Assessment of the accuracy and stability of frameless gamma knife radiosurgery

Chung, Hyun Tai; Park, Woo-Yoon; Kim, Tae Hoon; Kim, Yong Kyun; Chun, Kook Jin

doi:10.1002/acm2.12365

Cited by 35 publications

(41 citation statements)

References 18 publications

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“…On the Icon TM system, a cone-beam CT (CBCT) scanner is used for setup verification and subsequently an optical tracking device monitors the patient for motion in real-time. If the patient moves out of tolerance the treatment is immediately paused and the patient must undergo a repeat CBCT and subsequent plan evaluation, a process that adds an additional five minutes to the treatment time (Chung et al, 2018). Since the tolerability of the patient to the immobilization mask decreases with time, it is paramount to the success of treatment that the overall time is minimized.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

confidence: 99%

Simultaneous optimization of isocenter locations and sector duration in radiosurgery

et al. 2019

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“…Elekta has published a white paper on CBCT‐MRI demonstrating mean Target Registration Error (TRE) of less than or equal to 0.35 mm for CBCT co‐registration to 1 mm slice thickness MRI images for four separate patients and used synthetic CBCT and not an image acquired with the actual icon . Perhaps of more interest is the work of Chung et al who compared the results of stereotactic definition through the indicator box and the CBCT co‐registration with MRI and found a statistically significant improvement of 0.4 ± 2 mm in utilizing CBCT‐MRI co‐registration over the indicator box . This work seeks to corroborate the accuracy and precision of the CBCT localization of the Icon, compare it to the alternative indicator box method, and then evaluate its ability to detect small changes in patient position within the stereotactic frame.…”

Section: Sources Of Uncertaintymentioning

confidence: 99%

Gamma Knife^® icon CBCT offers improved localization workflow for frame‐based treatment

Duggar

Morris

Fatemi

et al. 2019

J Applied Clin Med Phys

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Object: The purpose of this study was to compare two methods of stereotactic localization in Gamma Knife treatment planning: cone beam computed tomography (CBCT) or fiducial. While the fiducial method is the traditional method of localization, CBCT is now available for use with the Gamma Knife Icon. This study seeks to determine whether a difference exists between the two methods and then whether one is better than the other regarding accuracy and workflow optimization.Methods: Cone beam computed tomography was used to define stereotactic space around the Elekta Film Pinprick phantom and then treated with film in place. The same phantom was offset known amounts from center and then imaged with CBCT and registered with the reference CBCT image to determine if measured offsets matched those known. Ten frameless and 10 frame-based magnetic resonance imaging (MRI) to CBCT patient fusions were retrospectively evaluated using the TG-132 TRE method. The stereotactic coordinates defined by CBCT and traditional fiducials were compared on the Elekta 8 cm Ball phantom, an anthropomorphic phantom, and actual patient data. Offsets were introduced to the anthropomorphic phantom in the stereotactic frame and CBCT's ability to detect those offsets was determined.Results: Cone beam computed tomography defines stereotactic space well within the established limits of the mechanical alignment system. The CBCT to CBCT registration can detect offsets accurately to within 0.1 mm and 0.5°. In all cases, some disagreement existed between fiducial localization and that of CBCT which in some cases was small, but also was as high as 0.43 mm in the phantom domain and as much as 1.54 mm in actual patients. Conclusion:Cone beam computed tomography demonstrates consistent accuracy in defining stereotactic space. Since both localization methods do not agree with each other consistently, the more reliable method must be identified. Cone beam computed tomography can accurately determine offsets occurring within stereotactic space that would be nondiscernible utilizing the fiducial method and seems to be more reliable. Using CBCT localization offers the opportunity to streamline workflow

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“…The Icon treatment system utilizes 192 Co‐60 sources divided into eight sectors that can be individually blocked, or collimated to 4, 8, and 16 mm shot sizes. The Icon is unique in that it utilizes on‐board cone beam computed tomography (CBCT) imaging system to enable fractionated and frameless treatments . The specifics on commissioning and QA for the Icon system can be found in the literature .…”

Section: Introductionmentioning

confidence: 99%

“…The Icon is unique in that it utilizes on‐board cone beam computed tomography (CBCT) imaging system to enable fractionated and frameless treatments . The specifics on commissioning and QA for the Icon system can be found in the literature . Dose is calculated for Icon patients using the TMR10 algorithm .…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a new secondary dose calculation software for Gamma Knife radiosurgery

Prusator

Zhao

Kavanaugh

et al. 2020

J Applied Clin Med Phys

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Current available secondary dose calculation software for Gamma Knife radiosurgery falls short in situations where the target is shallow in depth or when the patient is positioned with a gamma angle other than 90°. In this work, we evaluate a new secondary calculation software which utilizes an innovative method to handle nonstandard gamma angles and image thresholding to render the skull for dose calculation. 800 treatment targets previously treated with our GammaKnife Icon system were imported from our treatment planning system (GammaPlan 11.0.3) and a secondary dose calculation was conducted. The agreement between the new calculations and the TPS were recorded and compared to the original secondary dose calculation agreement with the TPS using a Wilcoxon Signed Rank Test. Further comparisons using a Mann-Whitney test were made for targets treated at a 90°gamma angle against those treated with either a 70 or 110 gamma angle for both the new and commercial secondary dose calculation systems. Correlations between dose deviations from the treatment planning system against average target depth were evaluated using a Kendall's Tau correlation test for both programs. The Wilcoxon Signed Rank Test indicated a significant difference in the agreement between the two secondary calculations and the TPS, with a P-value < 0.0001. With respect to patients treated at nonstandard gamma angles, the new software was largely independent of patient setup, while the commercial software showed a significant dependence (Pvalue < 0.0001). The new secondary dose calculation software showed a moderate correlation with calculation depth, while the commercial software showed a weak correlation (Tau = −.322 and Tau = −.217 respectively). Overall, the new secondary software has better agreement with the TPS than the commercially available secondary calculation software over a range of diverse treatment geometries. K E Y W O R D SGamma Knife, icon, secondary dose calculation, SRS

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Assessment of the accuracy and stability of frameless gamma knife radiosurgery

Cited by 35 publications

References 18 publications

Simultaneous optimization of isocenter locations and sector duration in radiosurgery

Simultaneous optimization of isocenter locations and sector duration in radiosurgery

Gamma Knife^® icon CBCT offers improved localization workflow for frame‐based treatment

Evaluation of a new secondary dose calculation software for Gamma Knife radiosurgery

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Assessment of the accuracy and stability of frameless gamma knife radiosurgery

Cited by 35 publications

References 18 publications

Simultaneous optimization of isocenter locations and sector duration in radiosurgery

Simultaneous optimization of isocenter locations and sector duration in radiosurgery

Gamma Knife® icon CBCT offers improved localization workflow for frame‐based treatment

Evaluation of a new secondary dose calculation software for Gamma Knife radiosurgery

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Gamma Knife^® icon CBCT offers improved localization workflow for frame‐based treatment