Automated noncoplanar treatment planning strategy in stereotactic radiosurgery of multiple cranial metastases: HyperArc and CyberKnife dose distributions

doi:10.1016/j.meddos.2019.02.004

Medical Dosimetry

Volume 44, Issue 4, Winter 2019, Pages 394-400

https://doi.org/10.1016/j.meddos.2019.02.004 Get rights and content

Abstract

The purpose of this study was to evaluate and compare the dosimetric effects of HyperArc-based stereotactic radiosurgery (SRS) and a robotic radiosurgery system-based planning using CyberKnife for multiple cranial metastases. In total, 11 cancer patients with multiple cranial metastases (3 to 5 tumors) treated with CyberKnife were examined. These patients were replanned using HyperArc (Varian Medical Systems, Palo Alto, USA). HyperArc plan were designed using 4 noncoplanar arc single-isocenter VMAT in 6 MV flattening filter free mode for simulated delivery with the True beam STx (Varian). The prescription dose was 23 Gy at single fraction. Dosimetric differences and blinded clinician scoring differences were evaluated. Conformity index (CI) and gradient index (GI) were 0.60 ± 0.11 and 3.94 ± 0.74, respectively, for the CyberKnife plan and 0.87 ± 0.08 and 5.31 ± 1.42, respectively, for the HyperArc plan (p < 0.05). Total brain V12-gross tumor volumes (GTVs) for the CyberKnife and HyperArc plans were 5.26 ± 2.83 and 4.02 ± 1.71 cm³, respectively. These results indicate that HyperArc plan showed better CI and total brain V12-GTV, while CyberKnife plan showed better GI. A blinded physician scoring evaluation did not show significant differences between CyberKnife and HyperArc plans. The HyperArc-based SRS plan is comparable with the CyberKnife plan, suggesting a greater potential to emerge as a suitable tool for SRS of multiple brain metastases.

Introduction

Brain metastases are prevalent in 40% of the patients with systemic cancers. The role of stereotactic radiosurgery (SRS) with or without whole-brain radiotherapy in the initial treatment of newly diagnosed brain metastases has been evaluated by 2 randomized clinical trials.1., 2. Andrews et al. have reported a significantly greater stability of function at 6 months among patients undergoing SRS as a part of their initial treatment, and the local control rate at 1 year improved from 71% to 82% with the addition of SRS.¹

Several approaches are available for the treatment of brain metastases using SRS techniques: Gamma Knife, CyberKnife (CK), and linear accelerator (Linac).

In Linac-based SRS, the Linacs are exclusively designed for SRS to further improve the targeting accuracy and to ensure high dose-rate delivery. Today, the mechanical isocenter accuracy of the C-arm Linac can reach submillimeter levels.3., 4. The flattening filters have been first redesigned to be more efficient and later completely removed to deliver higher dose rates.5., 6. The leaf resolution of multileaf collimator (MLC) has been redesigned, with 2.5-mm leaf widths at the isocenter, to improve the dose conformity to the target.⁷

More recently, HyperArc (Varian Medial Systems, Palo Alto, USA) has been developed to automate and simplify sophisticated treatments, such as SRS, using highly noncoplanar treatment strategies.8., 9., 10. However, few studies have examined the role of HyperArc in brain SRS.⁹

Thus, we aimed to evaluate and compare the dosimetric effects of automated noncoplanar treatment planning using HyperArc-based SRS (HyperArc plan) and a robotic radiosurgery system-based planning using CK (CK plan) for multiple cranial metastases.

Section snippets

CK plan

In total, 11 cancer patients with multiple cranial metastases (3 to 5 tumors) treated with CK M6 (Accuray Inc, Sunnyvale, USA) in the period from January 2016 to December 2017 were recruited for this study. All patients were examined using a GE CT scanner (Light Speed RT16, General Electric Medical Systems, Waukesha, USA), at a slice spacing of 1.25 mm. Multiplan (Accuray Inc, Sunnyvale, USA) Ray-Tracing dose calculation algorithm was used as the radiation treatment planning system. Gross tumor

Results

The outcomes for the dosimetric parameters in all patients are summarized in Table 2. The CI of the HyperArc plan (0.87) was significantly better than that of the CK plan (0.60). The EUD and GI of the CK plan were significantly better than those of the HyperArc plan (e.g., EUD: CK, 25.00 Gy; HyperArc, 24.36 Gy).

