When a new treatment technology comes on the scene, clinicians naturally want to be assured that it meets or exceeds the performance of established and familiar ones. Since HyperArc® high-definition radiotherapy was introduced at ASTRO in 2016, at least 80 centers have delivered HyperArc treatments for thousands of patients. From those centers at least 14 independently conducted studies have demonstrated that HyperArc can be used with confidence for stereotactic radiosurgery (SRS). HyperArc plans for delivery on Edge® or TrueBeam® systems are comparable to plans for other SRS approaches, often with significant benefits in delivery time. This review highlights some of these studies.
This is the first article in a two-part series.
HyperArc & CyberKnife: Small differences in plan quality; big differences in efficiency
Several studies evaluated HyperArc and CyberKnife® plans side-by-side.
Kadoya, et al,1 compared HyperArc and CyberKnife SRS plans for multiple cranial metastases.
Eleven patients treated with CyberKnife were replanned with HyperArc for SRS on the TrueBeam STx. Blind scoring of CyberKnife and HyperArc plans showed no statistically significant dosimetric differences. While CyberKnife scored slightly better on gradient index (GI), HyperArc showed better Conformity Index (CI).
HyperArc had a significantly lower total brain V12, a measure of the potential for the risk of radionecrosis, than CyberKnife. HyperArc plans had a total brain V12 of 4.02 ± 1.71 cm3, compared to 5.26 ± 2.83 cm3 to CyberKnife. The study concluded that HyperArc-based SRS plans were comparable to CyberKnife plans dosimetrically. However, the average CyberKnife treatment time was 113 minutes versus an estimate of 9 minutes for HyperArc. The study concluded HyperArc was a suitable tool for SRS of multiple brain metastases and suggested it had a “greater potential to emerge as a suitable tool for SRS of multiple brain metastases,” because of the treatment efficiency.
A similar study by Slosarek, et al,2 comparing standard VMAT, HyperArc, and CyberKnife plans for multiple brain metastases yielded similar results. The study found no statistically significant dosimetric differences among the techniques. CyberKnife plans achieved the lowest dose to organs at risk and HyperArc was best at minimizing whole brain dose. However, HyperArc showed a “remarkable improvement in delivery time.” CyberKnife beam delivery was 52 (37 -76) min versus 5.9 (2.2 – 11.5) min for VMAT-based HyperArc.
HyperArc stands up to Gamma Knife with shorter delivery time for comparable plans
According to an evaluation by Vergalasova, et al,3 whose multi-institutional study looked at 16 patients with 112 metastases, HyperArc and Gamma Knife® both produced clinically acceptable plans with only one significant difference. For targets of 1 cm or less, conformity and whole brain dose were comparable, with a slightly lower gradient index for Gamma Knife. On the other hand, for targets larger than 1 cm, HyperArc had superior conformity. Comparing beam-on times, Gamma Knife was 140 ± 24 minutes while HyperArc was 4.8 ±0.89 minutes. In short, the study showed that HyperArc-VMAT is “capable of achieving similar low-dose brain spillage and conformity as Gamma Knife, while significantly minimizing beam-on time.”
HyperArc plans are comparable to other linac-based mono-isocenter techniques
In a study of 20 patients with multiple brain metastases, Ruggieri, et al,4 found that mono-isocenter HyperArc plans achieved a higher CI and lower GI than standard multi-isocenter VMAT plans. Additionally, HyperArc performed well among other mono-isocenter techniques with non-coplanar arcs. As an example, another study by Ruggieri, et al,5 compared HyperArc plans to Brainlab’s Multiple Brain Mets Elements (MBME), a dynamic conformal arc technique specifically designed for multiple metastases. CI was significantly improved for HyperArc vs MBME: 0.94 vs 0.75 and V12 was lower for HyperArc compared to MBME: 23.7 vs 37.3 cm3. So while the authors concluded that dosimetric consistency and plan quality was satisfactory for both techniques, HyperArc achieved near-equal plan quality based on key indices.
