Extracranial dose and the risk of radiation-induced malignancy after intracranial stereotactic radiosurgery: is it time
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ORIGINAL ARTICLE - BRAIN TUMORS
Extracranial dose and the risk of radiation-induced malignancy after intracranial stereotactic radiosurgery: is it time to establish a therapeutic reference level? Ian Paddick 1
&
A. Cameron 2 & A. Dimitriadis 1
Received: 25 September 2020 / Accepted: 1 December 2020 # The Author(s) 2020
Abstract Background To measure extracranial doses from Gamma Knife Perfexion (GKP) intracranial stereotactic radiosurgery (SRS) and model the risk of malignancy after SRS for different treatment platforms. Methods Doses were measured for 20 patients undergoing SRS on a GKP at distances of 18, 43 and 75 cm from the target, corresponding to the approximate positions of the thyroid, breast and gonads respectively. A literature review was conducted to collect comparative data from other radiosurgery platforms. All data was used to calculate the dose to body organs. The National Cancer Institute (NCI) RadRAT calculator was used to estimate excess lifetime cancer risk from this exposure. Five different age groups covering childhood and younger adults were modelled for both sexes. Results Extracranial doses delivered during SRS with the GKP were a median 0.04%, 0.008% and 0.002% of prescription dose at 18 cm, 43 cm and 70 cm from the isocentre respectively. Comparison with the literature revealed that the extracranial dose was lowest from GKP, then linacs equipped with micro-multileaf collimators (mMLC), then linacs equipped with circular collimators (cones), and highest from Cyberknife (CK). Estimated lifetime risks of radiation-induced malignancy in the body for patients treated with SRS aged 5–45 years were 0.03–0.88%, 0.36–11%, 0.61–18% and 2.2–39% for GKP, mMLC, cones and CK respectively. Conclusions We have compared typical extracranial doses from different platforms and quantified the lifetime risk of radiationinduced malignancy. The risk varies with platform. This should be taken into account when treating children and young adults with SRS. The concept of a therapeutic reference level (TRL), similar to the diagnostic reference level (DRL) established in radiology, is proposed. Keywords Radiosurgery . Gamma Knife . Extracranial dose . SRS . Linac . Cyberknife . Radiation-induced malignancy
Background Intracranial stereotactic radiosurgery (SRS) is an established and growing treatment modality for a range of benign diseases Parts of this manuscript have been presented at the 13th International Stereotactic Society Meeting – Montreux, May 2017 as “Risk of extracranial secondary cancer after radiosurgery: comparison of different treatment platforms” Alison L Cameron, Alexis Dimitriadis, Ian Paddick This article is part of the Topical Collection on Brain Tumors * Ian Paddick [email protected] 1
Queen Square Radiosurgery Centre, National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
2
Bristol Haematology and Oncology Centre, Bristol BS2 8ED, UK
including acoustic neuroma, meningioma, pituitary adenoma and arteriovenous malformation (AVM). In addition, a gr
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