Modeling and comparison of alternative approaches for sector duration optimization in a dedicated radiosurgery system

Çevik, Mücahit; Ghomi, Pooyan Shirvani; Aleman, Dionne M.; Lee, Young Kyung; Berdyshev, A; Nordström, Håkan; Riad, Stella; Sahgal, Arjun; Ruschin, Mark

doi:10.1088/1361-6560/aad105

Cited by 13 publications

(26 citation statements)

References 26 publications

(47 reference statements)

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“…Existing approaches to radiotherapy optimization have relied upon non-QUBO SP methods for isocenter determination, including adaptations of the grassfire and skeletonization algorithms (30)(31)(32)(33). Others have chosen to focus on shot shape optimization while avoiding manipulation of shot positions (34,35). The Fwd-ROCKET plans presented in this work demonstrate that our SSO on its own has a positive impact on treatment quality with short computation times.…”

Section: Discussionmentioning

confidence: 96%

“…Other techniques for automatic treatment planning have been reported based on simulated annealing, linear programming, mixed-integer programming, or piecewise penalty methods (29,34,35,41,42). These models may achieve clinically acceptable plans in terms of quantitative metrics but may have shortcomings in terms of computation time, hardware limitations, or long delivery times.…”

Section: Discussionmentioning

confidence: 99%

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A computational optimization approach for the automatic generation of Gamma Knife radiosurgery treatment plans

Walker

Malekmohammadi

Coolens

et al. 2021

Preprint

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Gamma knife (GK) radiosurgery is a non-invasive treatment modality which allows single fraction delivery of focused radiation to one or more brain targets. Treatment planning mostly involves manual placement and shaping of shots to conform the prescribed dose to a surgical target. This process can be time consuming and labour intensive. An automated method is needed to determine the optimum combination of treatment parameters to decrease planning time and chance for operator-related error. Recent advancements in hardware platforms which employ parallel computational methods with stochastic optimization schemes are well suited to solving such combinatorial optimization problems efficiently. We present a method of generating optimized GK radiosurgery treatment plans using these techniques, which we name ROCKET (Radiosurgical Optimization Configuration Kit for Enhanced Treatments). Our approach consists of two phases in which shot isocenter positions are generated based on target geometry, followed by optimization of sector collimator parameters. Using this method, complex treatment plans can be generated, on average, in less than one minute, a substantial decrease relative to manual planning. Our results also demonstrate improved selectivity and treatment safety through decreased exposure to nearby organs-at-risk (OARs), compared to manual reference plans with matched coverage. Stochastic optimization is therefore shown to be a robust and efficient clinical tool for the automatic generation of GK radiosurgery treatment plans.

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

A computational optimization approach for the automatic generation of Gamma Knife radiosurgery treatment plans

Walker

Malekmohammadi

Coolens

et al. 2021

Preprint

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“…21 In terms of the optimization model to be used in the MRL framework in our study, we chose the linear programming model proposed by Nordstr € o m H, which was originally developed for sector duration optimization, 14 since it was reported in a recent study that linear programming tended to yield shorter beam-on time than convex quadratic penalty approaches and convex moment-based approaches. 23 The objective function that is used at each round of optimization but with different sets of isocenter candidates is formulated as…”

Section: B Methods Of Our Choicementioning

confidence: 99%

“…In terms of the optimization model to be used in the MRL framework in our study, we chose the linear programming model proposed by Nordstr

\overset{o}{true}

m H, which was originally developed for sector duration optimization, since it was reported in a recent study that linear programming tended to yield shorter beam‐on time than convex quadratic penalty approaches and convex moment‐based approaches . The objective function that is used at each round of optimization but with different sets of isocenter candidates is formulated as

\begin{matrix} {minimize}_{t} & \frac{ω_{TH}}{N_{T}} \sum_{i \in I_{T}} truemax ()(, D_{i} - D_{TH}, 0) + \frac{ω_{TL}}{N_{T}} \sum_{i \in I_{T}} truemax ()(, D_{TL} - D_{i}, 0) \\ + \frac{ω_{IS}}{N_{IS}} \sum_{i \in I_{italicIS}} truemax ()(, D_{i} - D_{IS}, 0) + \frac{ω_{OS}}{N_{OS}} \sum_{i \in I_{italicOS}} truemax ()(, D_{i} - D_{OS}, 0) \\ + \frac{ω_{O}}{N_{O}} \sum_{i \in I_{O}} truemax ()(, D_{i} - D_{O}, 0) \\ + ω_{italicBOT} \sum_{n = 1}^{N} {truemax}_{m = 1, 2, . ., 8} (\sum_{c = 1}^{3} t ()(, c, m, n)), \end{matrix}

subject t o t \geq 0

here,

t

is the be...…”

