Abstract
Introduction
The Gamma Knife® planning software (TMR 10, Elekta Instruments, AB, Sweden) affords two ways of defining the skull volume, the “historical” one using manual measurements (still perform in some centers) and the new one using image-based skull contours. Our objective was to assess the potential variation of the dose delivery calculation using consecutively in the same patients the two above-mentioned techniques.
Materials and methods
We included in this self-case-control study, 50 patients, treated with GKRS between July 2016 and January 2017 in Lausanne University Hospital, Switzerland, distributed among four groups: convexity targets (n = 18), deep-seated targets (n = 13), vestibular schwannomas (n = 11), and trigeminal neuralgias (n = 8). Each planning was performed consecutively with the 2 skull definition techniques. For each treatment, we recorded the beam-on time (min), target volume coverage (%), prescription isodose volume (cm3), and maximal dose (Gy) to the nearest organ at risk if relevant, according to each of the 2 skull definition techniques. The image-based contours were performed using CT scan segmentation, based upon a standardized windowing for all patients.
Results
The median difference in beam-on time between manual measures and image-based contouring was + 0.45 min (IQR; 0.2–0.6) and was statistically significant (p < 0.0001), corresponding to an increase of 1.28% beam-on time per treatment, when using image-based contouring. The target location was not associated with beam-on time variation (p = 0.15). Regarding target volume coverage (p = 0.13), prescription isodose volume (p = 0.2), and maximal dose to organs at risk (p = 0.85), no statistical difference was reported between the two skull contour definition techniques.
Conclusion
The beam-on time significantly increased using image-based contouring, resulting in an increase of the total dose delivery per treatment with the new TMR 10 algorithm. Other dosimetric parameters did not differ significantly. This raises the question of other potential impacts. One is potential dose modulation that should be performed as an adjustment to new techniques developments. The second is how this changes the biologically equivalent dose per case, as related to an increased beam on time, delivered dose, etc., and how this potentially changes the radiobiological effects of GKRS in an individual patient.
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References
Borius PY, Debono B, Latorzeff I, Lotterie JA, Plas JY, Cassol E, Bousquet P, Loubes F, Duthil P, Durand A, Caire F, Redon A, Berry I, Sabatier J, Lazorthes Y (2010) Dosimetric stereotactic radiosurgical accident: study of 33 patients treated for brain metastases. Neurochirurgie 56:368–373. https://doi.org/10.1016/j.neuchi.2010.07.002
Hopewell JW, Millar WT, Lindquist C (2012) Radiobiological principles: their application to gamma knife therapy. Progress in neurological surgery 25:39–54. https://doi.org/10.1159/000331173
Jones B, Hopewell JW (2018) Modelling the influence of treatment time on the biological effectiveness of single radiosurgery treatments: derivation of "protective" dose modification factors. Br J Radiol:20180111. https://doi.org/10.1259/bjr.20180111
Leksell L (1951) The stereotaxic method and radiosurgery of the brain. Acta Chir Scand 102:316–319
Leksell L (1968) Cerebral radiosurgery. I. Gammathalanotomy in two cases of intractable pain. Acta Chir Scand 134:585–595
Nakazawa H, Komori M, Mori Y, Hagiwara M, Shibamoto Y, Tsugawa T, Hashizume C, Kobayashi T (2014) Effect of skull contours on dose calculations in gamma knife Perfexion stereotactic radiosurgery. J Appl Clin Med Phys 15:4603. https://doi.org/10.1120/jacmp.v15i2.4603
Regis J, Tuleasca C (2011) Fifteen years of gamma knife surgery for trigeminal neuralgia in the journal of neurosurgery: history of a revolution in functional neurosurgery. J Neurosurg 115(Suppl):2–7
Rojas-Villabona A, Kitchen N, Paddick I (2016) Investigation of dosimetric differences between the TMR 10 and convolution algorithm for gamma knife stereotactic radiosurgery. J Appl Clin Med Phys 17:217–229. https://doi.org/10.1120/jacmp.v17i6.6347
Tuleasca C, George M, Faouzi M, Schiappacasse L, Leroy HA, Zeverino M, Daniel RT, Maire R, Levivier M (2016) Acute clinical adverse radiation effects after Gamma Knife surgery for vestibular schwannomas. J Neurosurg 125:73–82. https://doi.org/10.3171/2016.7.GKS161496
Tuleasca C, Paddick I, Hopewell JW, Jones B, Millar WT, Hamdi H, Porcheron D, Levivier M, Regis J (2019) Establishment of a therapeutic ratio for gamma knife radiosurgery of trigeminal neuralgia: the critical importance of biologically effective dose versus physical dose. World Neurosurg. https://doi.org/10.1016/j.wneu.2019.10.021
Tuleasca C, Regis J, Levivier M (2019) Letter: treatment outcomes and dose rate effects following gamma knife stereotactic radiosurgery for vestibular Schwannomas. Neurosurgery. https://doi.org/10.1093/neuros/nyz503
Tuleasca C, Zeverino M, Patin D, Marguet M, Lopes NR, Vallet V, Moeckli R, Levivier M (2019) Lausanne checklist for safe stereotactic radiosurgery. Acta Neurochir. https://doi.org/10.1007/s00701-019-03843-2
Wright G, Bownes P, Reiner B (2011) A comparison of four skull models for independent dose calculations for Gamma Knife PERFEXION. Med Phys 38:884–890. https://doi.org/10.1118/1.3532824
Xu AY, Bhatnagar J, Bednarz G, Niranjan A, Kondziolka D, Flickinger J, Lunsford LD, Huq MS (2015) Gamma knife radiosurgery with CT image-based dose calculation. J Appl Clin Med Phys 16:119–129. https://doi.org/10.1120/jacmp.v16i6.5530
Acknowledgments
Dr. Henri-Arthur Leroy contributed to this study during an international fellowship between the University Hospital of Lille (CHU Lille), France, and the University Hospital of Lausanne (CHUV), Switzerland. He gratefully acknowledges receipt of a “Bourse de Mobilité Internationale” from the University of Lille, Faculty of Medicine. He also acknowledges the Lausanne University Hospital (CHUV) and especially Pr Marc Levivier, head of the neurosurgical department for additional financial support.
Dr. Constantin Tuleasca gratefully acknowledges receipt of a “Young Researcher in Clinical Research Grant” (Jeune Chercheur en Recherche Clinique) from the University of Lausanne (UNIL), Faculty of Biology and Medicine (FBM) and the Lausanne University Hospital (CHUV).
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Leroy, HA., Tuleasca, C., Zeverino, M. et al. Impact of the skull contour definition on Leksell Gamma Knife® Icon™ radiosurgery treatment planning. Acta Neurochir 162, 2203–2210 (2020). https://doi.org/10.1007/s00701-020-04458-8
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DOI: https://doi.org/10.1007/s00701-020-04458-8