In terms of DVH parameters of the total brain, V12-GTV of the HyperArc plan was significantly smaller than that of the CK plan. The V2 of the CK plan was smaller than that of the

Discussion

This study evaluated the dosimetric effect of HyperArc planning for the SRS of multiple cranial metastases and compared these with the effects of CK. The HyperArc plan showed significantly better CI and total brain V12-GTV, whereas the CK plan showed significantly better EUD and GI. In addition, the blinded clinician scoring evaluation did not show significant differences between the CK and HyperArc plan. On the basis of these results, HyperArc-based SRS planning showed a greater potential to

Conclusions

In this study, for the first time, HyperArc and CK were compared in terms of their dosimetry effects in the SRS of multiple cranial metastases SRS. Our result demonstrated that HyperArc plan showed better CI and total brain V12-GTV, whereas CK showed better GI. Our findings indicate that HyperArc-based SRS planning has a greater potential to become the tool of choice for the SRS of the multiple cranial metastases.

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Cited by (28)

Organs-at-risk dose and normal tissue complication probability with dynamic trajectory radiotherapy (DTRT) for head and neck cancer
2024, Radiotherapy and Oncology
Comparison between the HyperArc™ technique and the CyberKnife® technique for stereotactic treatment of brain metastases
2023, Cancer/Radiotherapie
The purpose of this study was to compare the planimetric capacities between HyperArc™-based stereotactic radiosurgery and robotic radiosurgery system-based planning using CyberKnife® M6 for single and multiple cranial metastases.
We evaluated 51 treatment plans for cranial metastases, including 30 patients with a single lesion and 21 patients with multiple lesions, treated with the CyberKnife® M6. These treatment plans were optimized using the HyperArc™ (HA) system with the TrueBeam. The comparison of the quality of the treatment plans between the two treatment techniques (CyberKnife and HyperArc) was performed using the Eclipse treatment planning system. Dosimetric parameters were compared for target volumes and organs at risk.
Coverage of the target volumes was equivalent between the two techniques, whereas median Paddick conformity index and median gradient index for all target volumes were 0.9 and 3.4, respectively for HyperArc plans, and 0.8 and 4.5 for CyberKnife plans (P < 0.001). The median dose of gross tumor volume (GTV) for HyperArc and CyberKnife plans were 28.4 and 28.8, respectively. Total brain V18 Gy and V12Gy-GTVs were 11 cm³ and 20.2cm³ for HyperArc plans versus 18 cm³ and 34.1 cm³ for CyberKnife plans (P < 0.001).
The HyperArc provided better brain sparing, with a significant reduction in V12 Gy and V18 Gy, associated with a lower gradient index, whereas the CyberKnife gave a higher median GTV dose. The HyperArc technique seems to be more appropriate for multiple cranial metastases and for large single metastatic lesions.
L’objectif de cette étude était de comparer les capacités planimétriques entre la radiochirurgie stéréotaxique avec la technique HyperArc™ et une planification basée sur un système de radiochirurgie robotisée utilisant le CyberKnife® M6 pour des métastases crâniennes uniques ou multiples.
Nous avons évalué 51 plans de traitement de métastases crâniennes, dont 30 patients étaient atteints d’une lésion unique et 21 patients de lésions multiples, traitées par CyberKnife® M6. Ces plans de traitement ont également été optimisés à l’aide de l’option HyperArc™ disponible avec le TrueBeam. La comparaison de la qualité des plans de traitement entre les deux techniques de traitement (HyperArc™ et CyberKnife®) a été effectuée à l’aide du système de planification des traitements Eclipse™. Les paramètres dosimétriques ont été comparés pour les volumes cibles et les organes à risque.
La couverture des volumes cibles était équivalente entre les deux techniques, alors que l’indice de conformité médian de Paddick et l’indice de gradient médian pour tous les volumes cibles étaient de 0,9 et 3,4, respectivement pour les plans HyperArc, et de 0,8 et 4,5 pour les plans CyberKnife (p < 0,001). Les doses médianes dans le volume tumoral macroscopique pour les plans HyperArc™ et CyberKnife® étaient respectivement de 28,4 et 28,8. Les volumes recevant 18 Gy (V18 Gy) ou 12 Gy (V12 Gy) de l’encéphale total étaient de 11 cm³ et 20,2 cm³ pour les plans HyperArc contre 18 cm³ et 34,1 cm³ pour les plans du CyberKnife® (p < 0,001).
L’HyperArc™ a permis une meilleure épargne encéphalique, avec une réduction significative des V12 Gy et V18 Gy associée à un indice de gradient plus faible, tandis que le CyberKnife® a donné une dose médiane dans le volume tumoral macroscopique plus élevée. La technique HyperArc™ semble être plus appropriée pour les lésions métastatiques crâniennes multiples ainsi que pour les grandes lésions métastatiques uniques.
Two novel stereotactic radiotherapy methods for locally advanced, previously irradiated head and neck cancers patients
2023, Medical Dosimetry