Section: Methodsmentioning

confidence: 99%

A preliminary study on a multiresolution‐level inverse planning approach for Gamma Knife radiosurgery

et al. 2020

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Purpose: With many plan variables to determine, manual forward planning for Gamma Knife (GK) radiosurgery is very challenging. Inverse planning eases GK planning by determining the variables via solving an optimization problem. However, due to the vast search space, most inverse planning algorithms, including the one provided in Leksell GammaPlan (LGP) treatment planning system, have to predetermine the isocenter locations using some geometric methods and then optimize the shot shapes and durations at these preselected isocenters. This sequential planning scheme does not necessarily lead to optimal isocenter locations and hence globally optimal plans. In this study, we proposed a multiresolution-level (MRL) inverse planning approach, attempting to approach this large-scale GK optimization problem via an iterative method. Methods: In our MRL approach, several rounds of optimizations were performed with a progressively increased resolution used for isocenter candidates. At each round, an optimization problem was solved to optimize the beam-on time for each collimator and sector at each isocenter candidate. The isocenters that obtained nonzero beam-on times at the previous round and their neighbors on a finer resolution were used as new isocenter candidates for the next round of optimization. After plan optimization, shot sequencing was performed to group the optimized sectors to deliverable composite shots. Results: We have tested our MRL approach on six GK cases previously treated in our institution. For the five cases that have a single target, with similar target coverage obtained, our MRL inverse planning approach achieved better plan quality compared to manual forward planning and LGP inverse planning, with higher selectivity (0.73 AE 0.07 vs 0.72 AE 0.08 and 0.62 AE 0.10), lower gradient index (2.71 AE 0.25 vs 2.78 AE 0.24 and 3.00 AE 0.29), lower brainstem D 0.1cc dose (6.10 AE 4.46 Gy vs 8.87 AE 4.82 Gy and 9.17 AE 3.80 Gy), and shorter total beam-on time (62.1 AE 22.9 min vs 83.6 AE 28.2 min and 70.7 AE 16.7 min). For the case that have six targets, compared with manual planning and LGP inverse planning, our MRL approach achieved higher selectivity (0.68 vs 0.57 and 0.47) and lower gradient index (3.77 vs 4.51 and 5.11). The beam-on time of our plan was slightly longer than manual planning and LGP inverse planning (206.4 min vs 204.7 min and 199.3 min). We have also performed sector duration optimization at the isocenters determined by manual planning or the LGP inverse planning, and the resulting plan qualities were found to be inferior to our MRL approach for all the six cases. Conclusions: This preliminary study has demonstrated the efficacy and feasibility of our MRL inverse planning approach for GK radiosurgery.

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“…All of the aforementioned studies report high treatment plan quality in terms of satisfying the dosimetric clinical objectives with limited attention paid to satisfying clinical goals (2) and ( 3). In a recent study, Cevik et al (2018) investigate three modeling approaches for the SDO: linear programming, convex quadratic penalty approach, and convex moment-based approach. Although all three approaches yield plans satisfying the dosimetric clinical objectives, their findings suggest that the linear programming tends to yield the lowest beam-on time (BOT).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous optimization of isocenter locations and sector duration in radiosurgery

et al. 2019

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Stereotactic radiosurgery is an effective technique to treat brain tumors for which several inverse planning methods may be appropriate. We propose an integer programming model to simultaneous sector duration and isocenter optimization (SDIO) problem for Leksell Gamma Knife R Icon TM (Elekta, Stockholm, Sweden) to tractably incorporate treatment time. We devise a Benders decomposition scheme to solve the SDIO problem to optimality. The performances of our approaches are assessed using anonymized data from eight previously treated cases, and obtained treatment plans are compared against each other and against the clinical plans. The plans generated by our SDIO model all meet or exceed clinical guidelines while demonstrating high conformity.arXiv:1807.02607v1 [physics.med-ph] 7 Jul 2018 IntroductionStereotactic radiosurgery (SRS) is an effective method for treatment of brain tumors, vascular malformations, and other conditions such as tremors. During SRS, a large amount of radiation is delivered to tumors through the intact skull without damaging the surrounding normal brain tissue.SRS aims to obtain highly conformal dose distributions so that dose is delivered to target structures with high precision while sparing the surrounding healthy tissues, thus increasing the patient's survival chance and improving the quality of life after the treatment. One advanced SRS system is Leksell Gamma Knife R (LGK) (Elekta, Stockholm, Sweden) Icon TM . Icon TM has a single collimator with eight detached sectors that can either be robotically driven to three different collimator sizes (4, 8, and 16 mm) or be blocked. During SRS, the patient lies on a couch and radiation is emitted by 192 cobalt-60 sources to the targets where the intersection point of all the beams is called the isocenter. The radiation delivery follows a step-and-shoot manner, i.e., the couch is stationary during delivery of radiation at each isocenter location, and only moves when the beam is blocked. To fully leverage the robotic capability of the delivery system, an automated approach for planning is required. The clinical goals for such an automated approach are: (1) satisfy or exceed the dosimetric clinical objectives (e.g., coverage, conformality, healthy tissue dose); (2) achieve (1) with minimal irradiation time (i.e., beam-on time); and (3) achieve (1) and (2) with a plan as efficient as possible, including minimizing the number of isocenters and shots required.Most of the current literature has separated the task of isocenter placement from the task of sector duration optimization (SDO). In SDO, as in fluence map optimization in Intensity Modulated Radiation Therapy, the aim is to find the intensities (or irradiation times) of each beamlet in a fixed set of beams. Previous studies on SDO mainly focus on variants of convex quadratic penalty models (Oskoorouchi et al., 2011;Ghobadi et al., 2012;Ghaffari, 2012). In order to determine the isocenter locations, Ghobadi et al. (2012) propose an algorithm that combines the well-known

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Modeling and comparison of alternative approaches for sector duration optimization in a dedicated radiosurgery system

Cited by 13 publications

References 26 publications

A computational optimization approach for the automatic generation of Gamma Knife radiosurgery treatment plans

A computational optimization approach for the automatic generation of Gamma Knife radiosurgery treatment plans

A preliminary study on a multiresolution‐level inverse planning approach for Gamma Knife radiosurgery

Simultaneous optimization of isocenter locations and sector duration in radiosurgery

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