53 Phase I study of a miniature X-ray source for interstitial radiotherapy of brain metastases

Abstract

Despite a variety of stereotactic techniques used to increase intracranical local control, dose escalation strategies remain controversial, with respect to therapeutric gain, convenience, and cost effectiveness, in the setting of brain metastases. In this report, we summarize our experience with the safety and efficacy of a new miniature X-ray device for interstitial radiosurgical treatment of intracranial metastatic neoplasms. Although the role of surgical resection of solitary metastases is established, aggressive treatment with proton, gamma knife, and linac radiation therapy for these lesions is under investigation. The new miniature X-ray device offers a very localized, convenient, time and cost efficient means of delivering radiotherapy to these lesions, with lower normal tissue exposure than gamma knife or proton beam techniques. Retreatment of previously irradiated areas are also now under investigation as part of a Phase II trial. The photon radiosurgery system is a miniature battery operated 40 kV x-ray device designed by the Photoelectron Corporation for use in the interstitial treatment of small tumors ({ge}3 cm in diameter) in humans. This 10 cm long, low current, high voltage X-ray generator is easily mounted in a stereotactic frame and produces low energy (10-20 KeV) x-rays to be emitted from the 10 cm long,more » 3.2 mm diameter probe, after stereotactic insertion into the tumor. Two scintillation detectors positioned on the stereotactic frame near the patient`s scalp monitor radiation. The spherical X-ray beam behaves essentially as a point source, with dose rate nominally 150 cGy/min. at a distance of 10mm, for a beam current of 40 {mu}A and a voltage of 40 kv.« less