A Dose–Volume Response Model for Brain Metastases Treated With Frameless Single-Fraction Robotic Radiosurgery: Seeking to Better Predict Response to Treatment

Amsbaugh, Mark J.; Gaskins, Jeremy; Dragun, Anthony E.; Guan, Timothy; Woo, Shiao Y.

doi:10.1177/1533034616685025

Cited by 12 publications

(15 citation statements)

References 32 publications

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“…Finally, they observed that patients with fewer number of metastases had worse local control (OR: 0.815, 95% CI: 0.72-0.93). 8 Similar observation was made by Yamamoto et al in their study on stereotactic radiosurgery for multiple brain metastases. 9 They observed significant difference in local recurrence ratio and need for repeat treatment between group with 2-9 metastases (more recurrences) and group with 10 and more lesions.…”

Section: Discussionsupporting

confidence: 73%

“…Amsbaugh et al used the dose per lesion diameter and dose per volume parameters to construct dose-volume response relationships. 7,8 They found strong correlation between doses and volumes of the tumor which was quite obvious because all patients in their series were treated with single fraction, so the larger the volume, the smaller total dose was used. This resulted with worse results in patients with larger metastases who were treated with lower doses.…”

Section: Discussionmentioning

confidence: 97%

“…The first studies aimed at detailed analysis of the effect of the dose normalized to volume of the lesion and probability of local control were made by Amsbaugh et al but they analyzed single fraction regimens only. 7,8 The aim of our study was to assess the association between physical and biological dose delivered per volume unit of a metastatic tumor as well as clinical factors with local control in patients with brain metastases after robotic stereotactic radiosurgery.…”

Section: Introductionmentioning

confidence: 99%

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Clinical and volumetric predictors of local control after robotic stereotactic radiosurgery for cerebral metastases: active systemic disease may affect local control in the brain

Blamek

Stankiewicz

Maciejewski

2020

Radiology and Oncology

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BackgroundThe aim of the study was to assess the association between physical and biological dose normalized to volume of the metastatic tumor as well as clinical factors with local control in patients with brain metastases who underwent robotic stereotactic radiosurgery.Patients and methodsA cohort of 69 patients consecutively treated with robotic radiosurgery between 2011 and 2016 was analyzed. The patients were treated with either single fraction radiosurgery or hypofractionated regimens. Biologically effective dose (BED) was calculated assuming alpha/beta value = 10 and both physical dose and BED were normalized to the tumor volume to allow dose-volume effect evaluation. Moreover, clinical and treatment-related variables were evaluated to asses association with local control.ResultsA total of 133 tumors were irradiated and their volumes ranged between 0.001 and 46.99 cm3. Presence of extracranial progression was associated with worse local control whereas higher total dose, BED10 > 59 Gy and single metastasis predicted statistically significantly better local outcome. BED10/cm3 > 36 Gy, and BED2 > 60 Gy negatively affected local control in univariate analysis. In multivariate analysis performed on all these variables, presence of a single metastasis, BED10 > 59 Gy and extracranial progression retained their significance. Excluding a priori the BED2/ cm3 parameter resulted with a Cox model confirming significance of all remaining variables.ConclusionsHypofractionated treatment schemes have similar efficiency to single fraction treatment in terms of local control and the effect depends on BED irrespective of fractionation schedule. Effective control of extracranial sites of the disease is associated with higher probability of local control in the brain which in turn is consistently lower in patients with multiple lesions.

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Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Clinical and volumetric predictors of local control after robotic stereotactic radiosurgery for cerebral metastases: active systemic disease may affect local control in the brain

Blamek

Stankiewicz

Maciejewski

2020

Radiology and Oncology

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“…This creates a dose profile inside the target that is relatively inhomogeneous, which has been shown to improve local control. 4 Recent work has verified that significant improvements in gradient can be achieved by increasing dose inhomogeneity inside the target for various platforms. 21,22,24,29,34 As a result, the majority of radiosurgery practitioners are aligned with this treatment philosophy, and the indices proposed in this study encourage the use of this philosophy.…”

Section: Discussionmentioning

confidence: 99%

“…. [4] It is possible to calculate OARh 50% for any delineated structure. When multiple surrounding structures are delineated, the calculated OARh 50% values can be used as a guide for preferentially sparing radiosensitive surround-…”

