Linac radiosurgery as a tool in neurosurgery

Abstract

Stereotactic radiosurgery is a radiation technique that uses a high radiation dose focused on a stereotactic defined intracranial target in single fraction with high precision. In the 1980s, linear accelerators were introduced as a tool for radiosurgery beneath the already accepted gamma unit. Technique and mechanical precision of LINACs have become equal to the gamma unit and LINAC radiosurgery became more and more used recently. From January 1996 to August 2003 we have treated 237 patients with LINAC radiosurgery. A combination of the University of Florida system and the X Knife System, developed by Radionics, was used in all patients. A number of 110 patients had 161 brain metastases treated, whereas the local tumor control rate was 89.4%. The 1-year survival rate was 54.9% with a median survival of 54 weeks. In 55 patients we have treated 57 meningiomas, mostly located at the skull base (37 out of 55 patients). Local tumor control rate in our patients with skull base meningiomas at 5-year follow up was 97.2%. In this time period, we have also treated acoustic schwannoma, glioma, pituitary adenoma, arteriovenous malformations and patients with trigeminal neuralgia. LINAC radiosurgery has become a daily tool in neurosurgery and changed treatment strategies especially in the treatment of brain metastases and skull base meningiomas towards a less aggressive and multimodality approach. It is not only an alternative to open surgery, but also a very effective adjuvant treatment modality in many neuro-oncological patients, which helps us to enhance tumor control rate, minimize morbidity and increase postoperative quality of life.

Advances in the Treatment of Prolactinomas

“…This results in multiple small radiation spheres that are combined in a multiple isocenter technique to conform to the shape of nonspherical pituitary tumors (103). An alternative method of delivering single-dose radiation therapy is with the use of a LINAC-based system that has been modified to limit mechanical instability and inaccuracy (104,105). There is no clear advantage for either of these single-dose techniques (gamma knife vs., LINAC) in terms of their ability to spare normal tissue from high radiation doses (106).…”

Changing practice patterns of Gamma Knife versus linear accelerator-based stereotactic radiosurgery for brain metastases in the US

“…In contrast, linear accelerator (LINAC)-based radiosurgery was developed as an alternative to GK SRS in the 1980s, using a standard LINAC modified for stereotactic purposes. 8 This technique uses a collimated x-ray beam focused on an intracranial target, around which the LINAC gantry and couch can rotate to produce multiple noncoplanar intersecting arcs of radiation. 15 Following improvements in these modifications and treatment planning systems, LINAC SRS was marketed as having acceptably similar precision, accuracy, and mechanical stability.…”

Surgical Management of Skull Base Meningiomas – An Overview

“…In meningioma greater than 4 ml and with a distance of more than 2 mm between tumour and neural structures fractionated stereotactic radiotherapy seems to be more efficient for tumour control than radiosurgery (Deinsberger & Tidstrand 2005).…”