Intraoperative radiotherapy with low energy x-rays after neurosurgical resection of brain metastases – Augsburg University Medical Center experience

Abstract

Purpose External beam radiotherapy (EBRT) is the predominant method for localized brain radiotherapy (LBRT) after resection of brain metastases (BM). Intraoperative radiotherapy (IORT) with 50kV x-rays is an alternative way to irradiate the resection cavity focally after BM surgery with the option to shorten the overall treatment time and limit normal tissue irradiation.Methods We retrospectively analyzed the outcomes of all patients who underwent neurosurgical resection of BM and 50kV x-ray IORT between 2013 and 2020 at Augsburg University Medical Center.Results We identified 40 patients with 44 resected BM treated with 50kV x-ray IORT. Median diameter of the resected metastases was 2.8 cm (range 1.5–5.9 cm). Median applied dose was 20 Gy. All patients received standardized follow-up (FU) including 3-monthly MRI of the brain. Mean FU was 14.4 months, with a median MRI FU for patients alive of 12.2 months. Median overall survival (OS) of all treated patients was 26.4 months (estimated 1-year OS 61.6%). The observed local control (LC) rate of the resection cavity was 88.6% (estimated 1-year LC 84.3%). Distant brain control (DC) was 47.5% (estimated 1-year DC 33.5%). Only 25% of all patients needed WBI in the further course of disease. The observed radionecrosis rate was 2.5%.Conclusion IORT with 50kV x-rays is a safe and appealing way to apply LBRT after neurosurgical resection of BM with low toxicity and excellent LC. Close MRI FU is paramount to detect distant brain failure (DBF) early.

Intraoperative radiotherapy during awake craniotomies: preliminary results of a single-center case series

“…4, who underwent adjuvant chemoradiotherapy according to the Stupp protocol, all other patients were spared from a 4-week fractional percutaneous radiation therapy with typically five individual irradiations per week. This, in turn, represents a considerable relief for the patient himself and his relatives while increasing the patient’s convenience by integrating resection and radiotherapy into one procedure [ 14 ] with no further necessity of adjuvant radiotherapy after discharge from the hospital [ 9 ]. During a mean follow-up time of 6.3 ± 2.6 months, no new neurological deficits occurred.…”

“…The intraoperative irradiation is carried out with 50-kV x-rays via an INTRABEAM system (Fig. 2 ) (ZEISS MEDITEC AG, Oberkochen, Germany), whereby the irradiation time is determined individually [ 9 ]. During irradiation, the analgosedation is deepened and a laryngeal mask is inserted to avoid any movement of the patient with maintenance of spontaneous breathing.…”

“…Furthermore, the temporal distance between surgery and adjuvant radiotherapy is decreased drastically, during which cancer cells may proliferate [ 15 ]. Correspondingly, a recent retrospective data analysis of Kahl and co-workers verified that IORT with low energy 50 kV x-rays is a safe way to apply localized brain radiotherapy after resection of brain metastases with low toxicity and excellent local control [ 9 ]. To our knowledge, data on the feasibility of intraoperative radiotherapy during awake surgery have not been published yet.…”

Soft-tissue simulation of the breast for intraoperative navigation and fusion of preoperative planning

“…Computational preoperative planning of surgical interventions entails multiple benefits, in particular reduced risk to the patient and shorter interds, computational preoperative planning has seen success in applications such as radiotherapy Calvo et al (2014), neurosurgery Prada et al (2014); Kahl et al (2021); Nemoto et al (2002), or orthognathic surgery Alcañiz et al (2021).…”

“…IORT delivers a large dose of ionizing radiation to the tumor bed during surgery, thus maximizing the dose applied to the tumor while minimizing the dose applied to nearby healthy tissue. Preoperative planning of IORT involves calculation of a cumulative dose on a volume image that faithfully represents the patient's anatomy, and is successfully used in, e.g., neurosurgery Prada et al (2014); Kahl et al (2021); Nemoto et al (2002). However, to date IORT is hardly possible on breast cancer surgery, due to the strong mismatch between preoperative and intraoperative settings.…”