To determine the feasibility and utility of conebeam CT-guided stereotactic radiotherapy for locally recurrent, previously irradiated head and neck cancer (HNC) patients on the Halcyon, a ring delivery system (RDS). This research aims to quantify plan quality, treatment delivery accuracy, and overall efficacy by comparing against novel clinical TrueBeam HyperArc method. Ten recurrent HNC patients who were treated at our institution on TrueBeam (6MV-FFF) for 30 to 40 Gy in 3 to 5 fractions with noncoplanar HyperArc plans were re-planned on Halcyon (6MV-FFF). These plans were re-planned with the same Acuros-based dose engine. Additionally, we used site-specific full/partial coplanar VMAT arcs. PTV coverage, mean dose to GTV, maximum dose to organs-at-risk (OAR), beam-on time (BOT), and quality assurance (QA) results were investigated and compared. Halcyon provided highly conformal HNC SRT plans with slightly superior mean PTVD99 coverage (96.7% vs 95.5%, p = 0.071), and slightly lower mean GTV dose (37.8 Gy vs 38.2 Gy, p = 0.241) when compared to the HyperArc plans. Differences in plan conformality and maximum dose to OARs were statistically insignificant. Due to Halcyon's coplanar geometry, D2cm was significantly higher (p = 0.001) but Halcyon did result in a reduced normal brain dose by 1 Gy on average and up to 5.2 Gy in some cases. Halcyon provided similar patient-specific QA pass rates with a 2%/2mm gamma criteria (98.2% vs 98.5%) and independent in-house Monte Carlo second check results (97.7% vs 98.2%), suggesting identical treatment delivery accuracy. Halcyon plans resulted in slightly longer beam-on time (3.16 vs 2.30 minutes, p = 0.010), however door-to-door patient time is expected to be <10 minutes. Compared to clinical TrueBeam HyperArc, Halcyon SRT plans provided similar plan quality and treatment delivery accuracy with a potentially faster overall treatment using fully automated patient setup and verification. Rapid delivery of recurrent HNC SRT may reduce intrafraction motion errors while also improving patient compliance and comfort. To provide high-quality of HNC SRT similar to HyperArc, we recommend Halcyon users consider commissioning this novel method. This method will be useful for remote and underserved patient cohorts including Halcyon-only clinics as well.
Multi-center planning study of radiosurgery for intracranial metastases through Automation (MC-PRIMA) by crowdsourcing prior web-based plan challenge study
2022, Physica Medica
Citation Excerpt :
Vergalasova et al. in another multi-center study found that the DCA plans from AutoMBM produced generally worse target dose conformity than the other AP solution of VMAT by HyperArcTM (Eclipse, Varian) and non-AP solution of GammaKnife plans [13]. Nonetheless, all these studies and others [6,14] merely reflect the experiences of academically oriented practices and might not be generalizable to clinical environments where quality control and improvement program are less developed. The level of expertise of the participating institutions, case selection and the limited number of plans that could be generated in the experiment and the comparison arms, etc., prohibit unbiased results and objective conclusions in the above single and multi-center planning studies.
Planning radiosurgery to multiple intracranial metastases is complex and shows large variability in dosimetric quality among planners and treatment planning systems (TPS). This project aimed to determine whether autoplanning using the Muliple Brain Mets (AutoMBM) software can improve plan quality and reduce inter-planner variability by crowdsourcing results from prior international planning study.
Twenty-four institutions autoplanned with AutoMBM on a five metastases case from a prior international planning competition from which population statistics (means and variances) of 23 dosimetric metrics and resulting composite plan score (maximum score = 150) of other TPS (Eclipse, Monaco, RayStation, iPlan, GammaPlan, MultiPlan) were crowdsourced. Plan results of AutoMBM and each of the other TPS were compared using two sample t-tests for means and Levene’s tests for variances. Plan quality of AutoMBM was correlated with the planner’ experience and compared between academic and non-academic centers.
AutoMBM produced plans with comparable composite plan score to GammaPlan, MultiPlan, Eclipse and iPlan (127.6 vs. 131.7 vs. 127.3 vs. 127.3 and 126.7; all p > 0.05) and superior to Monaco and RayStation (118.3 and 108.6; both p < 0.05). Inter-planner variability of overall plan quality was lowest for AutoMBM among all TPS (all p < 0.05). AutoMBM’s plan quality did not differ between academic and non-academic centers and uncorrelated with planning experience (all p > 0.05).
By plan crowdsourcing prior international plan challenge, AutoMBM produces high and consistent plan quality independent of the planning experience and the institution that is crucial to addressing the technical bottleneck of SRS to intracranial metastases.
Applications of stereotactic radiosurgery in neuro-oncology
2022, Handbook of Neuro-Oncology Neuroimaging
