beams and 5 intensity levels (0.90, 0.79, and 0.84 for the HN, pancreas, and lung cases, respectively) is similar with that of conventional IMRT with seven beams and ten intensity levels (0.88, 0.79, and 0.83) and is higher than that of single-arc VMAT (0.75, 0.75, and 0.82). It is also found that the DASSIM-RT plans generally have better sparing of organs-at-risk than IMRT plans. It is estimated that the dose delivery time of DASSIM-RT with 15 beams and 5 intensity levels is about 4.5, 4.4, and 4.2 min for the HN, pancreas, and lung case, respectively, similar to that of IMRT plans with 7 beams and 10 intensity levels. Conclusion: DASSIS-RT bridges the gap between IMRT and VMAT and allows optimal sampling of angular space and intrabeam modulation, thus it provides improved conformity in dose distributions while maintaining high delivery efficiency.

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Rotational IMRT delivery using a digital linear accelerator in very high dose rate ‘burst mode’

Cited by 28 publications

References 19 publications

Planning for mARC treatments with the Eclipse treatment planning system

Planning for mARC treatments with the Eclipse treatment planning system

Direct aperture optimization using an inverse form of back‐projection

Bridging the gap between IMRT and VMAT: Dense angularly sampled and sparse intensity modulated radiation therapy

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