Studies suggest an advantage for HyperArc in lower whole brain dose and higher conformity
In summary, the recent studies cited here generally found two consistent advantages for HyperArc: lower whole brain V12 dose and higher CI. Lower V12 dose suggests that HyperArc may reduce the risk for radionecrosis. Higher CI suggests better dosimetry—the ability to cover the targets with the prescribed dose. And when compared to two conventional point and shoot SRS techniques, Gamma Knife and CyberKnife, these studies showed HyperArc beam-on time during single-isocenter radiosurgery to be on average an order of magnitude more efficient.
In conclusion, these and other studies covering years of clinical use suggest that clinicians can be confident that HyperArc is clinically comparable to other SRS techniques in use today, with some distinct advantages.
Footnotes
1 Kadoya N, Abe Y, Kajikawa T, Ito K, Yamamoto T, Umezawa R, Chiba T, Katsuta Y, Takayama Y, Kato T, Kikuchi Y, Jingu K. Automated noncoplanar treatment planning strategy in stereotactic radiosurgery of multiple cranial metastases: HyperArc and CyberKnife dose distributions. Med Dosim. 2019 Winter;44(4):394-400.
2 Slosarek K, Bekman B, Wendykier J, Grządziel A, Fogliata A, Cozzi L. In silico assessment of the dosimetric quality of a novel, automated radiation treatment planning strategy for linac-based radiosurgery of multiple brain metastases and a comparison with robotic methods. Radiat Oncol. 2018 Mar 15;13(1):41.
3 Vergalasova I, Liu H, Alonso-Basanta M, Dong L, Li J, Nie K, Shi W, Teo BK, Yu Y, Yue NJ, Zou W, Li T. Multi-Institutional Dosimetric Evaluation of Modern Day Stereotactic Radiosurgery (SRS) Treatment Options for Multiple Brain Metastases. Front Oncol. 2019 Jun 7;9:483.
4 Ruggieri R, Naccarato S, Mazzola R, Ricchetti F, Corradini S, Fiorentino A, Alongi F. Linac-based VMAT radiosurgery for multiple brain lesions: comparison between a conventional multi-isocenter approach and a new dedicated mono-isocenter technique. Radiat Oncol. 2018 Mar 5;13(1):38.
5 Ruggieri R, Naccarato S, Mazzola R, Ricchetti F, Corradini S, Fiorentino A, Alongi F. Linac-based radiosurgery for multiple brain metastases: Comparison between two mono-isocenter techniques with multiple non-coplanar arcs. Radiother Oncol. 2019 Mar;132:70-78.
Additional References
Ho HW, Lee SP, Lin HM, Chen HY, Huang CC, Wang SC, Yang CC, Lin YW. Dosimetric comparison between RapidArc and HyperArc techniques in salvage stereotactic body radiation therapy for recurrent nasopharyngeal carcinoma. Radiat Oncol. 2020 Jul 8;15(1):164. Chi Mei Medical Center, Tainan City, Taiwan.
Nicosia L, Figlia V, Mazzola R, Napoli G, Giaj-Levra N, Ricchetti F, Rigo M, Lunardi G, Tomasini D, Bonù ML, Corradini S, Ruggieri R, Alongi F. Repeated stereotactic radiosurgery (SRS) using a non-coplanar mono-isocenter (HyperArc™) technique versus upfront whole-brain radiotherapy (WBRT): a matched-pair analysis. Clin Exp Metastasis. 2020 Feb;37(1):77-83. Ospedale "Sacro Cuore", Negrar, Italy.