Radiosurgery involves the focal administration of conformal ionising radiation to a diseased tissue. The conformal nature of the radiation delivered limits injury to surrounding non-target tissue. Radiosurgery is an important treatment option in neurooncology with wide ranging clinical applications in the treatment of benign and malignant brain tumours. The foundations, imaging and applications of radiosurgery in neurooncology are discussed in this chapter.
Radiosurgery and stereotactic irradiation of multiple and contiguous brain metastases: A practical proposal of dose prescription methods and a literature review
2021, Cancer/Radiotherapie
Citation Excerpt :
So, CK usually is better than LA (IMRT, VMAT) to spare HBT at high/moderate doses (V24 Gy and V9 Gy in Zhang's work [19] and V20 Gy and V12 Gy in Han's study [18]. In the work of Kadoya et al. [20], V12Gy-GTV was significantly better in HyperArc VMAT compared with CK. The authors explained this result with the better conformity of the HyperArc in high- and moderate-dose regions using an MLC.
In literature, there are no guidelines on how to prescribe dose in the case of radiosurgery (SRS) or stereotactic irradiation of multiple and adjacent BM. Aim of this work is to furnish practical proposals of dosimetric methods for multiple neighboring BM, and to make a literature review about the SRS treatment of multiple BM, comparing radiotherapy techniques on the basis of different dosimetric parameters.
A theoretical proposal of dosimetric approaches to prescribe dose in case of multiple contiguous BM is done. A literature review between 2010 and 2020 was performed on MEDLINE and Cochrane databases according to the PRISMA methodology, with the following keywords dose prescription, radiosurgery, multiple BM. Papers not reporting dosimetric solutions to irradiate multiple BM were excluded.
Only one article in the literature reports a practical modality of dose prescription for multiple adjacent BM. Thus, we proposed other five practical solutions to prescribe radiation dose in case of two or more neighboring BM, describing advantages and drawbacks of each method in terms of different dosimetric parameters. The literature review about dosimetric solutions to irradiate multiple BM led to 56 titles; 14 articles met the chosen criteria and we reported their results in terms of dosimetric indexes and low doses to the normal brain tissue.
The six dosimetric approaches here described can be used by physicians for multiple contiguous BM, depending on the clinical situation. These methods may be applied in clinical studies to better evaluate their usefulness in practice.
En l’absence de consensus spécifique dans la littérature sur la prescription de la dose en radiochirurgie ou radiothérapie stéréotaxique en situation de métastases cérébrales multiples adjacentes, l’objectif de ce travail eétait d’évaluer l’impact des plusieurs méthodes de prescription identifiées sur les paramètres dosimétriques de couverture des volumes cibles et l’irradiation du cerveau sain.
Une proposition théorique d’approches dosimétriques de prescription de la dose dans le cas de métastases cérébrales multiples adjacentes (moins de 2 cm les unes des autres) a été réalisée. Une revue de la littérature de 2010 à 2020 a été effectuée sur MEDLINE et Cochrane selon la méthodologie PRISMA, avec les mots clés suivants: dose prescription/radiosurgery/multiple brain metastases. Les articles qui ne rapportaient pas de solution dosimétrique pour l’irradiation de métastases cérébrales multiples ont été exclus.
Quatorze articles ont décrit les solutions dosimétriques adoptées pour irradier des métastases cérébrales multiples et l’impact sur les indice dosimétriques et les doses dans l’encéphale sain, mais les études comparatives manquent (une seule étude). Nous avons identifié six solutions pratiques possibles pour prescrire la dose dans le cas de deux ou plus métastases cérébrales proches, et en avons décrit les avantages et inconvénients en termes de paramètres et indices dosimétriques.
La prescription de dose en situation de métastases cérébrales multiples adjacentes peut varier. L’impact clinique pourrait être significatif. Les méthodes identifiées pourraient être testées dans des études cliniques pour mieux évaluer leur utilité dans la pratique.

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Automated noncoplanar treatment planning strategy in stereotactic radiosurgery of multiple cranial metastases: HyperArc and CyberKnife dose distributions

Abstract

Introduction

Section snippets

CK plan

Results

Discussion

Conclusions

Lancet

Radiother. Oncol.

Phys. Med.

Phys. Medica.

Phys. Med.

Int. J. Radiat. Oncol. Biol. Phys.

Front Oncol.

Stereotactic radiosurgery plus whole-brain radiation therapy vs stereotactic radiosurgery alone for treatment of brain metastases: a randomized controlled trial

JAMA

Commissioning of the Varian TrueBeam linear accelerator: a multi-institutional study

Med. Phys.

Dosimetric characteristics of Novalis shaped beam surgery unit

Med. Phys.

Current status and future perspective of flattening filter free photon beams

Med. Phys.

Dosimetric characteristics of novalis Tx system with high definition multileaf collimator

Med. Phys.