Section: Efficiency Index For Oarsmentioning

confidence: 99%

A novel index for assessing treatment plan quality in stereotactic radiosurgery

Dimitriadis¹,

Paddick²

2018

Journal of Neurosurgery

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OBJECTIVEStereotactic radiosurgery (SRS) is characterized by high levels of conformity and steep dose gradients from the periphery of the target to surrounding tissue. Clinical studies have backed up the importance of these factors through evidence of symptomatic complications. Available data suggest that there are threshold doses above which the risk of symptomatic radionecrosis increases with the volume irradiated. Therefore, radiosurgical treatment plans should be optimized by minimizing dose to the surrounding tissue while maximizing dose to the target volume. Several metrics have been proposed to quantify radiosurgical plan quality, but all present certain weaknesses. To overcome limitations of the currently used metrics, a novel metric is proposed, the efficiency index (η50%), which is based on the principle of calculating integral doses: η50% = integral doseTV/integral dosePIV50%.METHODSThe value of η50% can be easily calculated by dividing the integral dose (mean dose × volume) to the target volume (TV) by the integral dose to the volume of 50% of the prescription isodose (PIV50%). Alternatively, differential dose-volume histograms (DVHs) of the TV and PIV50% can be used. The resulting η50% value is effectively the proportion of energy within the PIV50% that falls into the target. This value has theoretical limits of 0 and 1, with 1 being perfect. The index combines conformity, gradient, and mean dose to the target into a single value. The value of η50% was retrospectively calculated for 100 clinical SRS plans.RESULTSThe value of η50% for the 100 clinical SRS plans ranged from 37.7% to 58.0% with a mean value of 49.0%. This study also showed that the same principles used for the calculation of η50% can be adapted to produce an index suitable for multiple-target plans (Gη12Gy). Furthermore, the authors present another adaptation of the index that may play a role in plan optimization by calculating and minimizing the proportion of energy delivered to surrounding organs at risk (OARη50%).CONCLUSIONSThe proposed efficiency index is a novel approach in quantifying plan quality by combining conformity, gradient, and mean dose into a single value. It quantifies the ratio of the dose “doing good” versus the dose “doing harm,” and its adaptations can be used for multiple-target plan optimization and OAR sparing.

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Single isocenter SRS using CAVMAT offers improved robustness to commissioning and treatment delivery uncertainty compared to VMAT

Cullom

Xia

Chuang

et al. 2021

J Applied Clin Med Phys

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In this study, we evaluate and compare single isocenter multiple target VMAT (SIMT) and Conformal Arc Informed VMAT (CAVMAT) radiosurgery's sensitivity to uncertainties in dosimetric leaf gap (DLG) and treatment delivery. CAVMAT is a novel planning technique that uses multiple target conformal arcs as the starting point for limited inverse VMAT optimization.Methods: All VMAT and CAVMAT plans were recalculated with DLG values of 0.4, 0.8, and 1.2 mm. DLG effect on V 6Gy [cc], V 12Gy [cc], and V 16Gy [cc], and target dose was evaluated. Plans were delivered to a Delta 4 (ScandiDos, Madison, WI) phantom and gamma analysis performed with varying criteria. Log file analysis was performed to evaluate MLC positional error. Sixteen targets were delivered to a SRS Map-CHECK (Sun Nuclear Corp., Melbourne, FL) to evaluate VMAT and CAVMAT's dose difference (DD) as a function of DLG.Results: VMAT's average maximum and minimum target dose sensitivity to DLG was 9.08 AE3.50%/mm and 9.50 AE 3.30%/mm, compared to 3.20 AE 1.60%/mm and 4.72 AE 1.60%/mm for CAVMAT. For VMAT, V 6Gy [cc], V 12Gy [cc], and V 16Gy [cc] sensitivity was 35.83 AE 9.50%/mm, 34.12 AE 6.60%/mm, and 39.23 AE 8.40%/mm. In comparison, CAVMAT's sensitivity was 23.19 AE 4.50%/mm, 22.45 AE 4.40%/mm, and 24.88 AE 4.90%/mm, respectively. Upon delivery to the Delta 4 , CAVMAT offered superior dose agreement compared to VMAT. For a 1%/1 mm gamma analysis, VMAT and CAVMAT had a passing rate of 94.53 AE 4.40% and 99.28 AE 1.70%, respectively. CAVMAT was more robust to DLG variation, with the SRS MapCHECK plans yielding an absolute average DD sensitivity of 2.99 AE 1.30%/mm compared to 5.07 AE 1.10%/mm for VMAT. Log files demonstrated minimal differences in MLC positional error for both techniques.Conclusions: CAVMAT remains robust to delivery uncertainties while offering a target dose sensitivity to DLG less than half that of VMAT, and 65% of that of VMAT for V 6Gy [cc], V 12Gy [cc], and V 16Gy [cc]. The superior dose agreement and reduced

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A Dose–Volume Response Model for Brain Metastases Treated With Frameless Single-Fraction Robotic Radiosurgery: Seeking to Better Predict Response to Treatment

Cited by 12 publications

References 32 publications

Clinical and volumetric predictors of local control after robotic stereotactic radiosurgery for cerebral metastases: active systemic disease may affect local control in the brain

Clinical and volumetric predictors of local control after robotic stereotactic radiosurgery for cerebral metastases: active systemic disease may affect local control in the brain

A novel index for assessing treatment plan quality in stereotactic radiosurgery

Single isocenter SRS using CAVMAT offers improved robustness to commissioning and treatment delivery uncertainty compared to VMAT

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