Ohira S, Sagawa T, Ueda Y, Inui S, Masaoka A, Akino Y, Mizuno H, Miyazaki M, Koizumi M, Teshima T. Effect of collimator angle on HyperArc stereotactic radiosurgery planning for single and multiple brain metastases. 2020 Spring;45(1):85-91. Osaka International Cancer Institute, Osaka, Japan
Kadoya N, Abe Y, Kajikawa T, Ito K, Yamamoto T, Umezawa R, Chiba T, Katsuta Y, Takayama Y, Kato T, Kikuchi Y, Jingu K. Automated noncoplanar treatment planning strategy in stereotactic radiosurgery of multiple cranial metastases: HyperArc and CyberKnife dose distributions. Med Dosim. 2019 Winter;44(4):394-400 Tohoku University Graduate School of Medicine, Sendai, Japan
Sagawa T, Ohira S, Ueda Y, Akino Y, Mizuno H, Matsumoto M, Miyazaki M, Koizumi M, Teshima T. Dosimetric effect of rotational setup errors in stereotactic radiosurgery with HyperArc for single and multiple brain metastases. J Appl Clin Med Phys. 2019 Oct;20(10):84-91 Osaka International Cancer Institute, Osaka, Japan
Ueda Y, Ohira S, Yamazaki H, Mabuchi N, Higashinaka N, Miyazaki M, Teshima T. Dosimetric performance of two linear accelerator-based radiosurgery systems to treat single and multiplebrain metastases. Br J Radiol. 2019 Aug;92(1100):20190004. Osaka International Cancer Institute, Osaka, Japan
Hartgerink D, Swinnen A, Roberge D, Nichol A, Zygmanski P, Yin FF, Deblois F, Hurkmans C, Ong CL, Bruynzeel A, Aizer A, Fiveash J, Kirckpatrick J, Guckenberger M, Andratschke N, de Ruysscher D, Popple R, Zindler J. LINAC based stereotactic radiosurgery for multiple brain metastases: guidance for clinical implementation. Acta Oncol. 2019 Jul 1:1-8. MultiInstitution led by Maastro,, Maastricht, The Netherlands
Vergalasova I, Liu H, Alonso-Basanta M, Dong L, Li J, Nie K, Shi W, Teo BK, Yu Y, Yue NJ, Zou W, Li T. Multi-Institutional Dosimetric Evaluation of Modern Day Stereotactic Radiosurgery (SRS) Treatment Options for Multiple Brain Metastases. Front Oncol. 2019 Jun 7;9:483 Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, NJ
Ruggieri R, Naccarato S, Mazzola R, Ricchetti F, Corradini S, Fiorentino A, Alongi F. Linac-based radiosurgery for multiple brain metastases: Comparison between two mono-isocenter techniques with multiple non-coplanar arcs. Radiother Oncol. 2019 Mar;132:70-78 Ospedale "Sacro Cuore", Negrar, Italy.
Alongi F, Fiorentino A, Gregucci F, Corradini S, Giaj-Levra N, Romano L, Rigo M, Ricchetti F, Beltramello A, Lunardi G, Mazzola R, Ruggieri R. First experience and clinical results using a new non-coplanar mono-isocenter technique (HyperArc™) for Linac-based VMAT radiosurgery in brain metastases. J Cancer Res Clin Oncol. 2019 Jan;145(1):193-200. Ospedale "Sacro Cuore", Negrar, Italy
Alongi F, Fiorentino A, Ruggieri R, Ricchetti F, Kupelian P. Cost-effectiveness of Linac-based single-isocenter non-coplanar technique (HyperArcTM) for brain metastases radiosurgery. Clin Exp Metastasis. 2018 Oct;35(7):601-603.Ospedale "Sacro Cuore", Negrar, Italy
Slosarek K, Bekman B, Wendykier J, Grządziel A, Fogliata A, Cozzi L. In silico assessment of the dosimetric quality of a novel, automated radiation treatment planning strategy for linac-based radiosurgery of multiple brain metastases and a comparison with robotic methods. Radiat Oncol. 2018 Mar 15;13(1):41. Maria Sklodowska Curie Memorial Cancer Center and Institute of Oncology, Gliwice, Poland.
Ruggieri R, Naccarato S, Mazzola R, Ricchetti F, Corradini S, Fiorentino A, Alongi F. Linac-based VMAT radiosurgery for multiple brain lesions: comparison between a conventional multi-isocenter approach and a new dedicated mono-isocenter technique. Radiat Oncol. 2018 Mar 5;13(1):38. Ospedale "Sacro Cuore", Negrar, Italy
Ohira S, Ueda Y, Akino Y, Hashimoto M, Masaoka A, Hirata T, Miyazaki M, Koizumi M, Teshima T. HyperArc VMAT planning for single and multiple brain metastases stereotactic radiosurgery: a new treatment planning approach. Radiat Oncol. 2018 Jan 29;13(1):13. Osaka International Cancer Institute, Osaka, Japan.